[Document Name] DESCRIP T ION
[Title of Invention] SYSTEM FOR MEASUR ING
POSITION OF FLYING OBJECTS
[Technical Field]
5 The present invention relates to a flying object
position -m easuring system where a signal wave transmitted
from the fl ying object to be positioned is received by a
pluralit y of reception stations to perform a position
measurement of the fl ying obj ect, and to a signal processing
10 method and a control method used at a reception station for the
system.
[Background Art]
A fl ying object positi on-measuring s yst em can be used,
15 for example, for measuring the position of an aircraft . In a
fl ying object position -measuring syst em, a plurality of
reception st ations receive a signal wave transmitted from a
fl ying object and each of the reception stati ons associates the
signal wave with an exact reception time, and consequently, t he
20 position of t he flyi ng object can be measured b y cross -checking
the recepti on times against one another.
Techniques related to a flying object position -measuring
system are described i n, for example, PT L 1 and PTL 2.
PTL 1 and P TL 2 each describe an aircraft
25 position -m easuring system where the position measurement of
an aircraft is performed with a central station and a plurality of
reception st a t i o n s .
PTL 1 discl oses a te chni que to highl y accuratel y
synchroniz e reference times for the individual reception
2
stations during positi on -measuring of an aircraft, the reference
times being used for adding a time stamp to a received signal
wave.
PTL 2 discl oses a technique, with a secondary
5 surveillance radar system (SSR s ystem) that sends interrogati on
signals causing an aircraft to transmit different t ypes of
response signals, to perform information processing a t a central
station to be able to identify the types of the response s ignals
from an aircraft.
10 [Citation List]
[Patent Lit erature]
[PTL 1]
Japanese Unex amined Patent Application Publication No.
2010-230448
15 [PTL 2]
Japanese Unex amined Patent Application Publication No.
2 0 11 - 112 4 65
[Summar y of Invention]
[Technical Pro blem]
20 In a flying object position -measuring system, it is
conventionally difficult for each reception station to identif y a
pluralit y of signal waves transmitted by a fl yin g object as a
group of signals transmitted b y the same fl ying obj ect, when
the reception stations receive different types of signal waves
25 from the aircraft and a central station uses the signal waves to
measure the position of the aircraft . For this reason, each
reception st ation basicall y sends all the large amount of
information about signal waves along with added reception
times to a central station, and then the central st ation identifies
3
the position of a fl ying object through various information
processing (for example, the technique disclosed in PTL 2
above).
However, such techni ques need several improvements .
5 For one thing, the amount of information exchanged between
each reception station and a central stati on needs to be reduced .
In addition, another improvement is desired regarding the large
am ount of computational resources used for the
above-described techniques at a central station.
10 Neither of PTL 1 and PTL 2 addresses these problems.
The present invention has been created in view of t he
problems described above, and an object of the present
invention is to provide a flying object position -measuring
system where individual reception stations in the flying object
15 position -m easuring system identify a pluralit y of signal waves
transmitted by a f lying object as a group of signal waves
transmitted by the same fl ying object to reduce a processing
burden impos ed on a central station and the like.
[Solution t o Problem]
20 A fl ying object position -measuring s yst em according to
the present invention includes a plurality of reception stations
and a central station, wherein each of the pluralit y of reception
stations receives a pluralit y of signals, as reception signals,
transmitted from a fl ying object, and notifies the central
25 station of the individual reception signals, the central station
performs position meas urement of the flyi ng object based on
each reception signal which was transmitted by the fl ying
object and notification of which was given b y each of the
pluralit y of reception stations, and the reception station
4
includes: a reception unit that receives each of the pluralit y of
signals as reception s i g n a l s ; a reception signal phase difference
detecting unit that refers to a phase difference between a
carrier wave included in each of the reception signals and a
5 reference wave, and detects reception si gnals that have a
certain correlation; a reception si gnal association unit that
associates reception s ignals having a phase difference falling
within a predetermined range with one another as a group of
reception signals transmitted from the same flying object; and a
10 transmission unit that notifies the central unit of the group of
associated reception signals.
A reception station in a flying object position -measuring
system according to the present invention includes : a reception
unit that receives each of a plurality of signals , as a reception
15 signal, t ransmitted from a fl ying object; a reception signal
phase difference detecting unit that refers to a phase difference
between a carrier wave included in each of the reception signals
and a reference wave , and detects reception si gnals th at have a
certain correlation; a reception si gnal association unit that
20 associates reception s ignals having a phase difference falling
within a predetermined range with one another as a group of
reception signals transmitted from the same flying object; an d a
transmission unit that notifies a central unit of the group of
associated reception signals.
25 A method for measuring a positi on of a fl ying object
according to the present invention is performed by a flying
object position -measuring s yst em that includes a plurality of
reception st ations and a central station, wherein each of the
pluralit y of reception stations receives a pluralit y of signal s, as
5
reception si gnals, transmitted from a fl ying object, and noti fies
the central station of the indi vidual reception signals, the
central station performs position measurement of the fl ying
object based on each reception signal which was transmitted b y
5 the flying object and notificati on of whi ch was given b y each of
the pluralit y of reception stations, and, when receiving t he
pluralit y of reception signals, the reception station refers t o a
phase difference between a carrier wave included in each of t he
reception si gnals and a reference wave , and detects reception
10 signals that have a certain correlation; associates r eception
signals having a phase difference falling within a
predetermined range with one another as a group of reception
signals transmitted from the same flying object; and notifies
the central unit of the group of associat ed recepti on signals.
15 A program recorded in a recording medi um according to
the present invention causes a reception station incl uded in a
fl ying object position -measuring syst em to operate as: a
reception signal phase difference detecting unit that refer s to a
phase difference between a carrier wave included in each of the
20 reception signals and a reference wave , and detects reception
signals that have a certain correlation; and a reception signal
association unit that associates reception signals having a
phase difference falling within a predetermined range with one
another as a group of reception signals transmitted from the
25 same fl ying object.
[Advantageous Effect of Invention]
According to the present invent ion, there can be provided
a fl ying object position -measuring system where individual
6
reception st ations in the fl ying object position -measuring
system identify a plurality of signal waves transmitted by a
fl ying object as a group of signal waves t ransmitted by the same
fl ying object to reduce a processing burden imposed on a
5 cent ral station and the like.
[Brief Description of Drawings]
Fig. 1 is a s yst em configuration diagram i l l u s t r a t i ng a
fl ying object position -measuring syst em according to an
10 exemplar y em bodiment.
Fig. 2 is a block diagram i l l u s t r a t i ng an example
configur ation of a reception station according to an exempl ary
em bodiment.
Fig. 3 is a block diagram i l l u s t r a t i ng a configuration of a
15 reception st ation according to an example.
Fig. 4 is an explanatory diagram i l l u s t r a t i ng signal
structures of existing SSR resp onse signals.
Fig. 5 is an explanatory diagram i l l u s t r a t i ng the rule for
forming existing SSR response signal s.
20 Fig. 6 is an explanatory diagram i l l u s t r a t i ng various
signals processed in a reception signal carrier wave phase
identifying unit (phase diffe rence detection unit).
Fig. 7 is an explanatory diagram i l l u s t r a t i ng a
relationship among various replies (pulse train) processed in a
25 reception si gnal correlation detecting unit (reply phase
di fference correlating unit).
Fig. 8 is a flow chart illustrat ing example processes
performed b y a reception station according to the present
invention.
7
[Description of Embodiments]
The present invention will now be described with
reference to Figs. 1 to 8.
5 The following exemplary embodim ents describe a
configura tion where the geomet ric positi on of an aircraft,
namely a fl ying object, is measured through multilateration
(h yperbolic positioning) perform ed at a central station . Note
that, however, fl ying object position -measuring methods used
10 at a central station a re not limited to multil ateration
(h yperbolic positioning).
