DESC:TECHNICAL FIELD
[0001] The present invention relates generally to frequency measurement systems. The present invention, more particularly, relates to frequency measurement systems for surveillance devices.
BACKGROUND
[0002] Frequency measurement is one of the important functions of a surveillance receiver used in defence applications. The sensitivity of a receiver depends on operational bandwidth of a system. The frequency measurement receiver is a wide-open receiver with limited sensitivity due to its wider operational bandwidth. Existing systems are built with limited sensitivities, posing the operational limitations.

[0003] A Patent Number US4859934A discloses an apparatus for measuring the frequency of microwave signals. A microwave frequency detection receiver utilizing a pre-scaler comprised of one or a plurality of cascaded analog frequency dividers for down-converting received microwave signals to a predetermined compressed radio frequency bandwidth, connected to a combined frequency discriminator and a quantizer processor. The frequency discriminator can be either a single or multiple delay line(s) discriminator or a two-stage feed forward digital instantaneous frequency measurement device. The receiver is characterized by wide radio frequency input bandwidth as well as accurate frequency measurement capability on short single pulse signals. Delay line discriminators are operated with high data rates and in a dense signal environment with signal frequency detection and measurement.

[0004] There is still a need of an invention which solves the above defined problems and provides a multi-channel and multi-band frequency measurement receiving system for surveillance devices, which is compact and has high sensitivity with wide frequency coverage frequency.
SUMMARY

[0005] This summary is provided to introduce concepts related to a frequency measurement receiving system and method thereof. This summary is neither intended to identify essential features of the present invention nor is it intended for use in determining or limiting the scope of the present invention.

[0006] For example, various embodiments herein may include one or more frequency measurement receiving systems and methods thereof are provided. In one of the embodiments, a method for measuring frequency of signals includes a step of receiving, by a plurality of power dividers, the signals having frequency ranges. The method includes a step of dividing, by the power dividers, the signals into a number of channels based on frequency ranges, and with pre-determined bandwidths. The method includes a step of correlating, by a plurality of correlators, the channels and generating a digital output signal for each channel. The method includes a step of calibrating, by a calibration module, the digital output signal for each channel, and generating calibrated data. The method includes a step of measuring, by a measurement module, frequency of the signals based on the calibrated data.

[0007] In another embodiment, a frequency measurement receiving system includes a plurality of power dividers, a plurality of correlators, a calibration module, and a measurement module. The plurality of power dividers is configured to receive signals having frequency ranges. The power dividers are further configured to divide the signals into a number of channels based on the frequency ranges with pre-determined bandwidths. The plurality of correlators is configured to correlate the channels and generate a digital output signal for each channel. The calibration module is configured to calibrate the digital output signal for each channel, and generate calibrated data. The measurement module is configured to measure frequency of the signals based on the calibrated data.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

[0008] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and modules.

[0009] Figure 1 illustrates a schematic diagram depicting an arrangement of a frequency measurement receiving system, according to an exemplary implementation of the present invention.

[0010] Figure 2 illustrates a block diagram depicting a frequency measurement receiving system, according to an exemplary implementation of the present invention.

[0011] Figure 3 illustrates a block diagram depicting a correlator, according to an exemplary implementation of the present invention.

[0012] Figure 4 illustrates a schematic diagram depicting a field-programmable gate array, according to an exemplary implementation of the present invention.

[0013] Figure 5 illustrates a flowchart depicting a method for measuring frequency of signals, according to an exemplary implementation of the present invention.

[0014] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present invention. Similarly, it will be appreciated that any flowcharts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.
DETAILED DESCRIPTION
[0015] In the following description, for the purpose of explanation, specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these details. One skilled in the art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of systems.

[0016] The various embodiments of the present invention provide a frequency measurement receiving system and method thereof.

[0017] Furthermore, connections between components and/or modules within the figures are not intended to be limited to direct connections. Rather, these components and modules may be modified, re-formatted or otherwise changed by intermediary components and modules.

