Multiband radar detection method and apparatus

Abstract

This invention discloses a multi-band radar detection method, belonging to the technical field of combining microwave photonics and radar detection technology. This method utilizes microwave photonics technology to generate specific microwave multi-band transmitted signals and microwave multi-band reference signals. By de-skewing the microwave multi-band reference signals and echo signals through an electrical mixer, the de-skewing intermediate frequency signals corresponding to each band can be obtained in the frequency domain, thereby achieving high-resolution target detection. This invention also discloses a multi-band radar detection device. Compared with existing technologies, it effectively achieves frequency domain separation of multi-band radar echo de-skewing signals without requiring multiple receiving channels or complex digital signal processing, thus effectively reducing system complexity and implementation costs.

Description

Technical Field

[0001] This invention relates to a multi-band radar detection method and device, belonging to the technical field of combining microwave photonics and radar detection technology. Background Technology

[0002] As modern radar systems evolve towards multi-functionality and high resolution, single-band radar can no longer meet the demands of complex detection environments. Multi-band radar, by simultaneously transmitting and receiving signals from multiple frequency bands, can acquire the scattering characteristics of targets in different frequency bands, effectively improving anti-stealth and anti-jamming capabilities, and can achieve high-resolution imaging through multi-band data fusion.

[0003] Traditional multiband radars typically employ multiple independent transceiver devices, resulting in large system size, high cost, and complex structure. Microwave photonics technology, with its advantages of high bandwidth, low loss, and resistance to electromagnetic interference, offers a new technological approach for the integration and high performance of multiband radars. However, a key challenge in multiband radar reception is how to separate and process echo signals from different bands without crosstalk, without increasing the analog-to-digital converter sampling rate. Existing methods usually require multiple receiving channels or complex digital signal processing, increasing system cost and complexity. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing multi-band radar technology and provide a multi-band radar detection method and device that can effectively achieve frequency domain separation of multi-band radar echo descrambling signals without the need for multiple receiving channels or complex digital signal processing, thereby effectively reducing system complexity and implementation cost.

[0005] The specific technical solution proposed in this invention is as follows: A multi-band radar detection method includes the following steps: S1, Generate homologous entities with frequencies of f m Three continuous optical signals; S2. Based on the first continuous optical signal, generate a signal with a frequency of... f m The carrier and frequency are f sl ’ = f 0- kt A broadband linear frequency sweep optical signal with a frequency sweep slope. k = B / T, B, T These represent the bandwidth and period of the swept-frequency optical signal, respectively. f 0 represents the maximum frequency of the swept-frequency optical signal. f sl ’ < fm A transmitted light local oscillator signal is generated based on the second continuous optical signal, wherein the transmitted light local oscillator signal contains... N Each comb tooth has a frequency interval of [number] teeth. f The optical frequency comb signal, N For odd numbers greater than 2, their 6th... i Frequency of each comb tooth f TX,i satisfy f TX,i = f m + [ i -( N +1) / 2] f , i =1, 2, ..., N A reference optical local oscillator signal is generated based on the third continuous optical signal, wherein the reference optical local oscillator signal comprises... N Each comb tooth has a frequency interval of [number] teeth. f offset +Δ f The optical frequency comb signal, its first i Frequency of each comb tooth f TX,i satisfy f RX,i = f m + [ i -( N +1) / 2] f +( i -1) f offset ,in, i =1, 2, ..., N , , For the maximum echo delay, R max Where c is the maximum detection range of the radar, and c is the speed of light; S3. Couple the broadband linear sweep frequency optical signal with the emitted light local oscillator signal to generate a beat frequency, which includes... N The microwave multi-band transmission signal is transmitted in multiple bands; the broadband linearly swept frequency optical signal is coupled with the reference optical local oscillator signal and then beats to generate a signal containing... N The microwave multi-band reference signal is obtained in each band, and the microwave multi-band reference signal and the echo signal are processed by an electric mixer to remove skew, resulting in a signal separated in the frequency domain. N Multi-band intermediate frequency signals of an intermediate frequency signal; S4. Process the multi-band intermediate frequency signal to obtain target information.

[0006] In one embodiment, the method for generating the broadband linear sweep frequency optical signal is as follows: a first continuous optical signal is injected into a slave laser, and the slave laser is made to operate in a single-cycle oscillation state by adjusting the injection parameters; a low-speed corrected sawtooth wave electrical control signal is used to intensity modulate the first continuous optical signal input to the slave laser to achieve redshift sideband frequency. f sl ’ The dynamic scanning generates the broadband linear sweep frequency optical signal.

