Dual-chirp-rate microwave photon dual-band radar detection method and device

Abstract

The present invention discloses a dual-chirp-rate microwave photon dual-band radar detection method, which belongs to the field of radar technology. At the transmitting end, the optical carrier is divided into two paths, one path is modulated by a linear frequency-modulated microwave signal to generate a modulated optical signal, and the other path is not modulated; the polarization state of any path is rotated, and after coupling, an orthogonal polarized optical signal is generated and divided into two paths; one path is used as the reference optical signal of the receiver, and the other path is converted into a linearly polarized optical signal and photoelectrically detected to generate a dual-chirp-rate dual-band signal; at the receiving end, the reference optical signal is further divided into two paths, one path is modulated by the target echo signal after filtering; the optical signals of the two polarization states in the other path are coupled with the target modulated optical signal and photoelectrically detected to generate a de-skewed signal; the de-skewed signals of the dual bands are processed to achieve high-resolution detection. The present invention also discloses a dual-chirp-rate microwave photon dual-band radar detection device. Compared with the existing technology, the present invention has better anti-interference ability.

Description

Technical Field

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

[0002] High-resolution detection of complex targets and acquisition of complete observation information are particularly important in radar. Dual-band radar systems can operate in different bands and acquire the electromagnetic scattering characteristics of targets in different frequency bands, gathering more complete target signature information. Digital signal processing can also fuse the signals received from both bands, further improving target detection resolution and recognition capabilities. This is of great significance in radar applications such as small target detection and tracking, multi-target detection and separation, and high-resolution imaging. Furthermore, when dual-band radars can transmit signals at different chirp rates, their anti-interference capabilities can be enhanced. However, traditional radars using electronic technology are limited by bandwidth bottlenecks, making it difficult to generate and process dual-band radar signals on the same system, resulting in a waste of resources.

[0003] Compared with electronic technology, microwave photonic technology has advantages such as large bandwidth, low transmission loss, and resistance to electromagnetic interference. For example, with the help of microwave photonic frequency doubling technology, the frequency and bandwidth of microwave signals can be multiplied. By converting microwave signals into optical domain processing, radar transceivers can generate and process large-bandwidth signals in real time. Currently, there are reports on dual-band radars using microwave photonic technology, but the current implementation scheme requires two microwave signals with different parameters to drive the system, which is complex and costly (see [Peng S, Li S, Xue X, et al. “A photonics-based coherent dual-band radar for super-resolution range profile,” IEEE Photonics Journal, 2019, 11(4): 1-8.] [Cao J, Li R, Yang J, et al. “Photonic deramp receiver for dual-band LFM-CW radar,” Journal of Lightwave Technology, 2019, 37(10): 2403-2408.]). Therefore, the research on dual-chirp-rate microwave photon dual-band broadband radar with simple structure and easy implementation is of great significance to enrich the detection function of radar and improve the distance resolution and anti-interference capability of radar. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a dual-chirp-rate microwave photon dual-band radar detection method, which can simultaneously generate dual-chirp-rate dual-band signals and realize de-skewed reception and bandwidth fusion, thereby realizing anti-interference broadband microwave detection / imaging.

[0005] A dual-chirp-rate microwave photon dual-band radar detection method,

[0006] At the transmitting end, a linear frequency modulated microwave signal is used to perform carrier suppressed double-sideband modulation on an optical carrier, and the generated carrier suppressed double-sideband modulated optical signal is polarization-coupled with another cognate optical carrier to form an orthogonal polarization optical signal. The carrier suppressed double-sideband modulated optical signal and the other cognate optical carrier are respectively in two orthogonal polarization states of the orthogonal polarization optical signal, and the phases of the optical carrier and the two sidebands in the orthogonal polarization optical signal satisfy the relationship: Δθ up -Δθ down ≠2nπ+π / 2, where Δθ up is the phase difference between the optical carrier and the upper sideband, Δθ down is the phase difference between the optical carrier and the lower sideband, and n is an integer; the orthogonally polarized optical signal is divided into two paths, one path is used as the reference optical signal at the receiving end, and the other path is converted into a linearly polarized optical signal by a polarization analyzer; the linearly polarized optical signal is photoelectrically converted to generate a dual-band radar signal with chirp rates k and 2k, which is simultaneously transmitted by the transmitting antenna, where k is the chirp rate of the linear frequency modulated microwave signal;

