1. A wireless communication system, comprising: a transmitter; and a receiver, wherein 5 erein the transmitter includes a transmission information generating unit that generates transmission information, a first code generating unit that generates a first code that is repeated at a frequency fr, the first code being a 10 code in which an autocorrelation value between the same partial regions is higher than a cross-correlation value between different partial regions in partial regions obtained by dividing the first code corresponding to one period on a time axis, 15 a second code generating unit that generates a second code which is a code by which it is possible to detect whether or not the same codes of two sequences are identical to each other on the time axis, an encoding unit that encodes the transmission 20 information generated by the transmission information generating unit using the first code and the second code, and a transmitting unit that causes a carrier wave to be superimposed on the transmission information encoded by the encoding unit, generates a transmission signal in which a 25 polarization plane rotates at the frequency fr, and wirelessly transmits the transmission signal, and 100 the receiver includes a receiving unit that receives the transmission signal from the transmitter and removes a carrier wave from a received reception signal, a synchronization detecting unit that detects 5 a start point of an information signal from which the carrier wave has been removed by the receiving unit using the second code for the information signal, and a partial region information extracting unit that 10 extracts partial region information corresponding to the partial regions from the information signal using the starting point of the information signal and detects a phase shift of the partial region information. 15 2. The wireless communication system according to claim 1, wherein the transmitter further includes a third encoding unit that encodes information using a third code generated to reflect a characteristic of the transmission path when the partial region information 20 corresponding to the partial regions is transmitted to the receiver, the encoding unit and the third encoding unit encode the transmission information generated by the transmission information generating unit using the first code, the second 25 code, and the third code, the receiver further includes 101 an information decoding unit that decodes the partial region information extracted by the partial region information extracting unit using the third code.

3. The 5 wireless communication system according to claim 1, wherein the transmission information generating unit of the transmitter generates transmission information that is identical to each other in the partial regions, the receiver further includes 10 an information processing unit that determines whether or not a plurality of pieces of partial region information extracted by the partial region information extracting unit are identical to each other, 15 4. The wireless communication system according to claim 3, wherein the information processing unit of the receiver acquires information which is largest in the number of pieces of information that are identical among the plurality of pieces of partial region information as the transmission 20 information from the transmitter.

5. The wireless communication system according to claim 1, wherein the transmitting unit includes a carrier superimposing unit that causes the carrier wave 25 to be superimposed on the transmission information encoded by the encoding unit and generates a cosine wave signal of a 102 frequency fr and a sine wave signal of the frequency fr, a first antenna that wirelessly transmits the cosine wave signal, and a second antenna that is spatially orthogonal to the first antenna and wirelessly transmits the sinusoidal 5 oidal signal, and the receiving unit includes a third antenna that receives a synthetic signal of the cosine wave signal and the sine wave signal, 10 a fourth antenna that is spatially orthogonal to the third antenna and receives the synthetic signal, and a carrier wave removing unit that removes the carrier wave from the synthetic signal received by the third antenna and the fourth antenna. 15

6. The wireless communication system according to claim 5, Wherein the synchronization detecting unit of the receiver detects, based on a sum of a third information signal received by the third antenna and a fourth information signal 20 received by the fourth antenna, synchronization of the second code superimposed on the third information signal and the fourth information signal, the partial region information extracting unit of the receiver performs extraction of the partial region information 25 and detection of the phase shift of the partial region information based on the third information signal, and 103 performs extraction of the partial region information and detection of the phase shift of the partial region information based on the fourth information signal.

7. 5 The wireless communication system according to claim 5, wherein the carrier wave superimposing unit of the transmitter generates the cosine wave signal and the sine wave signal using frequencies f1 and f2 in which 1/2 of a difference between the frequencies f1 and f2 is the frequency 10 fr such that the transmission information encoded by the encoding unit is bifurcated, and a first signal is generated by causing the carrier wave of the frequency f1 to be superimposed on one bifurcated transmission information, a second signal is generated by causing the carrier wave of the 15 frequency f2 to be superimposed on the other bifurcated transmission information, and the first signal and the second signal are synthesized.

8. The wireless communication system according to claim 5, 20 wherein the carrier wave superimposing unit of the transmitter generates the cosine wave signal and the sine wave signal using a discrete-time delta sigma circuit.

9. The wireless communication system according to claim 5, 25 wherein the carrier wave removing unit of the receiver removes the carrier wave from the synthetic signal received by 104 the third antenna and the fourth antenna using a continuoustime delta sigma circuit.

10. An elevator control system using the wireless 5 communication system according to claim 5, wherein the receiver is installed in an elevator car of the elevator control system, and the third antenna and the fourth antenna of the receiver are installed above or below the elevator car, and 10 the first antenna and the second antenna of the transmitter are installed at positions facing the third antenna and the fourth antenna.

11. A substation equipment monitoring system using the 15 wireless communication system according to claim 1, wherein the substation monitoring system is configured to include at least one base station and at least one transformer, the transmitter is installed in the base station, and the receiver is installed in the transformer. 20

12. A transmitter, comprising: a transmission information generating unit that generates transmission information; a first code generating unit that generates a first code 25 that is repeated at a frequency fr, the first code being a code in which an autocorrelation value between the same 105 partial regions is higher than a cross-correlation value between different partial regions in partial regions obtained by dividing the first code corresponding to one period on a time axis; a second code generating unit that generates 5 a second code that is a cyclic code, the second code being a code by which it is possible to detect whether or not two second codes are identical to each other on the time axis; an encoding unit that encodes the transmission 10 information generated by the transmission information generating unit using the first code and the second code; and a transmitting unit that causes a carrier wave to be superimposed on the transmission information encoded by the encoding unit, generates a transmission signal in which a 15 polarization plane rotates at the frequency fr, and wirelessly transmits the transmission signal.

13. The transmitter according to claim 12, further comprising, a third encoding unit that encodes an information signal 20 using a third code generated to reflect a characteristic of the transmission path when the partial region information corresponding to the partial regions is transmitted to the receiver, wherein the encoding unit and the third encoding unit 25 encode the transmission information generated by the transmission information generating unit using the first code, 106 the second code, and the third code.

14. A receiver, comprising: a receiving unit that receives a wireless signal in which an information signal including a first code that is 5 repeated at a frequency fr and a second code which is a code by which it is possible to detect whether or not the same codes of the two sequences are identical to each other on a time axis is superimposed on a carrier wave, and a polarization plane 10 rotates at the frequency fr, and removes the carrier wave from the wireless signal; a synchronization detecting unit that detects a start point of the information signal from which the carrier wave has been removed by the receiving unit using the second code 15 for the information signal; and a partial region information extracting unit that extracts partial region information corresponding to partial regions obtained by dividing the first code corresponding to one period from the information signal using the starting 20 point of the information signal and detects a phase shift of the partial region information.

15. The receiver according to claim 14, an information decoding unit that decodes information 25 extracted by the partial region information extracting unit using the third code generated to reflect a characteristic of 107 a transmission path when the partial region information corresponding to the partial regions is transmitted from the transmitter that transmits the wireless signal to the receiver.

SPECIFICATION
WIRELESS COMMUNICATION SYSTEM, TRANSMITTER, AND RECEIVER
TECHNICAL FIELD
5 [0001]
The present invention relates to a wireless communication
system capable of providing high secure communication suitable
for control and monitoring of social infrastructure equipment.
10 BACKGROUND ART
[0002]
With the advancement of wireless communication technology
based on explosive popularization of mobile phones,
reliability of wireless communication has been remarkably
15 improved, and the application of wireless technology to
communication technology related to the social infrastructure
equipment in which wired communication considered to be the
only means is under review. There is great expectation for a
high efficiency operation of the social infrastructure
20 equipment using recent information communication technology,
and creation of a new energy/information convergence network
in which a smart grid is an example thereof is under review
all over the world.
[0003]
25 In the operation of the social infrastructure equipment
using an information communication technology, it should be
3
noted that the importance of high secure communication in
which confidentiality of communication information and
resistance to external intruders are guaranteed in addition to
reliability of communication has been increased with the
5 increase in reliability of communication.
[0004]
In terms of the high secure communication for the social
infrastructure equipment, in the case of wire communication
which is generally considered to be higher in reliability than
10 wireless communication, it is difficult to defense an attack
from an external intruder since it is possible to physically
specify a communication path. For this reason, there is a
great expectation for wireless communication in which it is
difficult to physically specify a communication path.
15 [0005]
In the wireless communication in which a transmission
path is automatically spread in a space between transmission
and reception points, a technique of multiplexing a
communication path between the transmission and reception
20 points is called "diversity." As the diversity, in addition to
a technique of multiplexing a communication path using a
plurality of regions in time and frequency axes, two physical
multiplexing schemes, that is, spatial diversity in which a
plurality of transmission and reception points are formed in a
25 space using a feature of an electromagnetic wave serving as a
medium of wireless communication and polarization diversity in
4
which a plurality of vector components are formed in a space
are known.
[0006]
An environment in which the social infrastructure
equipment is installed needs to resist external physical 5 force
such as high voltage in power stations and transmission
substations, high shocks in transportation facility,
construction machinery, and the like, and thus it is not
desirable to use a large number of antennas serving as a
10 protruding object in an external space, and diversity with a
small number of antennas is dominant.
[0007]
Background technologies for improving communication
reliability between the transmission and reception points
15 using polarization are disclosed in Patent Document 1 (JP
2007-36521 A) and Patent Document 2 (WO 2009/069798 A). Patent
Document 1 discloses a "technique in which a circularly
polarized radio wave which is obliquely incident on glass is
distorted and converted into an elliptically polarized wave,
20 but receiving units 210 and 220 separate and receive linearly
polarized components, and the linearly polarized components
are optimally synthesized through a synthesizing unit 230, and
at the time of transmission, an elliptically polarized wave
which is compensated in advance so that it is converted into a
25 circularly polarized wave after it is distorted by glass" (see
Abstract).
5
[0008]
Further, Patent Document 2 discloses a "technique in
which a transmitting unit performs dual polarization
transmission of transmitting two independent signals in the
same band using two polarized radio waves which 5 are orthogonal
to each other in addition to spatial multiplexing of MIMO as a
signal to be transmitted from each antenna on a transmission
side, and a receiving unit includes an interference
compensator and a MIMO signal processing circuit connected to
10 the interference compensator."
[0009]
In the above related arts, signals are transmitted using
two orthogonal polarized waves, and the receiving unit
synthesizes two independent signals obtained through two
15 orthogonal polarized waves by applying the same weight on a
time axis, reflects energy of a transmission signal in a
reception signal to the maximum extent possible, whereby
reception sensitivity is improved.
20 CITATION LIST
PATENT DOCUMENT
[0010]
Patent Document 1: JP 2007-36521 A
Patent Document 2: WO 2009/069798 A
25
SUMMARY OF THE INVENTION
6
PROBLEMS TO BE SOLVED BY THE INVENTION
[0011]
It is an object of the present invention to provide a
wireless communication technology which is capable of
identifying a transmission path through which 5 an arrived
information signals has passed.
SOLUTIONS TO PROBLEMS
[0012]
10 The present application includes a plurality of means for
solving the above problems, but a representative configuration
of the present invention is as follows. That is,
a wireless communication system includes
a transmitter; and
15 a receiver,
wherein the transmitter includes
a transmission information generating unit that generates
transmission information,
a first code generating unit that generates a first code
20 that is repeated at a frequency fr, the first code being a
code in which an autocorrelation value between the same
partial regions is higher than a cross-correlation value
between different partial regions in partial regions obtained
by dividing the first code corresponding to one period on a
25 time axis,
a second code generating unit that generates a second
7
code which is a code by which it is possible to detect whether
or not the same codes of two sequences are identical to each
other on the time axis,
an encoding unit that encodes the transmission
information generated by the transmission 5 ansmission information
generating unit using the first code and the second code, and
a transmitting unit that causes a carrier wave to be
superimposed on the transmission information encoded by the
encoding unit, generates a transmission signal in which a
10 polarization plane rotates at the frequency fr, and wirelessly
transmits the transmission signal, and
the receiver includes
a receiving unit that receives the transmission signal
from the transmitter and removes the carrier wave from a
15 received reception signal,
a synchronization detecting unit that detects a start
point of an information signal from which the carrier wave has
been removed by the receiving unit using the second code for
the information signal, and
20 a partial region information extracting unit that
extracts partial region information corresponding to the
partial regions from the information signal using the starting
point of the information signal and detects a phase shift of
the partial region information.
25
EFFECTS OF THE INVENTION
8
[0013]
According to the present invention, it is possible to
identify a transmission path through which an arrived
information signal has passed.
5
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
FIG. 1 is a configuration diagram of a wireless
communication system according to an embodiment of the present
10 invention.
FIG. 2A is a configuration diagram of a transmitter
according to a first embodiment of the present invention.
FIG. 2B is a configuration diagram of a receiver
according to the first embodiment of the present invention.
15 FIG. 2C is a configuration diagram of a modification of
the receiver according to the first embodiment of the present
invention.
FIG. 3A is a configuration diagram of a transmitter
according to a second embodiment of the present invention.
20 FIG. 3B is a configuration diagram of a transmitter
according to a third embodiment of the present invention.
FIG. 4A is a configuration diagram of a transmitter
according to a fourth embodiment of the present invention.
FIG. 4B is a configuration diagram of a receiver
25 according to a fourth embodiment of the present invention.
FIG. 5 is a configuration diagram of a transmitter
9
according to a fifth embodiment of the present invention.
FIG. 6 is a configuration diagram of a transmitter
according to a sixth embodiment of the present invention.
FIG. 7 is a configuration diagram of a receiver according
5 to a seventh embodiment of the present invention.
FIG. 8A is a configuration diagram of a transmitter
according to an eighth embodiment of the present invention.
FIG. 8B is a configuration diagram of a transmitter
according to a ninth embodiment of the present invention.
10 FIG. 8C is a configuration diagram of a receiver
according to a tenth embodiment of the present invention.
FIG. 9 is a diagram for describing a correlation in an
embodiment of the present invention.
FIG. 10 is a configuration diagram of an elevator system
15 (an eleventh embodiment) to which the wireless communication
system of the present invention is applied.
FIG. 11 is a configuration diagram of a substation
monitoring system (a twelfth embodiment) to which the wireless
communication system of the present invention is applied.
20
MODE FOR CARRYING OUT THE INVENTION
[0015]
FIG. 1 is a configuration diagram of a wireless
communication system according to an embodiment of the present
25 invention.
A wireless communication system according to an
10
embodiment of the present invention is configured to include a
transmitter 1000 and a receiver 2000.
[0016]
The transmitter 1000 includes a transmission information
generating unit 4 that generates transmission 5 information to
be transmitted to the receiver 2000, a first code generating
unit 1 that generates a first code which is repeated at a
frequency fr, a second code generating unit 2 that generates a
second code having a high autocorrelation value, a third code
10 storage unit 3 that stores a third code, a third encoding unit
5 that codes the transmission information generated by the
transmission information generating unit 4 using the third
code, an encoding unit 6 that encodes the transmission
information encoded by the third encoding unit 5 using the
15 first code and the second code, a carrier wave superimposing
unit 7, a first transmitting antenna 8, and a second
transmitting antenna 9 which is spatially orthogonal to the
transmitting antenna 8.