[0007] In another embodiment, the method for generating the broadband linear sweep frequency optical signal is as follows: a first continuous optical signal is input into a dual parallel Mach-Zehnder modulator; the broadband linear sweep frequency signal is passed through a 90° bridge to generate two signals with equal intensity and a 90° phase difference, and these signals are respectively loaded onto the upper and lower sub-modulators of the dual parallel Mach-Zehnder modulator to perform single-sideband modulation of the sweep frequency signal, thereby generating the broadband linear sweep frequency optical signal.

[0008] In one embodiment, the method for generating the emitted optical local oscillator signal is as follows: using a frequency of... f The radio frequency microwave signal modulates the second continuous optical signal at an intensity that operates at approximately the minimum transmission point, generating an optical frequency comb signal containing an optical carrier and ±(N-1) / 2 order sidebands, which is the transmitted light local oscillator signal.

[0009] In one embodiment, the method for generating the reference optical local oscillator signal is as follows: the frequency is... f offset The (N-1) / 2 RF microwave signal is split into two orthogonal signals by a 90° bridge, which drive the two RF inputs of a dual parallel intensity modulator. By adjusting the bias voltage of the sub-modulators of the dual parallel intensity modulator, carrier-suppressed single-sideband modulation is achieved, thereby obtaining a precise wavelength shift towards shorter wavelengths. f offset (N-1) / 2 frequency-shifted optical carriers; then using a frequency of f offset +Δ f The radio frequency microwave signal modulates the frequency-shifted optical carrier at an intensity that operates at approximately the minimum transmission point, generating an optical frequency comb signal containing the frequency-shifted optical carrier and ±(N-1) / 2 order sidebands, which is the reference optical local oscillator signal.

[0010] Based on the same inventive concept, the following technical solutions can also be obtained: A multi-band radar detection device, comprising: Light source, used to generate homogeneous light with a frequency off m Three continuous optical signals; The broadband swept-frequency optical signal generation module is used to generate a frequency-containing optical signal based on the first continuous optical signal. f m The carrier and frequency are f sl ’ = f 0- kt A broadband linear frequency sweep optical signal with a frequency sweep slope. k = B / T, B, T These represent the bandwidth and period of the swept-frequency optical signal, respectively. f 0 represents the maximum frequency of the swept-frequency optical signal. f sl ’ < f m ; The emitted light local oscillator generation module is used to generate an emitted light local oscillator signal based on a second continuous optical signal, wherein the emitted light local oscillator signal contains... N Each comb tooth has a frequency interval of [number] teeth. f The optical frequency comb signal, N For odd numbers greater than 2, their 6th... i Frequency of each comb tooth f TX,i satisfy f TX,i = f m + [ i -( N +1) / 2] f , i =1, 2, ..., N ; A reference optical local oscillator generation module is used to generate a reference optical local oscillator signal based on a third continuous optical signal. The reference optical local oscillator signal comprises... N Each comb tooth has a frequency interval of [number] teeth. f offset +Δ f The optical frequency comb signal, its first i Frequency of each comb tooth f RX,i satisfy f RX,i = f m + [ i -( N +1) / 2] f +( i-1) f offset ,in, i =1, 2, ..., N , , For the maximum echo delay, R max Where c is the maximum detection range of the radar, and c is the speed of light; The multi-band radar transceiver module is used to couple the broadband linearly swept frequency optical signal with the transmitted light local oscillator signal to generate a frequency response, including... N The microwave multi-band transmission signal is transmitted in multiple bands; the broadband linearly swept frequency optical signal is coupled with the reference optical local oscillator signal and then beats to generate a signal containing... N The microwave multi-band reference signal is obtained in each band, and the microwave multi-band reference signal and the echo signal are processed by an electric mixer to remove skew, resulting in a signal separated in the frequency domain. N Multi-band intermediate frequency signals of an intermediate frequency signal; The data processing module is used to process the multi-band intermediate frequency signal to obtain target information.

[0011] In one embodiment, the broadband swept-frequency optical signal generation module generates a broadband linear swept-frequency optical signal using the following method: injecting a first continuous optical signal into a slave laser, and adjusting the injection parameters to make the slave laser operate in a single-cycle oscillation state; using a low-speed corrected sawtooth wave electrical control signal to intensity modulate the first continuous optical signal input to the slave laser, so as to achieve redshift sideband frequency. f sl ’ The dynamic scanning generates the broadband linear sweep frequency optical signal.