The central station uses a time difference of arrival
(TDOA) between reception stations to measure the geometric
position of an aircraft . For the purpose of the multilateration,
15 each receiver no tifi es the central station of a pl u r a l i ty of signal
waves recei ved from the aircraft , along with reception times
associated with the signal waves . The aircraft uses different
t ypes of signal waves as the si gnal waves . The aircraft (radio
equipment) trans mits individual signal waves at a fixed carrier
20 f r eq u en c y.
As with an existing aircraft position -measuring s ystem,
an aircraft being pres ent in a coverage of the system according
to examples described below transmits individual signal waves
that include M ode A response signals, Mode C response signals,
25 Mode S responses, and squitter signals .
Mode A and Mode C response signals are response signals
transmitted by an aircraft in response to interrogation signals
sent from an existing SSR device . Under an installed existing
SSR system, an aircraft replies with Mode A and Mode C
8
response signals that are s ynchronized with Mode A and Mode C
interrogate signals, respectivel y.
Fig. 1 is a s yst em configuration diagram i l l u s t r a t i ng a
fl ying object position -measuring system according to an
5 exemplar y em bodiment.
In this system, the position measurement of an aircraft A
is performed at a central station 20 . This s ystem includes a
pluralit y of reception stations 10 (10-1 to 10-4) and a central
station 20, and furth er includes a transmission/reception
10 station 30 serving as an SSR s ystem.
Each recept ion station 10 intercepts a pl u r a l i ty of
response signals such as Mode A and Mode C signals
transmitted from the aircraft A, adds time stamps representing
reception times to the response signals such as Mode A and
15 Mode C signals, and notifies the central station 20 of the
signals with time stamps.
During this operation, each reception station 10 refers to
the phase difference between the carrier wave included in each
reception signal and the reference wave to detect a group of
20 reception si gnals having a certain correlation (in this case, a
group of different types of response signals transmitted from
the aircraft A). Then, each reception station 10 associates the
reception signals having a phase difference falling within a
predetermined range with one another, regarding them as a
25 group of reception signals transmitted from the same fl ying
object, and then adds a reception time to the signals, and
notifies the central stati on 20 of the signals in such a way that
each information piece can be identified . For example, if a
reception st ation 10 associates a Mode A response signal with a
9
Mode C response signal, the reception station ma y notify the
central station 20 of these si gnals as Mode A/C response
signals.
In a similar manner, each reception station 10
5 successivel y receives various si gnals transmitted from the
ai rcraft A, uses the phase of a carrier wave included in each
reception si gnal to associate those reception signa ls having a
certain correlation i n their carrier waves with one another,
regards such signals as a group of response signals transmitt ed
10 from the same aircraft, and notifies the central station 20 of
these signal s along with an added reception time.
When associating the reception signals having a certain
correlation in their carrier waves with one another, the
reception st ation ma y delete all but one reception signal from
15 the same t ype of reception signals that were transmitted at
al most the same timing an d that have a certain correlation .
Note that, however, this consol idation process is still effective
if the number of reception signals is decreased, instead of
deleting al l but one.
20 In other words, a reception station 10 consolidates
(integrates) the reception signals regarded as a group of
response signals that have been transmitted from the same
fl ying object and that have a certain correlation . On the other
hand, if different types of reception signals are regarded as a
25 group of response signals th at have been transmitted from the
same fl ying object and that have a certain correlat ion, the
reception st ation ma y associate these signals with one another
as a group of recepti on signals and may notify the central
station of such group of signals.
10
The central stat ion 20 collects information about times of
arrival at the reception stations 10 of the individual rece ption
signals that have been transmitted from the flying object A and
notified by the reception stations 10, and then measures the
5 position of the flying object A . In addition, the central
station 20 acquires information (e.g., identification code and
al titude) included in each of the response signals transmitted
from the fl ying object A.
The central station 20 is notified of the information
10 (n otified consolidated i nformation) in which a pluralit y of
reception si gnals having a certain correlation are associated
with one another b y each reception station 10 . Thus,
information processing on reception signals of the same content
can be reduced, un l i ke a system where each reception station 10
15 gives notification of reception signals that are not associated
with one another. As a result, processing resources needed for
obtaining a desired result can be reduced.
B y configuring and operating a s ystem in this way, in an y
ai rcraft position -measuring s yst em, each reception station can
20 associate the same type or different types of signal waves with
one another that have been transmitted b y an aircraft, and give
notification of these signal waves as the tar get i nformation, and
then the central station can accept such target information from
each reception station to measure the position of the aircraft.
25 An example configuration and example operations of the
reception st ation 10 will now be described . Concerning
various existing components not relevant to the pres ent
invention, their descriptions are omitted or simpli fied.
Fig. 2 is a block diagram i l l u s t r a t i ng an example
11
configuration of the reception station 10 .
The reception station 10 is configured t o include a
reception unit 11, a signal processing unit 12, and a
transmission unit 13.
5 The reception unit 11 receives a pluralit y of signal waves
transmitted from an aircraft via an antenna (not i l l u s t r a t e d ),
and outputs each of the plurali t y of signal w aves in the form of
a reception signal . In addition, the reception unit 11 outputs
to the signal processing unit 12 a carrier wave signal that makes
10 it possible to identify the phase of a carrier wave for each
reception si gnal.
The signal processing unit 12 refers to each carrier wave
signal, and, based on a phase difference between carri er wave
periods incl uded in each reception signal, associat es the
15 reception si gnals with one another that can be regarded as the
signal waves transmitt ed from the same ai rcraft (that is, the
reception si gnals that have a certain correlation i n their carrier
waves). In addition, the signal processing unit 12 adds a
reception time (information about the tim e when a si gnal
20 arrived at the local s tation) to a recepti on signal and outputs
the signal with the reception time to the transmission unit 13.
The transmission unit 13 notifies the central stati on 20 of
reception si gnals in the form of notified consolidated
information . However, the central station 20 may be notified
25 of separate individual reception signals, if necessary.
The signal processing unit 12 according to the present
exemplar y em bodiment can be configured with, as illustrated, a
reception si gnal carrier wave phase ident i fying unit 14, a
reception si gnal correla tion detecting unit 15, a reception
12
signal association unit 16, and a time information adding unit
17 . The reception signal carrier wave phase i dentifying unit
14 and the reception signal correlation detecting unit 15 act as
a reception signal phase diffe rence detecting unit . This
5 configuration is not r e s t r i c t i v e ; the signal processing unit 12
may be configured so as to meet system requirements as
appropriate.
The reception signal carrier wave phase identif ying unit
14 refers to each carrier wave signal to identif y the phase of a
10 carrier wave included in each reception signal, and outputs to
the recepti on signal correlation detecting unit 15 the phase
state of a carrier wave period included in each reception signal .
The amount of phase of a carrier wave for a reception signal
may be represented b y a numeric value b y using a reference
15 wave generated by a reception st ation 10, or the phase of a
carrier wave for a reception signal may be represent ed b y a
numeric val ue b y using a carrier wave for another rece ption
signal as a reference wave.
According t o the amount of phase difference between
20 phase states in a career wave period for each reception signal,
the recepti on signal correlation detecting unit 15 detects
reception si gnals having a certain correlation in their carrier
wave periods, and not i fi es the reception signal association unit
16 of the reception information correlation information that
25 indicates a group of correlated reception signals.
The reception signal association unit 16 associates the
reception signals with one another that have been notified in
the recepti on information correlation information.
The time information adding unit 17 adds a reception
13
time to the reception signals . Needless to sa y, the time
information is preferabl y highl y ac curat e. It is also
preferable that time information is s ynchronized among
reception st ations 10 with high precision . A reception time
5 may be added to a group of consolidated reception signals
according t o a predefined rule . For example, the reception
time of the reception signal first received or last received
am ong the consolidated reception signals m ay be added.