[0007] At the receiving end, the reference optical signal is split into two paths. The two polarization states of one reference optical signal are separated to generate two local oscillator optical signals. One sideband of the other reference optical signal is filtered out and then subjected to carrier-suppressed double-sideband modulation using the target echo signal to generate a target modulated optical signal. The target modulated optical signal is split into two paths and optically mixed with the two local oscillator optical signals. The resulting optical signals are then subjected to balanced photoelectric detection to obtain two de-skewed signals with frequencies of kτ and 2kτ, respectively, where τ is the delay between the target echo signal and the transmitted signal. Finally, the two de-skewed signals are processed to obtain target information.

[0008] Based on the same inventive concept, the following technical solutions can also be obtained:

[0009] A dual-chirp-rate microwave photon dual-band radar detection device comprises a transmitting end and a receiving end;

[0010] At the transmitting end, a linear frequency modulated microwave signal is used to perform carrier suppressed double-sideband modulation on an optical carrier, and the generated carrier suppressed double-sideband modulated optical signal is polarization-coupled with another cognate optical carrier to form an orthogonal polarization optical signal. The carrier suppressed double-sideband modulated optical signal and the other cognate optical carrier are respectively in two orthogonal polarization states of the orthogonal polarization optical signal, and the phases of the optical carrier and the two sidebands in the orthogonal polarization optical signal satisfy the relationship: Δθ up -Δθ down ≠2nπ+π / 2, where Δθ up is the phase difference between the optical carrier and the upper sideband, Δθ down is the phase difference between the optical carrier and the lower sideband, and n is an integer; the orthogonally polarized optical signal is divided into two paths, one path is used as the reference optical signal at the receiving end, and the other path is converted into a linearly polarized optical signal by a polarization analyzer; the linearly polarized optical signal is photoelectrically converted to generate a dual-band radar signal with chirp rates k and 2k, which is simultaneously transmitted by the transmitting antenna, where k is the chirp rate of the linear frequency modulated microwave signal;

[0011] At the receiving end, the reference optical signal is split into two paths. The two polarization states of one reference optical signal are separated to generate two local oscillator optical signals. One sideband of the other reference optical signal is filtered out and then subjected to carrier-suppressed double-sideband modulation using the target echo signal to generate a target modulated optical signal. The target modulated optical signal is split into two paths and optically mixed with the two local oscillator optical signals. The resulting optical signals are then subjected to balanced photoelectric detection to obtain two de-skewed signals with frequencies of kτ and 2kτ, respectively, where τ is the delay between the target echo signal and the transmitted signal. Finally, the two de-skewed signals are processed to obtain target information.

[0012] Preferably, the signal processing is specifically as follows: performing sampling rate conversion processing on one of the de-skewed signals so that its frequency is the same as that of the other de-skewed signal; then performing phase correction on the two de-skewed signals with the same frequency; and finally reconstructing the de-skewed signal of the full frequency band through compressed sensing.

[0013] Preferably, the linear frequency modulated microwave signal is used to perform carrier suppressed double sideband modulation on an optical carrier, and the generated carrier suppressed double sideband modulated optical signal is polarization-coupled with another cognate optical carrier into an orthogonal polarization optical signal, which is achieved through a dual polarization intensity modulator.

[0014] Preferably, the optical mixing is achieved by two identical optical mixers, or by two identical 2×2 optical couplers.

[0015] Preferably, the target modulated optical signal is generated by an intensity modulator operating at a minimum bias point.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0017] 1. The present invention adopts a microwave driving signal to realize the generation of dual-band signals, which can effectively reduce the system cost and the system is simple and easy to operate.

[0018] 2. The present invention breaks through the limitations of traditional electronic technology on system bandwidth, and the generated radar signal equivalent bandwidth is greater than the bandwidth of the original microwave signal.

[0019] 3. The system of the present invention simultaneously generates two dual-band microwave signals with different chirp rates and can process them simultaneously, thereby improving the anti-interference capability of the radar.