[0012] In another embodiment, the broadband sweep frequency optical signal generation module generates a broadband linear sweep frequency optical signal using the following method: a first continuous optical signal is input into a dual parallel Mach-Zehnder modulator; the broadband linear sweep frequency signal is passed through a 90° bridge to generate two signals with equal intensity and a 90° phase difference, and these signals are respectively loaded onto the upper and lower sub-modulators of the dual parallel Mach-Zehnder modulator to perform single-sideband modulation of the sweep frequency signal, thereby generating the broadband linear sweep frequency optical signal.

[0013] In one embodiment, the emitted light local oscillator generation module generates the emitted light local oscillator signal using the following method: using a frequency of f The radio frequency microwave signal modulates the second continuous optical signal at an intensity that operates at approximately the minimum transmission point, generating an optical frequency comb signal containing an optical carrier and ±(N-1) / 2 order sidebands, which is the transmitted light local oscillator signal.

[0014] In one embodiment, the reference optical oscillator generation module generates a reference optical oscillator signal using the following method: the frequency is... f offset The (N-1) / 2 RF microwave signal is split into two orthogonal signals by a 90° bridge, which drive the two RF inputs of a dual parallel intensity modulator. By adjusting the bias voltage of the sub-modulators of the dual parallel intensity modulator, carrier-suppressed single-sideband modulation is achieved, thereby obtaining a precise wavelength shift towards shorter wavelengths. f offset (N-1) / 2 frequency-shifted optical carriers; then using a frequency of f offset +Δ f The radio frequency microwave signal modulates the frequency-shifted optical carrier at an intensity that operates at approximately the minimum transmission point, generating an optical frequency comb signal containing the frequency-shifted optical carrier and ±(N-1) / 2 order sidebands, which is the reference optical local oscillator signal.

[0015] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: This invention utilizes microwave photonics technology to generate specific microwave multi-band transmission signals and microwave multi-band reference signals. By processing the microwave multi-band reference signals and echo signals through an electric mixer to remove skew, the de-skewed intermediate frequency signals corresponding to each band separated in the frequency domain can be obtained. This eliminates the need for multiple receiving channels or complex digital signal processing, thereby effectively reducing system complexity and implementation costs. Attached Figure Description

[0016] Figure 1 This is a structural principle block diagram of the multi-band radar detection device of the present invention; Figure 2 This is a schematic diagram illustrating the structural principle of a specific embodiment of the multi-band radar detection device of the present invention; Figure 3 The following are schematic diagrams of the spectra and frequency spectrum generated in a specific embodiment, wherein (a) is the output spectrum of the broadband swept-frequency optical signal generation module; (b) is the spectrum after frequency shifting of the optical carrier; (c) is the spectrum of the multi-band transmitted signal; (d) is the spectrum after coupling the transmitted local oscillator optical signal and the broadband swept-frequency optical signal; (e) is the spectrum after coupling the reference local oscillator optical signal and the broadband swept-frequency optical signal; and (f) is the spectrum of the multi-band reference signal. Figure 4 This is a schematic diagram illustrating the principle of crosstalk-resistant reception in this invention. Figure 5 To verify the multi-band radar transmission signal generated in the experiment, (a) is the time-domain waveform and (b) is the time-frequency diagram; Figure 6 To verify the multi-band radar reference signal generated in the experiment, (a) is the time-domain waveform and (b) is the time-frequency diagram; Figure 7 The spectrum of the intermediate frequency descrambling signal acquired by the data processing module. Detailed Implementation

[0017] To address the technical challenge of separating and processing echo signals from different bands without crosstalk without increasing the sampling rate of the analog-to-digital converter, this invention proposes using microwave photonics technology to generate specific microwave multi-band transmission signals and microwave multi-band reference signals. By deskewing the microwave multi-band reference signals and echo signals through an electric mixer, the deskewing intermediate frequency signals corresponding to each band separated in the frequency domain can be obtained. This eliminates the need for multiple receiving channels or complex digital signal processing, thereby effectively reducing system complexity and implementation costs.