[0018] References in the present invention to “one embodiment” or “an embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

[0019] The present invention relates a frequency measurement receiving system and method thereof. In one of the embodiments, a method for measuring frequency of signals includes a step of receiving, by a plurality of power dividers, the signals having frequency ranges. The method includes a step of dividing, by the power dividers, the signals into a number of channels based on frequency ranges, and with pre-determined bandwidths. The method includes a step of correlating, by a plurality of correlators, the channels and generating a digital output signal for each channel. The method includes a step of calibrating, by a calibration module, the digital output signal for each channel, and generating calibrated data. The method includes a step of measuring, by a measurement module, frequency of the signals based on the calibrated data.

[0020] In another implementation, the method includes selecting, by one or more band pass filters, appropriate bandwidths from the pre-determined bandwidths for each channel.

[0021] In another implementation, the method includes generating, by a plurality of digitizers, digital data for the digital output signal for each channel using the calibrated data.

[0022] In another implementation, the method includes performing, by a signal conditioner, conditioning on the channels and generating the digital data based on the conditioning of the channels.

[0023] In another implementation, the method includes, dividing, by the power dividers, frequency bands, and the frequency bands including one or more frequency ranges with the pre-determined bandwidths.

[0024] In another implementation, the method includes providing, by a plurality of phase discriminators, analog channels corresponding to each channel.

[0025] In another implementation, the method includes converting, by a conversion unit, the phase discriminators into frequency discriminators using a two port power divider and a pair of equal length cables, which are matched within the limiting values in amplitude and phase of the incoming signals.

[0026] In another implementation, generating the digital data includes converting and combining the measured frequency into a single frequency with a pre-defined length.

[0027] In another embodiment, a frequency measurement receiving system includes a plurality of power dividers, a plurality of correlators, a calibration module, and a measurement module. The plurality of power dividers is configured to receive signals having frequency ranges. The power dividers are further configured to divide the signals into a number of channels based on the frequency ranges with pre-determined bandwidths. The plurality of correlators is configured to correlate the channels and generate a digital output signal for each channel. The calibration module is configured to calibrate the digital output signal for each channel, and generate calibrated data. The measurement module is configured to measure frequency of the signals based on the calibrated data.

[0028] In another implementation, the system includes one or more band pass filters. The band pass filters are configured to select appropriate bandwidths from the pre-determined bandwidths for each channel.

[0029] In another implementation, the system includes a plurality of digitizers. The digitizers are configured to cooperate with the correlators and generate digital data for the digital output signal for each channel using the calibrated data.

[0030] In another implementation, the system includes a signal conditioner. The signal conditioner includes the correlators and the digitizers to perform conditioning on the channels and generate the digital data.

[0031] In another implementation, the power dividers are configured to divide frequency bands. The frequency bands include one or more frequency ranges with the pre-determined bandwidths using the band pass filters.

[0032] In another implementation, the system includes a plurality of phase discriminators. The phase discriminators provide analog channels corresponding to each channel.

[0033] In another implementation, the system includes a conversion unit. The conversion unit is configured to convert the phase discriminators into frequency discriminators using a two port power divider and a pair of equal length cables, which are matched within the limiting values in amplitude and phase of the incoming signals.

[0034] In another implementation, each of the digitizers include an analog to digital converter, and configured to convert and combine the measured frequency into a single frequency with a pre-defined length.

[0035] Figure 1 illustrates a schematic diagram depicting an arrangement (100) of a frequency measurement receiving system, according to an exemplary implementation of the present invention.

[0036] In an embodiment, frequency measurement is an important feature of a surveillance device. Figure 1 illustrates an arrangement of a frequency measurement receiving system (200) in the surveillance device. The frequency measurement receiving system (200) is one of the receiving systems at a second stage of the surveillance device. The surveillance device receives signals from one or more antennas (102) at a front end (104). The frequency measurement receiving system (200) is configured to measure frequency of the received signals. A processor (106) is configured to receive the measured frequency, and further process the signal. A display (104) is configured to receive the processed signal and generate an output, and provide on the display (104). In an embodiment, the display (104) can be a display unit (104) which includes a screen, a monitoring device, and the like.