[0020] 4. The radar in the present invention operates in two frequency bands. After receiving, the signals received in the two frequency bands can be separated, which expands the application of the radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structural principle of a specific embodiment of a dual-chirp-rate microwave-photon dual-band radar detection device of the present invention;

[0022] Figure 2 This is a schematic diagram of the structural principle of another specific embodiment of the dual-chirp-rate microwave photon dual-band radar detection device of the present invention;

[0023] Figure 3 Schematic diagram of the structural principle of the dual-polarization intensity modulator;

[0024] Figure 4 Schematic diagram of the spectrum of the output signal of the dual-polarization intensity modulator;

[0025] Figure 5 Schematic diagram of the time-frequency curve of the de-skew processing of the dual-band signal. DETAILED DESCRIPTION

[0026] Dual-chirp-rate microwave photon dual-band radar detection method,

[0027] At the transmitting end, a linear frequency modulated microwave signal is used to perform carrier suppressed double-sideband modulation on an optical carrier, and the generated carrier suppressed double-sideband modulated optical signal is polarization-coupled with another cognate optical carrier to form an orthogonal polarization optical signal. The carrier suppressed double-sideband modulated optical signal and the other cognate optical carrier are respectively in two orthogonal polarization states of the orthogonal polarization optical signal, and the phases of the optical carrier and the two sidebands in the orthogonal polarization optical signal satisfy the relationship: Δθ up -Δθ down ≠2nπ+π / 2, where Δθ up is the phase difference between the optical carrier and the upper sideband, Δθ downis the phase difference between the optical carrier and the lower sideband, and n is an integer; the orthogonally polarized optical signal is divided into two paths, one path is used as the reference optical signal at the receiving end, and the other path is converted into a linearly polarized optical signal by a polarization analyzer; the linearly polarized optical signal is photoelectrically converted to generate a dual-band radar signal with chirp rates k and 2k, which is simultaneously transmitted by the transmitting antenna, where k is the chirp rate of the linear frequency modulated microwave signal;

[0028] At the receiving end, the reference optical signal is split into two paths. The two polarization states of one reference optical signal are separated to generate two local oscillator optical signals. One sideband of the other reference optical signal is filtered out and then subjected to carrier-suppressed double-sideband modulation using the target echo signal to generate a target modulated optical signal. The target modulated optical signal is split into two paths and optically mixed with the two local oscillator optical signals. The resulting optical signals are then subjected to balanced photoelectric detection to obtain two de-skewed signals with frequencies of kτ and 2kτ, respectively, where τ is the delay between the target echo signal and the transmitted signal. Finally, the two de-skewed signals are processed to obtain target information.

[0029] Based on the same inventive concept, the following technical solutions can also be obtained:

[0030] A dual-chirp-rate microwave photon dual-band radar detection device comprises a transmitting end and a receiving end;

[0031] At the transmitting end, a linear frequency modulated microwave signal is used to perform carrier suppressed double-sideband modulation on an optical carrier, and the generated carrier suppressed double-sideband modulated optical signal is polarization-coupled with another cognate optical carrier to form an orthogonal polarization optical signal. The carrier suppressed double-sideband modulated optical signal and the other cognate optical carrier are respectively in two orthogonal polarization states of the orthogonal polarization optical signal, and the phases of the optical carrier and the two sidebands in the orthogonal polarization optical signal satisfy the relationship: Δθ up -Δθ down ≠2nπ+π / 2, where Δθ up is the phase difference between the optical carrier and the upper sideband, Δθ down is the phase difference between the optical carrier and the lower sideband, and n is an integer; the orthogonally polarized optical signal is divided into two paths, one path is used as the reference optical signal at the receiving end, and the other path is converted into a linearly polarized optical signal by a polarization analyzer; the linearly polarized optical signal is photoelectrically converted to generate a dual-band radar signal with chirp rates k and 2k, which is simultaneously transmitted by the transmitting antenna, where k is the chirp rate of the linear frequency modulated microwave signal;

[0032] At the receiving end, the reference optical signal is split into two paths. The two polarization states of one reference optical signal are separated to generate two local oscillator optical signals. One sideband of the other reference optical signal is filtered out and then subjected to carrier-suppressed double-sideband modulation using the target echo signal to generate a target modulated optical signal. The target modulated optical signal is split into two paths and optically mixed with the two local oscillator optical signals. The resulting optical signals are then subjected to balanced photoelectric detection to obtain two de-skewed signals with frequencies of kτ and 2kτ, respectively, where τ is the delay between the target echo signal and the transmitted signal. Finally, the two de-skewed signals are processed to obtain target information.