[0018] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings: The basic structure of the multi-band radar detection device proposed in this invention is as follows: Figure 1 As shown, it includes: Light source, used to generate homogeneous light with a frequency of f m Three continuous optical signals; The broadband swept-frequency optical signal generation module is used to generate a frequency-containing optical signal based on the first continuous optical signal. f m The carrier and frequency are f sl ’ = f 0- kt A broadband linear frequency sweep optical signal with a frequency sweep slope. k = B / T, B, T These represent the bandwidth and period of the swept-frequency optical signal, respectively. f 0 represents the maximum frequency of the swept-frequency optical signal. f sl ’ < f m ; The emitted light local oscillator generation module is used to generate an emitted light local oscillator signal based on a second continuous optical signal, wherein the emitted light local oscillator signal contains... N Each comb tooth has a frequency interval of [number] teeth. f The optical frequency comb signal, N For odd numbers greater than 2, their 6th... i Frequency of each comb tooth f TX,i satisfy f TX,i = f m + [ i -( N+1) / 2] f , i =1, 2, ..., N ; A reference optical local oscillator generation module is used to generate a reference optical local oscillator signal based on a third continuous optical signal. The reference optical local oscillator signal comprises... N Each comb tooth has a frequency interval of [number] teeth. f offset +Δ f The optical frequency comb signal, its first i Frequency of each comb tooth f RX,i satisfy f RX,i = f m + [ i -( N +1) / 2] f +( i -1) f offset ,in, i =1, 2, ..., N , , For the maximum echo delay, R max Where c is the maximum detection range of the radar, and c is the speed of light; The multi-band radar transceiver module is used to couple the broadband linearly swept frequency optical signal with the transmitted light local oscillator signal to generate a frequency response, including... N The microwave multi-band transmission signal is transmitted in multiple bands; the broadband linearly swept frequency optical signal is coupled with the reference optical local oscillator signal and then beats to generate a signal containing... N The microwave multi-band reference signal is obtained in each band, and the microwave multi-band reference signal and the echo signal are processed by an electric mixer to remove skew, resulting in a signal separated in the frequency domain. N A multi-band intermediate frequency (IF) signal. Due to frequency offset. f offset The presence of this signal causes the de-skewing intermediate frequency signals corresponding to different bands to be separated in the frequency domain. The frequency of the de-skewing signal for the first band is... ,in For the target echo delay; the first i The descrambling signal frequencies for each band are ( i -1) f offset + f IF 。; The data processing module is used to process the multi-band intermediate frequency signal to obtain target information.

[0019] The broadband sweep frequency optical signal generation module, the emitted light local oscillator generation module, and the reference light local oscillator generation module can all be implemented using various existing technologies according to actual needs.

[0020] In one embodiment, the broadband swept-frequency optical signal generation module generates a broadband linear swept-frequency optical signal using the following method: injecting a first continuous optical signal into a slave laser, and adjusting the injection parameters to make the slave laser operate in a single-cycle oscillation state; using a low-speed corrected sawtooth wave electrical control signal to intensity modulate the first continuous optical signal input to the slave laser, so as to achieve redshift sideband frequency. f sl ’ The dynamic scanning generates the broadband linear sweep frequency optical signal.

[0021] In another embodiment, the broadband sweep frequency optical signal generation module generates a broadband linear sweep frequency optical signal using the following method: a first continuous optical signal is input into a dual parallel Mach-Zehnder modulator; the broadband linear sweep frequency signal is passed through a 90° bridge to generate two signals with equal intensity and a 90° phase difference, and these signals are respectively loaded onto the upper and lower sub-modulators of the dual parallel Mach-Zehnder modulator to perform single-sideband modulation of the sweep frequency signal, thereby generating the broadband linear sweep frequency optical signal.

[0022] In one embodiment, the emitted light local oscillator generation module generates the emitted light local oscillator signal using the following method: using a frequency of f The radio frequency microwave signal modulates the second continuous optical signal at an intensity that operates at approximately the minimum transmission point, generating an optical frequency comb signal containing an optical carrier and ±(N-1) / 2 order sidebands, which is the transmitted light local oscillator signal.

[0023] In another embodiment, the emitted light local oscillator generation module uses a cascaded intensity modulator to generate the emitted light local oscillator signal: the second continuous optical signal passes through two electro-optic modulators in sequence, and the radio frequency single-tone signal generated by the microwave source is split into two paths by a power divider. One path is directly modulated onto the first electro-optic modulator, and the other path is modulated onto the second electro-optic modulator through a phase shifter, thereby generating the emitted light local oscillator signal. More detailed information about this scheme can be found in the reference [Zheng Dongyu, Dong Liang. Experimental study on optical frequency comb generation based on cascaded MZM and PM [J]. Optoelectronic Technology Application, 2021, 36(03):65-68.].

[0024] In one embodiment, the reference optical oscillator generation module generates a reference optical oscillator signal using the following method: the frequency is... f offsetThe (N-1) / 2 RF microwave signal is split into two orthogonal signals by a 90° bridge, which drive the two RF inputs of a dual parallel intensity modulator. By adjusting the bias voltage of the sub-modulators of the dual parallel intensity modulator, carrier-suppressed single-sideband modulation is achieved, thereby obtaining a precise wavelength shift towards shorter wavelengths. f offset (N-1) / 2 frequency-shifted optical carriers; then using a frequency of f offset +Δ f The radio frequency microwave signal modulates the frequency-shifted optical carrier at an intensity that operates at approximately the minimum transmission point, generating an optical frequency comb signal containing the frequency-shifted optical carrier and ±(N-1) / 2 order sidebands, which is the reference optical local oscillator signal.

