A microwave photon radar detection device and detection method thereof

Abstract

The present invention provides a microwave photon radar detection device and a detection method thereof, the device comprising a signal frequency modulation module, a transmitting end, a receiving end, a mixing module and a signal processing module; the signal frequency modulation module is used to modulate a baseband signal to generate a linear frequency modulation signal; the linear frequency modulation signal comprises a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal; the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal; the mixing module is used to mix the linear frequency modulation signal with an echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler frequency shift; the signal processing module is used to process the intermediate frequency signal to obtain a real-time Doppler frequency shift; the positive and negative of the Doppler frequency shift represent the radial velocity direction. By setting a dual-band linear frequency modulation signal, the present invention simplifies the signal processing process relative to a three-segment linear frequency modulation signal.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a microwave photon radar detection device and a detection method thereof. Background Art

[0002] Linear frequency modulation signal is a signal whose frequency changes linearly with time. It is widely used in pulse compression radar system because of its good pulse compression characteristics, which can effectively solve the contradiction between detection distance and distance resolution of traditional single pulse radar. However, for a moving object, the information carried by the intermediate frequency signal after radar echo de-skewing is the coupling of distance and radial velocity information. It is difficult for us to distinguish these two information, so the method of dual linear frequency modulation signal is proposed.

[0003] In existing research, dual linear frequency modulation signals are mostly X-shaped or V-shaped. After using this signal for detection, the distance information and radial velocity information of the target can be obtained respectively. However, as far as the radial velocity information is concerned, the magnitude of the radial velocity of the object can be obtained, but the radial velocity direction cannot be obtained in real time.

[0004] A team from Huazhong University of Science and Technology once used three-segment linear frequency modulation signals for target detection, in which two bands of signals had the same linear frequency modulation slope and bandwidth but different center frequencies, and the other band had the opposite linear frequency modulation slope, different center frequencies and the same bandwidth. Using this signal for detection can not only obtain the magnitude of the radial velocity but also the direction of the radial velocity in real time. However, this method uses three-segment linear frequency modulation signals for target detection, and the signal processing process is cumbersome. Summary of the invention

[0005] The embodiment of the present invention provides a microwave photon radar detection device to solve the problem of complicated signal processing process when the microwave photon radar detects the real-time radial velocity direction.

[0006] In a first aspect, an embodiment of the present invention provides a microwave photon radar detection device, including: a signal frequency modulation module, a transmitting end, a receiving end, a mixing module and a signal processing module;

[0007] The signal frequency modulation module is used to modulate the baseband signal to generate a linear frequency modulation signal; the linear frequency modulation signal includes a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal; the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal;

[0008] The transmitting end is used to transmit the linear frequency modulation signal;

[0009] The receiving end is used to receive the echo signal reflected by the target;

[0010] The mixing module is used to mix the linear frequency modulation signal with the echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler frequency shift;

[0011] The signal processing module is used to process the intermediate frequency signal to obtain a real-time Doppler frequency shift; the positive or negative value of the Doppler frequency shift represents the radial velocity direction.

[0012] In a possible implementation, the signal frequency modulation module includes a Mach-Zehnder modulator, an optical filter, a first photodetector, a low-pass filter, and a power divider;

[0013] The baseband signal is a laser signal;

[0014] The Mach-Zehnder modulator is used to modulate the laser signal according to the linear frequency modulation bias voltage signal to obtain a first modulated optical signal; the first modulated optical signal includes a carrier, two first-order sidebands and two second-order sidebands;

[0015] The optical filter is used to filter out the carrier and one of the first-order sidebands of the first modulated optical signal to obtain a first filtered optical signal; the wavelength difference between the first-order sideband of the first filtered optical signal and the two second-order sidebands is three times;

[0016] The first photodetector is used to beat the first filtered optical signal to obtain a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the second linear frequency modulation signal is three times the frequency of the first linear frequency modulation signal;

[0017] The low-pass filter filters the linear frequency modulation signal and transmits it to the power divider;

[0018] The power divider is used to divide the linear frequency modulation signal into two paths, one path is transmitted to the transmitting end, and the other path is transmitted to the mixing module.

[0019] In a possible implementation, the target generates a first echo signal after reflecting the first linear frequency modulation signal;

[0020] The target reflects the second linear frequency modulation signal to generate a second echo signal;

[0021] The mixing module mixes the first linear frequency modulation signal and the first echo signal to obtain a first intermediate frequency signal; the frequency of the first intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the first linear frequency modulation signal plus the Doppler frequency shift;

[0022] The mixing module mixes the second linear frequency modulation signal and the second echo signal to obtain a second intermediate frequency signal; the frequency of the second intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the second linear frequency modulation signal plus the Doppler frequency shift.