[0033] The signal processing can adopt various existing technologies. For example, the two de-skewed signals are processed separately using traditional methods to obtain target information, and then more accurate target information is obtained through information fusion. In order to more effectively utilize the two de-skewed signals with different frequencies to expand the de-skewed signal bandwidth, the signal processing is preferably as follows: sampling rate conversion is performed on one of the de-skewed signals to make its frequency the same as that of the other de-skewed signal; phase correction is then performed on the two de-skewed signals with the same frequency; and finally, compressed sensing is used to reconstruct the full-band de-skewed signal.

[0034] The generation of the orthogonal polarization optical signal can be achieved by combining multiple independent devices, such as using an intensity modulator, optical fiber and multiple optical couplers. However, the above method may seriously affect the phase noise of the generated signal and weaken the system reconfigurability. In addition, two intensity modulators and polarization rotators can also be used. In order to make the system structure more compact, more convenient to adjust, and have better system coherence, preferably, the linear frequency modulated microwave signal is used to perform carrier-suppressed double-sideband modulation on one optical carrier, and the generated carrier-suppressed double-sideband modulated optical signal is polarization-coupled with another cognate optical carrier to form an orthogonal polarization optical signal, which is achieved through a dual-polarization intensity modulator.

[0035] Preferably, the optical mixing is achieved by two identical optical mixers (either 90° or 180° optical mixers), or by two identical 2×2 optical couplers.

[0036] Preferably, the target modulated optical signal is generated by an intensity modulator operating at a minimum bias point.

[0037] To facilitate public understanding, the technical solution of the present invention is described in detail below through specific embodiments with reference to the accompanying drawings:

[0038] Figure 1The figure shows a specific implementation structure of the dual-chirp-rate microwave photon dual-band radar detection device of the present invention, which includes a transmitting end and a receiving end; the transmitting end includes a laser, a dual-polarization intensity modulator, an optical coupler, an analyzer, an optical filter, a photodetector, a transmitting antenna and an electrical signal generator. Figure 1 As shown, the optical carrier generated by the laser is divided into two paths; the electrical signal transmitter generates a linear frequency modulated microwave signal with a chirp rate of k, which modulates one optical carrier generated by the laser through a dual-polarization intensity modulator to generate a carrier-suppressed double-sideband modulated optical signal; the other optical carrier generated by the laser is also phase-controlled by the dual-polarization intensity modulator and then output, and is coupled into one path through a polarization rotator in the dual-polarization intensity modulator, thereby obtaining an orthogonally polarized optical signal containing the carrier optical signal and the carrier-suppressed double-sideband modulated optical signal. The carrier-suppressed double-sideband modulated optical signal and the optical carrier are respectively in two orthogonal polarization states of the orthogonal polarization optical signal; the orthogonal polarization optical signal is divided into two paths by an optical coupler, one of which serves as a reference optical signal at the receiving end, and the other is converted into a linearly polarized optical signal by a polarizer; the linearly polarized optical signal is beat in the photodetector to generate a dual-band radar signal with chirp rates of k and 2k, which is simultaneously transmitted by the transmitting antenna.