This configuration al lows each reception station 10 to
10 associate the reception signals with one another that have a
certain correlation i n th eir carrier waves and to notify the
central station 20 of the reception time of the reception signals .
As a result, it becomes possible to reduce the amount of
information given b y each reception station to the central
15 station in a flying object posi tio n-measuring system to reduce a
processing burden imposed on the central station and the like.
[Example s]
The present invention will now be described with an
example. The present example is described with signals that
20 are used in an existi ng aircraft posi tion-measuring system.
In the aircraft position -measuring system according to
the present example, an aircraft transmit s an SSR Mode A
response si gnal, an SSR Mode C response signal , and a Mode S
response signal or an SSR extended squitter signal in respo nse
25 to requests with interrogation signals from an SSR system, four
or more reception stations respectively receive and process
these signal s (determ ine correlations and add times), and the
central station performs multilateration on a group of reception
signals notified from each reception station to perform a
14
position measurement of the aircraft.
The aircraft is equipped with an ATCRBS transponder,
which transm its response signal s in an array of pulse waves
(pulse train) using a 1090 MHz carrier wave.
5 Each reception station 10 obtains the phase difference
between the carrier wave (1090 MHz signal) constituting pulses
of an SSR Mode A response signal , an SSR Mode C response
signal, or the like and the reference wave (1090 MHz signal)
generated b y the refe rence frequenc y oscillator in the local
10 station, and then compares phase differences among response
signals. Through the two - s t ep comparisons, each reception
station 10 associates the response signals whose amounts of
phase differences fall within a thres hold range with one
another, regarding these respons e signals as a group of response
15 signals having a certain correlation in t heir carrier waves.
As a result, even if the coverage includes man y aircrafts
transmitting a lot of response signals, response si gnals
transmitted from the same aircraft can be consolidated .
Response signals from another aircraft can be consolidated int o
20 a different group.
For ex ample, if an ai rcraft A has transmitted an SS R
Mode A response signal and an SSR Mode C response signal
as ynchronousl y in a coverage where a pluralit y of aircrafts are
fl ying over, these response signals can be notified to the
25 central station 20 as SSR Mode A/C response signal s with tim e
information added.
As a result, it becomes possible to reduce the a mount of
resources and the like required for multil ateration to be
performed on the central station 20 side to displa y the position
15
of the aircraft A and other information.
[Configuration]
Fig. 3 is a block diagram i l l u s t r a t i ng a configuration of a
recepti on station 100 according to an ex ample.
5 As illustrated in the figure, t he recepti on station 100 is
configured to include a reception unit 110, a signal processing
unit 120, a transmission unit 130, and a time information
generating unit 140.
The recepti on unit 110 successively accepts rece ived
10 waves, namely high -frequency SSR response signals , from an
ai rcraft being present in the coverage, and outputs them in the
form of individual reception signals . According to the
present ex ample, the reception unit 110 generates reception
video through signal processing that is perform ed on the
15 received waves via an amplifier 111, a reception processing
unit 112, and a reception video generating unit 113 .
In the course of the signal processing, t he recepti on unit
110 branches a signal wave and outputs it to the signal
processing unit 120 so that the signal processing 120 can obtain
20 the phase of a carrier wave for each reception signal . For the
purpose of this branching, the reception unit may be configured
to branch a high-frequency SSR response signal itself, or to
branch the signal portion onl y, or to branch each individual
pulse.
25 The signal processing unit 120 according to the present
example is configured with a limiting amplifier unit 121, a
phase difference detection unit 122, a pulse phase difference
correlating unit 123 - 1 , a reply phase difference correlating unit
123-2, a bracket pulse detecting unit 124, a reply p rocessing
16
u ni t 1 25 , a t a r g e t co r r el at in g u ni t 1 2 6, a n ATCR B S r es po n s e
p r o c e s s i n g unit 127, a Mode S r e s p o n s e p r o c e s s i ng unit 128,
and a target i n f o r m a t i o n g e n e r a t i n g unit 129 .
The phase d i f f e r e n c e d e t e c t i o n unit 122 acts as the
5 reception si g n a l c a r r i e r wave phase ident i f y i ng unit . The
p u l s e phase d i f f e r e n c e c o r r e l a t i n g unit 123 - 1 and the repl y
phase d i f f e r e n c e c o r r e l a t i n g unit 123 - 2 act as the r e c e p t i on
s i g n a l c o r r e l a t i o n d e t e c t i n g unit . The t a r g e t c o r r e l a t i n g unit
126 and the ATCRBS r e s p o n s e p r o c e s s i n g unit 127 act as the
10 reception si g n a l a s s o c i a t i o n unit and the time i n f o r m a t i on
a d d i n g unit .
The l i m i t i n g a m p l i f i e r unit 121 performs l i m i t i ng
am p l i f i c a t i o n on each signal wave d i s t r i b u t e d by the r e c e p t i on
unit 110 so as to remove a d i f f e r e n c e in i n f l u e n c e s of r e c e p t i on
15 levels and o u t p u t s each limit -ampl i f i ed signal wave to the
phase d i f f e r e n c e d e t e c t i o n unit 122.
The phase d i f f e r e n c e d e t e c t i o n unit 122 d e t e c t s the phase
of a c a r r i e r wave i n c l u d e d in each limit - a m p l i f i e d signal wave,
based on a 1090 MHz r e f e r e n c e si g n a l . That i s , the phase
20 di f f e r e n c e d e t e c t i o n unit d e t e c t s a phase d i f f e r e n c e b e t w e e n t he
c a r r i e r wave c o n s t i t u t i n g pulses of a high - f r e q u e n c y SSR
r e s p o n s e signal and the r e f e r e n c e signal . The frequency of
the r e f e r e n c e s i g n a l , 1090 MHz , is a carri e r frequency
em p l o y e d in a i r c r a f t s . If it is d e s i r e d to p r o c e s s a r e c e p t i on
25 signal of a different c a r r i e r frequenc y, the phase d i f f e r e n ce
d e t e c t i o n unit 122 need onl y use a r e f e r e n c e signal of the
d e s i r e d frequency. The unit ma y be c o n f i g u r e d to accept
di f f e r e n t types of c a r r i e r wave r e f e r e n c e s i g n a l s t o deal with
di f f e r e n t types of carri e r f r e q u e n c i e s.
17
The pulse phase difference correlating unit 123 -1
performs a determination process of regarding matching pulse
signals where a phase difference of a carri er wave on each pulse
is within a threshold range as the same pulse signal train, bas ed
5 on the bracket pulses of an SSR response signal detected b y t he
bracket pul se detecting unit 124 (see F1 and F2 in 2 . of Fig. 6
as described l a t e r ) . The pulse phase difference correlating
unit 123-1 generates repl y dat a from the group of pulse signals
that can be regarded as a pulse signal train outputted from the
10 same aircraft, and transmits the generated repl y data to the
reply phase difference correlating unit 123 - 2 . This
processing achieves extracting response signals that are solel y
composed of pulse waves on a direct wave (the same path) for
the same aircraft, even when, for example, there are multi -path
15 waves or pulse waves mix ed with signals from other aircrafts.
The reply phase difference correlating unit 123 -2
identifies repl y data pieces tha t match each other within a
threshold range of phase difference b y detecting a correlation
between the phase difference information contained in a reply
20 data piece and the phase difference information contained in
another repl y data piece (another pulse wa ve train) that is
subsequentl y inputted . The repl y phase difference correlating
unit 123-2 sends to the target correlating unit 126 the result of
the determination, designated as target reply correlation data,
25 performed on a group of response signals whos e correlation has
been detect ed . This determination resul t makes it possible to
consolidate response signals int o a group that were received at
di fferent timings but are determ ined to have been transmitted
from the same aircraft.