[0017]
20 A transmitting unit 10 is configured to include the
carrier wave superimposing unit 7, the first transmitting
antenna 8, and the second transmitting antenna 9. As will be
described later, the transmitting unit 10 generates a
transmission signal whose polarization plane rotates at the
25 frequency fr by causing a carrier wave to be superimposed on
the transmission information encoded by the encoding unit 6,
11
and wirelessly transmits the transmission signal.
[0018]
The first code generating unit 1 generates first codes
which differ in codes of partial regions in the partial
regions obtained by dividing the first code corresponding 5 to
one period on a time axis. In detail, the first code
generating unit 1 generates the first code so that a crosscorrelation
value between different partial regions (between
partial regions having different codes) is higher than an
10 autocorrelation value between the same partial regions
(between partial regions having the same code). In the present
embodiment, the partial regions are formed by equally dividing
the first code corresponding to one period on the time axis,
but the first code may not be equally divided.
15 [0019]
The second code generating unit generates the second code
which is a code having a high autocorrelation value, that is,
a code by which it is possible to detect whether or not the
same codes of two sequences are identical on the time axis.
20 The second code is, for example, a cyclic code. It is
desirable that a length of the second code be set to be longer
than a length of the first code.
[0020]
The third code is a code (cipher) for concealing the
25 transmission information and generated to reflect a
characteristic of a transmission path between the transmitter
12
1000 and the receiver 2000. The third code is, for example, a
code in which a state of a reception signal by reflection (an
amplitude of reception power, a signal quality, or the like)
is reflected. The details of the third code will be described
5 later.
The carrier wave superimposing unit 7 causes the carrier
wave to be superimposed on the transmission information
encoded by the encoding unit 6 and then generates a cosine
wave signal of the frequency fr and a sine wave signal of the
10 frequency fr.
[0021]
An overview of an operation of the transmitter 1000 is as
follows.
The transmitter 1000 encodes the transmission information
15 generated by the transmission information generating unit 4
through the third encoding unit 5 using the third code and
then encodes the transmission information using the first code
and the second code through the encoding unit 6. Thereafter,
the carrier wave superimposing unit 7 causes the carrier wave
20 to be superimposed on the transmission information encoded by
the encoding unit 6, and the electromagnetic wave 15 radiates
the carrier wave through the first transmission antenna 8 and
the second transmission antenna 9. In other words, the carrier
wave is superimposed through the carrier wave superimposing
25 unit 7, the cosine wave signal and the sine wave signal in
which an envelope curve sinusoidally vibrates at the frequency
13
fr, the cosine wave signal is wirelessly transmitted through
the first transmitting antenna 8, and the sine wave signal is
wirelessly transmitted through the second transmitting antenna
9 which is spatially orthogonal to the first transmitting
5 antenna 8.
[0022]
The cosine wave signal radiated from the first
transmission antenna 8 and the sine wave signal radiated from
the second transmission antenna 9 are radiated as linearly
10 polarized electromagnetic waves, respectively. As described
above, electromagnetic waves 15 radiated from the first
transmitting antenna 8 and the second transmitting antenna 9
travel through the space so that a sinusoidal amplitude is
spatially orthogonal with a phase difference of 90. The
15 electromagnetic wave 15 forms a rotary polarized wave in which
a polarization vector thereof rotates at the frequency fr
within a plane vertical to a traveling direction of the
electromagnetic wave 15 (that is, a direction of an electric
field rotates at the frequency fr while the magnitude of the
20 electric field is changed).
[0023]
The receiver 2000 includes a first receiving antenna 21,
a second receiving antenna 22 which is spatially orthogonal to
the first receiving antenna 21, a carrier wave removing unit
25 23, a synchronization detecting unit 24, a partial region
information extracting unit 25, an information decoding unit
14
27, and an information processing unit 28.
[0024]
A receiving unit 26 is configured to include a first
receiving antenna 21, a second receiving antenna 22, and a
carrier wave removing unit 23. As 5 will be described later, the
receiving unit 26 receives the transmission signal from the
transmitter 1000 and removes the carrier wave from the
received reception signal.
[0025]
10 Each of the first receiving antenna 21 and the second
receiving antenna 22 receives a wireless signal transmitted
from the transmitter 1000 (a synthetic signal of the cosine
wave signal transmitted from the first transmission antenna 8
and the sine wave signal transmitted from the second
15 transmission antenna 9). The carrier wave removing unit 23
removes the carrier wave from the wireless signal received by
through first receiving antenna 21 and the second receiving
antenna 22. The synchronization detecting unit 24 detects a
start point of the information signal received using the
20 second code for an information signal from which the carrier
wave has been removed by the carrier wave removing unit 23.
[0026]
The partial region information extracting unit 25
extracts partial region information corresponding to the
25 partial regions of the first code of the first code generating
unit 1 of the transmitter 1000 from the information signal
15
using the starting point of the information signal, and
detects a phase shift of each partial region information (a
shift on the time axis). This phase shift is caused by the
occurrence of a polarization angle shift according to a
polarization angle at the time of reflection when 5 the
electromagnetic wave transmitted from the transmitter 1000 is
reflected in the transmission path. The details of the
polarization angle shift will be described later.
[0027]
10 The information decoding unit 27 decodes the information
extracted through the partial region information extracting
unit 25 using the third code. In addition, the information
decoding unit 27 notifies the information processing unit 28
of the phase shift of each partial region information.
15 [0028]
The information processing unit 28 performs various kinds
of information processes on the information decoded by the
information decoding unit 27. Further, the information
processing unit 28 recognizes the phase shift in each partial
20 region, that is, indirectly recognizes and identifies a
transmission path through which the reached information signal
has passed based on the phase shift in each partial region.
[0029]
The operation outline of the receiver 2000 is as follows.
25 The receiver 2000 receives the electromagnetic wave 15
(the electromagnetic wave in which the polarization vector
16
rotates) from the transmitter 1000 using the first receiving
antenna 21 and the second receiving antenna 22, that is,
receives the synthetic signal of the cosine wave signal and
the sine wave signal from the transmitter 1000. The
polarization angle of the reception signal is shifted due 5 to
influence of reflection in the radio wave transmission path
compared with when it is transmitted from the transmitter 1000.
An amount of polarization angle shift differs according to the
polarization angle at the time of reflection, that is, differs
10 for each partial region. Then, the receiver 2000 removes the
carrier wave from the reception signal through the carrier
wave removing unit 23 and extracts the information signal.
[0030]
Then, the receiver 2000 detects the start point of the
15 information signal using the second code through the
synchronization detecting unit 24. Based on the start point of
the information signal, the partial region information
extracting unit 25 extracts information corresponding to each
partial region from the information signal using the first
20 code, and extracts the phase shift in each partial region.
Then, the information decoding unit 27 decodes the information
extracted through the partial region information extracting
unit 25 by using the third code. Then, the information
processing unit 28 performs various kinds of information
25 processes on the information decoded through the information
decoding unit 27. Further, the information processing unit 28
17
recognizes the amount of phase shift in each partial region.
[0031]
When it is not necessary to strictly conceal the
transmission information wirelessly transmitted from the
transmitter 1000, it is not necessary to encode 5 the
transmission information generated through the transmission
information generating unit 4 using the third code. In other
words, when it is not necessary to strictly conceal the
transmission information transmitted from the transmitter 1000,
10 the third code storage unit 3 and the third encoding unit 5 of
the transmitter 1000 and the information decoding unit 27 of
the receiver 2000 may be omitted.
[0032]
(First embodiment)
15 Hereinafter, a first embodiment of the present embodiment
will be described with reference to FIGS. 2A and 2B.
FIG. 2A is a configuration diagram of a transmitter
according to the first embodiment of the present invention.
FIG. 2B is a configuration diagram of a receiver according to
20 the first embodiment. In FIGS. 2A and 2B, the same components
as those in FIG. 1 are denoted by the same reference numerals,
and description thereof will be appropriately omitted.
[0033]
A transmitter 1001 of the first embodiment includes a
25 transmission information generating unit 4 that generates
transmission information I, a first code generating unit 1
18
that generates a first code, and a second code generating unit
2 that generates a second code, a third code storage unit 3
that stores a third code, a third encoding unit 5 which is
configured with a multiplier, an encoding unit 6 which is a
first multiplier, a carrier wave generating circuit 11 5 that
generates a carrier wave, a second multiplier 12, a cosine
weighting circuit 13, a sine weighting circuit 14, a first
transmitting antenna 8, and a second transmitting antenna 0
which is spatially orthogonal to the first transmitting
10 antenna 8 as illustrated in FIG. 2A.
[0034]
The carrier wave superimposing unit 7 of FIG. 1 is
configured to include a carrier wave generating circuit 11, a
second multiplier 12, a cosine weighting circuit 13, and a
15 sine weighting circuit 14.
[0035]
The first code generating unit 1 generates a first code
which is a repetition code of the frequency fr, that is, a
period Tr (Tr = 1/fr). The first code is a code in which the
20 autocorrelation is maximum, and the cross-correlation is
minimum in each of intervals (partial regions) obtained by
equally dividing the period Tr using an integer M. In the
example of FIG. 2A, the period Tr is equally divided into four,
and four intervals A1 to A4 are generated. For example, the
25 code of the interval A1 is generated so that the
autocorrelation is maximum, and the cross-correlation with the
19
code of each of the other intervals A2 to A4 is minimized. The
code of the interval A2 is generated so that the
autocorrelation is maximum, and the cross-correlation with the
codes of each of the other intervals A1, A3, and A4 is
minimized. The same applies to the codes of the 5 intervals A3
and A4.
[0036]
As described above, the second code is a code by which it
is possible to detect whether or not the second codes of the
10 two sequences are identical on the time axis, and for example,
a pseudo noise (PN) code is used as the second code. A sum of
the PN codes has a local maximum value when the PN codes of
the two sequences are identical on the time axis and has a
local minimum value when the PN codes of the two sequences are
15 not identical. For example, a sum of PN 7 codes of 2 sequences
is 7 when they are identical on the time axis and 0 when they
are not identical. In the present embodiment, the length of
the second code is set to be larger than the length of the
first code.
20 [0037]
The third code storage unit 3 stores a third code which
is a cipher for concealing the information I. A cipher which
is commonly used can be used as the third code, but it is
desirable to use a code generated based on the state of the
25 transmission path between the transmitter 1001 and the
receiver 2001 (that is, the reflection state). The code
20
generated based on the state of the transmission path is a
code generated to reflect the characteristic of the
transmission path of the reception signal received by the
receiver 2001. As will be described later, the reception
signal corresponding to each partial region of the 5 he first code
passes through a different transmission paths for each partial
region according to the state of the transmission path (that
is, the reflection state).
[0038]
10 For example, the third code is a code in which a temporal
change in the amplitude of the reception power of the
reception signal corresponding to each partial region of the
first code or a time change in the signal quality in the
receiver 2001 is reflected or a code in which the phase shift
15 of the reception signal corresponding to each partial region
is reflected.
[0039]
For example, the third code is taken into the transmitter
1001 from the outside by an operator and stored in the third
20 code storage unit 3. For example, when the transmitter 1001 is
a transceiver having the function of the receiver 2001, the
third code can be generated to reflect the characteristic of
the transmission path when the information signal transmitted
from the transmitter 1001 of a transmission counterpart is
25 received via the transmission path. For example, a code in
which the temporal change of the amplitude of the received
21
power of the reception signal, the temporal change of the
signal quality such as a signal to noise ratio (SN ratio), or
the temporal change in the phase shift amount is reflected in
the partial regions of A1 to A4 of the information extracting
unit 25 can be detected by the second demodulating circuit 5 54
and set as the third code.
[0040]
In this case, information unique to the transmission path
from the transmitter 1001 to the receiver 2001, that is,
10 unique information in which a property of a reflector in the
transmission path is reflected is included in the third code.
Thus, when the third code is used, it is difficult for a third
party at a different place on the transmission path to decode
the third code.
15 [0041]
In the example of the present embodiment, the
transmission information I generated by the transmission
information generating unit 4 has a period TI which is much
larger than the period Tr of the first code, that is, a
20 frequency fI which is much lower than the frequency fr of the
first code. In other words, the transmission information I
generated by the transmission information generating unit 4
can be regarded to be the same signal in the four intervals A1
to A4 of the first code. For example, frequency fI is about 10
25 kHz, and the frequency fr is about 1 MHz. Further, the
transmission information I generated by the transmission
22
information generating unit 4 can be configured so that the
four intervals A1 to A4 of the first code are different from
each other.
[0042]
The output (transmission information I) of 5 f the
transmission information generating unit 4 is encoded by the
third encoding unit 5 according to the third code stored in
the third code storage unit 3 and then synthesized with the
output of the first code generating unit 1 and the output of
10 the second code generating unit 2 through the encoding unit 6.
At this time, for example, the second code is included in one
bit of the first code. For example, when the first code is
assumed to be [b1, b2, b3, b4, B5 ...] (bi = 1 or -1), the
first code to which the second code (CODE2) is applied is [b1
15 (CODE2), b2 (CODE2), b3 (CODE2), b4 (CODE 2), ...]. Conversely,
the first code may be included in one bit of the second code.
[0043]
The output of the encoding unit 6 is superimposed on the
output of the carrier wave generating circuit 11 by the second
20 multiplier 12 and then bifurcated. The cosine weighting
circuit 13 of the frequency fr applies a cosine weighting to
one bifurcated signal, and then a resulting signal is radiated
into the air through the first transmitting antenna 8. The
sine weighting circuit 14 of the frequency fr applies a sine
25 weighting to the other bifurcated signal, and then a resulting
signal is radiated into the air through the second
23
transmitting antenna 9. The application of the cosine
weighting indicates, for example, weighting (that is,
multiplying) the cosine wave (cos2πfrt) of the frequency fr,
and the application of the sine weighting indicates, for
example, weighting (that is, multiplying) the sine 5 wave
(sin2πfrt) of the frequency fr. For example, the frequency of
the carrier wave is about 400 MHz.
[0044]
As described above, the transmitter 1001 applies the
10 cosine weighting and the sine weighting to the same signal and
then radiates the resulting signal into the space through the
first transmitting antenna 8 and the second transmitting
antenna 9 which are spatially orthogonal to each other. Since
the cosine weighting and the sine weighting change at a
15 certain frequency fr, the polarization vector of the
electromagnetic wave radiated in the space rotates at the
frequency fr (that is, the polarization plane rotates). In
other words, in the electromagnetic waves radiated from the
first transmitting antenna 8 and the second transmitting
20 antenna 9, the sinusoidal amplitudes of frequency fr are
spatially orthogonal to each other with a phase difference of
90. Accordingly, an electromagnetic wave that performs
rotatory polarization in which the polarization vector rotates
at the frequency fr is formed and travels through the space.