[0039] like Figure 1 As shown, the receiving end includes an optical filter, a receiving antenna, an intensity modulator, a polarization controller, a polarization beam splitter, an optical coupler, an optical mixer, a balanced photodetector, and a signal processing module; the reference optical signal is divided into two paths, one of which is filtered out of one sideband by the optical filter, and is modulated by the target echo signal in the intensity modulator to output the target modulated optical signal, which is divided into two paths by the optical coupler; the polarization controller is used to adjust the polarization state of the other reference optical signal so that one polarization direction of the reference optical signal is aligned with one of the main axes of the polarization beam splitter, and the polarization beam splitter is used to separate this reference optical signal into The system receives local oscillator (LO) optical signals in two polarization states. The LO optical signal and the target modulated optical signal are optically mixed through two identical optical mixers. The resulting four optical mixing signals are sent to a balanced photodetector for beat frequency, generating two de-skewed signals with frequencies of kτ and 2kτ, respectively. τ is the delay between the target echo signal and the transmitted signal, thereby achieving de-skewed reception of dual-band signals. The signal processing module performs sampling rate conversion on one of the de-skewed signals to make it have the same frequency as the other de-skewed signal. Phase correction is then performed on the two de-skewed signals with the same frequency. Finally, compressed sensing is used to reconstruct the full-band de-skewed signal.

[0040] Figure 2 The present invention shows a specific implementation structure of the dual-chirp rate microwave photon dual-band radar detection device. Figure 1 The structure is basically the same as that of FIG. 1 , except that two identical 2×2 optical couplers are used to implement the optical mixing.

[0041] In order to make the public better understand the technical solution and technical effects of the present invention, Figure 2 The structure shown further explains the principle of the present invention in detail:

[0042] Assume that the optical carrier generated by the laser is

[0043] E in (t) = E0exp(j2πf0t) (1)

[0044] Where E0 is the optical signal amplitude and f0 is the center frequency of the optical signal. The optical signal is coupled into the dual-polarization intensity modulator through the polarization controller.

[0045] Assume that the linear frequency modulated microwave signal generated by the electrical signal generator is

[0046] V(t)=V m cos(2πf RF t+πkt 2 ) (2)

[0047] Among them, V m is the amplitude of the signal, k is the chirp rate, f RF The microwave signal is input into one arm of the dual polarization intensity modulator to modulate the optical carrier generated by the laser. The structure and principle of the dual polarization intensity modulator are as follows: Figure 3 As shown, it includes two intensity modulators and a polarization rotator; the resulting carrier suppressed double sideband

[0048] The modulated optical signal can be expressed as

[0049] E X (t)∝exp(j2πf0t){exp[j(2πf RF t+πkt 2 )]+exp[-j(2πf RF t+πkt 2 )]} (3)

[0050] The other arm of the dual polarization intensity modulator does not apply a microwave driving signal. By controlling its bias voltage, the phase of the optical carrier is changed, introducing a phase The carrier optical signal generated in this polarization state can be expressed as:

[0051]

[0052] Thus, the dual polarization intensity modulator generates orthogonal polarization light signals, and the spectrum of its output signal is as follows: Figure 4The orthogonal polarization light signal is divided into two paths through an optical coupler. One path is used as the reference light signal of the receiver, and the other path is converted into a linearly polarized light signal using a polarization analyzer. The obtained signal can be expressed as:

[0053] E(t)∝E X (t)cosθ+E Y (t)sinθ (5)

[0054] Where θ is the analyzer angle. After photoelectric conversion is achieved in the photodetector, the radar transmission signal can be expressed as:

[0055]

[0056] Here, a and b are both related to the polarization analyzer's angle. By adjusting the polarization analyzer's angle and the phase of the carrier optical signal, we can obtain dual-band transmission signals with the same amplitude and chirp rates of k and 2k. It is reasonable to assume that the amplitudes of the two signals are equal.

[0057] At the receiving end, the reference optical signal is split into two paths, assuming there is no time delay difference between the two paths of reference optical signals transmitted to the balanced photodetector. One path of the local oscillator optical signal passes through the polarization controller, after which the polarization beam splitter separates the signals in the two polarization states. The other path passes through an optical filter to filter out any sidebands. The filtered reference optical signal can be set as:

[0058] e(t)∝exp(j2πf0t)exp[j(2πf RF t+πkt 2 )] (7) The target echo received by the receiving antenna is:

[0059] R(t)∝cos[2πf RF (t-τ)+πk(t-τ) 2 ]+cos[4πf RF (t-τ)+2πk(t-τ) 2 ] (8)

[0060] Where τ is the delay between the target echo and the radar transmission signal. The echo signal is applied to the receiver's intensity modulator to modulate the reference optical signal. The DC bias is adjusted to operate the modulator at the minimum bias point, achieving carrier-suppressed double-sideband modulation. The output modulated signal is:

[0061]

[0062] The signal is separated by an optical coupler and coupled with the local oscillator optical signals in the two polarization states through a 2×2 optical coupler. The output signal of the optical coupler is:

[0063]

[0064] Here, i represents the X polarization state and the Y polarization state.