18
The target correlating u nit 126 associates each of the
response signals (target reply data) generated b y t he repl y
processing unit 125 with time i nformation, and, according to
the target reply c orrelation data generat ed by the repl y phase
5 di fference correlating unit 123 - 2 , associ ates the response
signals with one another into target information, and outputs
the target information to the ATCRBS response processing unit
127.
In addition, according to the t arget repl y correlat ion
10 data, the target correlating unit 126 discards an y ta rget
information that can be determined to be the same t ype of target
information that is from the same aircraft and falli ng within a
predetermined period . The predetermined period may be set
to an y appropriate tim e . For example, to consolidate response
15 signals outputted b y an aircraft, the peri od may be set to a
hundred and several tens of milliseconds for a possible period
for which Mode A response signals and Mode C response signals
will be successively transmitted . With this predetermined
period, the same type of response signals included in a single
20 reply train can be consolidated as described later with
reference to Fig. 7. The period may be set to an y value as
appropriate so as to meet system requirem ents . This
processing can reduce a processing load imposed on the central
station.
25 To consolidate the correlated pieces of t arget information
into a group of signals that were transmitted from the aircraft,
the ATCRBS response processing unit 127 outputs the final
Mode A/C target information to the t arget information
generating unit 129 when the number of repl y data pieces
19
reaches a predetermined parameter value.
The Mode S response processing unit 128 adds time
information, receives reception video signals, and outputs
Mode S target information and Mode S squitter target
5 information to the target inform ation generating unit 129.
The target information generating unit 129 outputs to the
notification unit 130 the target informati on (notifi ed
consolidated information) that has been created in a
predete rmined format by mixing the Mode S target information
10 and Mode S squitter target information received from the Mode
S response processing unit 128 with the SSR Mode A/C target
information received from the ATCRBS response processing
unit 127 . Note that all the time information added b y the
target correlating unit 126 and the Mode S response processing
15 unit 128 to the reception signals may not be necessaril y left .
For ex ample, the signal processing unit 120 may employ the
reception time of the reception si gnal that was first received,
am ong the same type of reception signals included in the
outputted t arget information . Alternativel y, the signal
20 processing unit 120 may emplo y t he reception time of the
reception signal that was last received, among the same type of
reception si gnals . Likewise, when different types of
reception si gnals are consolidat ed, the signal processing unit
120 may select a reception time that is given in accordance with
25 a predefined rule, such as the reception time of the reception
signal first received or the reception time of the reception
signal first received among signals of a specific t ype . For
example, among the replies consolidated i nto a group of Mode
A/C response signals, the reception time of the Mode C
20
response si gnal that indicates altitude information and that was
first received can be used as the reception time of Mode A/C
responses.
The notification unit 130 outputs to the central station
5 200 a group of signal waves, designated as target i nformation
(notified consolidated information), that were outputted from
the same aircraft and given a reception time.
In the present configuration, t he time information
generating unit 140 includes a GPS (global positioning s ystem )
10 receiver 141 and a ti m e synchronization signal gener ating unit
142. The time information generating unit 140 may use other
techniques than acqui ring time information from GP S signals,
such as using a high -precision clock to generate time
information . Likewise, techniques to synchroniz e reception
15 stations and central stations are not limited to using GPS; an y
suitable s ynchronization technique may be used.
The aircraft position -measuring syst em including the
reception st ation 100 operates as described below. As with
the relationship illustrated in Fig. 1, the s ystem is configured
20 to include a pluralit y of reception stations 100 -1 to 100-4 and a
central station 200.
The reception stations 100 -1 to 100-4 and the central
station 200 use GPS si gnals broadcast b y a GPS s a t e l l i t e to
synchroniz e stations and gen erate time information.
25 The reception unit 110 in each of the reception stations
100-1 to 100-4 successivel y receives Mode A responses, Mode
C responses, and Mode S responses/extended squitter signals
from the target aircraft and other aircrafts being pre sent in the
coverage of the system.
21
The signal processing unit 120 in each of the reception
stations 100 -1 to 100 -4 decodes various reception signal s that
have been received, consolidates the reception signals that have
a certain correlation in their carr ier waves ident ifying these
5 reception si gnals, and adds a time stamp to the consolidated
signals, and then the transmission unit 130 notifies the central
station 200 of the target information for each aircraft.
The central station 200 performs a position measurement
of each aircraft based on differences of times at which a signal
10 wave transmitted by an aircraft arrives at reception stations
100-1 to 100-4, the time differences being derived from the
time stamps representing arrival times added to the indiv idual
target information pi eces received by the central station 200 .
In this position measur ement, positional coordinates including
15 an altitude of an aircraft can be identifi ed with four or more
s t a t i o n s .
In an existing aircraft position -measuring s ystem that
uses Mode A/C interrogate signals/response signals, Mode A/C
response signals from an aircraft are asynchronousl y operated,
20 and each reception station is m onitoring all the Mode A/C
response signals from one or more aircrafts present in a
coverage under surveillance .
Thus, existing aircraft position -measuring systems do not
al low each reception station to consolidate received response
25 signals into a group of response signals coming from a single
ai rcraft.
According t o the above-described example, ea ch
reception st ation can consolidat e such asynchronous Mode A
and Mode C response si gnals into a group t aking the types of
22
signals into consideration . Accordingl y, unlike an existing
reception st ation, the reception station no longer needs to
notify the central station of all the response signals it
monitored . As a result, a bandwidth for communicating target
5 information between t he central station 200 and each reception
station 100 can be reduced . In addition, processing resources
can be reduced because the need for processing a huge amount
of target i nformation at the central station 200 is eliminated .
The reduction in a communication bandwidth makes it eas y to
10 extend the distance between the central station and a reception
station, whi ch greatl y contr ibut es to expansion of t he coverage
of the s ystem . Furt hermore, the number of aircrafts that can
be simultaneousl y handled can be increased owing to the
reduction in processing resources needed at the central station
15 200 per aircraft.
As seen above, the detection ability of a system can be
improved by introduci ng into a reception station 100 a
mechanism by which a large number of received signals are
examined with respect to a correlation in their carrier waves to
20 consolidate correlated signals.
Characteristics of the present invention will now be
described b y using existing signals that are used on a
transponder in an aircraft.
Figs. 4 and 5 are explanatory diagrams i l l u s t r a t i ng
25 existing SSR response signals .
As illustrated in Fig. 4, signal waves t r ansmi tted from an
ai rcraft (transponder) are form ed into a pulse train of response
signals by using a 1090 MHz carrier wave and turning the radio
wave on and off in a pulsed manner.
23
The relationship among SSR Mode A signal s, SSR Mode C
signals, and SSR Mode A/C signal s is illustrated in Fig. 5.
Fig. 6 is an explanatory diagram illustrating various
signals processed in the recepti on signal carrier wave phase
5 identifying unit (phase difference detection unit).
As illustrated in Fig. 6, the reference sign al generated b y
a reception station (1090 MHz reference wave) and t he signal
wave forming pulses of received SSR response signal s (carrier
wave from an aircraft transponder: 1090 MHz) has the same
10 period but the phases are shifted from each other. The
sym bols T A and TB in the figure represent a delay/advance time
relative to the reference signal for each pulse signal . The
delay/advance time corresponds to the phase difference ( θ A , θB
in the figure) between the carrier wave and the reference wave.
15 When the pulses can be regarded as having the same phase
di fference by co mparing the phase differences, the reception
signal phase difference detecting unit treats those pulses as the
pulses transmitted from the same flying object . In contrast, a
signal wave (carrier wave) forming a train of pulses included in
20 response signal s transmitted from another fl ying object or
transmitted at another time (position) has a different phase
di fference value, and thus involves no correlation . The
reception si gnal phase differ ence detecting unit treats
uncorrelated pulses as a different reception signal (part of a
25 di fferent pulse signal train).