25 [0045]
The receiver 2001 of the first embodiment includes a
24
first receiving antenna 21, a second receiving antenna 22
spatially orthogonal to the first receiving antenna 21, a
first mixer 31a, a second mixer 31b, a local signal generating
circuit 32, a first analog filter 33a, a second analog filter
33b, a first adder 34, a first variable delay circuit 5 35, the
first exclusive OR (XROR) operation circuit 36, a
synchronization code generating circuit 38 that generates the
same code (the second code) as the second code generating unit
2 of the transmitter 1001, a first demodulating circuit 37, a
10 second variable delay circuit 41a, a second exclusive OR
operation circuit 42a, a third variable delay circuit 41b, a
third exclusive OR operation circuit 42b, 2M fourth variable
delay circuits 51(1) to 51(2M), 2M partial code generating
circuits 53(1) to 53(2M), 2M fourth exclusive OR operation
15 circuits 52(1) to 52(2M), 2M second demodulating circuits 54
(1) to 54 (2M), an information decoding unit 27 (decoding
circuit), and an information processing unit 28 as illustrated
in FIG. 2B.
[0046]
20 The fourth variable delay circuits 51(1) to 51(2M), the
fourth exclusive OR operation circuits 52 (1) to 52 (2M),
partial code generating circuits 53(1) to 53(2M), the second
demodulating circuits 54(1) to 54(2M) are referred to
collectively as a "fourth variable delay circuit 51," a
25 "fourth exclusive OR operation circuit 52," a "partial code
generating circuit 53," and a "second demodulating circuit
25
54," respectively. In the example of FIG. 2B, the number M
corresponds to twice the number of partial regions of the
first code generating unit 1, and M = 8.
[0047]
The carrier wave removing unit 23 of FIG. 1 is conf5 igured
to include the first mixer 31a, the second mixer 31b, the
local signal generating circuit 32, the first analog filter
33a, and the second analog filter 33b.
[0048]
10 The synchronization detecting unit 24 of FIG. 1 is
configured to include the first adder 34, the first variable
delay circuit 35, the first exclusive OR operation circuit 36,
the synchronization code generating circuit 38, and the first
demodulating circuit 37.
15 [0049]
The partial region information extracting unit 25 of FIG.
1 is configured to include the second variable delay circuit
41a, the second exclusive OR operation circuit 42a, the third
variable delay circuit 41b, the third exclusive OR operation
20 circuit 42b, the fourth variable delay circuit 51, the fourth
exclusive OR operation circuit 52, the partial code generating
circuit 53, and the second demodulating circuit 54.
[0050]
The reception signal received from the first receiving
25 antenna 21 is multiplied by the output of the local signal
generating circuit 32 by the first mixer 31a and then passes
26
through the first analog filter 33a, and thus a carrier wave
frequency is removed. The output of the first analog filter
33a serves as an input A of a field-programmable gate array
(FPGA) 3001 and then bifurcated at an internal point C of the
FPGA 3001. One bifurcated signal serves as a first 5 irst input of
the first adder 34. In the first embodiment, in FIG. 2B, the
remaining components excluding the first receiving antenna 21,
the second receiving antenna 22, and the carrier wave removing
unit 23 constitute the FPGA 3001.
10 [0051]
The reception signal received from the second receiving
antenna 22 is multiplied by the output of the local signal
generating circuit 32 by the second mixer 31b and then passes
through the second analog filter 33b, and thus the carrier
15 wave frequency is removed. The output of the second analog
filter 33b serves as an input B of the FPGA 3001 and then
bifurcated at an internal point D of the FPGA 3001. One
bifurcated signal serves as a second input of the first adder
34. The first input and the second input of the first adder 34
20 are added by the first adder 34 and then output.
[0052]
The output of the first adder 34 passes through the first
variable delay circuit 35 and is then XORed with the output of
the synchronization code generating circuit 38 by the first
25 exclusive OR operation circuit 36 together with. The
synchronization code generating circuit 38 outputs the second
27
code (PN code). The first exclusive OR operation circuit 36
performs a multi-bit exclusive OR operation on the output of
the synchronization code generating circuit 38 and the output
of the first variable delay circuit 35.
5 [0053]
As described above, the exclusive OR operation is
performed on the second code (PN code) which is the output of
the synchronization code generating circuit 38 and the second
code included in the output of the first variable delay
10 circuit 35. The operation result is input to the first
demodulating circuit 37. The first demodulating circuit 37
performs a correlation detection operation by adding the
multi-bit exclusive OR operation results. As described above,
the PN codes of the two sequences are maximum when the time
15 axes are identical and are minimum when the time axes are not
identical. The first demodulating circuit 37 performs the
correlation detection operation based on the exclusive OR
operation results and, generates a delay amount control signal
for controlling a delay amount based on the correlation
20 detection operation result, and outputs the delay amount
control signal to the first variable delay circuit 35, the
second variable delay circuit 41a, and the third variable
delay circuit 41b.
[0054]
25 At this time, the first demodulating circuit 37 controls
the delay amount of the first variable delay circuit 35 so
28
that a timing at which a value of the correlation detection
operation result is a predetermined value or more (that is, a
correlation is detected) and the output of the first exclusive
OR operation circuit 36 (that is, the strength of the
reception signal) is a predetermined value or more is 5 obtained.
As described above, the first demodulating circuit 37 can
locate the start point of the code included in the
transmission signal based on the timing at which the value of
the correlation detection operation result is the
10 predetermined value or more, and the reception strength is the
predetermined value or more and synchronize the reception
signal with the transmission signal transmitted from the
transmitter 1001.
[0055]
15 Among the outputs of the first analog filter 33a, the
other bifurcated signal passes through the second variable
delay circuit 41a, is then input to the second exclusive OR
operation circuit 42a, and XORed with the output of the
synchronization code generating circuit 38 The output of the
20 second exclusive OR operation circuit 42a from which the
second code has been removed as described above is further
bifurcated into M and then input to the fourth variable delay
circuits 51(1) to 51(M) as signals E(1) to E(M).
[0056]
25 Among the outputs of the second analog filter 33b, the
other bifurcated signal passes through the third variable
29
delay circuit 41b, is then input to the third exclusive OR
operation circuit 42b, and XORed with the output of the
synchronization code generating circuit 38. The output of the
second exclusive OR operation circuit 42b from which the
second code has been removed as described above is 5 further
bifurcated into M and input to the fourth variable delay
circuits 51(M+1) to 51(2M) as signals E(M+1) to E(2M).
[0057]
At this time, the delay amounts of the second variable
10 delay circuit 41a and the third variable delay circuit 41b are
controlled by the first demodulating circuit 37 to be equal to
the delay amounts of the first variable delay circuit 35.
[0058]
The signals E(M+1) to E(2M) are delayed by the fourth
15 variable delay circuits 51(1) to 51(M), respectively, and then
XORed with the outputs of the partial code generating circuits
53(1) to 53(M) by the fourth exclusive OR operation circuits
52(1) to 52(M).
[0059]
20 The signals E(M+1) to E(2M) are delayed by the fourth
variable delay circuits 51(M+1) to 51(2M) and then XORed with
the outputs of the partial code generating circuits 53(M+1) to
53(2M) by the fourth exclusive OR operation circuits 52(M+1)
to 52(2M).
25 [0060]
A plurality of partial code generating circuits 53(1) to
30
53(M) generate different partial codes corresponding to the
partial regions of the first code generating unit 1 of the
transmitter 1001. Similarly, the partial code generating
circuits 53(M+1) to 53(2M) generate different partial codes
corresponding to the partial regions of the first 5 code
generating unit 1. As described above, the partial code
generating circuits 53(1) to 53(M) outputs the same code as
the first code in the partial regions which is similar to that
of the first code generating unit 1. The partial code
10 generating circuits 53(M+1) to 53(2M) also output codes which
are similar to those of the partial code generating circuit
53(1) To 53(M).
[0061]
For example, the partial code generating circuit 53(1)
15 and the partial code generating circuit 53(M+1), that is, the
partial code generating circuit 53(1) and the partial code
generating circuit 53(5) output the first code corresponding
to the region A1 of the first code generating unit 1 of the
transmitter 1001 as illustrated in FIG. 2B. The partial code
20 generating circuit 53(M) and partial code generating circuit
53(2M), that is, the partial code generating circuit 53(4) and
the partial code generating circuit 53(8) output the first
code corresponding to the region A4 of the first code
generating unit 1 of the transmitter 1001.
25 [0062]
The fourth exclusive OR operation circuits 52(1) to 52
31
(2M) perform the exclusive OR operation on the outputs of the
partial code generating circuits 53(1) to 53(2M) and the
outputs of the fourth variable delay circuits 51(1) to 51(2M).
The second demodulating circuits 54(1) to 54(2M) perform the
correlation detection operation using the operation results 5 of
the fourth exclusive OR operation circuits 52(1) to 52(2M).
For example, the second demodulating circuit 54(1) performs
the correlation detection operation by adding bits of the
operation result of the fourth exclusive OR operation circuit
10 52(1). At this time, when a sign of the output of the fourth
variable delay circuit 51(1) is identical to a sign of the
output of the partial code generating circuit 53(1), the value
of the correlation detection operation result becomes maximum.
[0063]
15 FIG. 9 is a diagram for describing a correlation
according to the embodiment of the present invention.
FIG. 9 illustrates an example in which the correlation
detection operation of repetition codes C1 to CM is performed.
Correlation values between two of the repetition codes C1 to CM
20 of two sequences having the same content are, for example, an
autocorrelation value a1 between C1 and C1, an autocorrelation
value a2 between C2 and C2, and an autocorrelation value aM
between CM and CM become maximum as illustrated in FIG. 9. On
the other hand, a cross correlation value between C1 and C2
25 does not become maximum.
[0064]
32
Referring back to FIG. 2B, the description will be
continued.
For example, the signal E(1) passes through the fourth
variable delay circuit 51(1) and is then XORed with the output
of the partial code generating circuit 53(1) by the 5 fourth
exclusive OR operation circuit 52(1). The exclusive OR
operation result is input to the second demodulating circuit
54(1). The second demodulating circuit 54(1) performs the
correlation detection operation based on the exclusive OR
10 operation result, and transfers the delay amount to the
variable delay circuit 51(1) based on the correlation
detection operation result. At this time, the second
demodulating circuit 54(1) controls the delay amount of the
variable delay circuit 51(1) such that the value of the
15 correlation detection operation result is a predetermined
value or more, and the signal strength of the output of the
exclusive OR operation circuit 52, that is, the signal
strength of the signal E(1) is a predetermined value or more.
[0065]
20 As described above, the second demodulating circuit 54(1)
controls the delay amount of the variable delay circuit 51(1)
such that the value of the correlation detection operation
result is a predetermined value or more, and the signal
strength of the signal E(1) is a predetermined value or more.
25 The delay amount corresponds to the phase shift of the
reception signal received from the transmitter 1001 and is one
33
in which information unique to the transmission path in which
the electromagnetic wave transmitted from the transmitter 1001
is transmitted (that is, information unique to a property of a
reflector in the transmission path) is reflected.
5 [0066]
Similarly, the second demodulating circuits 54(2) to
54(M) control the delay amounts of the variable delay circuits
51(2) to 51(M) such that the value of the correlation
detection operation result is a predetermined value or more,
10 and the signal strength of the signals E(2) to E(M) is a
predetermined value or more. Each of the delay amounts
corresponds to the phase shift of the reception signal
received from the transmitter 1001 and is one in which
information unique to the transmission path in which the
15 electromagnetic wave transmitted from the transmitter 1001 is
transmitted is reflected.
[0067]
When there is a plurality of reflectors in the
transmission path, the electromagnetic wave transmitted from
20 the transmitter 1001 arrives at via a plurality of paths
having different path lengths due to a plurality of
reflections by a plurality of reflectors. Further, as
described above, the electromagnetic wave transmitted from the
transmitter 1001 undergoes the polarization angle shift
25 according to the polarization angle of the electromagnetic
wave at the time of reflection, that is, undergoes the
34
polarization angle shift which differs according to each
partial region.
[0068]
On the other hand, since each of the antennas 21 and 22
is unable to receive an electromagnetic waves of a 5 certain
polarization angle (that is, a polarization angle orthogonal
to a reception polarization angle of the antenna), the signal
strength of each of the signals received through the antennas
21 and 22 differs according to the polarization angle (that is,
10 each partial region). In other words, the signal strengths of
the signals E(1) to E(2M) differs according to each partial
region.
[0069]
Then, the second demodulating circuit 54 controls the
15 delay amount of the variable delay circuit 51 such that the
value of the correlation detection operation result between
the reception signal (that is, the signal E) and the output of
the partial code generating circuit 53 is a predetermined
value or more, and the signal strength of the reception signal
20 (that is, the signal E) is a predetermined value or more. As a
result, the reception signal (the signal E) whose signal
strength is a predetermined value or more is selected for each
partial region. In other words, the transmission path at which
the reception signal whose intensity is a predetermined value
25 or more arrives is selected as the transmission path of the
information signal extracted in each partial region.
35
[0070]
As described above, each of the delay amounts of the
variable delay circuits 51(1) to 51(2M) corresponds to the
phase shift of the reception signal received from the
transmitter 1001 is one in which the transmission 5 path in
which the electromagnetic wave from the transmitter 1001 is
transmitted is reflected.
[0071]
Further, the second demodulating circuits 54(1) to 54(M)
10 output the exclusive OR operation results (that is, the
information I corresponding to the partial regions A1 to A4 of
the first code generating unit 1) to the information decoding
unit 27 (the decoding circuit) as information F(1) to F(M).
Similarly, the second demodulating circuits 54(M+1) to 54(2M)
15 output the exclusive OR operation results from the fourth
exclusive OR operation circuits 52(M+1) to 52(2M) (that is,
the information I corresponding to the partial regions A1 to
A4 of the first code generating unit 1) to the information
decoding unit 27 (the decoding circuit) as information F(M+1)
20 to F(2M).
[0072]
For example, the information decoding unit 27 performs a
logical sum (OR) of the input information F(1) to F(M) and the
information F(M+1) to F(2M) and performs decoding using the
25 third code. The decoded information is output to the
information processing unit 28. Further, the information
36
decoding unit 27 receives the phase shift amounts in the
partial regions A1 to A4 from the second demodulating circuit
54 and outputs the phase shift amounts to the information
processing unit 28. The information processing unit 28
performs a process using the information decoded by 5 the
information decoding unit 27. The information processing unit
28 detects and recognizes the phase shift amounts in the
partial regions.
[0073]
10 As described above, the receiver 2001 extracts a start
timing of the entire reception signal through the first
demodulating circuit 37 using the second code of the
synchronization code generating circuit 38 for the synchronous
detection of the reception signal. Then, using the timing, the
15 receiver 2001 extracts a start timing of the reception signal
of each partial region through the fourth exclusive OR
operation circuit 52 and detects the phase shift amounts in
the partial regions.
[0074]
20 The operation of the synchronization detecting unit 24
will be further described.
When the electromagnetic waves radiated in different
directions from the transmitter 1001 are reflected on surfaces
of a plurality of reflectors (electromagnetic wave scatterers)
25 between transmission and reception and synthesized in the
receiver 2001 as described above, energy of the received
37
electromagnetic wave is greatly attenuated. In this case, the
energy of the received electromagnetic wave is maximized at
the polarization angle orthogonal to the polarization angle
thereof. Thus, by obtaining the reception signals from the
electromagnetic waves of a different polarization angle and 5 a
polarization angle orthogonal thereto and adding the reception
signals, it is possible to receive the energy of signals
coming at all polarization angles without omission.