[0025] To facilitate public understanding, the technical solution of the present invention will be further described in detail below through a specific embodiment: The specific structure of the multi-band radar detection device in this embodiment is as follows: Figure 2 As shown, it includes a light source, a broadband swept-frequency optical signal generation module, a transmitted light local oscillator generation module, a reference light local oscillator generation module, a multi-band radar transceiver module, and a data processing module. Figure 2 As shown, the light source includes a master laser and a 1×3 optical power divider; the broadband swept-frequency optical signal generation module includes an intensity modulator, a circulator, and a slave laser; the emitted light local oscillator generation module includes an intensity modulator; the reference light local oscillator generation module includes a dual parallel intensity modulator and an intensity modulator; the multi-band radar transceiver module includes an optical power divider, two optical couplers, two photodetectors, and an electrical mixer.

[0026] The main laser generates a frequency of f m The continuous optical signal is split into three paths by an optical power divider, which serve as the light sources for the broadband swept-frequency optical signal module, the emitted optical local oscillator generation module, and the reference optical local oscillator generation module, respectively.

[0027] In the broadband swept-frequency optical signal generation module, the intensity modulator uses an external control signal (such as a low-speed corrected sawtooth wave electrical signal) to modulate the intensity of the first continuous optical signal input. The modulated optical signal is then injected into the slave laser via a circulator. By adjusting the injection parameters, the slave laser is made to operate in a single-cycle oscillation state, and its output spectrum contains frequencies of... f m Injecting a regenerated signal and a first-order red-shift sideband; by dynamically controlling the intensity modulator, the frequency of the red-shift sideband can be adjusted. f sl ’ It changes linearly with time, thus producing a frequency of . f m The carrier and frequency aref sl ’ = f 0- kt A broadband linear frequency sweep optical signal with a frequency sweep slope. k = B / T, B, T These represent the bandwidth and period of the swept-frequency optical signal, respectively. f 0 represents the maximum frequency of the swept-frequency optical signal, and has f sl ’ < f m The sweep frequency range, sweep period, and other parameters of this signal can be flexibly reconstructed by adjusting the control signal and injection parameters. The output spectrum of the broadband swept-frequency optical signal generation module is as follows: Figure 3 As shown in (a) of the diagram.

[0028] In the local oscillator generation module for emitted light, a frequency of [frequency value missing] is used. f The radio frequency microwave signal is used to intensity modulate the second continuous optical signal. By adjusting the operating voltage of the intensity modulator to make it operate at approximately its minimum operating point (where the power of the carrier wave and the sideband power generated by modulation are close), a signal containing... N Each comb tooth (i.e., the optical carrier and ±(N-1) / 2 order sidebands) and the frequency spacing is f The optical frequency comb signal, N Let the number be an odd number greater than 2, and denote the th... i Each comb tooth ( i =1, 2, ..., N The frequency of ) is f TX,I Its satisfaction f TX,i = f m + [ i -( N +1) / 2] f .

[0029] In the reference optical local oscillator generation module, the frequency is first... f offset The (N-1) / 2 RF microwave signal is split into two orthogonal signals by a 90° bridge, which drive the two RF input terminals of the dual parallel intensity modulator respectively. By adjusting the bias voltage of the sub-modulator of the dual parallel intensity modulator, carrier-suppressed single-sideband modulation is achieved, thereby precisely shifting the wavelength of the input third optical carrier towards a shorter wavelength. f offset The spectrum diagram after frequency shifting of the optical carrier (N-1) / 2 is shown below. Figure 3As shown in (b); subsequently, the frequency-shifted optical carrier enters a second intensity modulator, which receives frequencies of... f offset +Δ f The radio frequency microwave signal, operating at an approximate minimum transmission point, generates a signal containing... N A fiber optic comb with 1 comb tooth, frequency interval of 1 f offset +Δ f Ultimately, the reference optical local oscillator signal output by the reference optical local oscillator generation module is frequency-shifted with a frequency interval of [value missing]. f offset +Δ f The optical frequency comb signal, denoted as the first i Each comb tooth ( i =1, 2, ..., N The frequency of ) is f RX,I Its satisfaction f RX,i = f m + [ i -( N +1) / 2] f +( i -1) f offset ;in, f offset Should meet , For the maximum echo delay, R max denoted as ρ, where ρ is the maximum detection range of the radar, and c is the speed of light.