B y detecting the correlation to treat the pulses having a
di fferent phase difference (multi -path noise or pulses
transmitted from anot her fl ying object) as the pulses excluded
from a pulse train forming a reception signal, it becomes
24
p o s s i b l e to identif y a pulse t r a i n ( r e c e p t i o n s i g n a l ) onl y from
the p u l s e s t r a n s m i t t e d from the same fl y i n g o b j e c t.
As a r e s u l t , it becomes p o s s i b l e to rec o g n i z e , with noise
r e s i s t a n c e , the r e c e i v e d SSR r e s p o n s e s i g n a l s d e p i c t e d in 2 . of
5 Fi g. 6 ( t h e pulse t r a i n from F1 to F2) as a group to i d e n t i fy
t h em as o n e rep l y.
In a d d i t i o n , it becomes p o s s i b l e to ident ify and
c o n s o l i d a t e the same type or di f f e r e n t t yp e s of r e p l i es
t r a n s m i t t e d from the same fl y i n g object at about the same time
10 ( p o s i t i o n ).
F i g . 7 is an e x p l a n a t o r y d i a g r am i l l u s t r a t i n g the
r e l a t i o n s h i p among v a r i o u s r e p l i e s ( p u l s e t r a i n ) p r o c e s s e d in
the r e c e p t i on signal phase d i f f e r e n c e det e c t i n g uni t ( t he
r e c e p t i o n si g n a l c o r r e l a t i o n d e t e c t i n g unit 15 or reply phase
15 di f f e r e n c e c o r r e l a t i n g unit 123 - 2 ) . Ever y s i n g l e box in the
fi gu r e r ep r es en t s o n e re pl y.
Since the r e c e p t i o n signal phase d i f f e r e n c e d e t e c t i n g unit
makes a d e t e r m i n a t i o n between r e p l i e s , t h e unit can d i s t i n g u i sh
between the r e p l i e s t r a n s m i t t e d from the same fl y i n g object and
20 the r e p l i e s t r a n s m i t t e d from another f l y i n g object . With the
r e s u l t of the d i s t i n c t i o n , it becomes p o s s i b l e to c o n s o l i d a te
r e p l i e s int o a s i n g l e repl y t r a i n for each f l y i n g o b j e c t.
As for e x i s t i n g a v i a t i o n s i g n a l s , the same a i r c r a ft
t r a n s m i t s Mode A and Mode C r e s p o n s e s i g n a l s in 6 to 15
25 replies usuall y at i n t e r v a l s of s e v e r a l m i l l i s e c o n d s in r e s p o n se
to an SSR i n t e r r o g a t e s i g n a l , as i l l u s t r a t e d in "1 . SSR r e s p o n se
s i g n a l s ( r e p l y t r a i n ) " i n Fig. 7.
A r e c e p t i o n s t a t i o n can consoli d a t e repli e s of about the
same phase t a k i n g the t y p e s of r e p l i e s i n t o c o n s i d e r a t i o n , by
25
determining the phase difference of each repl y based on a
reference si gnal.
As a result, irrespective of whether response signals
(repl y trai ns) transm i t t ed from a pluralit y of flying objects at
5 di fferent times are received as in the fi gure i l l u s t r a t i ng reply
trains from two flying objects, a reception station can
distinguish between response si gnals . This is achieved
because the response signals have their own phases being
di fferent from one another.
10 As seen in the above descriptions of exemplary
em bodiments and examples, each reception station can
associate correlated reception signals with one anot her an d
notify the central station of the associat ed signals by referring
to carrier waves with respect t o each of the aircrafts present in
15 the airspace under surveillance , irrespective of whether a
pluralit y of signals are transmitted asynchronousl y.
Thus, acc ording to the present invention, there can be
provided a flying object position -measuring s ystem where
individual reception s tations in the flying object
20 position -m easuring system recognize a plurality of signal
waves transm i t t ed by a flying object as a gr oup of signal waves
transmitted by the same fl ying object to reduce a processing
burden impos ed on a central station and the like.
The signal processing unit in a reception station i n the
25 fl ying object position -measuring syst em may be implemented
with a c ombination of hardware and software . In an
em bodiment with a combination of hardware and software, the
individual units ma y be implemented b y deploying a program
for reception stations into random access memor y (RAM) and
26
causing the control unit (central processing unit: CPU) and
other hardware pieces to operate based on the program . Such
program may be recorded in a recording medium in a
non-t ransitor y manner to be distributed . The program
5 recorded in such recording medium is loaded into memory via a
wi red or wireless medium or via the recording medium itself to
cause the control uni t and the l ike to operate . Examples of the
recording m edium may i nclude an optical disk, a magnetic disk,
a semiconductor memory device, and a hard disk.
10 The above exemplar y embodiment can also be expressed
as follows: the program causes t he processor included in a
reception st ation to operate so as to refer to the phase of a
carrier wave included in each reception signal, cons olidate t he
reception si gnals having a certain c orrelation in the carrier
15 waves, and add a reception time to the signals.
The processor included in a reception station causes the
signal processing means and the transmissi on means to operate
based on the program . Fig. 8 i l l u s t r a t e s an ex ample process
flow chart. According t o the process flow in Fig. 8, the
20 processor in a reception station, serving as the si gnal
processing unit, identifies the phase of a carrier wave for each
reception si gnal (S101), detects a correlation among reception
signals (S102), associates correlated reception signals with one
another (S103), and add time information t o the signals as
25 appropriate (S104).
The present invention has been described by i l l u s t r a t i ng
exemplar y em bodiments and examples, but t he present
invention is not limited to the above descriptions .
Modifications such as separating or consolidating some block
27
components of an exemplary embodiment or example or
replacing some steps may be freely made as long as the purport
of the present invention and the described f unctions are
fulfilled.
5 The whole or part of the above exemplary embodiments
can be described as the followi ng supplementa r y notes.
However, the present i nvention is not limited to the se
supplementary notes.
[Supplementary N ote 1]
10 A fl ying object positi on-measuring s yst em including:
a plurality of reception stations and a central station,
wherein each of the pluralit y of reception stations
receives a pluralit y of signals, as reception signals, transmitted
from a flying object, and notifies the central stati on of the
15 individual reception signals,
wherein the central station performs position
measurement of the fl ying object based on each reception signal
which was transmitted b y the fl yin g object and notification of
which was given b y each of the plural ity of reception stations,
20 and wherein the reception station includes :
a reception unit that receives each of the pluralit y of
signals as reception signals;
a reception signal phase difference detecting unit that
refers to a phase difference between a c arrier wave included in
25 each of the reception signals and a reference wave , and detects
reception si gnals that have a certain correlation;
a reception signal association unit that associates
reception si gnals having a phase difference falling within a
predetermined range with one another as a group of reception
28
signals transmitted from the same flying object; and
a transmission unit that notifies the central unit of the
group of associated reception signals.
[Supplementary N ote 2]
5 The flying object posit ion-measuring system according to
the above supplementar y note,
wherein the reception station collectivel y adds a
reception time to the group of associated reception signals and
notifies the central station of the group of associated recept ion
10 signals.
[Supplementar y Note 3]
The flying object position -measuring system according to
any one of the above supplementary notes,
wherein, when associating the reception signals with one
15 another, the reception station deletes all but one reception
signal from the same t ype of reception signals, while
associating different t ypes of reception s ignals with one
another as one group of reception signals, and notifies the
central station of the group of associated reception signals.
20 [Supplementary N ote 4]
The flying obj ect position-measuring system according to
any one of the above supplementary notes,
wherein, if a pulse train in an array of pulse waves
formed by using the carrier wave is recei ved as the plurality of
25 signals transmitted from the flying object,
the reception station,
when associating the reception signals with one another,
refers to phases of a carrier wave and a reference wave
for each pulse forming one reception signal and collectively
29
treats pulses having a certain correlation as one reception
sign a l.
