Claims:1. A system (100) for converting non-coherent radar to coherent radar, the system comprising:
a waveform generator and controller (106) configured in a transmitter (102), the radar waveform generator generates a first set of signals at low frequency using direct digital synthesizer (DDS), the first set of signals pertaining to radar waveform and control signal, the control signals are derived from the radar waveform, the control signals pertaining to sweep trigger and dwell trigger;
one or more local oscillators (110-1, 110-2) configured in the transmitter, the one or more local oscillators generate a second set of signals, the second set of signals pertaining to local oscillator signals,
wherein, the generated first set of signals and the second set of signals are synchronized with DDS clock signal,
a receiver (104) configured to receive the return signals from the target through receive antennae to down-convert the received return signals; and
a processor (114) coupled to the receiver, the processor configured to
receive, from the receiver, the down-converted signal; and
process the down-converted signal to a digital set of signals, wherein the processed digital set of signals effect phase-coherent set of signals.
2. The system as claimed in claim 1, wherein the one or more local oscillators comprising a first local oscillator (110-1), a second local oscillator (110-2) and a third local oscillator (110-3), wherein the first local oscillator (110-1), the second local oscillator (110-2) configured in the transmitter (102) and the third local oscillator (110-3) configured in the receiver (104).
3. The system as claimed in claim 2, wherein the first local oscillator (110-1) coupled to a first mixer (112-1), the second local oscillator (110-2) coupled to a second mixer (112-2) and third local oscillator (110-3) coupled to a third mixer (112-3).
4. The system as claimed in claim 3, wherein the first mixer (112-1) and the second mixer (112-2) are up-converters and the third mixer (112-3) is a down-converter.
5. The system as claimed in claim 4, wherein the first mixer (112-2), and the second mixer (112-2) operable to perform up-conversion of the received first set of signals (106) in the transmitter.
6. The system as claimed in claim 4, wherein the third mixer (112-3) operable to perform down-conversion of the received return signals in the receiver.
7. The system as claimed in claim 1, wherein DDS configured in the waveform generator and controller.
8. The system as claimed in claim 1, wherein a reference source is coupled to the waveform generator and controller, up-converter, down-converter and the processor.
9. The system as claimed in claim 1, wherein the scheduling of RF, and IF frequency is performed for a given pulse repetition time (PRT) to obtain coherency.
10. A method (300) for converting non-coherent radar to coherent radar, the method comprising:
generating (302), at a waveform generator and controller, a first set of signals at low frequency using direct digital synthesizer (DDS), the first set of signals pertaining to radar waveform and control signals, the waveform generator and controller configured in a transmitter, the control signals are derived from the radar waveform, the control signals pertaining to sweep trigger and dwell trigger;
generating (304), at one or more local oscillators, a second set of signals, the second set of signals pertaining to local oscillators signals, the one or more local oscillators configured in the transmitter, wherein, the generated first set of signals, and the second set of signals are synchronized with DDS clock signal;
receiving (306), at a receiver, the return signals from the target to down-convert the received return signals; and
processing (308), at a computing device, the down-converted signal to a digital set of signals, wherein the processed digital set of signals effect phase coherent set of signals.
, Description:TECHNICAL FIELD
[0001] The present disclosure relates, in general, to radar systems, and more specifically, relates to a system and method to convert non-coherent FMCW radar to coherent radar.

BACKGROUND
[0002] Radar systems commonly used to detect targets e.g., objects, geographic features, or other types of targets in proximity to watercraft, aircraft, vehicles, and fixed locations. Frequency modulated continuous wave (FMCW) radar systems are well known and have been widely used in a variety of applications for many years. In such systems, the range to a target is measured by systematically varying the frequency of a transmitted radio frequency (RF) signal. Conventional radar systems typically employ magnetrons to generate radar signals. However, magnetrons and their hardware architecture are often expensive, physically cumbersome to operate.