[0075]
10 The receiver 2001 receives the signals transmitted
through the electromagnetic waves in which the polarization
vector rotates through the two antennas 21 and 22 that are
spatially orthogonal to each other. Then, the synchronization
detecting unit 24 generates a sum signal of the received two
15 reception signals, performs the exclusive OR operation of the
delayed sum signal and the second code generated by the
synchronization code generating circuit 38 while sequentially
changing the delay amount of the sum signal, and locates the
start point of the second code included in the transmission
20 signal.
[0076]
By performing the exclusive OR operation on the sum
signal of the two signals received through the two antennas 21
and 22 using the second code, the receiver 2001 can easily
25 locate the start timing of the information transmitted from
the transmitter 1001, that is, the start timing of the second
38
code used for modulating the transmitted information.
[0077]
As described above, the second code of the
synchronization code generating circuit 38 for the synchronous
detection of the reception signal has a longer code 5 length
than the first code of the partial code generating circuit 53.
Therefore, the accuracy of extraction of the start timing of
the entire reception signal can be improved.
[0078]
10 However, since the second code of the synchronization
code generating circuit 38 has a longer code length than the
first code of the partial code generating circuit 53, the
operation of the first exclusive OR operation circuit 36
controlled by the first demodulating circuit 37 is larger in
15 an operation amount than the operation of the fourth exclusive
OR operation circuit 52 controlled by the second demodulating
circuit 54.
[0079]
In this regard, as described above, the first
20 demodulating circuit 37 sets a certain threshold value to the
correlation detection operation result and performs control
such that the correlation detection operation result is the
threshold value or more. Further, when the correlation
detection operation result is the threshold value or more, the
25 first demodulating circuit 37 regards that the synchronization
is established, and ends the operation of the first exclusive
39
OR operation circuit 36. As a result, the operation amount of
the first exclusive OR operation circuit 36 can be
significantly reduced under the condition in which a rapid
change in a radio wave propagation environment over time
hardly occurs such as a wireless network for monitoring 5 onitoring and
controlling of the social infrastructure equipment. The
threshold value may be determined according to a previous
operation result.
[0080]
10 As described above, under the condition in which the
rapid change in the radio wave propagation environment over
time hardly occurs, the start timing of the entire reception
signal decided by the first demodulating circuit 37 rarely
change over time. In this regard, it is efficient that the
15 change in the radio wave propagation environment which rarely
occurs in terms of time is dealt with through the process by
the first demodulating circuit 37 whose operation amount is
large (the process of extracting the start timing of the
entire reception signal), and the other small changes are
20 dealt with through a process by the second demodulating
circuit 54 (the process of extracting the start timings of the
partial regions). As described above, the process is performed
in two stages, and thus the digital signal processing amount
of the entire receiver 2001 can be greatly reduced, and the
25 extraction speed of the start timing can be increased.
[0081]
40
Further, It is possible to omit the synchronization
detecting unit 24 (the first adder 34, the first variable
delay circuit 35, the first exclusive OR operation circuit 36,
the synchronization code generating circuit 38, and the first
demodulating circuit 37), but if the synchronization 5 detecting
unit 24 is omitted, the accuracy related to the start timing
of the entire reception signal extracted by one operation
process deteriorates, and a repetition time of the operation
process by deterioration in the accuracy increases. Further, a
10 sum signal of reception electric fields of the two antennas 21
and 22 which are orthogonal to each other is used in the
synchronization detecting unit 24, whereas a signal of a
reception electric field of a single antenna is used in the
partial region information extracting unit 25. For this reason,
15 in the partial region information extracting unit 25, since
the energy of the reception signal is lowed, the SN ratio
deteriorates, and the accuracy of detection of the
synchronization of the reception signal decreases.
[0082]
20 The operation of the partial region information
extracting unit 25 will be further described.
As described above, when there are a plurality of
reflectors between the transmitter 1001 and the receiver 2001,
the electromagnetic wave radiated from the transmitter 1001
25 passes through a plurality of reflectors and arrives at the
receiver 2001. When the electromagnetic wave is reflected, the
41
electromagnetic wave undergoes the polarization angle shift
unique to the polarization angle of the polarization vector on
the reflecting surface. The polarization angle shift amount
differs according to each polarization angle of the
polarization vector. In 5 n other words, the electromagnetic waves
of the partial regions (A1 to A4) of the first code generating
unit 1 are different in the polarization angle and thus
undergo different polarization angle shifts.
[0083]
10 The electromagnetic waves that have passed through a
plurality of transmission paths arrive at the receiver 2001,
but the antennas 21 and 22 of the receiver 2001 are unable to
receive electromagnetic waves of a certain polarization angle
(that is, a polarization angle orthogonal to a reception
15 polarization angle of the antenna). Therefore, among signals
received by the antennas 21 and 22 of the receiver 2001, a
signal of a certain polarization angle, that is, a signal that
has passed through a certain transmission path is not included.
In other words, the signals received by the antennas 21 and 22
20 of the receiver 2001 are signals obtained by synthesizing
signals that have passed through a plurality of transmission
paths excluding the certain transmission path.
[0084]
Therefore, in the receiver 2001, the reception signals
25 corresponding to the partial regions (A1 to A4) are signals
that have passed through different transmission paths. For
42
example, the reception signal corresponding to the partial
region A1 and the reception signal corresponding to the
partial region A2 are signals that have passed through
different transmission paths. A signal of the transmission
path whose reception strength is high among the signals 5 that
have passed through the plurality of transmission paths is
selected by the second demodulating circuit 54.
[0085]
Specifically, the electromagnetic waves radiated from the
10 transmitter 1001 arrive at the receiver 2001 via the
transmission paths having different path lengths due to
influence of reflection. For example, when the electromagnetic
waves radiated from the transmitter 1001 arrive at the
receiver 2001 via transmission paths L1, L2, L3, and L4 having
15 different path lengths (path lengths: L1 < L2 < L3 < L4). At
this time, the electromagnetic waves that have arrived at via
the transmission paths L1, L2, L3, and L4 in the order of the
transmission paths L1, L2, L3, and L4, that is, phases thereof
are shifted from one another.
20 [0086]
In the electromagnetic wave arriving at the receiver 2001,
the starting point of the information signal is detected by
the synchronization detecting unit 24. In detail, when a
condition C1 that the value of the correlation detection
25 operation result between the reception signal and the second
code of the synchronization code generating circuit 38 is a
43
predetermined value or more, and the strength of the reception
signal is a predetermined value or more is satisfied, the
start point of the information signal is detected.
[0087]
For example, when the reception signal 5 of the
transmission path L1 satisfies the condition C1, the start
point of the information signal is detected in the reception
signal of the transmission path L1. When the reception signal
of the transmission path L1 does not satisfy the condition C1,
10 it is determined whether or not the reception signal of the
transmission path L2 that arrives at next satisfies the
condition C1. Further, when the reception signal of the
transmission path L2 satisfies the condition C1, the
transmission path L2, the starting point of the information
15 signal is detected in the reception signal of the transmission
path L2.
[0088]
Further, the reception signal received by the first
receiving antenna 21 passes through the second variable delay
20 circuit 41a and the second exclusive OR operation circuit 42a,
and are input to the fourth variable delay circuits 51(1) to
51(4) as the signals E(1) to E(4), and undergoes the
correlation detection operation with the partial code
generating circuits 53(1) to 53(4). Then, when a condition C2
25 that the value of the correlation detection operation result
is a predetermined value or more, and strengths of the signals
44
E(1) to E(4) are a predetermined value or more is satisfied,
the signals E(1) to E(4) are extracted as the partial region
information corresponding to the partial regions A1 to A4 of
the partial code generating circuits 53(1) to 53(4).
5 [0089]
Similarly, the reception signal received by the second
receiving antenna 22 passes through the third variable delay
circuit 41b and the third exclusive OR operation circuit 42b,
are input to the fourth variable delay circuits 51(5) to 51(8)
10 as the signals E(5) to E(8), and undergoes the correlation
detection operation with the partial code generating circuits
53(5) to 53(8). Then, when the condition C2 that the value of
the correlation detection operation result is a predetermined
value or more, and strengths of the signals E(5) to E(8) are a
15 predetermined value or more is satisfied, the signals E(5) to
E(8) are extracted as the partial region information
corresponding to the partial regions A1 to A4 of the partial
code generating circuits 53(5) to 53(8).
[0090]
20 For example, in the second demodulating circuit 54(1)
checks whether or not the reception signal of the transmission
path L1 satisfies the condition C2, and when the condition C2
is satisfied, the reception signal of the transmission path L1
is extracted as the partial region information corresponding
25 to the partial region A1 of the partial code generating
circuit 53(1). In this case, there is no phase shift of the
45
partial region information corresponding to the partial region
A1 with respect to the start point of the information signal.
[0091]
For example, in the second demodulating circuits 54(2) to
54(4) determine whether or not the reception signal of 5 the
transmission path L1 satisfies the condition C2, and when the
condition C2 is satisfied, the reception signal of the
transmission path L1 is extracted as the partial region
information corresponding to the partial regions A2 to A4 of
10 the partial code generating circuits 53(2) to 53(4). In this
case, there is no phase shift of the partial region
information corresponding to the partial regions A2 to A4 with
respect to the start point of the information signal.
[0092]
15 However, for example, when the second demodulating
circuit 54(2) determines that the reception signal of the
transmission path L1 does not satisfy the condition C2, the
reception signal of the transmission path L1 is not extracted
as the partial region information corresponding to the partial
20 region A2 of the partial code generating circuit 53(2). The
reason why the reception signal of the transmission path L1
does not satisfy the condition C2 is because the reception
signal of the transmission path L1 is reflected in the
transmission path and undergoes the polarization angle shift
25 in the partial region A2, and thus the strength of the
reception signal received by the first receiving antenna 21 is
46
insufficient.
[0093]
Further, for example, when the second demodulating
circuit 54(2) determines the reception signal of the
transmission path L2 satisfies the condition C2, the 5 reception
signal of the transmission path L2 is extracted as the partial
region information corresponding to the partial region A2 of
the partial code generation circuit 53(2). In this case, the
phase shift amount of the partial region information
10 corresponding to the partial region A2 with respect to the
start point of the information signal is a time difference
between the reception signal of the transmission path L1 and
the reception signal of the transmission path L2.
[0094]
15 Similarly, for example, when the second demodulating
circuit 54(5) determines that the reception signal of the
transmission path L2 satisfies the condition C2, the reception
signal of the transmission path L2 is extracted as the partial
region information corresponding to the partial region A1 of
20 the partial code generation circuit 53(5). In this case, the
phase shift amount of the partial region information
corresponding to the partial region A1 with respect to the
start point of the information signal is a time difference
between the reception signal of the transmission path L1 and
25 the reception signal of the transmission path L2.
[0095]
47
Similarly, for example, when the second demodulating
circuit 54(8) determines that the reception signal of the
transmission path L4 satisfies the condition C2, the reception
signal of the transmission path L4 is extracted as the partial
region information corresponding to the partial region A4 5 of
the partial code generation circuit 53(8). In this case, the
phase shift amount of the partial region information
corresponding to the partial region A4 with respect to the
start point of the information signal is a time difference
10 between the reception signal of the transmission path L1 and
the reception signal of the transmission path L4.
[0096]
As described above, the reception signals selected by the
second demodulating circuit 54 in the partial regions (A1 to
15 A4) (the reception signals having the high reception strength)
are signals that have passed through different transmission
paths and have different phase shifts consequently.
[0097]
In the above description, the condition that the strength
20 of the reception signal is a predetermined value or more is
used as the condition C1 and the condition C2, but a condition
that the SN ratio is a predetermined value or more or a
condition that the strength and the SN ratio of the reception
signal are a predetermined value or more may be used instead.
25 [0098]
Further, in the present wireless communication system, it
48
is possible to detect an external intruder as follows.
The transmitter 1001 transmits the same information
signal using different code strings corresponding to the
partial regions (A1 to A4) of the first code generating unit 1,
that is, different code strings corresponding to 5 corresponding
to polarization angles (a partial code of the first code).
Then, the receiver 2001 restores the received information in
the partial region using the code string (the partial code of
the first code), that is, using the code string corresponding
10 to the partial regions (A1 to A4) of the partial code
generating circuit 53, and compares the restored information
signals of the partial regions are compared by the information
processing unit 28 of the receiver 2001.
[0099]
15 When there is a mismatch in the restored information of
the partial regions, the information processing unit 28 can
recognize that information manipulation has been performed by
the external intruder in the transmission path corresponding
to the partial region in which a mismatch occurs. In this case,
20 the information processing unit 28 may reject the information
in the partial region on which the information manipulation
has been performed. Accordingly, it is possible to detect the
presence of the external intruder and suppress a spoofing
action by the external intruder. The spoofing action by an
25 external intruder indicates an action of mixing illegal
information.
49
[0100]
Further, in this wireless communication system, it is
possible to realize an improvement in the reliability of
communication in addition to detection of the external
5 intruder.
In this case, the transmitter 1001 transmits the same
information signal by using different code strings
corresponding to the partial regions (A1 to A4) of the first
code generating unit 1 (the partial code of the first code).
10 The information processing unit 28 of the receiver 2001
selects an appropriate one from the result of the same
information signal arriving at the receiver 2001 from the
transmitter 1001, that is, the information of the partial
regions (A1 to A4) of the partial region information
15 extracting unit 25. For example, the information processing
unit 28 regards information whose contents is identical or
information that is largest in the number of pieces of
information which are identical to one another among the
information of the partial regions (A1 to A4) as information
20 transmitted from the transmitter 1001.
[0101]
Further, in the present wireless communication system, it
is possible to conceal the information signal to be
transmitted using the third code as follows.
25 In this case, first, the transmitter 1001 encodes a known
information signal using the first code and the second code
50
and transmitted the encoded information signal wirelessly.
Then, the receiver 2001 checks a mutual relation of the
information signals of the partial regions of the partial
region information extracting unit 25. Then, the third code is
generated using the mutual relation. The transmitter 5 nsmitter 1001
encodes the information signal to be transmitted using the
third code and transmits the encoded information signal
wirelessly.
[0102]
10 Specifically, the mutual relation between the information
signals in the partial regions of the partial region
information extracting unit 25, for example, the mutual
relation of the temporal change in the amplitude of the
reception power in the partial regions, the temporal change of
15 the signal quality, the phase shift amount, or the like is
transmitted and checked, and a specific code string (the third
code) is generated using the mutual relation. The transmitter
1001 modifies the original signal (the information signal to
be transmitted) by causing the information signal to be
20 transmitted to be superimposed on the code string (the third
code), and then transmits the modified signal.
[0103]
As a result, the receiver 2001 can generate the mutual
relation (that is, the third code) from the reception signal
25 and thus restore the information signal using the third code,
the external intrusion in a different transmission path is
51
unable to generate the mutual relation (that is, the third
code) from the reception signal and thus unable to restore the
information signal. As described above, the third code
functions as a secret code for keeping the information signal
5 to be transmitted secret.