[0030] In the multi-band radar transceiver module, a combination of an optical power divider and optical couplers 1 and 2 is first used to couple the broadband swept-frequency optical signal to the transmitted optical local oscillator and the reference optical local oscillator, respectively; the signal spectrum after coupling the broadband linear swept-frequency optical signal with the transmitted optical local oscillator signal is as follows: Figure 3 As shown in (c) above, the signal spectrum after coupling the broadband linearly swept frequency optical signal with the reference optical local oscillator signal is as follows. Figure 3 As shown in (d) in the diagram. The beat frequency generated by photodetector 1 contains... N The spectrum of a microwave multi-band transmission signal in each band is as follows: Figure 3 As shown in (e), for the first i Each band ( i =1, 2, ..., N ), the frequency of its transmitted signal f RF_TX,i ,for f RF_TX,i =f TX,i - f sl ’ After being amplified by an RF power amplifier, it is transmitted; after being beat by a photodetector, it generates a frequency containing... N The spectrum of the microwave multi-band reference signal in each band is as follows: Figure 3 As shown in (f), for the th i Each band ( i =1, 2, ..., N ), the frequency of its reference signal f RF_RX,i ,for f RF_RX,i = f RX,i - f sl ’ Therefore, with the first i Compared to the transmitted signal of the first band, the second band... i The center frequency of the reference signal in each band increases ( i -1) f offset After receiving the echo signal, the echo signal is amplified by a low-noise amplifier and then mixed with a microwave multi-band reference signal through an electrical mixer for deskewing. Figure 4 As shown. Due to the existence of the stepped frequency offset, the de-skewing intermediate frequency signals corresponding to different bands are separated in the frequency domain. For the first... i Each band has a descrambling intermediate frequency signal frequency. ,in The target echo delay.

[0031] Data processing module acquisition N The de-skewing intermediate frequency signals from each band are fused using digital signal processing (such as sparse reconstruction algorithms) to achieve high-resolution target detection. This is a mature existing technology and will not be elaborated further here.

[0032] To demonstrate the effectiveness of the technical solution of this invention, experimental verification was conducted on the above specific embodiments. The device parameters used in the experiment are as follows: the main laser (CoBrite Tunable laser) output wavelength is 1549.285 nm, and the output power is 16 dBm; the slave laser is a DFB laser (LP-ML1001C-55-FA), and the laser controller bias current is set to 22 mA, the temperature to 26.5℃, the free resonant wavelength to 1549.299 nm, and the output power to 4.6 dBm; the photodetector (DSC40S) has a working bandwidth of 40 GHz; the real-time oscilloscope (Tektronix DSA72004B) has a sampling rate of 80 GSa / s; and the microwave RF source (Keysight, N5183B) has a bandwidth of 20 GHz. The control signal voltage amplitude was set to 1.25V, and the optical signal generated by the broadband sweep frequency optical signal module was directly beat-frequency-modulated to produce a linear frequency-modulated signal with a center frequency of 13 GHz, a bandwidth of 2 GHz, and a duration of 10 μs. Then, in order to generate radar signals in N=3 bands, f Set to 3GHz f offset The frequency was set to 50MHz, therefore the optical carrier frequency shift of the reference optical oscillator was 50MHz. After the swept optical signal beats the optical oscillator signal, a multi-band radar signal is obtained.

[0033] Figure 5 (a) and (b) in the figure are the time-domain waveforms of the generated multi-band radar transmission signals and the time-frequency diagrams obtained by short-time Fourier transform, respectively. It can be seen that three bands were generated, with frequency ranges of 10-12 GHz, 13-15 GHz and 16-18 GHz, and a time width of 10 μs. Figure 6 Figures (a) and (b) show the time-domain waveform of the generated multi-band radar reference signal and the time-frequency diagram obtained through short-time Fourier transform, respectively. It can be seen that three bands were generated, with frequency ranges of 10-12 GHz, 13.05-15.05 GHz, and 16.1-18.1 GHz, and a time width of 10 μs. In the specific experimental detection scenario, the target was placed 4.5 meters from the antenna. The target echo was received by the receiving antenna and amplified by a low-noise amplifier before entering the electric mixer for de-skewing processing with the reference signal. Due to the pre-introduced step-wise frequency offset in the reference signal, the echo signals of different bands were mapped to different intermediate frequency bands. The signal output from the mixer was acquired by a single-channel analog-to-digital converter and subjected to Fast Fourier Transform (FFT). The resulting multi-band radar detection spectrum is shown below. Figure 7As shown, these three peaks correspond to the target information in band 1 (6.1MHz), band 2 (56.1MHz), and band 3 (106.1MHz), respectively. The descrambling signals in the three bands are separated and independent of each other in the spectrum, and no spectral aliasing occurs.