[0003] Few exemplary existing technologies in the field of radar system includes a device for retaining phases of transmitted pulses, for phase detection of received radar pulses with respect to transmitted pulses associated with the present and preceding reception period, and for integrating phase detected signals in a coherent manner. Other devices include complex demodulation on an attenuated and limited waveform of the transmitter produced pulse. Although multiple radar system exists today, these existing systems suffer from significant drawbacks.
[0004] Therefore, there is a need in the art to provide a means that converts non-coherent FMCW radar to coherent radar and thereby reduces the cost required for complex high-end hardware.

OBJECTS OF THE PRESENT DISCLOSURE
[0005] An object of the present disclosure relates, in general, to radar systems, and more specifically, relates to a system and method to convert non-coherent FMCW radar to coherent radar.
[0006] Another object of the present disclosure is to provide a system that converts non-coherent heterodyne FMCW radar to coherent radar by controlling radar waveform and radar control signal generation.
[0007] Another object of the present disclosure is to provide a system that maintains pulse-to-pulse phase coherency.
[0008] Another object of the present disclosure is to provide a system that detect moving targets as well as extract micro-Doppler radar signatures.
[0009] Another object of the present disclosure reduces the cost of the system.
[0010] Yet another object of the present disclosure is to provide a system that require minimum hardware.

SUMMARY
[0011] The present disclosure relates, in general, to radar systems, and more specifically, relates to a system and method to convert non-coherent FMCW radar to coherent radar.
[0012] The present disclosure relates to converting non-coherent to coherent heterodyne FMCW Radar. In the heterodyne systems, to detect moving targets and micro-Doppler extraction, radar has to work on pulse-to-pulse coherency. In this method, pulse-to-pulse coherency is achieved with double up-conversion and single down-converted non-coherent radar system. Frequency planning and deriving the radar control signals synchronously from the radar waveform generator made the system coherent.
[0013] In an aspect, the present disclosure provides a system for converting non-coherent radar to coherent radar, the system includes a waveform generator and controller configured in a transmitter, the waveform generator and controller generates a first set of signals at low frequency using direct digital synthesizer (DDS), the first set of signals pertaining to radar waveform and control signal, the control signals are derived from the radar waveform, the control signals pertaining to sweep trigger and dwell trigger, one or more local oscillators configured in the transmitter, the one or more local oscillators generate a second set of signals, the second set of signals pertaining to local oscillator signals, wherein, the generated first set of signals and the second set of signals are synchronized with DDS clock signal, a receiver configured to receive the return signals from the target through receiver antennae to down-convert the return signals; and a processor coupled to the receiver, the processor configured to receive, from the receiver, the down-converted signal; and process the down-converted signal to a digital set of signals, wherein the processed digital set of signals effect phase coherent set of signals.
[0014] In an embodiment, the one or more local oscillators may include a first local oscillator, a second local oscillator and a third local oscillator, the first local oscillator, the second oscillator local configured in the transmitter and the third local oscillator configured in the receiver.
[0015] In another embodiment, the first local oscillator coupled to a first mixer, the second local oscillator coupled to a second mixer and third local oscillator coupled to a third mixer.
[0016] In another embodiment, the first mixer and the second mixer may be up-converter and the third mixer may be a down-converter.
[0017] In another embodiment, the first mixer and the second mixer operable to perform up-conversion of the received first set of signals in the transmitter.
[0018] In another embodiment, the third mixer operable to perform down-conversion of the received return signals in the receiver.
[0019] In another embodiment, the DDS configured in the waveform generator and controller.
[0020] In another embodiment, a reference source is coupled to the waveform generator and controller, up-converter, down-converter and the processor.
[0021] In another embodiment, the scheduling of RF and IF frequency for a given pulse repetition time (PRT) to obtain coherency.