[0023] In a possible implementation, the signal processing module is further used to obtain radial velocity magnitude and target distance;

[0024] The radial velocity is the Doppler frequency divided by the center frequency of the second linear frequency modulation signal multiplied by the speed of light;

[0025] The target distance is the echo delay multiplied by the speed of light divided by two.

[0026] In a possible implementation, the microwave photon radar detection device further includes an optical beam splitter, an adjustable delay line, an adjustable attenuator, a second photodetector and a coupler.

[0027] The Mach-Zehnder modulator is further used to generate a second modulated optical signal, wherein the second-order sideband of the second modulated optical signal has a phase opposite to that of the second-order sideband of the first modulated optical signal;

[0028] The optical filter is further used to filter out the carrier and one of the first-order sidebands of the second modulated optical signal to obtain a second filtered optical signal;

[0029] The optical beam splitter is used for beam splitting, transmitting the first filtered optical signal to the first photodetector, and transmitting the second filtered optical signal to the adjustable delay line;

[0030] The adjustable delay line is used to delay the second filtered optical signal to obtain a delayed optical signal;

[0031] The adjustable attenuator is used to attenuate the optical power of the delayed optical signal to obtain an attenuated optical signal;

[0032] The second photodetector is used to beat the attenuated optical signal to obtain a third linear frequency modulation signal and a fourth linear frequency modulation signal; the phase of the third linear frequency modulation signal is opposite to the phase of the first linear frequency modulation signal; the phase of the fourth linear frequency modulation signal is opposite to the phase of the second linear frequency modulation signal;

[0033] The coupler is used to couple the third linear frequency modulation signal with the first echo signal to eliminate the interference of the first linear frequency modulation signal of the transmitting end to the receiving end;

[0034] The coupler is also used to couple the fourth linear frequency modulation signal with the second echo signal to eliminate the interference of the second linear frequency modulation signal at the transmitting end on the receiving end.

[0035] In a second aspect, an embodiment of the present invention provides a microwave photon radar detection method, the method comprising:

[0036] Modulating the baseband signal to generate a linear frequency modulation signal; the linear frequency modulation signal includes a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal; the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal;

[0037] Transmitting a linear frequency modulation signal;

[0038] Receive the echo signal reflected by the target;

[0039] Mixing the linear frequency modulation signal with the echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler frequency shift;

[0040] The intermediate frequency signal is processed to obtain a real-time Doppler frequency shift; the positive or negative value of the Doppler frequency shift represents the radial velocity direction.

[0041] In a possible implementation, the baseband signal is modulated to generate a linear frequency modulation signal; the linear frequency modulation signal includes a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal; the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal, including:

[0042] Modulating the baseband signal to generate a first modulated optical signal, wherein the first modulated optical signal includes a carrier, two first-order sidebands, and two second-order sidebands;

[0043] Filtering out the carrier and one of the first-order sidebands of the first modulated optical signal to obtain a first filtered optical signal; the wavelength difference between the first-order sideband of the first filtered optical signal and the two second-order sidebands is three times;

[0044] The first filtered optical signal is beat to obtain a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the second linear frequency modulation signal is three times the frequency of the first linear frequency modulation signal.

[0045] In a possible implementation, the receiving target reflected echo signal; mixing the linear frequency modulation signal with the echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler frequency shift, including:

[0046] receiving a first echo signal, where the first echo signal is an echo signal generated after a target reflects a first linear frequency modulation signal;

[0047] receiving a second echo signal, where the second echo signal is an echo signal generated after the target reflects the second linear frequency modulation signal;

[0048] Mixing the first linear frequency modulation signal and the first echo signal to obtain a first intermediate frequency signal; the frequency of the first intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the first linear frequency modulation signal plus the Doppler frequency shift;

[0049] The second linear frequency modulation signal and the second echo signal are mixed to obtain a second intermediate frequency signal; the frequency of the second intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the second linear frequency modulation signal plus the Doppler frequency shift.

[0050] In a possible implementation, the processing of the intermediate frequency signal to obtain a real-time Doppler frequency shift, wherein the positive or negative value of the Doppler frequency shift represents a radial velocity direction, further comprises:

[0051] The intermediate frequency signal is processed to obtain radial velocity magnitude and target distance; the radial velocity magnitude is the Doppler frequency shift divided by the center frequency of the second linear frequency modulation signal, multiplied by the speed of light; the target distance is the echo delay multiplied by the speed of light divided by two.