[0065] Finally, the balanced photoelectric detector beat frequency is used to realize the de-slant reception of the dual-band radar echo signal.

[0066] The process can be expressed as:

[0067]

[0068] The two de-skewed signals obtained are:

[0069]

[0070] After fast Fourier transform, the peak frequencies in the obtained spectrum are kτ and 2kτ respectively; 2 The term is the residual video phase term and can be ignored in the fusion process.

[0071] The time-frequency curve of the dual-band signal de-skew processing is as follows Figure 5 As shown, B is the bandwidth of the linear frequency modulated microwave signal,

[0072] T p is the signal pulse width. The solid line in the higher frequency part of the figure is the time-frequency curve of the radar transmission signal, the dotted line is the time-frequency curve of the echo signal, and the dotted line in the low frequency part of the figure is the time-frequency relationship curve of the de-skewing signal, where f de1 and f de2 They correspond to the de-slant signal frequencies kτ and 2kτ of the two bands respectively.

[0073] In signal processing, frequency correction is first performed through sampling rate conversion to obtain the signal:

[0074]

[0075] Among them, γ is the phase-related parameter after the preprocessing is completed to correct the remaining video phase items. The above signals with the same frequency are time-shifted, and the time shift amount is After phase correction, the two de-skewed signals can be coherently fused. Finally, the full-band de-skewed signal is reconstructed using compressed sensing reconstruction theory.

[0076] The system achieves simultaneous generation and reception of dual-chirp-rate, dual-band signals. First, using dual-band signals for radar detection increases the radar's operating frequency range. Simultaneously, the radar transmits signals at different chirp rates, enhancing the system's anti-interference capabilities. Furthermore, the system can also achieve coherent fusion of dual-chirp-rate, dual-band radar signals, expanding the radar's equivalent operating bandwidth and significantly improving the range resolution of radar detection and imaging.

Claims

1. A dual-chirp-rate microwave photon dual-band radar detection method, characterized in that: At the transmitting end, a linear frequency modulated microwave signal is used to perform carrier suppressed double-sideband modulation on an optical carrier, and the generated carrier suppressed double-sideband modulated optical signal is polarization-coupled with another cognate optical carrier to form an orthogonal polarization optical signal. The carrier suppressed double-sideband modulated optical signal and the other cognate optical carrier are respectively in two orthogonal polarization states of the orthogonal polarization optical signal, and the phases of the optical carrier and the two sidebands in the orthogonal polarization optical signal satisfy the relationship: Δθ up -Δθ down ≠2nπ+π / 2, where Δθ up is the phase difference between the optical carrier and the upper sideband, Δθ down is the phase difference between the optical carrier and the lower sideband, and n is an integer; the orthogonally polarized optical signal is divided into two paths, one path is used as the reference optical signal at the receiving end, and the other path is converted into a linearly polarized optical signal by a polarization analyzer; the linearly polarized optical signal is photoelectrically converted to generate a dual-band radar signal with chirp rates k and 2k, which is simultaneously transmitted by the transmitting antenna, where k is the chirp rate of the linear frequency modulated microwave signal; At the receiving end, the reference optical signal is split into two paths. The two polarization states of one reference optical signal are separated to generate two local oscillator optical signals. One sideband of the other reference optical signal is filtered out and then subjected to carrier-suppressed double-sideband modulation using the target echo signal to generate a target modulated optical signal. The target modulated optical signal is split into two paths and optically mixed with the two local oscillator optical signals. The resulting optical signals are then subjected to balanced photoelectric detection to obtain two de-skewed signals with frequencies of kτ and 2kτ, respectively, where τ is the delay between the target echo signal and the transmitted signal. Finally, the two de-skewed signals are processed to obtain target information.