[0037] Figure 2 illustrates a block diagram depicting a frequency measurement receiving system (200), according to an exemplary implementation of the present invention.

[0038] The frequency measurement receiving system (200) (hereinafter referred to as “system”) includes a plurality of power dividers (202), a plurality of correlators (206), a calibration module (214), and a measurement module (216).

[0039] The system (200) is configured to receive incoming signals from an antenna (102). In an embodiment, the antenna is an Ultra-Wideband (UWB) antenna. In another embodiment, the system (100) is configured to receive radio frequency signals from the antenna (102). In another embodiment, the system (100) is configured to receive radio frequency modulated signals from the antenna (102). At least one power divider (202) having n number of ports (1, 2, 3, …., n) is configured to receive the incoming signals. The incoming signals have frequency ranges. The power divider (202) is configured to receive the incoming signals having frequency ranges from the antenna, and is further configured to divide the incoming signals into a number of channels based on the frequency ranges with pre-determined bandwidths. In an embodiment, the system (200) includes one or more band pass filters (204a, …. 204n). The band pass filters (204a, …. 204n) are configured to cooperate with the power dividers (202) to select appropriate bandwidths from the pre-determined bandwidths for each channel. In an embodiment, the power dividers (202, 202a,….. 202n) are configured to divide frequency bands, where the frequency bands include one or more frequency ranges with the pre-determined bandwidths using the band pass filters (204a, … 204n). In one embodiment, each band pass filter (204a,… 204n) is configured to cooperate with each power divider (202a… 202n). For example, a first band pass filter (BPF1) (204a) is configured to receive a channel from the first port of the power divider (202), and is further configured to select appropriate bandwidth for the channel, and transmit the bandwidth details along with the channel to a first power divider (202a). In an embodiment, the first power divider (202a) also having n number of ports (for example, ports 11, 21, 31, p1). Similarly, the nth power divider (202n) also having n number of ports (for example, ports 1n, 2, 3n, pn).

[0040] The plurality of correlators (206) is configured to cooperate with the power dividers (202) to receive the channels, and is further configured to correlate the channels and generate a digital output signal for each channel. In an embodiment, each of the correlators (206a, … 206n) are configured to cooperate with at least one power divider (202a, …. 202n). For example, a plurality of first correlators (206a) includes a correlator-11, a correlator-21, a correlator-31, and a correlator-P1), and each correlator is configured to cooperate with each port (11, 21, 31, p1) of the at least one power divider (202a), i.e. the correlator-11 is configured to cooperate with the first port (11) of the first power divider (202a), the correlator-21 is configured to cooperate with the second port 21), the correlator-31 is configured to cooperate with the third port 31), and the like. Similarly, a plurality of nth correlators (206n) includes a correlator-1n, a correlator-2n, a correlator-3n, and a correlator-pn), and each correlator is configured to cooperate with each port (1n, 2n, 3n, pn) of the at least one power divider (202n), i.e. the correlator-1n is configured to cooperate with the first port (1n) of the nth power divider (202n), the correlator-2n is configured to cooperate with the second port (2n), the correlator-3n is configured to cooperate with the third port 3n), and the like. Each of the correlators ((11, 21, … p1)…. (1n, 2n,... pn)) correlate the channels and generate a digital output signal for each channel.

[0041] In an embodiment, the system (200) includes a plurality of digitizers (208). Each of the digitizers (208) are configured to cooperate with each correlator (((11, 21, … p1)…. (1n, 2n,... pn)). The digitizers (208) are configured to generate digital data for the digital output signal for each channel by using the calibrated data. In an embodiment, each digitizer (208) includes an analog to digital converter (not shown in a figure). The analog to digital converter is configured to convert and combine the measured frequency into a single frequency with a pre-defined length.

[0042] In an embodiment, the system (200) includes a signal conditioner (210). The signal conditioner (210) includes the correlators (206) and the digitizers (208) to perform conditioning on the channels, and generate digital data using the digitizers (208).