[0052] In a possible implementation, the step of modulating the baseband signal to generate a linear frequency modulation signal further includes:

[0053] generating a second modulated optical signal, wherein a second-order sideband of the second modulated optical signal has a phase opposite to that of the second-order sideband of the first modulated optical signal;

[0054] filtering out a carrier and one of the first-order sidebands of the second modulated optical signal to obtain a second filtered optical signal;

[0055] Delaying the second filtered optical signal to obtain a delayed optical signal;

[0056] Attenuating the optical power of the delayed optical signal to obtain an attenuated optical signal;

[0057] The attenuated optical signal is beat-frequencyed to obtain a third linear frequency modulation signal and a fourth linear frequency modulation signal; the phase of the third linear frequency modulation signal is opposite to the phase of the first linear frequency modulation signal; the phase of the fourth linear frequency modulation signal is opposite to the phase of the second linear frequency modulation signal;

[0058] Accordingly, before mixing the linear frequency modulation signal with the echo signal to obtain an intermediate frequency signal, the method further includes:

[0059] coupling the third linear frequency modulation signal with the first echo signal to eliminate interference of the first linear frequency modulation signal at the transmitting end to the receiving end;

[0060] The fourth linear frequency modulation signal is coupled with the second echo signal to eliminate interference of the second linear frequency modulation signal at the transmitting end to the receiving end.

[0061] An embodiment of the present invention provides a microwave photon radar detection device, comprising a signal frequency modulation module, a transmitting end, a receiving end, a mixing module and a signal processing module; the signal frequency modulation module is used to modulate a baseband signal to generate a linear frequency modulation signal; the linear frequency modulation signal comprises a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal; the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal; the transmitting end is used to transmit the linear frequency modulation signal; the receiving end is used to receive an echo signal reflected by a target; the mixing module is used to mix the linear frequency modulation signal with the echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler frequency shift; the signal processing module is used to process the intermediate frequency signal to obtain a real-time Doppler frequency shift; the positive and negative values ​​of the Doppler frequency shift represent the radial velocity direction. By setting a dual-band linear frequency modulation signal, the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal, and the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal. Compared with the three-segment linear frequency modulation signal, the signal processing process is simplified; the detection frequency is increased to three times the baseband frequency, thereby improving the target resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0063] Figure 1 is a schematic structural diagram of a microwave photon radar detection device provided by an embodiment of the present invention;

[0064] Figure 2 is a structural schematic diagram of a signal frequency modulation module provided by an embodiment of the present invention;

[0065] Figure 3 It is a schematic structural diagram of an interference elimination microwave photon radar detection device provided by an embodiment of the present invention;

[0066] Figure 4 It is a spectrum diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0067] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0068] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0069] The following is a detailed description of the implementation of the present invention in conjunction with the specific drawings:

[0070] Figure 1 A schematic diagram of the structure of a microwave photon radar detection device provided by an embodiment of the present invention. Figure 1 The device includes: a signal frequency modulation module 1, a transmitting end 2, a receiving end 3, a mixing module 4 and a signal processing module 5.

[0071] The signal frequency modulation module 1 is used to modulate the baseband signal to generate a linear frequency modulation signal; linear frequency modulation is a spread spectrum modulation technology; the change of its frequency is linearly related to time.

[0072] The linear frequency modulation signal includes a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal; and the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal.

[0073] The second linear frequency modulation signal triples the frequency of the baseband signal, thereby improving the detection resolution.

[0074] The transmitting end 2 is used for transmitting a linear frequency modulation signal.

[0075] The receiving end 3 is used to receive the echo signal reflected by the target; the echo signal is generated because after the signal is reflected by the target, a part of the energy is absorbed by the target, resulting in attenuation delay.

[0076] The mixing module 4 is used to mix the linear frequency modulation signal with the echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler shift; the slope of the linear time-frequency relationship of the linear frequency modulation signal is the linear frequency modulation slope.

[0077] The signal processing module 5 is used to process the intermediate frequency signal to obtain the real-time Doppler frequency shift; the positive and negative values ​​of the Doppler frequency shift represent the radial velocity direction.

[0078] The radial velocity is the velocity component of the object's movement in the direction toward the radar, that is, the projection of the velocity vector in the direction toward the radar.

[0079] Exemplarily, a positive Doppler shift indicates that the object is moving away from the radar; a negative Doppler shift indicates that the object is moving toward the radar.