[0104]
For example, the same information signal is transmitted
using different codes (the partial code of the first code)
corresponding to the polarization angles, and thus the
10 information signal can be transmitted. Since the information
signal undergoes the polarization angle shift that differs
according to the polarization angle in the transmission path,
the synthetic relation of the electromagnetic waves arriving
at the receiver 2001 becomes specific to the transmission
15 point (the transmitter 1001) and the reception point (the
receiver 2001) due to symmetry of transmission and reception
of communication. Thus, the external intruder who is not
present at the transmission point and the reception point is
unable to know the synthetic relation (that is, the mutual
20 relation of the information signals in the partial regions).
[0105]
FIG. 2C is a configuration diagram of a modification of
the receiver according to the first embodiment of the present
invention. A modified example of FIG 2C is different from the
25 example of FIG 2B in the following points. That is, the
modified example of FIG 2C, the fourth variable delay circuits
52
51(M+1) to 51(2M)､the fourth exclusive OR operation circuits
52(M+1) to 52(2M), the partial code generating circuits
53(M+1) to 53(2M), and the second demodulating circuits
54(M+1) to 54(2M) are deleted, and switches 43(1) to 43(M),
switches 44(1) to 44(M), and second adders 45(1) to 45(M) 5 are
added. The switches 43(1) to 43(M), the switches 44(1) to
44(M), and the second adders 45(1) to 45(M) are referred to
collectively as a "switch 43," a "switch 44," and a "second
adder 45," respectively. In the example of FIG. 2C, M = 4.
10 [0106]
The switch 43 is controlled by the first demodulating
circuit 37 and the second demodulating circuit 54 such that
the output of the second exclusive OR operation circuit 42a is
switched in a time division manner and output to the second
15 adder 45. In detail, the switch 43(1) enters an ON state in
which the output of the second exclusive OR operation circuit
42a is output to the adder 45(1) only in the period of the
partial region A1 of the partial code generating circuit 53.
Similarly, the switches 43(2) to 43(4) enters an ON state in
20 which the output of the second exclusive OR operation circuit
42a is output to the adders 45(2) to 45(4) only in the periods
of the partial regions A2 to A4 of the partial code generating
circuit 53.
[0107]
25 After the switch 43 performs the time division switching
in the periods of the partial regions A1 to A4 of the partial
53
code generating circuit 53, the switch 44 is controlled by the
first demodulating circuit 37 and the second demodulating
circuit 54 in the periods of the next partial regions A1 to A4
such that the output of the third exclusive OR operation
circuit 42b is switched in the time division manner and 5 output
to the second adder 45. In detail, after the switch 43(4)
switches the output of the second exclusive OR operation
circuit 42a to be output to the adder 45(4) only in the period
of the partial region A4, the switch 44(1) enters the ON state
10 in which the output state of the third exclusive OR operation
circuit 42b is output to the adder 45(1) only in the period of
the partial region A1 of the partial code generating circuit
53. Similarly, the switches 44(2) to 44(M) enter the ON state
in which the output state of the third exclusive OR operation
15 circuit 42b is output to the adders 45(2) to 45(4) only in the
periods of the partial regions A2 to A4 of the partial code
generating circuit 53.
[0108]
In detail, the second demodulating circuit 54(1) to 54(4)
20 turns on the switch 43 and the switch 44 in the periods of the
partial regions A1 to A4 of the partial code generating
circuit 53. The first demodulating circuit 37 turns on the
switch 43 and the switch 44 in a period obtained by adding a
predetermined time before and after the periods of the partial
25 regions A1 to A4. For example, the first demodulating circuit
37 turns on the switch 43(1) and the switch 44(1) in the
54
period obtained by adding a predetermined time before and
after the period of the partial region A1.
[0109]
As described above, in the example of FIG. 2C, the output
of the second exclusive OR operation circuit 42a and 5 the
output of the third exclusive OR operation circuit 42b are
switched in the time-division manner in the periods of the
partial regions A1 to A4, and thus the number of fourth
variable delay circuits 51, the number of fourth exclusive OR
10 operation circuits 52, the number of partial code generating
circuits 53, and the number of second demodulating circuits 54
are reduced.
[0110]
According to the first embodiment, at least the following
15 effects can be obtained.
(A1) The wireless communication system is configured such
that the transmitter encodes the transmission information
using the first code and the second code, then causes the
carrier wave to be superimposed on the transmission
20 information, generates the transmission signal in which the
polarization plane rotates at the frequency fr, and wirelessly
transmits the transmission signal, and the receiver detects
the start point of the information signal using the second
code in the reception signal received from the transmitter,
25 extracts the partial regions corresponding to the partial
regions of the first code using the starting pint of the
55
information signal, and detects the phase shifts of the
partial region information, and thus when the information
signal arrives via a plurality of transmission paths between
transmission and reception, it is possible to identify the
phase shift of information corresponding to the 5 partial
regions, that is, identify the transmission path through which
the information signal has passed.
(A2) When the wireless communication system is configured
such that the transmitter further encodes the third code
10 generated so that the characteristic of the transmission path
when the partial region information is transmitted to the
receiver is reflected, and the receiver decode information
corresponding to the partial regions extracted using the first
code using the third code, it is possible to suppress
15 acquisition of transmission information by an external
eavesdropper.
(A3) When the wireless communication system is configured
such that the transmission information in the partial regions
is identical to each other, and the receiver extracts the
20 partial region information and then determines whether or not
a plurality of pieces of extracted partial region information
are identical, it is possible to improve the reliability of
communication or detect the presence or absence of the
external intruder.
25 (A4) When the wireless communication system is configured
such that the transmission information in the partial regions
56
is identical to each other, and the receiver acquires
information that is large in the number of pieces of
information which are identical to one another among the
partial region information as the transmission information
from the transmitter, it is possible to 5 improve the
reliability of communication, or it is possible to suppress
the spoofing act by the external intruder.
(A5) The wireless communication system is configured such
that the transmitter encodes the transmission information
10 using the first code and the second code, then generates the
cosine wave signal and the sine wave signal of the frequency
fr, wirelessly transmits the cosine wave signal through a
first antenna, and wirelessly transmits the sine wave Signal
through a second antenna which is spatially orthogonal to the
15 first antenna, and the receiver receives the cosine wave
signal and the sine wave signal using a third antenna and a
fourth antenna which is spatially orthogonal to the third
antenna, detects the starting point of the information signal
using the second code, extracts the partial region information
20 corresponding to the partial regions of the first code based
on the starting point of the information signal, and detects
the phase shifts of the partial region information, and thus
it is possible to easily implement the functions of the
transmitter and the receiver according to the present
25 invention.
(A6) The wireless communication system is configured such
57
that the receiver detects synchronization of the second code
superimposed on third and fourth information signals based on
the sum of the third information signal received through the
third antenna and the fourth information signal received
through the fourth antenna, and thus it is easy to 5 receive
energy of signals coming at all polarization angles without
omission.
(A7) The wireless communication system is configured such
that extraction of the partial region information and
10 detection of the phase shift of the partial region information
are performed based on the third information signal received
through the third antenna, and extraction of the partial
region information and detection of the phase shift of the
partial region information are performed based on the fourth
15 information signal received through the fourth antenna, and
thus when the information signal arrives via a plurality of
transmission paths between transmission and reception, it is
easy to identify the phase shift of the partial region
information, that is, identify the transmission path through
20 which the information signal passed.
(A8) The wireless communication system is configured such
that the change in the radio wave propagation environment that
rarely occurs over time is dealt with through the process by
the first demodulating circuit 37 whose operation amount is
25 large (the process of extracting the start timing of the
entire reception signal), and the other small changes are
58
dealt with through the process by the second demodulating
circuit 54 (the process of extracting the start timings of the
partial regions), and thus it is possible to significantly
reduce the digital signal processing amount of the entire
receiver and increase the extraction speed of the start 5 timing.
[0111]
(Second embodiment)
Next, a second embodiment of the present invention will
be described.
10 The present embodiment will be described in connection
with an example in which the configuration of the carrier wave
superimposing unit 7 in the transmitter 1001 of the first
embodiment is modified.
[0112]
15 FIG. 3A is a configuration diagram of a transmitter 1002
of the second embodiment. In the transmitter 1002, a carrier
wave superimposing unit 7 is configured to include a carrier
wave generating circuit 11, a second multiplier 12, a sine
wave generating device 301 of a frequency fr, a third
20 multiplier 302, and a 90 phase shift circuit 303 corresponding
to the frequency fr. The remaining configuration is the same
as that of the transmitter 1001 of the first embodiment. The
same components as in FIG. 2A described above are denoted by
the same reference numerals, and description thereof is
25 omitted.
[0113]
59
An output of the sine wave generating device 301 of the
frequency fr is superimposed on an output of the second
multiplier 12 through the third multiplier 302. A signal on
which the sine wave of the frequency fr is superimposed is
bifurcated into two. One of the signals is radiated 5 into the
air through a first transmitting antenna 8. The other
bifurcated signal is radiated into the air from the second
transmitting antenna 9 through the 90 phase shift circuit 303
corresponding to the frequency fr.
10 [0114]
Since the envelope of the amplitude of the signal on
which the sine wave of the frequency fr different from the
carrier wave frequency is superimposed is configured with the
sine wave of frequency fr, it is radiated into the air with a
15 difference of 90 spatially and temporally, and thus it is
possible to generate the electromagnetic wave in which the
polarization vector rotates at the frequency fr, similarly to
the first embodiment.
[0115]
20 According to the second embodiment, compared with the
transmitter 1001 of the first embodiment of FIG. 2A, the sine
weighting circuit 14 and the cosine weighting circuit 13 which
are generally configured with a non-linear circuits can be
deleted, and the transmitter can be implemented using the
25 simple phase shift circuit 303. Thus, it is effective in
reducing the device cost of the transmitter.
60
[0116]
(Third embodiment)
Next, a third embodiment of the present invention will be
described.
The present embodiment will be described 5 in connection
with another example in which the configuration of the carrier
wave superimposing unit 7 in the transmitter 1001 of the first
embodiment is modified will be described.
[0117]
10 FIG. 3B is a configuration diagram of a transmitter 1003
of the third embodiment. In the transmitter 1003, a carrier
wave superimposing unit 7 is configured to include a carrier
wave generating circuit 11, a second multiplier 12, a sine
wave generating device 311 of a frequency fr, a third
15 multiplier 302, a cosine wave generating device 312 of the
frequency fr, and a fourth multiplier 313. The remaining
configuration is the same as that of the transmitter 1001 of
the first embodiment. The same components as those in FIGS. 2A
and 3A described above are denoted by the same reference
20 numerals, and description thereof is omitted.
[0118]
An output of the second multiplier 12 is bifurcated into
two, and an output of the sine wave generating device 311 of
the frequency fr is superimposed on one bifurcated signal
25 through the third multiplier 302 and radiated into the air
from through first transmitting antenna 8. An output of the
61
cosine wave generating device 312 of the frequency fr is
superimposed on the other signal bifurcated from the second
multiplier 12 through the fourth multiplier 313 and radiated
into the air through the second transmitting antenna 9.
5 [0119]
As described above in the second embodiment, Since the
envelope of the amplitude of the signal on which the frequency
fr different from the carrier wave frequency is superimposed
is configured with the sine wave of frequency fr, it is
10 radiated into the air with a difference of 90 spatially and
temporally, and thus it is possible to generate the
electromagnetic wave in which the polarization vector rotates
at the frequency fr, similarly to the first embodiment.
[0120]
15 According to the third embodiment, since the 90 phase
shift circuit 303 which is large in a physical dimension is
not used when the rotation frequency fr of the polarization
vector is small, the size of the transmitter 1003 can be
realized to be smaller than in the second embodiment.
20 [0121]
(Fourth embodiment)
Next, a fourth embodiment of the present invention will
be described.
In a transmitter 1004 of the present embodiment, an
25 example in which the configuration of the carrier wave
superimposing unit 7 in the transmitter 1001 of the first
62
embodiment is modified will be described. Further, in the
receiver 2004 of the present embodiment, an example in which
the carrier wave removing unit 23 in the receiver 2001 of the
first embodiment is modified will be described.
5 [0122]
FIG. 4A is a configuration diagram of the transmitter
1004 of the fourth embodiment. In the transmitter 1004, a
carrier wave superimposing unit 7 is configured to include a
first carrier wave generating circuit 401 of a frequency fc1,
10 a second multiplier 12, a second carrier wave generating
circuit 402 of the frequency fc2, a third multiplier 302, a
transmission synthesizing circuit 403, and a 90 phase shift
circuit 303. The remaining configuration is the same as that
of the transmitter 1001 of the first embodiment. The same
15 components as those in FIGS. 2A, 3A, and 3B described above
are denoted by the same reference numerals, and description
thereof is omitted.
[0123]
FIG. 4B is a configuration diagram of the receiver 2004
20 according to the fourth embodiment. In the receiver 2004, a
carrier wave removing unit 23 is configured to include a local
signal generating circuit 32 of the frequency fc1, a first
mixer 31a, a first analog filter 33a, a third local signal
generating circuit 426 of the frequency fc2, a third mixer 423,
25 a third analog filter 428, a first receiving synthesizing
circuit 421, a second local signal generating circuit 425 of
63
the frequency fc1, a second mixer 31b, a second analog filter
33b, a fourth local signal generating circuit 427 of the
frequency fc2, a fourth mixer 424, a fourth analog filter 429,
and a second reception synthesizing circuit 422. The remaining
configuration is the same as that of the receiver 2001 5 001 of the
first embodiment. The same components as those in FIG. 2B
described above are denoted by the same reference numerals,
and description thereof is omitted.
[0124]
10 In the transmitter 1004, an output of the encoding unit 6
is bifurcated into two. An output of the first carrier wave
generating circuit 401 of the frequency fc1 is superimposed on
one bifurcated signal through the second multiplier 12. An
output of the second carrier wave generating circuit 402 of
15 the frequency fc2 is superimposed on the other bifurcated
signal through the third multiplier 302. The frequencies fc1
and fc2 has a relation I which 1/2 of a difference between fc1
and fc2 is the frequency fr (fr = |fc1 - fc2|/2). The output
of the second multiplier 12 and the output of the third
20 multiplier 302 are synthesized by a transmission synthesizing
circuit 403 and then bifurcated into two. One bifurcated
signal is radiated into the air through the first transmitting
antenna 8. The other bifurcated signal is radiated into the
air through the second transmitting antenna 9 via the 90 phase
25 shift circuit 303 corresponding to the frequency fr = |fc1 -
fc2|/2.
64
[0125]
In the receiver 2004, the reception signal received from
the first receiving antenna 21 is bifurcated into two. One
bifurcated reception signal is multiplied by the output of the
first local signal generating circuit 32 through the 5 first
mixer 31a, the carrier wave frequency is then removed through
the first analog filter 33a, and then the resulting signal
functions as one input of the first receiving synthesizing
circuit 421.
10 [0126]
The other bifurcated reception signal is multiplied by
the output of the third local signal generating circuit 426
through the third mixer 423, the carrier wave frequency is
then removed through the third analog filter 428, and then the
15 resulting signal functions as the other input of the first
receiving synthesizing circuit 421. An output of the first
receiving synthesizing circuit 421 functions as the input A of
the FPGA 3001 illustrated in FIG. 2B.