[0043] The calibration module (214) is configured to cooperate with the plurality of the correlators (206) to receive the generated digital output signal. The calibration module (214) is further configured to calibrate the digital output signal for each channel, and generate calibrated data. In an exemplary embodiment, the calibration module (214) is configured to cooperate with the correlators (206a, … 206n) to receive the digital output signals for each channel, and is further configured to calibrate the digital output signal and generate calibrated data. In an embodiment, the system (200) is configured to split the signals into more than one frequency ranges with predetermined bandwidths by use of parallel correlators with that bandwidths combine with high speed digital circuits and thus form parallel digital output signals are combined and calibrate to get accurate measurement of frequency of incoming radar signals.

[0044] The measurement module (216) is configured to cooperate with the power dividers and the calibration module (214). The measurement module (216) is configured to measure frequency of the signals based on the calibrated data.

[0045] In an embodiment, the system (200) includes a memory (212). The memory (212) is configured to store digital data for each channel, which is further used to generate frequency data. In an embodiment, the memory (212) is a high volume memory which can store large volume of data. In another embodiment, the memory (212) is configured to store pre-programmed data. In another embodiment, the size of the memory depends on the volume of the data that is generated by the number of correlators (206).

[0046] In another embodiment, the output digital frequency is calibrated in the high speed programmable circuit to reduce the frequency errors of the incoming radar signals. The frequency measurement accuracy is within 0.5 MHz using a 16 bit analog to digital converter.

[0047] In another embodiment, the calibration is carried out with the help of a standard frequency generator and a computer system. In another embodiment, the frequency range is split into four octave bands for enhancement of sensitivity of the system (202). In another embodiment, the system (100) splits four octave frequency ranges of 2-4 GHz, 4-8 GHz, 8-12 GHz and 12-18 GHz and using a 16 bits analog to digital converter and calibrated to improve the accuracy of the frequency measurement.

[0048] Figure 3 illustrates a block diagram (300) depicting a correlator, according to an exemplary implementation of the present invention.

[0049] In Figure 3, a plurality of power dividers (202) is configured to receive the incoming signals. The incoming signals have frequency ranges, i.e. f1 to f2, where f1 < fi < f2. In an embodiment, the power divider (202) is configured to receive the incoming signals having frequency ranges f1 to f2 from the antenna, and is further configured to divide the incoming signals into a number of channels based on the frequency ranges i.e. f1 to fi and fi to f2.

[0050] The power dividers (202a, 202b) are configured to receive the divided signals. The power dividers (202a, 202b) are further configured to divide the signals and transmit the signals to a frequency discriminator (302) and the power divider (202c). The frequency discriminator (302) is configured to convert frequency changes into amplitude changes by receiving the signals from the power dividers (202a, 202b), and is further configured to transmit the converted signals to a Field-programmable gate array of a system on a chip (SOC), as shown in Figure 4. Further, the power divider (202c) is configured to divide the signals, where the first signal is directly transmitted to a phase discriminator (306), and the second signal transmits to the phase discriminator (306) via printed delay on micro strip (304). The signals outputted from the phase discriminator (306) transmits to a Field-programmable gate array of a system on a chip (SOC), as shown in Figure 4. In an embodiment, the phase discriminator (306) is configured to generate a voltage signal which provides the difference in phase between two received signals, i.e. the first signal and the second signal. In an embodiment, the system (100) includes a plurality of phase discriminators (306) configured to cooperate with the power dividers (202) and provide analog channels corresponding to each channel. In another embodiment, a conversion unit (308) is configured to cooperate with the phase discriminators (306) and the frequency discriminators (302). The conversion unit (308) is configured to convert the phase discriminators (306) into the frequency discriminators (302) using a two port power divider and a pair of equal length cables, which are matched within the limiting values in amplitude and phase of the signals. In one embodiment, the limiting values are pre-determined values, and stored in the memory (212) of Figure 2.