[0080] Figure 2 is a schematic diagram of the structure of the signal frequency modulation module provided in an embodiment of the present invention; Figure 2 :

[0081] In an optional embodiment, the signal frequency modulation module 1 includes a Mach-Zehnder modulator 101 , an optical filter 102 , a first photodetector 103 , a low-pass filter 104 and a power divider 105 .

[0082] The baseband signal is a laser signal.

[0083] Exemplarily, the laser signal is a single-frequency continuous wave generated by a narrow linewidth laser.

[0084] The Mach-Zehnder modulator 101 is used to modulate the laser signal according to the linear frequency modulation bias voltage signal to obtain a first modulated optical signal; Figure 4 In a, the horizontal axis of the spectrum diagram provided by the embodiment of the present invention represents the wavelength, and the vertical axis represents the light intensity. The spectrum of the first modulated optical signal includes a carrier, two first-order sidebands and two second-order sidebands.

[0085] The optical filter 102 is used to filter out the carrier and one of the first-order sidebands of the first modulated optical signal to obtain a first filtered optical signal; Figure 4 In b, the spectrum of the optical signal after the first filtering includes a first-order sideband and two second-order sidebands; the wavelength difference between the first-order sideband of the optical signal after the first filtering and the two second-order sidebands is three times; the above wavelength difference is proportional to the frequency after the photoelectric detector beats.

[0086] The first photodetector 103 is used to beat the first filtered optical signal to obtain a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the second linear frequency modulation signal is three times the frequency of the first linear frequency modulation signal.

[0087] The low-pass filter 104 filters the linear frequency modulation signal and transmits it to the power divider 105. Low-pass filtering is a filtering method, and the rule is that low-frequency signals can pass normally, while high-frequency signals exceeding a set critical value are blocked and weakened. The above-mentioned low-pass filter 104 is specifically used to filter out the high-frequency quadruple frequency signal generated by the photoelectric detector during the beat frequency process.

[0088] The power divider 105 is used to divide the linear frequency modulation signal into two paths, one path is transmitted to the transmitting end 2, and the other path is transmitted to the mixing module 4.

[0089] In an optional embodiment, the target generates a first echo signal after reflecting the first linear frequency modulation signal.

[0090] The target reflects the second linear frequency modulation signal to generate a second echo signal.

[0091] The mixing module 4 mixes the first linear frequency modulation signal and the first echo signal to obtain a first intermediate frequency signal; the frequency of the first intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the first linear frequency modulation signal plus the Doppler frequency shift.

[0092] The mixing module 4 mixes the second linear frequency modulation signal and the second echo signal to obtain a second intermediate frequency signal; the frequency of the second intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the second linear frequency modulation signal plus the Doppler frequency shift.

[0093] The intermediate frequency signal in the embodiment of the present invention may be:

[0094] f 1 =k 1 τ+Ω d

[0095] f 2 =k 2 τ+Ω d

[0096] Among them, f 1 represents the first intermediate frequency signal; f 2 represents the second intermediate frequency signal; k 1 k represents the linear frequency modulation slope of the first linear frequency modulation signal; 2 represents the linear frequency modulation slope of the second linear frequency modulation signal; τ represents the echo delay; Ω d represents the Doppler shift; where k 1 *3=k 2 .

[0097] For example, when the target is stationary, Ω d is 0, the intermediate frequency signal in the embodiment of the present invention may be:

[0098] f 1 =k 1 τ

[0099] f 2 =k 2 τ

[0100] In an optional embodiment, the signal processing module 5 is also used to obtain the radial velocity magnitude and the target distance.

[0101] The radial velocity is the Doppler frequency shift divided by the center frequency of the second linear frequency modulation signal multiplied by the speed of light.

[0102] The target distance is the echo delay multiplied by the speed of light divided by two.

[0103] Most radar systems use a dual-antenna transceiver mode, where transmission and reception are performed simultaneously, and the power of the transmitted signal is much greater than the power of the received signal. The receiving end 3 will inevitably receive interference signals from the transmitting end 2.

[0104] Figure 3 is a schematic diagram of the structure of the interference elimination microwave photon radar detection device provided by an embodiment of the present invention; Figure 3 :

[0105] In an optional embodiment, the microwave photon radar detection device further includes an optical beam splitter 106, an adjustable delay line 107, an adjustable attenuator 108, a second photodetector 109 and a coupler 110.

[0106] The Mach-Zehnder modulator 101 is also used to generate a second modulated optical signal; Figure 4 In c, the second-order sideband of the second modulated optical signal has an opposite phase to the second-order sideband of the first modulated optical signal.