[0022] In an aspect, the present disclosure provides a method for converting non-coherent radar to coherent radar, the method including generating, at a waveform generator and controller, a first set of signals at low frequency using direct digital synthesizer (DDS), the first set of signals pertaining to radar waveform and control signals, the waveform generator and controller configured in a transmitter, the control signals are derived from the radar waveform, the control signals pertaining to sweep trigger and dwell trigger, generating, at one or more local oscillators, a second set of signals, the second set of signals pertaining to local oscillators signals, the one or more local oscillators configured in the transmitter, wherein, the generated first set of signals, and the second set of signals are synchronized with DDS clock signal, receiving, at a receiver, the return signals from the target to down-convert the received return signals; and processing, at a computing device, the down-converted signal to a digital set of signals, wherein the processed digital set of signals effect phase coherent set of signals.
[0023] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The following drawings form part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[0025] FIG. 1 illustrates an exemplary representation of synchronised heterodyne radar system, in accordance with an embodiment of the present disclosure.
[0026] FIG. 2A illustrates an exemplary view of linearity of FMCW signal, in accordance with an embodiment of the present disclosure.
[0027] FIG. 2B illustrates an exemplary view of unsynchronized sweep control and IF, in accordance with an embodiment of the present disclosure.
[0028] FIG. 2C illustrates an exemplary view of synchronized sweep control and IF, in accordance with an embodiment of the present disclosure.
[0029] FIG. 2D illustrates an exemplary view of synchronized radar controls signal, in accordance with an embodiment of the present disclosure.
[0030] FIG. 3 illustrates an exemplary view of flow diagram of a method for converting non-coherent radar to coherent radar, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0031] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0032] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0033] The present disclosure relates, in general, to radar systems, and more specifically, relates to a system and method to convert non-coherent FMCW radar to coherent radar. The present disclosure relates to the conversion of non-coherent FMCW radar to coherent FMCW radar by controlling radar waveform and control signals generation. The synchronisation of the reference source, pulse repetition frequency, the duty cycle of waveform with down-converted receiver intermediate frequency (IF) results to realise a pulse-to-pulse coherent heterodyne FMCW radar system.
[0034] The present disclosure relates to converting non-coherent to coherent heterodyne FMCW radar. In the heterodyne systems, to detect moving targets and micro-Doppler extraction, radar has to work on pulse-to-pulse coherency. In this method, pulse-to-pulse coherency is achieved with double up-conversion and single down-converted non-coherent radar system. Frequency planning and deriving the radar control signals synchronously from the radar waveform generator made the system coherent. The present disclosure can be described in enabling detail in the following examples, which may represent more than one embodiment of the present disclosure.
[0035] FIG. 1 illustrates an exemplary representation of synchronised heterodyne radar system, in accordance with an embodiment of the present disclosure.
[0036] Referring to FIG. 1, radar system 100 (also referred to as a system 100, herein) may be configured to convert non-coherent radar to coherent radar. The system 100 may include a transmitter 102 and a receiver 104, where the transmitter 102 may be electrically isolated from the receiver 104. The transmitter 102 may be coupled to transmit antenna and the receiver 104 may be coupled to receive antenna. The system 100 may include waveform generator and controller 106 (also interchangeably referred to as radar waveform generator (WGM) and radar controller (RC) 106, herein), a reference oscillator 108, one or more local oscillators (110-1, 110-2, 110-3) (also interchangeably referred to as LO1, LO2, LO3 (110-1, 110-2, 110-3)), one or more mixers (112-1, 112-2, 112-3), a processor 114 and a display 116. The system 100 can maintain pulse-to-pulse coherency to detect moving targets as well as to extract micro-Doppler radar signatures.
[0037] In an embodiment, the system 100 may include an up-converter that may be configured in the transmitter 102 and down-converter may be configured in the receiver 104, where the up-converter may be dual stage conversion whereas down-convertor is single stage. The present disclosure achieves pulse-to- pulse coherency with double up-conversion and single down-converted non-coherent radar system. The system 100 may be configured for use on watercraft, aircraft, vehicles, fixed locations, and other environments.