[0127]
20 The reception signal received from the second receiving
antenna 22 is bifurcated into two. One bifurcated reception
signal is multiplied by the output of the second local signal
generating circuit 425 through the second mixer 31b, the
carrier wave frequency is then removed through the second
25 analog filter 33b, and then the resulting signal function as
one input of the second reception synthesizing circuit 422.
65
[0128]
The other bifurcated reception signal is multiplied by
the output of the fourth local signal generating circuit 427
through the fourth mixer 424, the carrier wave frequency is
then removed through the fourth analog filter 429, and 5 then
the resulting signal function as the other input of the second
reception synthesizing circuit 422. An output of the second
reception synthesizing circuit 422 functions as the input B of
the FPGA 3001 illustrated in FIG. 2B.
10 [0129]
In the first embodiment, the high-frequency circuit using
the frequency fr (the frequency at which the polarization
vector rotates) belonging to a frequency band (for example, 1
MHz) different from the carrier wave frequency (for example,
15 400 MHz) is necessary. On the other hand, in the present
embodiment, the transmitter and the receiver preferably
include the high frequency circuit using the frequencies (fc1
and fc2) of the two carrier waves belonging to the same
frequency band, and the high frequency circuit using frequency
20 fr is not necessary.
[0130]
As described above, in the present embodiment, the
transmitter is configured to bifurcate the transmission
information encoded using the first code and the second code
25 using the frequencies f1 and f2 in which 1/2 of the difference
between the frequency f1 and the frequency f2 is the frequency
66
fr, generate the first signal by causing the carrier wave of
the frequency f1 to be superimposed on one bifurcated
transmission information, generate the second signal by
causing the carrier wave of the frequency f2 to be
superimposed on the other of the bifurcated 5 transmission
information, and generate the cosine wave signal of the
frequency fr and the sine wave signal of the frequency fr by
synthesizing the first signal and the second signal and thus
the transmitter and the receiver do not include an oscillator
10 of the frequency fr which is a frequency band different from
the frequency band of the carrier wave. Thus, in the present
embodiment, in addition to the same effect as in the first
embodiment, an effect of suppressing external radiation
(spurious radiation) of an unnecessary frequency band
15 generated in a radio is obtained.
[0131]
(Fifth embodiment)
Next, a fifth embodiment of the present invention will be
described.
20 In a transmitter 1005 of the present embodiment, another
example which the configuration of the carrier wave
superimposing unit 7 in the transmitter 1004 of the fourth
embodiment is modified will be described. A wireless signal
transmitted from the transmitter 1005 of the present
25 embodiment can be received by the receiver 2004 of the fourth
embodiment.
67
[0132]
FIG. 5 is a configuration diagram of the transmitter 1005
of the fifth embodiment. In the transmitter 1005, a carrier
wave superimposing unit 7 is configured to include a first
carrier wave generating circuit 401 of the frequency fc1, 5 , a
second multiplier 12, a second carrier wave generating circuit
402 of the frequency fc2, a third multiplier 302, a
transmission synthesizing circuit 403, a third carrier wave
generating circuit 501 of the frequency fc1, a second 90 phase
10 shift circuit 505 of the frequency fc1, a fourth multiplier
313, a fourth carrier wave generating circuit 502 of the
frequency fc2, a third 90 phase shift circuit 506
corresponding to the frequency fc2, a fifth multiplier 503,
and a second transmission synthesizing circuit 504. The
15 remaining configuration is the same as that of the transmitter
1004 of the fourth embodiment. The same components as those in
FIGS. 2A, 3A, 3B, and 4A described above are denoted by the
same reference numerals, and description thereof is omitted.
[0133]
20 An output of the encoding unit 6 is bifurcated into two
systems, and one of the bifurcated systems is further
bifurcated into B1 and B2. An output of the first carrier wave
generating circuit 401 of the frequency fc1 is superimposed on
a signal of B1 of one bifurcated system through the second
25 multiplier 12. An output of the second carrier wave generating
circuit 402 of the frequency fc2 is superimposed on a signal
68
of B2 of the other bifurcated system through the third
multiplier 302. The frequency fc1 and frequency fc2 have a
relation of the frequency fr = |Fc1 - fc2|/2. The output of
the second multiplier 12 and the output of the third
multiplier 302 are synthesized through the first 5 transmission
synthesizing circuit 403 and then radiated into the air
through the first transmitting antenna 8.
[0134]
The other bifurcated system of the output of the encoding
10 unit 6 is further bifurcated to B3 and B4. An output of the
third carrier wave generating circuit 501 of the frequency fc1
is superimposed on a signal of B3 of one bifurcated system by
the fourth multiplier 313 via the second 90 phase shift
circuit 505. An output of the fourth carrier wave generating
15 circuit 502 of frequency fc2 is superimposed on a signal of B4
of the other bifurcated system through the fifth multiplier
503 via the third 90 phase shift circuit 506. The output of
the fourth multiplier 313 and the output of the fifth
multiplier 503 are synthesized through the second transmission
20 synthesizing circuit 504 and then radiated into the air
through the second transmitting antenna 9.
[0135]
According to the present embodiment, similarly to the
fourth embodiment of FIG. 4A, the transmitter does not include
25 the oscillator of the frequency fr which is a frequency band
different from the frequency band of the carrier wave, and
69
thus there is an effect of suppressing external radiation
(spurious Radiation) of an unnecessary frequency band.
[0136]
In the fourth embodiment of FIG. 4A, a large phase shift
amount corresponding to the frequency fr of the rota5 ry
polarized wave is necessary in the phase shift circuit 303. On
the other hand, since the phase shift circuits 505 and 506 of
the present embodiment is a phase shift circuit of a carrier
wave frequency of a higher frequency than the frequency fr,
10 and a phase shift amount thereof is extremely small. A ratio
of the phase shift amount of the phase shift circuit of the
present embodiment and the phase shift amount of the phase
shift circuit of the fourth embodiment is substantially equal
to a ratio of the carrier wave frequency and the frequency fr
15 of the polarized wave. Thus, in the present embodiment, there
is an effect in that the size of the transmitter can be
reduced.
[0137]
(Sixth embodiment)
20 Next, a sixth embodiment of the present invention will be
described.
In a transmitter 1006 of the present embodiment, another
example in which the configuration of the carrier wave
superimposing unit 7 in the transmitter 1005 of the fifth
25 embodiment is modified will be described. A wireless signal
transmitted from the transmitter 1006 of the present
70
embodiment can be received by the receiver 2004 of the fourth
embodiment.
[0138]
FIG. 6 is a configuration diagram of the transmitter 1006
according to the sixth embodiment. In the transmitter 1006, 5 a
carrier wave superimposing unit 7 is configured to include a
first digital cosine wave signal generating circuit 601 of the
frequency fc1, a first transmission delta sigma circuit 602, a
first transmission digital filter 603, a second multiplier 12,
10 a second digital cosine wave signal generating circuit 604 of
the frequency fc2, a second transmission delta sigma circuit
605, a second transmission digital filter 606, a third
multiplier 302, a transmission synthesizing circuit 403, a
first digital sine wave signal generating circuit 611 of the
15 frequency fc1, a third transmission delta sigma circuit 612, a
third transmission digital filter 613, a fourth multiplier 313,
a second digital sine wave signal generating circuit 614 of
the frequency fc2, a fourth transmission delta sigma circuit
615, a fourth transmission digital filter 616, a fifth
20 multiplier 503, and a second transmission synthesizing circuit
504. The remaining configuration is the same as that of the
transmitter 1005 of the fifth example. The same components as
those in FIG. 2A, 3A, 3B, 4A, and 5 are denoted by the same
reference numerals, and description thereof is omitted.
25 [0139]
An output of the encoding unit 6 is bifurcated into two
71
systems, and one of the bifurcated systems is further
bifurcated into B1 and B2. An output C1 of the first
transmission digital filter 603 is superimposed on a signal of
B1 of one bifurcated system through the second multiplier 12.
The first digital cosine wave signal generating circuit 5 601,
the first transmission delta sigma circuit 602, and the first
transmission digital filter 603 that generate the carrier wave
of the frequency fc1 are cascade-connected, an output of the
first digital cosine wave signal generating circuit 601 is
10 input to the first transmission delta sigma circuit 602, and
an output of the first transmission delta sigma circuit 602 is
input to the first transmission digital filter 603.
[0140]
An output C2 of the second transmission digital filter
15 606 is superimposed on a signal of B2 of the other bifurcated
system through by the third multiplier 302. The second digital
cosine wave signal generating circuit 604, the second
transmission delta sigma circuit 605, and the second
transmission digital filter 606 that generate the carrier wave
20 of the frequency fc2 are cascade-connected, an output of the
second digital cosine wave signal generating circuit 604 is
input to the second transmission delta sigma circuit 605, and
an output of the second transmission delta sigma circuit 605
is the second transmission digital filter 606.
25 [0141]
An output of the second multiplier 12 and an output of
72
the third multiplier 302 are synthesized through the first
transmission synthesizing circuit 403 and then radiated into
the air through the first transmitting antenna 8. The
frequency fc1 and the frequency fc2 have a relationship of the
frequency fr = |fc1 - fc2|/5 2.
[0142]
The other bifurcated system of the output of the encoding
unit 6 is further bifurcated to B3 and B4. An output C3 of the
third transmission digital filter 613 is superimposed on a
10 signal of B3 of one bifurcated system through the fourth
multiplier 313. The first digital sine wave signal generating
circuit 611, the third transmission delta sigma circuit 612,
and the third transmission digital filter 613 that generate
the carrier wave of the frequency fc1 are cascade-connected,
15 an output of the first digital sine wave signal generating
circuit 611 is input to the third transmission delta sigma
circuit 612, and an output of the third transmission delta
sigma circuit 612 is input to the third transmission digital
filter 613.
20 [0143]
An output C4 of the fourth transmission digital filter
616 is superimposed on a signal of B4 of the other bifurcated
system through the fifth multiplier 503. The second digital
sine wave signal generating circuit 614, the fourth
25 transmission delta sigma circuit 615, and the fourth
transmission digital filter 616 that generate the carrier wave
73
of frequency fc2 are cascade-connected, an output of the
second digital sine wave signal generating circuit 614 is
input to the fourth transmission delta sigma circuit 615, and
an output of the fourth transmission delta sigma circuit 615
is 5 the fourth transmission digital filter 616.
[0144]
An output of the fourth multiplier 313 and an output of
the fifth multiplier 503 are synthesized through the second
transmission synthesizing circuit 504 and then radiated into
10 the air through the second transmitting antenna 9. The
remaining circuits of the transmitter 1006 excluding the two
transmitting antennas 8 and 9 are in an FPGA 3006.
[0145]
In the present embodiment, since the transmitter is
15 configured to generate the cosine wave signal of the frequency
fr and the sine wave signal of the frequency fr using the
discrete-time delta sigma circuit, all the circuits excluding
the antennas 8 and 9 can be installed in an FPGA 3006. Thus,
the size of the transmitter can be reduced to be much smaller
20 than the transmitter 1005 of the fifth embodiment.
[0146]
(Seventh embodiment)
Next, a seventh embodiment of the present invention will
be described.
25 In a receiver 2007 of the present embodiment, an example
in which the configuration of the carrier wave removing unit
74
23 in the receiver 2001 of the first embodiment is modified
will be described. The receiver 2007 of the present embodiment
can be receive the wireless signal which is transmitted from
the transmitter 1004 of the fourth embodiment, the transmitter
1005 of the fifth embodiment, or the transmitter 1006 of 5 the
sixth embodiment.
[0147]
FIG. 7 is a configuration diagram of the receiver 2007
according to the seventh embodiment. In the receiver 2007, a
10 carrier wave removing unit 23 is configured to include a first
reception analog filter 33a, a first delta sigma adder circuit
716, a first delta sigma analog filter 715, a first delta
sigma comparator 714, a second delta sigma adder circuit 726,
a second delta sigma analog filter 725, a second delta sigma
15 comparator 724, a second reception analog filter 33b, a third
delta sigma adder circuit 736, a third delta sigma analog
filter 735, a third delta sigma comparator 734, a fourth delta
sigma adder circuit 746, a fourth delta sigma analog filter
745, a fourth delta sigma comparator 744, a first internal
20 clock 711, a first delta sigma quantizer 712, a first delta
sigma sample hold circuit 713, a second internal clock 721, a
second delta sigma quantizer 722, a second delta sigma sample
hold circuit 723, a synthesizing circuit 727, a third internal
clock 731, a third delta sigma quantizer 732, a third delta
25 sigma sample hold circuit 733, a fourth internal clock 741, a
fourth delta sigma quantizer 742, a fourth delta sigma sample
75
hold circuit 743, and a synthesizing circuit 747. The
remaining configuration is the same as that of the receiver
2001 of the first embodiment. The same components as those in
FIG. 2B described above are denoted by the same reference
5 numerals, and description thereof is omitted.
[0148]
Further, the first internal clock 711, the first delta
sigma quantizer 712, the first delta sigma sample hold circuit
713, the second internal clock 721, the second delta sigma
10 quantizer 722, the second delta sigma sample hold circuit 723,
the synthesizing circuit 727, the third internal clock 731,
the third delta sigma quantizer 732, the third delta sigma
sample hold circuit 733, the fourth internal clock 741, the
fourth delta sigma quantizer 742, the fourth delta sigma
15 sample hold circuit 743, and the synthesizing circuit 747
among the components of the carrier wave removing unit 23 are
included in the FPGA 3007.
[0149]
In the receiver 2007, the reception signal received from
20 the first receiving antenna 21 is bifurcated into two through
the first reception analog filter 33a. One bifurcated
reception signal is connected to an input A of the FPGA 3007
via a cascade connection of the first delta sigma adder
circuit 716, the first delta sigma analog filter 715 that
25 operates at the frequency fc1 (in detail, increases a pass
level of a frequency component of fc1), and the first delta
76
sigma comparator 714.
[0150]
The other bifurcated reception signal is connected to an
input A' of the FPGA 3007 via a cascade connection of the
second delta sigma adder circuit 726, the second delta 5 sigma
analog filter 725 that operates at the frequency fc2, and the
second delta sigma comparator 724.
[0151]
The reception signal received from the second receiving
10 antenna 22 is bifurcated into two through the second reception
analog filter 33b. One bifurcated reception signals is
connected to an input B of the FPGA 3007 via cascade
connection of the third delta sigma adder circuit 736, the
third delta sigma analog filter 735 that operates at the
15 frequency fc1, and the third delta sigma comparator 734.
[0152]
The other bifurcated reception signal is connected to an
input B' of the FPGA 3007 via a cascade connection of the
fourth delta sigma adder circuit 746, the fourth delta sigma
20 analog filter 745 that operates at the frequency fc2, and the
fourth delta sigma comparator 744.
[0153]
The FPGA 3007 converts the signal of the input A into a
discrete signal through the first delta sigma quantizer 712
25 which is connected with the first internal clock 711, and
outputs the discrete signal to the synthesizing circuit 727.
77
Further, the FPGA 3007 adds the discrete signal to the input
of the first delta sigma adder circuit 716 as a continuous
signal via the first delta sigma sample hold circuit713.