[0107] Exemplarily, the Mach-Zehnder modulator 101 may be a dual-polarization dual-drive Mach-Zehnder modulator.

[0108] The optical filter 102 is also used to filter out the carrier and one of the first-order sidebands of the second modulated optical signal to obtain a second filtered optical signal; Figure 4 In d, the second filtered optical signal includes a first-order sideband and two second-order sidebands, and the second-order sidebands of the second filtered optical signal are opposite in phase to the second-order sidebands of the first filtered optical signal.

[0109] The optical beam splitter 106 is used for beam splitting, transmitting the first filtered optical signal to the first photodetector 103 , and transmitting the second filtered optical signal to the adjustable delay line 107 .

[0110] Exemplarily, the optical beam splitter 106 may be a polarization beam splitter.

[0111] The adjustable delay line 107 is used to delay the second filtered optical signal to obtain a delayed optical signal.

[0112] The adjustable attenuator 108 is used to attenuate the optical power of the delayed optical signal to obtain the attenuated optical signal.

[0113] The second photodetector 109 is used to beat the attenuated optical signal to obtain a third linear frequency modulation signal and a fourth linear frequency modulation signal; the phase of the third linear frequency modulation signal is opposite to that of the first linear frequency modulation signal; the phase of the fourth linear frequency modulation signal is opposite to that of the second linear frequency modulation signal.

[0114] The coupler 110 is used to couple the third linear frequency modulation signal with the first echo signal to eliminate interference of the first linear frequency modulation signal of the transmitting end 2 on the receiving end 3 .

[0115] The coupler 110 is further used to couple the fourth linear frequency modulation signal with the second echo signal to eliminate interference of the second linear frequency modulation signal at the transmitting end 2 on the receiving end 3 .

[0116] The signal frequency modulation module 1 generates a third linear frequency modulation signal and a fourth linear frequency modulation signal at the same time as generating the first linear frequency modulation signal and the second linear frequency modulation signal, which are 180° out of phase with the respective frequency points and have the same other indicators. The interference signal can be eliminated by adjusting the delay and amplitude of the third linear frequency modulation signal and the fourth linear frequency modulation signal to be the same as the interference signal directly leaked from the transmitting end 2 to the receiving end 3, and then coupling with the echo signal.

[0117] That is, the adjustable delay line 107 is specifically used to adjust the delay of the second filtered optical signal so that the delay of the third linear frequency modulation signal is consistent with the delay of the first linear frequency modulation signal received by the receiving end 3, and the delay of the fourth linear frequency modulation signal is consistent with the delay of the second linear frequency modulation signal received by the receiving end 3.

[0118] Correspondingly, the adjustable attenuator 108 is specifically used to adjust the optical power of the delayed optical signal so that the amplitude of the third linear frequency modulation signal is consistent with the amplitude of the first linear frequency modulation signal received by the receiving end 3, and the amplitude of the fourth linear frequency modulation signal is consistent with the amplitude of the second linear frequency modulation signal received by the receiving end 3.

[0119] An embodiment of the present invention provides a microwave photon radar detection method, the method comprising:

[0120] The baseband signal is modulated to generate a linear frequency modulation signal; the linear frequency modulation signal includes a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal; the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal. The second linear frequency modulation signal triples the frequency of the baseband signal, thereby improving the detection resolution.

[0121] Transmits a linear frequency modulation signal.

[0122] Receive the echo signal reflected by the target;

[0123] The linear frequency modulation signal is mixed with the echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler frequency shift. The slope of the linear time-frequency relationship of the linear frequency modulation signal is the linear frequency modulation slope.

[0124] The intermediate frequency signal is processed to obtain the real-time Doppler frequency shift; the positive and negative values ​​of the Doppler frequency shift represent the radial velocity direction.

[0125] The radial velocity is the velocity component of the object's movement in the direction toward the radar, that is, the projection of the velocity vector in the direction toward the radar.

[0126] Exemplarily, a positive Doppler shift indicates that the object is moving away from the radar; a negative Doppler shift indicates that the object is moving toward the radar.

[0127] In an optional embodiment, modulating a baseband signal to generate a linear frequency modulation signal includes:

[0128] Modulate the baseband signal to generate a first modulated optical signal; Figure 4 In a, the horizontal axis of the spectrum represents wavelength, the vertical axis represents light intensity, and the first modulated optical signal includes a carrier, two first-order sidebands and two second-order sidebands.