2. The dual-chirp-rate microwave-photon dual-band radar detection method according to claim 1, wherein: The signal processing is specifically as follows: performing sampling rate conversion on one of the de-skewed signals to make its frequency the same as that of the other de-skewed signal; then performing phase correction on the two de-skewed signals with the same frequency; and finally reconstructing the full-band de-skewed signal through compressed sensing.

3. The dual-chirp-rate microwave-photon dual-band radar detection method according to claim 1, wherein: The method uses a linear frequency modulated microwave signal to perform carrier suppressed double sideband modulation on an optical carrier, and polarization-couples the generated carrier suppressed double sideband modulated optical signal with another optical carrier of the same source into an orthogonal polarization optical signal, which is achieved through a dual polarization intensity modulator.

4. The dual-chirp-rate microwave-photon dual-band radar detection method according to claim 1, wherein: The optical mixing is achieved by two identical optical mixers, or by two identical 2×2 optical couplers.

5. The dual-chirp-rate microwave-photon dual-band radar detection method according to claim 1, wherein: The target modulated optical signal is generated by an intensity modulator operating at a minimum bias point.

6. A dual-chirp-rate microwave photon dual-band radar detection device, comprising a transmitting end and a receiving end; characterized in that: At the transmitting end, a linear frequency modulated microwave signal is used to perform carrier suppressed double-sideband modulation on an optical carrier, and the generated carrier suppressed double-sideband modulated optical signal is polarization-coupled with another cognate optical carrier to form an orthogonal polarization optical signal. The carrier suppressed double-sideband modulated optical signal and the other cognate optical carrier are respectively in two orthogonal polarization states of the orthogonal polarization optical signal, and the phases of the optical carrier and the two sidebands in the orthogonal polarization optical signal satisfy the relationship: Δθ up -Δθ down ≠2nπ+π / 2, where Δθ up is the phase difference between the optical carrier and the upper sideband, Δθ down is the phase difference between the optical carrier and the lower sideband, and n is an integer; the orthogonally polarized optical signal is divided into two paths, one path is used as the reference optical signal at the receiving end, and the other path is converted into a linearly polarized optical signal by a polarization analyzer; the linearly polarized optical signal is photoelectrically converted to generate a dual-band radar signal with chirp rates k and 2k, which is simultaneously transmitted by the transmitting antenna, where k is the chirp rate of the linear frequency modulated microwave signal; At the receiving end, the reference optical signal is split into two paths. The two polarization states of one reference optical signal are separated to generate two local oscillator optical signals. One sideband of the other reference optical signal is filtered out and then subjected to carrier-suppressed double-sideband modulation using the target echo signal to generate a target modulated optical signal. The target modulated optical signal is split into two paths and optically mixed with the two local oscillator optical signals. The resulting optical signals are then subjected to balanced photoelectric detection to obtain two de-skewed signals with frequencies of kτ and 2kτ, respectively, where τ is the delay between the target echo signal and the transmitted signal. Finally, the two de-skewed signals are processed to obtain target information.

7. The dual-chirp-rate microwave-photon dual-band radar detection device according to claim 6, characterized in that: The signal processing is specifically as follows: performing sampling rate conversion on one of the de-skewed signals to make its frequency the same as that of the other de-skewed signal; then performing phase correction on the two de-skewed signals with the same frequency; and finally reconstructing the full-band de-skewed signal through compressed sensing.

8. The dual-chirp-rate microwave-photon dual-band radar detection device according to claim 6, characterized in that: The method uses a linear frequency modulated microwave signal to perform carrier suppressed double sideband modulation on an optical carrier, and polarization-couples the generated carrier suppressed double sideband modulated optical signal with another optical carrier of the same source into an orthogonal polarization optical signal, which is achieved through a dual polarization intensity modulator.

9. The dual-chirp-rate microwave-photon dual-band radar detection device according to claim 6, characterized in that: The optical mixing is achieved by two identical optical mixers, or by two identical 2×2 optical couplers.

10. The dual-chirp-rate microwave-photon dual-band radar detection device according to claim 6, characterized in that: The target modulated optical signal is generated by an intensity modulator operating at a minimum bias point.

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