Claims

1. A multi-band radar detection method, characterized in that, Includes the following steps: S1, Generate homologous entities with frequencies of f m Three continuous optical signals; S2. Based on the first continuous optical signal, generate a signal with a frequency of... f m The carrier and frequency are f sl ’ = f 0- kt A broadband linear frequency sweep optical signal with a frequency sweep slope. k = B / T, B, T These represent the bandwidth and period of the swept-frequency optical signal, respectively. f 0 represents the maximum frequency of the swept-frequency optical signal. f sl ’ < f m A transmitted light local oscillator signal is generated based on the second continuous optical signal, wherein the transmitted light local oscillator signal contains... N Each comb tooth has a frequency interval of [number] teeth. f The optical frequency comb signal, N For odd numbers greater than 2, their 6th... i Frequency of each comb tooth f TX,i satisfy f TX,i = f TX,i + [ i -( N +1) / 2] f , i =1, 2, ..., N A reference optical local oscillator signal is generated based on the third continuous optical signal, wherein the reference optical local oscillator signal comprises... N Each comb tooth has a frequency interval of [number] teeth. f offset +Δ f The optical frequency comb signal, its first i Frequency of each comb tooth f RX,i ,satisfy f RX,i = f m + [ i -( N +1) / 2] f +( i -1) f offset ,in, i =1, 2, ..., N , , For the maximum echo delay, R max Where c is the maximum detection range of the radar, and c is the speed of light; S3. Couple the broadband linear sweep frequency optical signal with the emitted light local oscillator signal to generate a beat frequency, which includes... N The microwave multi-band transmission signal is transmitted in multiple bands; the broadband linearly swept frequency optical signal is coupled with the reference optical local oscillator signal and then beats to generate a signal containing... N The microwave multi-band reference signal is obtained in each band, and the microwave multi-band reference signal and the echo signal are processed by an electric mixer to remove skew, resulting in a signal separated in the frequency domain. N Multi-band intermediate frequency signals of an intermediate frequency signal; S4. Process the multi-band intermediate frequency signal to obtain target information.

2. The multi-band radar detection method as described in claim 1, characterized in that, The method for generating the broadband linear sweep frequency optical signal is as follows: a first continuous optical signal is injected into the slave laser, and the slave laser is made to operate in a single-cycle oscillation state by adjusting the injection parameters; the intensity of the first continuous optical signal input to the slave laser is modulated using a control signal of a low-speed corrected sawtooth wave electrical signal, so as to achieve redshift sideband frequency. f sl ’ The dynamic scanning generates the broadband linear sweep frequency optical signal.

3. The multi-band radar detection method as described in claim 1, characterized in that, The method for generating the broadband linear sweep frequency optical signal is as follows: a first continuous optical signal is input into a dual parallel Mach-Zehnder modulator; the broadband linear sweep frequency signal is passed through a 90° bridge to generate two signals with equal intensity and a 90° phase difference, and these signals are respectively loaded onto the upper and lower sub-modulators of the dual parallel Mach-Zehnder modulator for single-sideband modulation of the sweep frequency signal, thereby generating the broadband linear sweep frequency optical signal.

4. The multi-band radar detection method as described in claim 1, characterized in that, The method for generating the emitted optical local oscillator signal is as follows: using a frequency of f The radio frequency microwave signal modulates the second continuous optical signal at an intensity that operates at approximately the minimum transmission point, generating an optical frequency comb signal containing an optical carrier and ±(N-1) / 2 order sidebands, which is the transmitted light local oscillator signal.

5. The multi-band radar detection method as described in claim 1, characterized in that, The specific method for generating the reference optical local oscillator signal is as follows: the frequency is... f offset The (N-1) / 2 RF microwave signal is split into two orthogonal signals by a 90° bridge, which drive the two RF inputs of a dual parallel intensity modulator. By adjusting the bias voltage of the sub-modulators of the dual parallel intensity modulator, carrier-suppressed single-sideband modulation is achieved, thereby obtaining a precise wavelength shift towards shorter wavelengths. f offset (N-1) / 2 frequency-shifted optical carriers; then using a frequency of f offset +Δ f The radio frequency microwave signal modulates the frequency-shifted optical carrier at an intensity that operates at approximately the minimum transmission point, generating an optical frequency comb signal containing the frequency-shifted optical carrier and ±(N-1) / 2 order sidebands, which is the reference optical local oscillator signal.