[0129] Filter out the carrier and one of the first-order sidebands of the first modulated optical signal to obtain a first filtered optical signal; refer to Figure 4 In b, the spectrum of the optical signal after the first filtering includes a first-order sideband and two second-order sidebands; the wavelength difference between the first-order sideband of the optical signal after the first filtering and the two second-order sidebands is three times; the above wavelength difference is proportional to the frequency after the photoelectric detector beats.

[0130] The first filtered optical signal is beat to obtain a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the second linear frequency modulation signal is three times the frequency of the first linear frequency modulation signal.

[0131] In an optional embodiment, an echo signal reflected by a target is received; a linear frequency modulation signal is mixed with the echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler frequency shift, including:

[0132] A first echo signal is received, where the first echo signal is an echo signal generated after the target reflects the first linear frequency modulation signal.

[0133] A second echo signal is received, where the second echo signal is an echo signal generated after the target reflects the second linear frequency modulation signal.

[0134] Mixing the first linear frequency modulation signal and the first echo signal to obtain a first intermediate frequency signal; the frequency of the first intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the first linear frequency modulation signal plus the Doppler frequency shift;

[0135] The second linear frequency modulation signal and the second echo signal are mixed to obtain a second intermediate frequency signal; the frequency of the second intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the second linear frequency modulation signal plus the Doppler frequency shift.

[0136] The intermediate frequency signal in the embodiment of the present invention may be:

[0137] f 1 =k 1 τ+Ω d

[0138] f 2 =k 2 τ+Ω d

[0139] Among them, f 1 represents the first intermediate frequency signal; f 2 represents the second intermediate frequency signal; k 1 k represents the linear frequency modulation slope of the first linear frequency modulation signal; 2 represents the linear frequency modulation slope of the second linear frequency modulation signal; τ represents the echo delay; Ω d represents the Doppler shift; where k 1 *3=k 2 .

[0140] For example, when the target is stationary, Ω d is 0, the intermediate frequency signal in the embodiment of the present invention may be:

[0141] f 1 =k 1 τ

[0142] f 2 =k 2 τ

[0143] In an optional embodiment, the intermediate frequency signal is processed to obtain a real-time Doppler frequency shift; the positive and negative values ​​of the Doppler frequency shift represent the radial velocity direction, and the method further includes:

[0144] The intermediate frequency signal is processed to obtain the radial velocity and target distance; the radial velocity is the Doppler frequency divided by the center frequency of the second linear frequency modulation signal, multiplied by the speed of light; the target distance is the echo delay multiplied by the speed of light divided by two.

[0145] Most radar systems use a dual-antenna transceiver mode, where transmission and reception are performed simultaneously, and the power of the transmitted signal is much greater than the power of the received signal. The receiving end 3 will inevitably receive interference signals from the transmitting end 2.

[0146] In an optional embodiment, modulating the baseband signal to generate a linear frequency modulation signal further includes:

[0147] Generate a second modulated optical signal; Figure 4 In c, the second-order sideband of the second modulated optical signal is in opposite phase to the second-order sideband of the first modulated optical signal;

[0148] Filter out the carrier and one of the first-order sidebands of the second modulated optical signal to obtain a second filtered optical signal; refer to Figure 4 In d, the second filtered optical signal includes a first-order sideband and two second-order sidebands, and the second-order sidebands of the second filtered optical signal are opposite in phase to the second-order sidebands of the first filtered optical signal.

[0149] The second filtered optical signal is delayed to obtain a delayed optical signal.

[0150] The optical power of the delayed optical signal is attenuated to obtain the attenuated optical signal.

[0151] The attenuated optical signal is beat to obtain a third linear frequency modulation signal and a fourth linear frequency modulation signal; the phase of the third linear frequency modulation signal is opposite to that of the first linear frequency modulation signal; the phase of the fourth linear frequency modulation signal is opposite to that of the second linear frequency modulation signal.

[0152] Accordingly, before mixing the linear frequency modulation signal with the echo signal to obtain the intermediate frequency signal, the following steps are also included:

[0153] The third linear frequency modulation signal is coupled with the first echo signal to eliminate interference of the first linear frequency modulation signal of the transmitting end 2 on the receiving end 3 .

[0154] The fourth linear frequency modulation signal is coupled with the second echo signal to eliminate interference of the second linear frequency modulation signal of the transmitting end 2 on the receiving end 3 .