[0038] In an exemplary embodiment, the radar system 100 as presented in the example may be frequency modulated continuous wave (FMCW) radar. As can be appreciated, the present disclosure may not be limited to this configuration but may be extended to other configurations. The system 100 ensures conversion of non-coherent heterodyne FMCW radar to coherent heterodyne FMCW radar. The present disclosure maintains pulse-to-pulse phase coherency before sampling the received radar signals.
[0039] In another embodiment, the one or more local oscillators may include a first local oscillator 110-1, a second local oscillator 110-2 and a third local oscillator 110-3. The first local oscillator 110-1 and the second local oscillator 110-2 may be configured in the transmitter 102. The third local oscillator 110-3 may be configured in the receiver 104. The first local oscillator 110-1 may be coupled to a first mixer 112-1, the second local oscillator 110 -2 may be coupled to a second mixer 112-2 and the third local oscillator 110-3 may be coupled to a third mixer 112-3. The first mixer 112-1 and the second mixer 112-2 may be up-converters and the third mixer 112-3 may be the down-converter.
[0040] In an embodiment, the transmitter 102 may include waveform generator and controller 106 that may be coupled to the first mixer 112-1, the waveform generator and radar controller 106 may generate a first set of signals pertaining to radar waveform e.g., FMCW waveform and control signal like sweep trigger and dwell trigger. The waveform generator and controller 106 may generate pulse-to-pulse synchronous radar waveform at low frequency using direct digital synthesizer (DDS), the control signals may be derived from the radar waveform. DDS is a component in radar waveform generator and radar controller sub module.
[0041] The first mixer 112-1, and the second mixer 112-2 may be operable to perform up-conversion of the first set of signals in the transmitter 103. The third mixer 112-3 may be operable to perform down-conversion of the received return signals in the receiver 104 to form intermediate frequency signal. Due to one or more local oscillators (110-1, 110-2, 1103) different frequencies and a different number of frequency conversions stages at transmitter 102, which includes a low radio frequency (L-RF), and high radio frequency (H-RF) and receiver 104 affect pulse-to -pulse coherency at the receiver output.
[0042] In another embodiment, the receive antenna at the receiver 104 may receive the return signals from the target and fed the received return signal to the third mixer 112-3. The third local oscillator 110-3 may be coupled to the third mixer 112-3. The received return signal may be down-converted and may be received by the processor 114. The processor 114 coupled to the receiver 104may be configured to receive the down-converted signal and convert to a digital form. In an exemplary embodiment, the processor 114 may be a signal processing unit 114.
[0043] For example, the down-converted IF may be fed to the processor 114. The processor 114 may receive the down-converted signals, the processor 114 may digitize and process the down-converted signals. Common reference source 108 (also interchangeably referred to as reference oscillator 108) may be used for all sub modules of the radar system 100. The reference source 108 may be coupled to the waveform generator and controller 106, up-converter, down-converter and the processor 114. The scheduling of RF and IF frequency for a given pulse repetition time (PRT) to obtain coherency. The display 116 may be used to present radar data, images, or information received or processed by the system 100.
[0044] The present disclosure achieves pulse-to-pulse coherency at the receiver IF by generation of pulse-to-pulse synchronous radar waveforms at low frequency using DDS, deriving radar control signals like sweep trigger and dwell trigger from the radar waveform, where the control signals, pulse-to-pulse radar waveforms and local oscillator signals are synchronized with DDS clock signal. The synchronization of frequency for local oscillators, pulse repetition frequency (PRF) and radar control signals mentioned in equation shown below:
,
Where N=Transmitted Frequency * PRF
Phs=Phase in FMCW waveform.
[0045] In an implementation, the system 100 configured to convert non-coherent radar to coherent radar, the system may include the waveform generator and controller 106 configured in the transmitter 102, the waveform generator and controller 106 may generate the first set of signals at low frequency using DDS. The first set of signals pertaining to radar waveform and control signal, the control signals are derived from the radar waveform, the control signals pertaining to sweep trigger and dwell trigger. The one or more local oscillators (110-1, 110-2) may generate a second set of signals, the second set of signals pertaining to local oscillator signals, where, the generated first set of signals and the second set of signals are synchronized with DDS clock signal.