[0051] In another embodiment, the system (200) splits a frequency band into multiple bands is comprised with more than one frequency ranges with predetermined bandwidths using a set of high selectivity band pass filters (204) and the phase discriminators (306) to provide analog signals corresponding to the incoming radar signals. In another embodiment, the phase discriminators (306) are converted into frequency discriminators (302) using a two port power divider and a pair of equal length cables, which are matched within the limiting values in amplitude and a phase of the incoming radar signals. In another embodiment, an output of the digitizer circuit comprising of high speed analog to digital converter and combining the measured frequency into single frequency word with predefined word length.

[0052] Figure 4 illustrates a schematic diagram depicting a field-programmable gate array (400), according to an exemplary implementation of the present invention.

[0053] Figure 4 illustrates a high speed field-programmable gate array (FPGA) of a system on a chip (402). The FPGA is configured to receive 20 bits digital data from the memory (212), as shown in Figure 2, and signals from the frequency discriminators (302) and the phase discriminators (306), as shown in Figure 3. The FPGA (402) then produce pulse by pulse frequency bits as an output.

[0054] Figure 5 illustrates a flowchart depicting a method for measuring frequency of signals, according to an exemplary implementation of the present invention.

[0055] The flowchart (500) starts at a step (502), receiving, by a plurality of power dividers (202), the signals having frequency ranges. In an embodiment, a plurality of power dividers (202) is configured to receive the signals having frequency ranges. At a step (504), dividing, by the power dividers (202), the signals into a number of channels based on frequency ranges, and with pre-determined bandwidths. In an embodiment, the power dividers (202) are configured to divide the signals into a number of channels based on frequency ranges, and with pre-determined bandwidths. At a step (506), correlating, by a plurality of correlators (206), the channels and generating digital output signal for each channel. In an embodiment, a plurality of correlators (206) is configured to correlate the channels and generate digital output signal for each channel. At a step (508), calibrating, by a calibration module (214), the digital output signal for each channel, and generating calibrated data. In an embodiment, a calibration module (214) is configured to calibrate the digital output signal for each channel and generate calibrated data. At a step (510), measuring, by a measurement module (216), frequency of the signals based on the calibrated data. In an embodiment, a measurement module (216) is configured to measure frequency of the signals based on the calibrated data.
EXPERIMENTAL RESULTS
[0056] In an exemplary embodiment, the system (200) is configured to measure frequency of signals in various conditions. Table 1 illustrates test conditions which are performed by the system (200), and Table 2 illustrates test results, which shows improvement over existing methodologies.

Test PWnS/
perioduS Fstep MHz Fstart MHz Fstop
MHz PWR dBm TRIGGER
Frequency Accuracy Test 1 50/1 25 8000 12000 -60 INT
Frequency Accuracy Test 2 1000/1000 25 8000 12000 -60 EXT
Frequency Accuracy Test 3 CW 25 8000 12000 -60 INT
Frequency Accuracy Test 4 50/1 25 8000 12000 0 EXT
Frequency Accuracy Test 5 1000/1000 25 8000 12000 0 INT
Frequency Accuracy Test 6 CW 25 8000 12000 0 EXT
TABLE 1: TEST CONDITIONS
Test Specification
(Root Mean Square Accuracy) Measured PASS/FAIL
Frequency Accuracy Test 1 = 3MHz 2.20 MHz PASS
Frequency Accuracy Test 2 = 3MHz 2.05 MHz PASS
Frequency Accuracy Test 3 = 3MHz 2.06 MHz PASS
Frequency Accuracy Test 4 = 3MHz 2.05 MHz PASS
Frequency Accuracy Test 5 = 3MHz 2.03 MHz PASS
Frequency Accuracy Test 6 = 3MHz 2.05 MHz PASS
TABLE 2: TEST RESULTS
[0057] In an embodiment, the system (200) is configured to provide designing of a wide band frequency receiver with very high sensitivity for surveillance systems. In another embodiment, the system (200) is configured to achieves high sensitivity in a single frequency measurement receiver module. In another embodiment, the system (200) is configured to reduce inherent frequency errors.