[0154]
The FPGA 3007 converts the signal of the input A' into 5 a
discrete signal through the second delta sigma quantizer 722
which is connected with the second internal clock 721 and
outputs the discrete signal to the synthesizing circuit 727.
Also, the FPGA 3007 adds the discrete signal to the input of
10 the second delta sigma adder circuit 726 as a continuous
signal via the second delta sigma sample hold circuit 723. An
output of the synthesizing circuit 727 reaches an internal
point C of the FPGA 3007.
[0155]
15 The FPGA 3007 converts the signal of the input B into a
discrete signal through the third delta sigma quantizer 732
which is connected with the third internal clock 731 and
outputs the discrete signal to the synthesizing circuit 747.
The FPGA 3007 adds the discrete signal to the input of the
20 third delta sigma adder circuit 736 as a continuous signal via
the third delta sigma sample hold circuit 733.
[0156]
Further, the FPGA 3007 converts a signal of the input B'
into a discrete signal through the fourth delta sigma
25 quantizer 742 which is connected with the fourth internal
clock 741, and outputs the discrete signal to the synthesizing
78
circuit 747. Further, the FPGA 3007 adds the discrete signal
to the input of the fourth delta sigma adder circuit 746 as a
continuous signal via the fourth delta sigma sample hold
circuit 743. An output of the synthesizing circuit 747 reaches
an 5 internal point D of the FPGA 3007.
[0157]
The internal point C and the internal point D of the FPGA
3007 are located at the same positions as the internal point C
and the internal point D of the FPGA 3001 in FIG. 2B. In other
10 words, the configuration of the FPGA 3007 after the internal
point C and internal point D is the same as the configuration
of the FPGA 3001 after the inner point C and the inner point D.
The input A and the input B of the FPGA 3007 are different
from the input A and the input B of the FPGA 3001 as apparent
15 from FIG. 7.
[0158]
In the present embodiment, since the receiver is
configured to remove the carrier wave from the wireless
signals received by the third antenna and the fourth antenna
20 using the continuous-time delta sigma circuit, the carrier-tonoise
ratio of the signal input to the receiver can be
improved through the noise shaving function of the delta sigma
circuit (the above-described components 711 to 716, 721 to 726,
731 to 736, and 741 to 746), and the reception sensitivity of
25 the receiver can be improved.
[0159]
79
Next, an example of a transmitter having two systems each
of which includes the first code generating unit 1, the second
code generating unit 2, the third code storage unit 3,
transmission information generating unit 4, the third encoding
unit 5, and the encoding unit 6 of FIG. 1 will be described 5 in
eighth and ninth embodiments. Further, an example of a
receiver having two systems each of which includes the
synchronization detecting unit 24 and the partial region
information extracting unit 25 of FIG. 1 will be described in
10 a tenth embodiment.
[0160]
(Eighth embodiment)
An eighth embodiment of the present invention will be
described.
15 In a transmitter 1007 of the present embodiment, an
example of a transmitter having two systems each of which
includes the first code generating unit 1, the second code
generating unit 2, the third code storage unit 3, the
transmission information generating unit 4, the third encoding
20 unit 5, and the encoding unit 6 of FIG. 4A in the transmitter
1004 of the fourth embodiment will be described. A wireless
signal transmitted from the transmitter 1007 of the present
embodiment can be received by a receiver 2008 of the tenth
embodiment to be described later.
25 [0161]
FIG. 8A is a configuration diagram of the transmitter
80
1007 of the eighth embodiment. The same components as those in
FIG. 4A described above are denoted by the same reference
numerals, and description thereof is omitted.
In the transmitter 1007, the components 1 to 6 of the
transmitter 1004 of FIG 4A are duplexed. In other words, 5 , the
components 1' to 6' are provided, separately from the
components 1 to 6. The components 1' to 6' have the same
functions as the components 1 to 6, respectively. However, the
information I' generated by the component 4' (the transmission
10 information generating unit) is different from the information
I generated by the transmission information generating unit 4,
and the frequency fI1 of the information signal of the
component 4' is different from the frequency fI2 of the
information signal of the component 4.
15 [0162]
The output of the component 6 is input to the third
multiplier 302, and the output of the component 6' is input to
the second multiplier 12. The remaining components of the
transmitter 1007 (the first carrier wave generating circuit
20 401, the second multiplier 12, the second carrier wave
generating circuit 402, the third multiplier 302, the
transmission synthesizing circuit 403, the 90 phase shift
circuit 303, the first transmitting antenna 8, and the second
transmitting antenna 9) are similar to the components of the
25 transmitter 1004 in FIG. 4A.
[0163]
81
According to the present embodiment, it is possible to
perform a signal process similar to that of the transmitter
1004 of FIG. 4A on different frequencies of the frequencies
fc1 and fc2. In the transmitter 1007 of FIG. 8A, signals of
the different carrier wave frequencies fc1 and fc2 5 are
superimposed on the information signal of the low frequency
region which is regarded to be constant, compared to the
frequency fr of the rotary polarized wave and the first code
or the frequency of the second code. Since the signals
10 transmitted at the different frequencies fc1 and fc2 are
independent from each other, information decoded by a system
of fc1 (a system of C-D) and information decoded by a system
of fc2 (a system of C'-D') in the receiver 2008 of the tenth
embodiment to be described later are also independent from
15 each other, and the receiver side can easily reconstruct the
information I and the information I' transmitted from the
transmitter 1007 of FIG. 8A through the digital filter.
Therefore, according to the present embodiment, an information
transmission amount from the transmitter to the receiver can
20 be doubled. Alternatively, when the information I and the
information I' have the same content, a communication quality
between transmission and reception can be improved.
[0164]
(Ninth embodiment)
25 Next, a ninth embodiment of the present invention will be
described.
82
In a transmitter 1008 of the present embodiment, an
example in which two systems each of which includes the first
code generating unit 1, the second code generating unit 2, the
third code storage unit 3, the transmission information
generating unit 4, the third encoding unit 5, and the 5 encoding
unit 6 of FIG. 5 in the transmitter 1005 of the fifth
embodiment are provided will be described. A wireless signal
transmitted from the transmitter 1008 of the present
embodiment can be received by the receiver 2008 of the tenth
10 embodiment to be described later.
FIG. 8B is a configuration diagram of the transmitter
1008 of the ninth embodiment. The same components as those in
FIG. 5 described above are denoted by the same reference
numerals, and description thereof is omitted.
15 [0165]
In the transmitter 1008 of FIG. 8B, the components 1 to 6
of the transmitter 1005 of FIG. 5 are duplexed. In other words,
the components 1' to 6' are provided, separately from the
components 1 to 6. The components 1' to 6' have the same
20 function as the components 1 to 6. However, the information I'
generated by the component 4' (the transmission information
generating unit) is different from the information I generated
by the transmission information generating unit 4, and the
frequency fI1 of the information signal of the component 4' is
25 different from the frequency fI2 of the information signal of
the component 4. The frequency fI1 and fI2 of the information
83
signal are limited to be low enough to be regarded to be
constant compared with the carrier wave frequencies fc1 and
fc2 and the frequency fr of the rotary polarized wave (that is,
the frequency of the first code).
5 [0166]
An output from component 6 is input to the third
multiplier 302 and the fifth multiplier 503, and an output
from component 6' is input to the second multiplier 12 and the
fourth multiplier 313. The remaining components of transmitter
10 1008 (the first carrier wave generating circuit 401, the
second multiplier 12, the second carrier wave generating
circuit 402, the third multiplier 302, transmission
synthesizing circuit 403, the third carrier wave generating
circuit 501, the second 90 phase shift circuit 505, the fourth
15 multiplier 313, the fourth carrier wave generating circuit 502,
the third 90 phase shift circuit 506, the fifth multiplier 503,
the second transmission synthesizing circuit 504, the first
transmitting antenna 8, and the second transmitting antenna 9)
are similar to the components of the transmitter 1005 in FIG.
20 5.
[0167]
Thus, the transmitter 1008 can wirelessly transmit the
information I from the component 4 and the information I' from
the component 4' simultaneously through the antenna 8 and the
25 antenna 9.
[0168]
84
According to the present embodiment, it is possible to
perform a signal process similar to that of the transmitter
1005 of FIG. 5 on different frequencies of the frequencies fc1
and fc2. In the transmitter 1008 of FIG. 8B, similarly to the
transmitter 1007 of FIG. 8A, signals of the different 5 erent carrier
wave frequencies fc1 and fc2 are superimposed on the
information signal of the low frequency region which is
regarded to be constant, compared to the frequency fr of the
rotary polarized wave and the first code or the frequency of
10 the second code. Since the signals transmitted at the
different frequencies fc1 and fc2 are independent from each
other, information decoded by a system of fc1 (a system of CD)
and information decoded by a system of fc2 (a system of C'-
D') in the receiver 2008 of the tenth embodiment to be
15 described later are also independent from each other, and the
receiver side can easily reconstruct the information I and the
information I' transmitted from the transmitter 1008 of FIG.
8B through the digital filter. Therefore, according to the
present embodiment, an information transmission amount from
20 the transmitter to the receiver can be doubled, or the
communication quality between transmission and reception can
be improved.
[0169]
The transmitter 1006 of the sixth embodiment can be
25 configured to include the two systems each of which includes
the first code generating unit 1, the second code generating
85
unit 2, the third code storage unit 3, the transmission
information generating unit 4, the third encoding unit 5, and
the encoding unit 6. A wireless signal transmitted from the
transmitter 1008 having this configuration can be received by
the receiver 2008 of the tenth embodiment to be 5 described
later.
[0170]
In this case, similarly to the configuration in which the
output of the component 6 and the output of the component 6'
10 are connected to the carrier wave superimposing unit 7 of FIG.
5 in the transmitter 1008 of the ninth embodiment, the output
of the component 6 and the output of the component 6' are
connected to the carrier wave superimposing unit 7 of FIG. 6
in the transmitter 1008. In other words, the output from
15 component 6 is input to the third multiplier 302 and the fifth
multiplier 503, and the output from component 6' is input to
the second multiplier 12 and the fourth multiplier 313. The
remaining components of the transmitter 1009 are similar to
those of the transmitter 1006 of FIG. 6.
20 [0171]
In this case, similarly to the ninth embodiment, the
reception side can easily reconstruct the information I and
the information I' transmitted from the transmitter 1008
through the digital filter. Thus, an information transmission
25 amount from the transmitter to the receiver can be doubled, or
the communication quality between transmission and reception
86
can be improved.
[0172]
(Tenth Example)
Next, a tenth embodiment of the present invention will be
5 described.
In the receiver 2008 of the present embodiment, an
example in which two systems each of which includes the
synchronization detecting unit 24 and the partial region
information extracting unit 25 of FIG. 1 are provided in the
10 receiver 2007 of the seventh embodiment will be described.
FIG. 8C is a configuration diagram of the receiver 2008
of the tenth embodiment. The same components as those in FIG.
7 described above are denoted by the same reference numerals,
and description thereof is omitted.
15 [0173]
An FPGA 3008 with which the receiver 2008 is equipped has
two functions of the synchronization detecting unit 24 and the
partial region information extracting unit 25 of FIG. 1, and
These functions are performed in parallel. In other words, two
20 systems each of which include the first adder 34, the first
variable delay circuit 35, the first exclusive OR operation
circuit 36, the first demodulating circuit 37, the
synchronization code generating circuit 38, the second
variable delay circuit 41a, and the third variable delay
25 circuit 41b in the FPGA 3007 of FIG. 7 are provided, and these
functions are performed in parallel.
87
[0174]
In the FPGA 3008, the components 711 to 716, the
components 721 to 726, the components 731 to 736, and the
components 741 to 746 are the same as the components having
the same numerals in the FPGA 3007 in FIG. 7, and 5 d performs the
same operations as those in the FPGA 3007. However, the
synthesizing circuit 727 and the synthesizing circuit 747 in
the FPGA 3007 are not included in the FPGA 3008, and a
connection destination of the output of the first delta sigma
10 quantizer 712, a connection destination of the output of the
second delta sigma quantizer 722, and a connection destination
of the output of the third delta sigma quantizer 732, and a
connection destination of the output of the fourth delta sigma
quantizer 742 are different from those in the FPGA 3007.
15 [0175]
In other words, in the FPGA 3008, the output of the first
delta sigma quantizer 712 arrives at the internal point C of
the FPGA 3007, is then bifurcated, and input to the first
adder 34 and the second variable delay circuit 41a. Further,
20 the output of the second delta sigma quantizer 722 arrives at
the internal point C', is then bifurcated, and input to the
first adder 34' and the second variable delay circuit 41a'.
Further, the output of the third delta sigma quantizer 732
arrives at the internal point D, is then bifurcated, and input
25 to the first adder 34 and the third variable delay circuit 41b.
Furthermore, the output of the fourth delta sigma quantizer
88
742 arrives at the internal point D', is then bifurcated, and
input to the first adder 34' and the third variable delay
circuit 41b'.
[0176]
According to the present embodiment, it is possible 5 ible to
perform a signal process similar to that of the transmitter
1004 of FIG. 4A or the receiver 2007 of FIG. 7 on different
frequencies of the frequencies fc1 and fc2. Since the signals
transmitted at the different frequencies fc1 and fc2 from the
10 transmitter 1007 of FIG. 8A and the transmitter 1008 of FIG.
8B are independent from each other, information decoded by a
system of fc1 (a system of C-D) and information decoded by a
system of fc2 (a system of C'-D') of FIG. 8C are also
independent from each other, and it is possible to easily
15 reconstruct the information I and the information I'
transmitted from the transmitter 1007 of FIG. 8A or the
transmitter 1008 of FIG. 8B through the digital filter of the
receiver 2008. Therefore, according to the present embodiment,
an information transmission amount from the transmitter to the
20 receiver can be doubled, and the communication quality between
transmission and reception can be improved.
[0177]
(Eleventh embodiment)
Next, an eleventh embodiment of the present invention
25 will be described. In the preset embodiment, an exemplary
configuration of a communication system using a transceiver to
89
which the wireless system of the present invention is applied
will be described. FIG. 10 is an example of a configuration
diagram of an elevator system to which a polarization angle
division diversity radio according to the present invention is
5 applied.
[0178]
In an elevator system 100 of the present embodiment, the
elevating car 111 moves up and down in a building 101. A base
station radio 103a and a base station two-orthogonal
10 polarization integrated antenna 102a according to the present
invention are installed to be coupled to a floor in the
building 101. A base station radio 103b and a base station
two-orthogonal polarization integrated antenna 102b according
to the present invention are installed to be coupled to a
15 ceiling in the building 101.
[0179]
Each of the base station radios 103a and 103b includes
the functions of the transmitter 1000 and the receiver 2000 of
FIG. 1. Each of the base station two-orthogonal polarization
20 integrated antennas 102a and 102b includes the first
transmitting antenna 8, the second transmitting antenna 9, the
first receiving antenna 21, and the second receiving antenna
22.
[0180]
25 A terminal station two-orthogonal polarization integrated
antenna 112 a is installed on an outer floor surface of the
90
elevating car 111 and coupled to a terminal radio 113 via a
high frequency cable 114. Further, a terminal station twoorthogonal
polarization integrated antenna 112b is installed
on an external ceiling of the elevating car 111 and is coupled
to the terminal radio 113 by the 5 high frequency cable 114.