[0155] While generating the first linear frequency modulation signal and the second linear frequency modulation signal, a third linear frequency modulation signal and a fourth linear frequency modulation signal are generated, which are 180° out of phase with the frequency points and have the same other indicators. The interference signal can be eliminated by adjusting the delay and amplitude of the third linear frequency modulation signal and the fourth linear frequency modulation signal to be the same as the interference signal directly leaked from the transmitting end 2 to the receiving end 3, and then coupling with the echo signal.

[0156] That is, the delay of the second filtered optical signal is adjusted so that the delay of the third linear frequency modulation signal is consistent with the delay of the first linear frequency modulation signal received by the receiving end 3, and the delay of the fourth linear frequency modulation signal is consistent with the delay of the second linear frequency modulation signal received by the receiving end 3.

[0157] Accordingly, the optical power of the delayed optical signal is adjusted so that the amplitude of the third linear frequency modulation signal is consistent with the amplitude of the first linear frequency modulation signal received by the receiving end 3, and the amplitude of the fourth linear frequency modulation signal is consistent with the amplitude of the second linear frequency modulation signal received by the receiving end 3.

[0158] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microwave photon radar detection device, characterized in that: It includes a signal frequency modulation module, a transmitting end, a receiving end, a mixing module and a signal processing module; The signal frequency modulation module is used to modulate the baseband signal to generate a linear frequency modulation signal; the linear frequency modulation signal includes a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal; the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal; The transmitting end is used to transmit the linear frequency modulation signal; The receiving end is used to receive the echo signal reflected by the target; The mixing module is used to mix the linear frequency modulation signal with the echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler frequency shift; The signal processing module is used to process the intermediate frequency signal to obtain a real-time Doppler frequency shift; the positive and negative values ​​of the Doppler frequency shift represent the radial velocity direction; The signal frequency modulation module includes a Mach-Zehnder modulator, an optical filter, a first photodetector, a low-pass filter and a power divider; The baseband signal is a laser signal; The Mach-Zehnder modulator is used to modulate the laser signal according to the linear frequency modulation bias voltage signal to obtain a first modulated optical signal; the first modulated optical signal includes a carrier, two first-order sidebands and two second-order sidebands; The optical filter is used to filter out the carrier and one of the first-order sidebands of the first modulated optical signal to obtain a first filtered optical signal; the wavelength difference between the first-order sideband of the first filtered optical signal and the two second-order sidebands is three times; The first photodetector is used to beat the first filtered optical signal to obtain a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the second linear frequency modulation signal is three times the frequency of the first linear frequency modulation signal; The low-pass filter filters the linear frequency modulation signal and transmits it to the power divider; The power divider is used to divide the linear frequency modulation signal into two paths, one path is transmitted to the transmitting end, and the other path is transmitted to the mixing module.

2. A microwave photon radar detection device as claimed in claim 1, characterized in that: The target reflects the first linear frequency modulation signal to generate a first echo signal; The target reflects the second linear frequency modulation signal to generate a second echo signal; The mixing module mixes the first linear frequency modulation signal and the first echo signal to obtain a first intermediate frequency signal; the frequency of the first intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the first linear frequency modulation signal plus the Doppler frequency shift; The mixing module mixes the second linear frequency modulation signal and the second echo signal to obtain a second intermediate frequency signal; the frequency of the second intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the second linear frequency modulation signal plus the Doppler frequency shift.

3. A microwave photon radar detection device as claimed in claim 2, characterized in that: The signal processing module is also used to obtain radial velocity magnitude and target distance; The radial velocity is the Doppler frequency divided by the center frequency of the second linear frequency modulation signal multiplied by the speed of light; The target distance is the echo delay multiplied by the speed of light divided by two.

4. A microwave photon radar detection device as claimed in claim 2, characterized in that: Also includes an optical beam splitter, an adjustable delay line, an adjustable attenuator, a second photodetector and a coupler The Mach-Zehnder modulator is further used to generate a second modulated optical signal, wherein the second-order sideband of the second modulated optical signal has a phase opposite to that of the second-order sideband of the first modulated optical signal; The optical filter is further used to filter out the carrier and one of the first-order sidebands of the second modulated optical signal to obtain a second filtered optical signal; The optical beam splitter is used for beam splitting, transmitting the first filtered optical signal to the first photodetector, and transmitting the second filtered optical signal to the adjustable delay line; The adjustable delay line is used to delay the second filtered optical signal to obtain a delayed optical signal; The adjustable attenuator is used to attenuate the optical power of the delayed optical signal to obtain an attenuated optical signal; The second photodetector is used to beat the attenuated optical signal to obtain a third linear frequency modulation signal and a fourth linear frequency modulation signal; the phase of the third linear frequency modulation signal is opposite to the phase of the first linear frequency modulation signal; the phase of the fourth linear frequency modulation signal is opposite to the phase of the second linear frequency modulation signal; The coupler is used to couple the third linear frequency modulation signal with the first echo signal to eliminate the interference of the first linear frequency modulation signal of the transmitting end to the receiving end; The coupler is also used to couple the fourth linear frequency modulation signal with the second echo signal to eliminate the interference of the second linear frequency modulation signal at the transmitting end on the receiving end.