6. A multi-band radar detection device, characterized in that, include: Light source, used to generate homogeneous light with a frequency of f m Three continuous optical signals; The broadband swept-frequency optical signal generation module is used to generate a frequency-sweeping optical signal based on the first continuous optical signal. f m The carrier and frequency are f sl ’ = f 0- kt A broadband linear frequency sweep optical signal with a frequency sweep slope. k = B / T, B, T These represent the bandwidth and period of the swept-frequency optical signal, respectively. f 0 represents the maximum frequency of the swept-frequency optical signal. f sl ’ < f m ; The emitted light local oscillator generation module is used to generate an emitted light local oscillator signal based on a second continuous optical signal, wherein the emitted light local oscillator signal contains... N Each comb tooth has a frequency interval of [number] teeth. f The optical frequency comb signal, N For odd numbers greater than 2, their 6th... i Frequency of each comb tooth f TX,i satisfy f TX,i = f m + [ i -( N +1) / 2] f , i =1, 2, ..., N ; A reference optical local oscillator generation module is used to generate a reference optical local oscillator signal based on a third continuous optical signal. The reference optical local oscillator signal comprises... N Each comb tooth has a frequency interval of [number] teeth. f offset +Δ f The optical frequency comb signal, its first i Frequency of each comb tooth f TX,i satisfy f RX,i = f m + [ i -( N +1) / 2] f +( i -1) f offset ,in, i =1, 2, ..., N , , For the maximum echo delay, R max Where c is the maximum detection range of the radar, and c is the speed of light; The multi-band radar transceiver module is used to couple the broadband linearly swept frequency optical signal with the transmitted light local oscillator signal to generate a frequency response, including... N The microwave multi-band transmission signal is transmitted in multiple bands; the broadband linearly swept frequency optical signal is coupled with the reference optical local oscillator signal and then beats to generate a signal containing... N The microwave multi-band reference signal is obtained in each band, and the microwave multi-band reference signal and the echo signal are processed by an electric mixer to remove skew, resulting in a signal separated in the frequency domain. N Multi-band intermediate frequency signals of an intermediate frequency signal; The data processing module is used to process the multi-band intermediate frequency signal to obtain target information.

7. The multi-band radar detection device as described in claim 6, characterized in that, The broadband sweep frequency optical signal generation module generates a broadband linear sweep frequency optical signal using the following method: a first continuous optical signal is injected into the slave laser, and the slave laser is made to operate in a single-cycle oscillation state by adjusting the injection parameters; The intensity of the first continuous optical signal input to the laser is modulated using a low-speed corrected sawtooth wave electrical control signal to achieve redshift sideband frequency control. f sl ’ The dynamic scanning generates the broadband linear sweep frequency optical signal.

8. The multi-band radar detection device as described in claim 6, characterized in that, The broadband sweep frequency optical signal generation module generates a broadband linear sweep frequency optical signal using the following method: a first continuous optical signal is input into a dual parallel Mach-Zehnder modulator; the broadband linear sweep frequency signal is passed through a 90° bridge to generate two signals with equal intensity and a 90° phase difference, which are then loaded onto the upper and lower sub-modulators of the dual parallel Mach-Zehnder modulator to perform single-sideband modulation of the sweep frequency signal, thereby generating the broadband linear sweep frequency optical signal.

9. The multi-band radar detection device as described in claim 6, characterized in that, The emitted light local oscillator generation module generates the emitted light local oscillator signal using the following method: The frequency used is... f The radio frequency microwave signal modulates the second continuous optical signal at an intensity that operates at approximately the minimum transmission point, generating an optical frequency comb signal containing an optical carrier and ±(N-1) / 2 order sidebands, which is the transmitted light local oscillator signal.

10. The multi-band radar detection device as described in claim 6, characterized in that, The reference optical oscillator generation module generates the reference optical oscillator signal using the following method: frequency is f offset The (N-1) / 2 RF microwave signal is split into two orthogonal signals by a 90° bridge, which drive the two RF inputs of a dual parallel intensity modulator. By adjusting the bias voltage of the sub-modulators of the dual parallel intensity modulator, carrier-suppressed single-sideband modulation is achieved, thereby obtaining a precise wavelength shift towards shorter wavelengths. f offset (N-1) / 2 frequency-shifted optical carriers; then using a frequency of f offset +Δ f The radio frequency microwave signal modulates the frequency-shifted optical carrier at an intensity that operates at approximately the minimum transmission point, generating an optical frequency comb signal containing the frequency-shifted optical carrier and ±(N-1) / 2 order sidebands, which is the reference optical local oscillator signal.

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