[0046] The receiver 104 configured to receive the return signals from the target through receive antennae to down-convert the return signals, and the processor 114 coupled to the receiver 104, the processor 114 configured to receive, from the receiver 104, the down-converted signal. The processor114 may process the down-converted signal to a digital set of signals, where the processed digital set of signals effect phase-coherent set of signals.
[0047] The embodiments of the present disclosure described above provide several advantages. The one or more of the embodiments provide the system 100 that can convert non-coherent heterodyne FMCW radar to coherent radar by controlling radar waveform and radar control signal generation. The system 100 can maintain pulse-to-pulse phase coherency to detect moving targets as well as extract micro-Doppler radar signatures. Local oscillator and intermediate frequency planning for a given PRT to achieve coherency Further, the system 100 reduces the cost required for complex high-end hardware.
[0048] FIG. 2A illustrates an exemplary view of linearity of FMCW signal 200, in accordance with an embodiment of the present disclosure. The captured parameters of generated FMCW may be analysed on a spectrum analyser, which may represent frequency vs time domain response of waveform.
[0049] FIG. 2B illustrates an exemplary view of unsynchronized sweep control and IF, in accordance with an embodiment of the present disclosure. As shown in FIG. 2B, the persistence mode of cathode ray oscilloscope (CRO), where radar control signals and IF is captured. From the plot, it is clear that there is change in phase with every time capture with respect to radar control signals.
[0050] FIG. 2C illustrates an exemplary view of synchronized sweep control and IF, in accordance with an embodiment of the present disclosure. The persistence mode of CRO, where radar control signals and IF is captured. Timing parameters of radar control signals are adjusted as per equation shown above. From the plot, it is clear that there is a repetition in phase with every time captured with respect to radar control signals.
[0051] FIG. 2D illustrates an exemplary view of synchronized radar controls signal, in accordance with an embodiment of the present disclosure. FIG. 2D illustrates synchronized radar control signals, where trace-1 indicated sweep, trace-2 indicated dwell and trace-3 indicated radar reference clock.
[0052] FIG. 3 illustrates an exemplary view of flow diagram of a method for converting non-coherent radar to coherent radar, in accordance with an embodiment of the present disclosure.
[0053] At block 302, the waveform generator and controller configured in a transmitter, the waveform generator and controller generate a first set of signals at low frequency using direct digital synthesizer (DDS), the first set of signals pertaining to radar waveform and control signal, the control signals are derived from the radar waveform, the control signals pertaining to sweep trigger and dwell trigger. At block 304, the one or more local oscillators configured in the transmitter, the one or more local oscillators generate a second set of signals, the second set of signals pertaining to local oscillator signals, where, the generated first set of signals and the second set of signals are synchronized with DDS clock signal.
[0054] At block 306, the receiver configured to receive the return signals from the target to down-convert the return signals; and at block 308, the computing device coupled to the receiver, the computing device configured to process the down-converted signal to a digital set of signals, where the processed digital set of signals affect phase coherent set of signals, where the computing device may include the processor.
[0055] It will be apparent to those skilled in the art that the system 100 of the disclosure may be provided using some or all of the mentioned features and components without departing from the scope of the present disclosure. While various embodiments of the present disclosure have been illustrated and described herein, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the disclosure, as described in the claims.

ADVANTAGES OF THE PRESENT DISCLOSURE
[0056] The present disclosure provides a system that converts non-coherent heterodyne FMCW radar to coherent radar by controlling radar waveform and radar control signal generation.
[0057] The present disclosure provides a system that maintains pulse-to-pulse phase coherency.
[0058] The present disclosure provides a system that detect moving targets as well as extract micro-Doppler radar signatures.
[0059] The present disclosure reduces the cost of the system.
[0060] The present disclosure provides a system that require minimum hardware.