[Supplementary N ote 5]
The flying object position -measuring system according to
5 any one of the above supplementary notes,
wherein, when associating the reception signals with one
another,
the recepti on station uses, as the reference wave, a
reference signal having the same frequency as a carrier wave
10 frequency used for the flying object to be positioned to identify
a phase difference of each of the reception si gnals relative to
the reference wave, and detects a correlation b y comparing
phase differen ces among the reception signals.
[Supplementary N ote 6]
15 The flying object position -measuring system according to
any one of the above supplementary notes,
wherein, when detecti ng a correlation among the
reception si gnals, the reception station limitedly amplifies
each of the reception signals, and then determines whether the
20 reception si gnals include carrier waves having a certain
correlation, by using the reference wave.
[Supplementary N ote 7]
The flying object position -measuring system according to
any one of the above supplementary notes,
25 wherein, when associating the reception signals with one
another that have a certain correlation in a period of a carrier
wave, the reception station det ermines whether there is a
correlation based on a threshold val ue of an amount of phase
di fference relative to the reference wave.
30
[ S u p p l e m e n t a r y N o t e 8]
A fl y i n g object p o s i t i o n - m e a s u r i n g s yst em i n c l u d i n g:
a p l u r a l i t y of r e c e p t i o n s t a t i o n s and a c e n t r a l s t a t i o n,
wherein each of the p l u r a l i t y of r e c e p t i o n s t a t i o ns
5 receives, as r e c e p t i o n s i g n a l s , different t ypes of r e s p o n se
s i g n a l s i n c l u d i n g an SSR Mode A r e s p o n s e signal and an SSR
Mode C r e s p o n s e signal , the s i g n a l s being t r a n s m i t t e d from an
ai r c r a f t , and n o t i f i e s the cent r a l s t a t i o n of the r e c e p t i o n si g n a l s
as target informat i o n ,
10 wherein the c e n t r a l s t a t i o n performs a p o s i t i o n al
measurement of the a i r c r a f t by using a p l u r a l i t y of p i e c e s of the
t a r g e t i n f o r m a t i o n r e s p e c t i v e l y n o t i f i e d b y the p l u r a l i t y of
r e c e p t i o n st a t i o n s ,
wherein the r e c e p t i o n s t a t i o n i n c l u d e s:
15 a r e c e p t i o n unit that r e c e i v e s different types of t he
r e s p o n s e s i g n a l s;
a signal p r o c e s s i n g unit that refers to a phase d i f f e r e n ce
between a c a r r i e r wave that is i n c l u d e d in a pulse c o n s t i t u t i ng
each of the r e s p o n s e s i g n a l s and a r e f e r e n c e wave , and r e g a r ds
20 pulses having a phase d i f f e r e n c e f a l l i n g within a p r e d e t e r m i n ed
range as one r e s p o n s e signal t r a n s m i t t e d from the same fl y i ng
o b j e c t ,
and that a s s o c i a t e s d i f f e r e n t t y p e s of the r e s p o n s e s i g n a ls
h a v i n g a phase d i f f e r e n c e f a l l i n g within a p r e d e t e r m i n e d r a n ge
25 with one another i n t o one group of r e s p o n s e s i g n a l s ; and
a t r a n s m i s s i o n unit t hat n o t i f i e s the c e n t r a l s t a t i o n of the
group of a s s o c i a t e d response s i g n a l s.
[ S u p p l e m e n t a r y N o t e 9]
A r e c e p t i o n s t a t i o n in a f l y i n g object p o s i t i o n - m e a s u r i n g
31
system, the reception station including:
a reception unit that receives each of a pluralit y of
signals, as a reception signal , transmitted from a flying object;
a reception signal phase difference detecting unit that
5 refers to a phase difference between a carrier wa ve included in
each of the reception signals and a reference wave , and detects
reception si gnals that have a certain correlation;
a reception signal association unit that associates
reception si gnals having a phase difference falling within a
10 predetermined range with one anot her as a group of reception
signals transmitted from the same flying object; and
a transmission unit that notifies a central unit of the
group of associated reception signals.
[Supplementary N ote 10]
15 The reception station according t o an y one of the above
supplementary note,
wherein the reception station collectivel y adds a
reception time to the group of associated reception signals and
notifies the central station of the group of associated recept ion
20 signals.
[Supplementary N ote 11]
The reception station according to an y one of the above
supplementary note,
wherein, when associating the reception signals with one
25 another,
the recepti on station deletes all but one reception signal
from the same t yp e of reception signals, while asso c i a t i ng
di fferent types of reception si gnals with one another as one
group of reception signals, and notifies the central station of
32
the group of associated reception signals.
[Supplementary N ote 12]
The reception station according to an y one of the above
supplementary notes,
5 wherein, if a pulse train in an array of pulse waves
formed by using the carrier wave is recei ved as the plurality of
signals transmitted from the flying object,
when associating the reception signals with one another,
the recepti on station refers to phases of a carrier wave
10 and a reference wave for each pulse forming one reception
signal and collectivel y treats pulses havi ng a cert ain
correlation as one reception signal.
[Supplementary N ote 13]
The reception station according to a n y one of the above
15 supplementary notes,
wherein, when associating the reception signals with one
another,
the recepti on station uses, as the reference wave, a
reference si gnal havi ng the sam e frequency as a carrier wave
20 frequency used for the flying obj ect to be posit ioned to identify
a phase difference of each of the reception si gnals relative to
the reference wave, and detects a correlation b y comparing
phase differences among the reception signals.
[Supplementary N ote 14]
25 The reception station accord ing to any one of the above
supplementary notes,
wherein, when detecti ng a correlation among the
reception si gnals, the reception station limitedly amplifies
each of the reception signals, and then determines whether the
33
reception si gnals include carrier waves having a certain
correlation, by using the reference wave.
[Supplementary N ote 15]
The reception station according to an y one of the above
5 supplementary notes,
wherein, when associating the reception signals with one
another that have a certain cor r e l a t i on in a period of a carrier
wave, the reception station det ermines whether there is a
correlation based on a threshold value of an amount of phase
10 di fference relative to the reference wave.
[Supplementary N ote 16]
The reception station according to an y one of the above
supplementary notes,
wherein the reception station receives , as reception
15 signals, different t ypes of response signals including an S SR
Mode A response signal and an SSR Mode C response signal , the
signals bei ng t ransmitted from an ai rcraft, and notifies the
central station of the group of associated reception signals as
target information,
20 wherein the reception signal phase difference detecting
unit refers to a phase difference between a carrier wave that is
included in a pulse const i t u t i ng each of the response signals
and a reference wave , and regards pulses having a phase
di fference falling within a predetermined range as one response
25 signal transmitted from the same fl ying object,
and wherein the reception signal association unit
associates different t ypes of the response signals having a
phase difference falling within a predetermined range with one
another into one group of response signals.