[0181]
The terminal radio 113 has the functions of the
transmitter 1000 and the receiver 2000 of FIG. 1. Each of the
terminal station two-orthogonal polarization integrated
10 antennas 112a and 112b includes the first transmitting antenna
8, the second transmitting antenna 9, the first receiving
antenna 21, and the second receiving antenna 22 of FIG. 1.
[0182]
Since the base station radio 103 (103a and 103b) and the
15 terminal station radio 113 use as the inside of the building
101 as a wireless transmission medium, the electromagnetic
waves transmitted between the base station radio 103 and the
terminal station radio 113 undergo multiple reflection by the
inner wall of the building 101 and the outer wall of the
20 elevating car 111, and thus a multi-wave interference
environment is formed.
[0183]
In the present embodiment, since the present invention is
applied to the base station radio 103 and the terminal station
25 radio 113, high secure wireless transmission can be
implemented even under the multi-wave interference environment.
91
Thus, it is possible to control and monitor the elevating car
111 remotely from the building 101 side through a wireless
connection means using the base station radio 103 and the
terminal station radio 113. Thus, since it is unnecessary to
use a wired connection means such as a cable between 5 the
elevating car 111 and the base station radio 103, it is
possible to implement the same transportation capability in a
small building volume. Alternatively, the transportation
capability can be improved without increasing the size of the
10 elevator in the same building volume.
[0184]
(Twelfth embodiment)
Next, a twelfth embodiment of the present invention will
be described. In the present embodiment, an exemplary
15 configuration of a communication system using a transceiver to
which the wireless system of the present invention is applied
will be described. FIG. 11 is an example of a configuration
diagram of a substation monitoring system to which a
polarization angle division diversity radio according to the
20 present invention is applied.
[0185]
In a substation monitoring system 120 of the present
embodiment, a plurality of transformers 121 (12 in the example
of FIG. 11) and a plurality of base station devices 124 (4 in
25 the example of FIG. 11) which are smaller in number than the
transformers 121 are installed. The base station device 124 is
92
installed near a plurality of transformers 121.
[0186]
The terminal station radio 123 and the terminal station
two-orthogonal polarization integrated antenna 122 according
to the present invention are connected to and installed in 5 the
transformer 121. The base station radio 126 and the base
station two-orthogonal polarization integrated antenna 125
according to the present invention are connected to and
installed in the base station device 124.
10 [0187]
The terminal station radio 123 and the base station radio
126 include the functions of the transmitter 1000 and the
receiver 2000 of FIG 1, respectively. Each of the terminal
station two-orthogonal polarization integrated antenna 122 and
15 the base station two-orthogonal polarization integrated
antenna 125 includes the first transmitting antenna 8, the
second transmitting antenna 9, the first receiving antenna 21,
and the second receiving antenna 22.
[0188]
20 Since the size of the transformer is an order of several
meters and overwhelmingly larger than a wavelength
corresponding to the frequency of the electromagnetic wave
(several hundred MHz to several GHz) used by the terminal
station radio 123 and the base station radio 126, the
25 electromagnetic wave between the transformer 121 and the base
station devices 124 multiple reflection by a plurality of
93
transformers 121, and thus a multi-wave interference
environment is formed.
[0189]
In the present embodiment, since the present invention is
applied to the terminal station radio 123 and the base stat5 ion
radio 126, high secure wireless transmission can be
implemented even under the multi-wave interference environment.
Thus, it is possible to control and monitor the transformer
121 remotely from the base station device 124 through a
10 wireless connection means using the terminal station radio 123
and the base station radio 126. Thus, it is possible to solve
a problem of high voltage induction power which becomes a
problem when a wired connection means such as a cable is used
between the transformer 121 and the base station device 124,
15 and it is possible to reduce a laying cost of the cable, and
thus it is effective in a safety improvement and cost
reduction of a system of controlling and monitoring the
transformer 121.
[0190]
20 The present invention is not limited to the abovedescribed
embodiments, and it will be appreciated that various
modifications can be made without departing from the gist
thereof.
25 REFERENCE SIGNS LIST
[0191]
94
1 first code generating unit
2 second code generating unit
3 third code storage unit
4 transmission information generating unit
5 5 third encoding unit
6 encoding unit (first multiplier)
7 carrier wave superimposing unit
8 first transmitting antenna
9 second transmitting antenna
10 10 transmitting unit
15 electromagnetic wave
11 carrier wave generating circuit
12 second multiplier
13 cosine weighting circuit
15 14 sine weighting circuit
21 first receiving antenna
22 second receiving antenna
23 carrier wave removing unit
24 synchronization detecting unit
20 25 partial region information extracting unit
26 receiving unit
27 information decoding unit (decoding circuit)
28 information processing unit
31a first mixer
25 31b second mixer
32 local signal generating circuit
95
33a first analog filter
33b second analog filter
34 first adder
35 first variable delay circuit
36 5 first exclusive OR operation circuit
37 first demodulating circuit
38 synchronization code generating circuit
41a second variable delay circuit
41b third variable delay circuit
10 42a second exclusive OR operation circuit
42b third exclusive OR operation circuit
43 switch
44 switch
45 second adder
15 51 fourth variable delay circuit
52 fourth exclusive OR operation circuit
53 partial code generating circuit
54 second demodulating circuit
100 elevator system
20 101 building
102 base station two-orthogonal polarization integrated
antenna
103 base station radio
111 elevating car
25 112 terminal station two-orthogonal polarization integrated
antenna
96
113 terminal radio
114 high frequency cable
120 substation monitoring system
121 transformer
122 terminal station two-5 orthogonal polarization integrated
antenna
123 terminal station radio
124 base station device
125 base station two-orthogonal polarization integrated
10 antenna
126 base station radio
301 sine wave generating device
302 third multiplier
303 90 phase shift circuit
15 311 sine wave generating device
312 cosine wave generating device
313 fourth multiplier
401 first carrier wave generating circuit
402 second carrier wave generating circuit
20 403 transmission synthesizing circuit
421 first reception synthesizing circuit
422 second reception synthesizing circuit
423 third mixer
424 fourth mixer
25 425 second local signal generating circuit
426 third local signal generating circuit
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427 fourth local signal generating circuit
428 third analog filter
429 fourth analog filter
501 third carrier wave generating circuit
502 5 fourth carrier wave generating circuit
503 fifth multiplier
504 second transmission synthesizing circuit
505 second 90 phase shift circuit
506 third 90 phase shift circuit
10 601 first digital cosine wave signal generating circuit
602 first transmission delta sigma circuit
603 first transmission digital filter
604 second digital cosine wave signal generating circuit
605 second transmission delta sigma circuit
15 606 second transmission digital filter
611 first digital sine wave signal generating circuit
612 third transmission delta sigma circuit
613 third transmission digital filter
614 second digital sine wave signal generating circuit
20 615 fourth transmission delta sigma circuit
616 fourth transmission digital filter
711 first internal clock
712 first delta sigma quantizer
713 first delta sigma sample hold circuit
25 714 first delta sigma comparator
715 first delta sigma analog filter
98
716 first delta sigma adder circuit
721 second internal clock
722 second delta sigma quantizer
723 second delta sigma sample hold circuit
724 5 second delta sigma comparator
725 second delta sigma analog filter
726 second delta sigma adder circuit
727 synthesizing circuit
731 third internal clock
10 732 third delta sigma quantizer
733 third delta sigma sample hold circuit
734 third delta sigma comparator
735 third delta sigma analog filter
736 third delta sigma adder circuit
15 741 fourth internal clock
742 fourth delta sigma quantizer
743 fourth delta sigma sample hold circuit
744 fourth delta sigma comparator
745 fourth delta sigma analog filter
20 746 fourth delta sigma adder circuit
747 synthesizing circuit
1000 to 1008 transmitter
2000, 2001, 2004, 2007, 2008 receiver
3001, 3006, 3007, 3008 FPGA
25
99
WE CLAIM:
1. A wireless communication system, comprising:
a transmitter; and
a receiver,
wherein 5 erein the transmitter includes
a transmission information generating unit that generates
transmission information,
a first code generating unit that generates a first code
that is repeated at a frequency fr, the first code being a
10 code in which an autocorrelation value between the same
partial regions is higher than a cross-correlation value
between different partial regions in partial regions obtained
by dividing the first code corresponding to one period on a
time axis,
15 a second code generating unit that generates a second
code which is a code by which it is possible to detect whether
or not the same codes of two sequences are identical to each
other on the time axis,
an encoding unit that encodes the transmission
20 information generated by the transmission information
generating unit using the first code and the second code, and
a transmitting unit that causes a carrier wave to be
superimposed on the transmission information encoded by the
encoding unit, generates a transmission signal in which a
25 polarization plane rotates at the frequency fr, and wirelessly
transmits the transmission signal, and
100
the receiver includes
a receiving unit that receives the transmission signal
from the transmitter and removes a carrier wave from a
received reception signal,
a synchronization detecting unit that detects 5 a start
point of an information signal from which the carrier wave has
been removed by the receiving unit using the second code for
the information signal, and
a partial region information extracting unit that
10 extracts partial region information corresponding to the
partial regions from the information signal using the starting
point of the information signal and detects a phase shift of
the partial region information.
15 2. The wireless communication system according to claim 1,
wherein the transmitter further includes
a third encoding unit that encodes information using a
third code generated to reflect a characteristic of the
transmission path when the partial region information
20 corresponding to the partial regions is transmitted to the
receiver,
the encoding unit and the third encoding unit encode the
transmission information generated by the transmission
information generating unit using the first code, the second
25 code, and the third code,
the receiver further includes
101
an information decoding unit that decodes the partial
region information extracted by the partial region information
extracting unit using the third code.
3. The 5 wireless communication system according to claim 1,
wherein the transmission information generating unit of
the transmitter generates transmission information that is
identical to each other in the partial regions,
the receiver further includes
10 an information processing unit that determines whether or
not a plurality of pieces of partial region information
extracted by the partial region information extracting unit
are identical to each other,
15 4. The wireless communication system according to claim 3,
wherein the information processing unit of the receiver
acquires information which is largest in the number of pieces
of information that are identical among the plurality of
pieces of partial region information as the transmission
20 information from the transmitter.
5. The wireless communication system according to claim 1,
wherein the transmitting unit includes
a carrier superimposing unit that causes the carrier wave
25 to be superimposed on the transmission information encoded by
the encoding unit and generates a cosine wave signal of a
102
frequency fr and a sine wave signal of the frequency fr,
a first antenna that wirelessly transmits the cosine wave
signal, and
a second antenna that is spatially orthogonal to the
first antenna and wirelessly transmits the sinusoidal 5 oidal signal,
and
the receiving unit includes
a third antenna that receives a synthetic signal of the
cosine wave signal and the sine wave signal,
10 a fourth antenna that is spatially orthogonal to the
third antenna and receives the synthetic signal, and
a carrier wave removing unit that removes the carrier
wave from the synthetic signal received by the third antenna
and the fourth antenna.
15
6. The wireless communication system according to claim 5,
Wherein the synchronization detecting unit of the
receiver detects, based on a sum of a third information signal
received by the third antenna and a fourth information signal
20 received by the fourth antenna, synchronization of the second
code superimposed on the third information signal and the
fourth information signal,
the partial region information extracting unit of the
receiver performs extraction of the partial region information
25 and detection of the phase shift of the partial region
information based on the third information signal, and
103
performs extraction of the partial region information and
detection of the phase shift of the partial region information
based on the fourth information signal.
7. 5 The wireless communication system according to claim 5,
wherein the carrier wave superimposing unit of the
transmitter generates the cosine wave signal and the sine wave
signal using frequencies f1 and f2 in which 1/2 of a
difference between the frequencies f1 and f2 is the frequency
10 fr such that the transmission information encoded by the
encoding unit is bifurcated, and a first signal is generated
by causing the carrier wave of the frequency f1 to be
superimposed on one bifurcated transmission information, a
second signal is generated by causing the carrier wave of the
15 frequency f2 to be superimposed on the other bifurcated
transmission information, and the first signal and the second
signal are synthesized.
8. The wireless communication system according to claim 5,
20 wherein the carrier wave superimposing unit of the
transmitter generates the cosine wave signal and the sine wave
signal using a discrete-time delta sigma circuit.
9. The wireless communication system according to claim 5,
25 wherein the carrier wave removing unit of the receiver
removes the carrier wave from the synthetic signal received by
104
the third antenna and the fourth antenna using a continuoustime
delta sigma circuit.
10. An elevator control system using the wireless
5 communication system according to claim 5,
wherein the receiver is installed in an elevator car of
the elevator control system, and the third antenna and the
fourth antenna of the receiver are installed above or below
the elevator car, and
10 the first antenna and the second antenna of the
transmitter are installed at positions facing the third
antenna and the fourth antenna.
11. A substation equipment monitoring system using the
15 wireless communication system according to claim 1,
wherein the substation monitoring system is configured to
include at least one base station and at least one transformer,
the transmitter is installed in the base station, and the
receiver is installed in the transformer.
20
12. A transmitter, comprising:
a transmission information generating unit that generates
transmission information;
a first code generating unit that generates a first code
25 that is repeated at a frequency fr, the first code being a
code in which an autocorrelation value between the same
105
partial regions is higher than a cross-correlation value
between different partial regions in partial regions obtained
by dividing the first code corresponding to one period on a
time axis;
a second code generating unit that generates 5 a second
code that is a cyclic code, the second code being a code by
which it is possible to detect whether or not two second codes
are identical to each other on the time axis;
an encoding unit that encodes the transmission
10 information generated by the transmission information
generating unit using the first code and the second code; and
a transmitting unit that causes a carrier wave to be
superimposed on the transmission information encoded by the
encoding unit, generates a transmission signal in which a
15 polarization plane rotates at the frequency fr, and wirelessly
transmits the transmission signal.
13. The transmitter according to claim 12, further comprising,
a third encoding unit that encodes an information signal
20 using a third code generated to reflect a characteristic of
the transmission path when the partial region information
corresponding to the partial regions is transmitted to the
receiver,
wherein the encoding unit and the third encoding unit
25 encode the transmission information generated by the
transmission information generating unit using the first code,
106
the second code, and the third code.
14. A receiver, comprising:
a receiving unit that receives a wireless signal in which
an information signal including a first code that is 5 repeated
at a frequency fr and a second code which is a code by which
it is possible to detect whether or not the same codes of the
two sequences are identical to each other on a time axis is
superimposed on a carrier wave, and a polarization plane
10 rotates at the frequency fr, and removes the carrier wave from
the wireless signal;
a synchronization detecting unit that detects a start
point of the information signal from which the carrier wave
has been removed by the receiving unit using the second code
15 for the information signal; and
a partial region information extracting unit that
extracts partial region information corresponding to partial
regions obtained by dividing the first code corresponding to
one period from the information signal using the starting
20 point of the information signal and detects a phase shift of
the partial region information.
15. The receiver according to claim 14,
an information decoding unit that decodes information
25 extracted by the partial region information extracting unit
using the third code generated to reflect a characteristic of
107
a transmission path when the partial region information
corresponding to the partial regions is transmitted from the
transmitter that transmits the wireless signal to the receiver.