5. A microwave photon radar detection method, characterized in that: The method comprises: Modulating the baseband signal to generate a linear frequency modulation signal; the linear frequency modulation signal includes a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal; the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal; Transmitting a linear frequency modulation signal; Receive the echo signal reflected by the target; Mixing the linear frequency modulation signal with the echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler frequency shift; Processing the intermediate frequency signal to obtain a real-time Doppler frequency shift; the positive and negative values ​​of the Doppler frequency shift represent the radial velocity direction; The baseband signal is modulated to generate a linear frequency modulation signal; the linear frequency modulation signal includes a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the first linear frequency modulation signal is the same as the frequency of the baseband signal; the frequency of the second linear frequency modulation signal is three times the frequency of the baseband signal, including: Modulating the baseband signal to generate a first modulated optical signal, wherein the first modulated optical signal includes a carrier, two first-order sidebands, and two second-order sidebands; Filtering out the carrier and one of the first-order sidebands of the first modulated optical signal to obtain a first filtered optical signal; the wavelength difference between the first-order sideband of the first filtered optical signal and the two second-order sidebands is three times; The first filtered optical signal is beat to obtain a first linear frequency modulation signal and a second linear frequency modulation signal; the frequency of the second linear frequency modulation signal is three times the frequency of the first linear frequency modulation signal.

6. A microwave photon radar detection method as claimed in claim 5, characterized in that: The receiving target reflected echo signal; mixing the linear frequency modulation signal with the echo signal to obtain an intermediate frequency signal; the frequency of the intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope plus the Doppler frequency shift, including: receiving a first echo signal, where the first echo signal is an echo signal generated after a target reflects a first linear frequency modulation signal; receiving a second echo signal, where the second echo signal is an echo signal generated after the target reflects the second linear frequency modulation signal; Mixing the first linear frequency modulation signal and the first echo signal to obtain a first intermediate frequency signal; the frequency of the first intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the first linear frequency modulation signal plus the Doppler frequency shift; The second linear frequency modulation signal and the second echo signal are mixed to obtain a second intermediate frequency signal; the frequency of the second intermediate frequency signal is the echo delay multiplied by the linear frequency modulation slope of the second linear frequency modulation signal plus the Doppler frequency shift.

7. A microwave photon radar detection method as claimed in claim 6, characterized in that: The processing of the intermediate frequency signal to obtain a real-time Doppler frequency shift wherein the positive or negative sign of the Doppler frequency shift represents the radial velocity direction further includes: The intermediate frequency signal is processed to obtain radial velocity magnitude and target distance; the radial velocity magnitude is the Doppler frequency shift divided by the center frequency of the second linear frequency modulation signal, multiplied by the speed of light; the target distance is the echo delay multiplied by the speed of light divided by two.

8. A microwave photon radar detection method as claimed in claim 7, characterized in that: The method of modulating the baseband signal to generate a linear frequency modulation signal also includes: generating a second modulated optical signal, wherein a second-order sideband of the second modulated optical signal has a phase opposite to that of the second-order sideband of the first modulated optical signal; filtering out a carrier and one of the first-order sidebands of the second modulated optical signal to obtain a second filtered optical signal; Delaying the second filtered optical signal to obtain a delayed optical signal; Attenuating the optical power of the delayed optical signal to obtain an attenuated optical signal; The attenuated optical signal is beat to obtain a third linear frequency modulation signal and a fourth linear frequency modulation signal; the phase of the third linear frequency modulation signal is opposite to the phase of the first linear frequency modulation signal; the phase of the fourth linear frequency modulation signal is opposite to the phase of the second linear frequency modulation signal; Accordingly, before mixing the linear frequency modulation signal with the echo signal to obtain an intermediate frequency signal, the method further includes: coupling the third linear frequency modulation signal with the first echo signal to eliminate interference of the first linear frequency modulation signal at the transmitting end to the receiving end; The fourth linear frequency modulation signal is coupled with the second echo signal to eliminate interference of the second linear frequency modulation signal at the transmitting end to the receiving end.

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