34
[ S u p p l e m e n t a r y N o t e 17]
A method for m e a s u r i n g a p o s i t i on of a fl y i n g object
performed b y a flying object p o s i t i o n - m e a s u r i n g s y s t em that
i n c l u d e s a p l u r a l i t y of r e c e p t i o n s t a t i o n s and a c e n t r a l s t a t i o n,
5 wherein each of the p l u r a l i t y of r e c e p t i o n s t a t i o ns
r e c e i v e s a p l u r a l i t y of s i g n a l s , as r e c e p t i o n s i g n a l s , t r a n s m i t t ed
from a flying o b j e c t , and n o t i f i e s the c e n t r a l s t a t i o n of the
i n d i v i d u a l r e c e p t i o n s i g n a l s,
wherein the c e n t r a l s t a t i o n performs p o s i t i on
10 measurement of the fl y i n g object based on each r e c e p t i o n s i g n al
which was t r a n s m i t t e d b y the fl y in g object and n o t i f i c a t i o n of
which was given by each of the p l u r a l i t y of r e c e p t i o n s t a t i o n s,
and wherein, when r e c e i v i n g the p l u r a l i t y of r e c e p t i on
s i g n a l s , t h e r e c e p t i o n s t a t i on
15 refers to a phase d i f f e r e n c e between a c a r r i e r wave
i n c l u d e d in each of t he r e c e p t i o n s i g n a l s and a r e f e r e n c e wave ,
and d e t e c t s r e c e p t i o n s i g n a l s that have a c e r t a i n c o r r e l a t i o n;
a s s o c i a t e s r e c e p t i o n s i g n a l s having a phase d i f f e r e n ce
f a l l i n g within a p r e d e t e r m i n e d range with one another as a
20 group of r e c e p t i o n s i g n a l s t r a n s m i t t e d from the same fl y i ng
o b j e c t ; and
n o t i f i e s the c e n t r a l unit of the group of a s s o c i a t ed
r e c e p t i o n si g n a l s .
[ S u p p l e m e n t a r y N o t e 18]
25 The method for m e a s u r i n g a p o s i t i o n of a flying object
a c c o r d i n g t o the above s u p p l e m e n t a r y n o t e,
wherein the r e c e p t i o n s t a t i o n c o l l e c t i v e l y adds a
r e c e p t i o n time to the group of a s s o c i a t ed r e c e p t i o n s i g n a l s and
n o t i f i e s the c e n t r a l s t a t i o n of the group of a s s o c i a t e d recept i on
35
s i g n a l s .
[ S u p p l e m e n t a r y N o t e 19]
The method for m e a s u r i n g a p o s i t i o n of a flying object
a c c o r d i n g t o an y one of the above s u p p l e m e n t a r y not e s ,
5 wherein, when a s s o c i a t i n g the r e c e p t i o n s i g n a l s with one
a n o t h e r , t h e r e c e p t i on s t a t i o n d e l e t e s all but one r e c e p t i on
s i g n a l from the same t ype of r e c e p t i o n s i g n a l s , while
a s s o c i a t i n g different t y p e s of r e c e p t i o n s i g n a l s with one
another as one group of r e c e p t i o n s i g n a l s , and n o t i f i e s the
10 central s t a t i o n of the group of a s s o c i a t e d r e c e p t i o n s i g n a l s.
[ S u p p l e m e n t a r y N o t e 20]
The method for m e a s u r i n g a p o s i t i o n of a flying object
a c c o r d i n g t o an y one of the above s u p p l e m e n t a r y n o t e s,
w h e r e i n , if a pulse t r a i n in an array of pulse waves
15 formed by using the c a r r i e r wave is recei ved as the p l u r a l i t y of
s i g n a l s t r a n s m i t t e d from the flying object,
when a s s o c i a t i n g the r e c e p t i o n s i g n a l s with one another,
the r e c e p t i o n s t a t i on
r e f e r s to phases of a c a r r i e r wa ve and a r e f e r e n c e wave
20 for each pulse forming one r e c e p t i o n signal and c o l l e c t i v e ly
t r e a t s pulses having a c e r t a i n c o r r e l a t i o n as one r e c e p t i on
s i g n a l .
[ S u p p l e m e n t a r y N o t e 21]
The method for m e a s u r i n g a p o s i t i o n of a flying object
25 according t o an y one of the above s u p p l e m e n t a r y n o t e s,
w h e r e i n , when a s s o c i a t i n g the r e c e p t i o n s i g n a l s with one
a n o t h e r ,
the r e c e p t i on s t a t i o n u s e s , as the r e f e r e n c e wave, a
r e f e r e n c e si g n a l havi ng the sam e frequency as a c a r r i e r wave
36
frequency used for the flying object to be positioned to identif y
a phase difference of each of the reception si gnals relative to
the reference wave, and detects a correlation b y comparing
phase differences among the reception signals.
5 [Supplementary N ote 22]
The method for measuring a position o f a flying object
according t o an y one of the above supplementary notes,
wherein, when detecti ng a correlation among the
reception si gnals, the reception station limitedly amplifies
10 each of the reception signals, and then determines whether the
reception signals include carri er waves having a certain
correlation, by using the reference wave.
[Supplementary N ote 23]
The method for measuring a position of a flying object
15 according t o an y one of the above supplementary notes,
wherein, when associating the r eception signals with one
another that have a certain correlation in a period of a carrier
wave, the reception station det ermines whether there is a
correlation based on a threshold value of an amount of phase
20 di fference relative to the reference wave.
[Supplementar y Note 24]
The method for measuring a position of a flying object
according t o an y one of the above supplementary notes,
wherein the reception station receives , as reception
25 signals, different t ypes of response signals including an S SR
Mode A response signal and an SSR Mode C response signal , the
signals bei ng t ransmitted from an aircraft, and notifies the
central station of the group of associated reception signals as
target information,
37
wherein the reception station refers to a phase differen ce
between a carrier wave that is included in a pulse constituting
each of the response signals and a reference wave , and regards
pulses having a phase difference falling within a predetermined
5 range as one response signal transmitted from the same fl ying
object; and
associates different t ypes of the response signals having
a phase difference falling withi n a predetermined range with
one another into one group of response signals.
10 [Supplementary N ote 25]
A program causing a control unit of a reception sta tion
included in a fl yi ng object position -measuring system to
operate as:
a reception signal phase difference detecting unit that
15 refers to a phase difference between a carrier wave included in
each of the reception signals and a reference wave , and detects
reception signals that have a certain correlation; and
a reception signal association unit that associates
reception si gnals having a phase difference falling within a
20 predetermined range with one another as a group of reception
signals transmitted fro m the same fl ying object.
[Supplementary N ote 26]
The program according to the above supplementar y note,
wherein the program causes the control unit to
25 collectively add a reception tim e to the group of associated
received signals and to notif y t he centra l station of the group of
associated received si gnals.
[Supplementary N ote 27]
The program according to any one of the above
38
s u p p l e m e n t a r y n o t e s,
wherein the program causes the c o n t r o l unit to :
when a s s o c i a t i n g the r e c e p t i o n s i g n a l s with one another,
d e l e t e all but one r e c e p t i o n signal from the same type of
5 reception si g n a l s , whil e a s s o c i a t i n g different types of
r e c e p t i o n si g n a l s with one another as one group of r e c e p t i on
s i g n a l s , and to notif y the c e n t r a l s t a t i o n of the group of
a s s o c i a t e d r e c e p t i o n si g n a l s .
[ S u p p l e m e n t a r y N o t e 28]
10 The program a c c o r d i n g to any one of the above
s u p p l e m e n t a r y n o t e s,
w h e r e i n , if a pulse t r a i n in an array of pulse waves
formed by using the c a r r i e r wave is recei ved as the p l u r a l i t y of
s i g n a l s t r a n s m i t t e d from the flying ob j e c t ,
15 the program causes the c o n t r o l unit to :
when a s s o c i a t i n g the r e c e p t i o n s i g n a l s with one another,
refer to phases of a c a r r i e r wave and a r e f e r e n c e wave for
each pulse forming one r e c e p t i o n signal and to c o l l e c t i v e l y
t r e a t pulses having a c e r t a i n c o r r e l a t i o n as one r e c e p t i on
20 signal.
[ S u p p l e m e n t a r y N o t e 29]
The program a c c o r d i n g to any one of the above
s u p p l e m e n t a r y n o t e s,
wherein the program causes the c o n t r o l unit to :
25 when a s s o c i a t i n g the r e c e p t i o n s i g n a l s with one another,
u s e , as the r e f e r e n c e wave, a r e f e r e n c e signal having the
same frequency as a c a r r i e r wave frequency used for the flying
object to be p o s i t i o n e d to i d e n t i f y a phase d i f f e r e n c e of each of
the r e c e p t i on s i g n a l s r e l a t i v e to the r e f e r e n c e wave, and t o
39
detect a correlation by comp aring phase differences among the
reception si gnals.