[0058] It should be noted that the description merely illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present invention. Furthermore, all examples recited herein are principally intended expressly to be only for explanatory purposes to help the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

,CLAIMS:

1. A method for measuring frequency of signals, said method comprising:
receiving, by a plurality of power dividers (202), the signals having frequency ranges;
dividing, by said power dividers (202), said signals into a number of channels based on frequency ranges, and with pre-determined bandwidths;
correlating, by a plurality of correlators (206), said channels and generating digital output signal for each channel;
calibrating, by a calibration module (214), said a digital output signal for each channel, and generating calibrated data; and
measuring, by a measurement module (216), frequency of said signals based on said calibrated data.

2. The method as claimed in claim 1, wherein said method includes selecting, by one or more band pass filters (204), appropriate bandwidths from said pre-determined bandwidths for each channel.

3. The method as claimed in claim 1, wherein said method includes generating, by a plurality of digitizers (208), digital data for the digital output signal for each channel using said calibrated data.

4. The method as claimed in claim 1 or 3, wherein said method includes performing, by a signal conditioner (210), conditioning on said channels and generating said digital data based on said conditioning of said channels.

5. The method as claimed in claim 1, wherein said method includes, dividing, by said power dividers (202), frequency bands, and said frequency bands including one or more frequency ranges with said pre-determined bandwidths.

6. The method as claimed in claim 1, wherein said method includes providing, by a plurality of phase discriminators (306), analog channels corresponding to each channel.

7. The method as claimed in claim 1, wherein said method includes converting, by a conversion unit (308), said phase discriminators (306) into frequency discriminators (302) using a two port power divider (202) and a pair of equal length cables, which are matched within the limiting values in amplitude and phase of said incoming signals.

8. The method as claimed in claim 3, wherein said generating the digital data includes converting and combining the measured frequency into a single frequency with a pre-defined length.

9. A frequency measurement receiving system (200), comprising:
a plurality of power dividers (202) configured to receive signals having frequency ranges, said power dividers (202) configured to divide said signals into a number of channels based on said frequency ranges with pre-determined bandwidths;
a plurality of correlators (206) configured to cooperate with said power dividers (202) to receive said channels, said correlators (206) configured to correlate said channels and generate a digital output signal for each channel;
a calibration module (214) configured to cooperate with said correlators (206), said calibration module (214) configured to calibrate said digital output signal for each channel, and generate calibrated data; and
a measurement module (216) configured to cooperate with said power dividers (202) and said calibration module (214), said measurement module (216) configured to measure frequency of said signals based on said calibrated data.

10. The system (200) as claimed in claim 9, wherein said system (200) includes one or more band pass filters (204), said band pass filters (204) are configured to cooperate with said power dividers (202) to select appropriate bandwidths from said pre-determined bandwidths for each channel.

11. The system (200) as claimed in claim 9, wherein said system (200) includes a plurality of digitizers (208), said digitizers (208) are configured to cooperate with said correlators generate digital data for the digital output signal for each channel using the calibrated data.

12. The system (200) as claimed in claim 9 or 11, wherein said system (200) includes a signal conditioner (210), said signal conditioner (210) includes said correlators (206) and said digitizers (208) to perform conditioning on said channels and generate said digital data.

13. The system (200) as claimed in claim 9, wherein said power dividers (202) are configured to divide frequency bands, said frequency bands including one or more frequency ranges with said pre-determined bandwidths using said band pass filters (204).

14. The system (200) as claimed in claim 9, wherein said system (200) includes a plurality of phase discriminators (306), said phase discriminators (306) configured to cooperate with said power dividers (202) and provide analog channels corresponding to each channel.

15. The system (200) as claimed in claim 9, wherein said system (200) includes a conversion unit (308), said conversion unit (308) is configured to convert said phase discriminators (306) into frequency discriminators (302) using a two port power divider (202) and a pair of equal length cables, which are matched within the limiting values in amplitude and phase of said incoming signals.

16. The system (200) as claimed in claim 11, wherein each of said digitizers (208) includes an analog to digital converter, and configured to convert and combine the measured frequency into a single frequency with a pre-defined length.