[Supplementary N ote 30]
The program according to any one of the above
5 supplementary notes,
wherein the program causes the control unit to :
when detecting a correlation among the reception signals,
limitedly amplify each of the reception signals, and then
to determine whether the recepti on signals include carrier
10 waves having a certain correlation , b y using the reference
wave.
[Supplementary N ote 31]
The program according to any one of the above
supplementar y notes,
15 wherein the program causes the control unit to :
when associating the reception signals with one another
that have a certain correlation in a period of a carrier wave,
determine whether there is a correlation based on a
threshold value of an amount of phase difference relative to the
20 reference wave.
[Supplementary N ote 32]
The program according to any one of the above
supplementary notes,
wherein the program causes the control unit to:
25 refer to a phase difference between a carrier wave that is
included in a pulse constituting each of the response signals
and a reference wave , and to regard pulses having a phase
di fference falling within a predetermined range as one response
signal transmitted from the same fl ying object; and to
40
associat e di fferent types of the response signals having a
phase difference falling within a predetermined range with one
another into one group of response signals.
[Supplementary N ote 33]
5 A recording medium that records the program according
to an y one of the supplementar y notes on a non -transitory basis.
This application claims priorit y based on Japanese Patent
Application No. 2014-041172 filed on March 4, 2014, the entire
10 disclosure of which is herein incorporated.
[Reference signs List]
10 (10-1 to 10 -4) Reception station
11 Reception unit
15 12 Signal processing unit
13 Transmission unit
14 Reception signal carrier wave phase ident ifyin g unit
15 Reception signal correlation detecting unit
16 Reception signal a s s o c i a t i o n unit
20 17 Time inform a t i o n addi ng unit
20 Central s t a t i on
30 Transmission/reception s t a t i on
100 Reception s t a t i on
110 Reception unit
25 111 A m p l i f i er
112 Reception processing unit
113 Reception video generating unit
120 Signal processing unit
121 Limiting am plifier unit
41
122 Phase difference detecti on unit
123-1 Pulse phase difference correlating unit
123-2 Repl y phase difference correlating unit
124 Bracket pulse detecting unit
5 125 Repl y processing unit
126 Target correlating unit
127 ATCRBS response processing unit
128 Mode S r e s p o n s e p r o c e s s i n g un i t
1 2 9 Ta rg e t i n fo rm a t i o n g e ner at i n g un it
10 130 Transmission unit
140 Time inform ation generating unit
141 GPS receiver
142 Time s ynchronization signal generating unit

[Document Name] CLA IMS
[Claim 1]
A fl ying object position -measuring s yst em comprising a
pluralit y of reception stations and a central station, wherein
each of the pluralit y of recept ion stations receives a
pluralit y of signals, as reception signals, transmitted from a
flying object, and notifies the central station of the individual
reception signals,
the central station performs position measurement of the flying object based on each reception signal which was
transmitted by the flying object and noti fication of which was given by each of the plurality of reception stations, and the recepti on station comprises :
a reception unit that receives each of the plurality of signals as reception signals;
a reception signal phase difference detecting unit that refers to a phase difference between a carrier wave included in
each of the reception sign als and a reference wave , and detects
reception si gnals that have a certain correlation; a reception signal association unit that associates reception si gnals having a phase difference falling within a
predetermined range with one another as a group of re ception signals transmitted from the same flying object; and
a transmission unit that notifies the central unit of the
25 group of associated reception signals.
[Claim 2]
The flying object position -measuring system according to
cl aim 1, wherein
the recepti on st ation coll ectively a dds a reception time to
43
the group of associated reception signals and notifies the
central station of the group of associated reception signals.
[Claim 3]
The flying object position -measuring system according to
5 any one of claim 1 or 2, wherein,
when associating the reception signals with one another,
the recepti on station deletes al l but one reception signal from
the same t ype of reception signals, while associating different
t ypes of reception signals with one another as one group of
10 reception si gnals, and notifies the central station of the group
of associat ed recepti on signals.
[Claim 4]
The flying object position -measuring system according to
any one of claims 1 to 3, wherein,
15 if a pulse train in an arra y of pulse waves formed b y
using the carrier wave is received as the pluralit y of signals
transmitted from the fl ying object,
the recepti on station,
when associating the reception signals with one another,
20 refers to phases of a carrier wave and a reference wave
for each pulse forming one reception signal and collectivel y
treats pulses having a certain correlation as one reception
signal.
[Claim 5]
25 The flying object position -measuring system according to
any one of claims 1 to 4, wherein,
when associating the reception signals with one another,
the recepti on station uses, as the reference wave, a
reference si gnal havi ng the sam e frequency as a carrier wave
44
frequency used for the flying object to be positioned to identify
a phase difference of each of the reception si gnals relative to
the reference wave, and detects a correlation b y comparing
phase differences among the reception signals.
5 [Claim 6]
The flying object position -measuring system according to
any one of claims 1 to 5, wherein,
when detecting a correlation among the r ecept ion signals,
the recepti on station limitedly amplifies each of the reception
10 signals, and then det ermines whether the reception signals
include carrier waves having a certain correlation , by using the
reference wave.
[Claim 7]
The flying object posit ion-measuring system according to
15 any one of claims 1 to 6, wherein,
when associating the reception signals with one another
that have a certain correlation in a period of a carrier wave, the
reception st ation determines whether there is a correlation
based on a threshold value of an amount of phase difference
20 relative to the reference wave.
[Claim 8]
A fl ying object position -measuring s yst em comprising a
pluralit y of reception stations and a central station, wherein
each of the pluralit y of recept ion stat ions receives, as
25 reception signals, different t ypes of response signals including
an SSR Mode A response signal and an SSR Mode C response
signal, the signals being transmitted from an aircraft, generates
target information and notifies t he central statio n of the
reception si gnals respectively,
45
the central station performs a positional measurement of
the aircraft by using a pluralit y of pieces of the t arget
information respectivel y notified by the pluralit y of reception
stations,
5 the recepti on station comprises:
a reception unit that receives different types of t he
response signals;
a signal processing unit that refers to a phase difference
between a carrier wave that is included in a pulse constituting
10 each of the response signals and a reference wave , and regards
pulses having a phase difference falling within a predetermined
range as one response signal transmitted from the same fl ying
object, and that associates different t ypes of the response
signals having a phase difference falling within a
15 predet ermined range with one another into one group of
response signals; and
a transmission unit t hat notifies the central station of the
group of associated response signals.
[Claim 9]
20 A reception station in a flying object position -measuring
system, the reception station comprising:
a reception unit that receives each of a pluralit y of
signals, as a reception signal , transmitted from a flying object;
a reception signal phase difference detecting unit that
25 refers to a phase difference between a carrier wave included in
each of the reception signals and a reference wave , and detects
reception si gnals that have a certain correlation;
a reception signal association unit that associates
reception si gnals having a phase difference falling within p r e d e t e r m i n e d range with one another as a group of reception signals transmitted from the same fl ying
object; and
notifies the central unit of the group of associated
reception si gnals.
5 [Claim 12]
A recording m edium recording a program causing a
reception station incl uded in a fl yi ng obj ect position -measuring
system to operate as:
a reception signal phase difference detecting unit that
10 refers to a phase difference between a carrier wave included in
each of the reception signals and a reference wave , and detects
reception signals that have a certain correlation; and a reception signal association unit that associates
reception signals having a phase difference fall ing within a predetermined range with one another as a group of reception signals transmitted from the same flying object.