An inversion positioning method for micro-motion targets based on multi-channel detection

Abstract

The present invention discloses an inversion positioning method for micro-moving targets based on multi-channel detection, which belongs to the field of radar target detection technology and solves the technical problem that micro-moving targets cannot be detected and positioned in the prior art. The inversion positioning method includes: step 1, removing the carrier frequency of two sub-apertures and performing fast time matched filtering processing; step 2, compensating for the additional Doppler centroid deviation caused by the azimuth deviation of the dual-channel antenna; step 3, performing azimuth processing using azimuth reference function convolution to obtain imaging results; step 4, interpolating and aligning the two complex images to compensate for the phase error caused by the azimuth position deviation of the receiving aperture; step 5, obtaining the micro-moving target energy, and determining the target position based on the micro-moving target energy. The present invention can extract moving targets on SAR images and obtain motion parameter information of the moving targets.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar target detection, and in particular relates to an inversion positioning method for micro-motion targets based on multi-channel detection. Background Art

[0002] Traditional SAR is only suitable for detecting and imaging targets in static scenes. However, in actual reconnaissance areas, high-value targets often exhibit unusual motion, such as the vibration of bridges and aircraft wings; the rotation of tracked vehicle tracks, helicopter rotors, and radar antennas; and the pitch and roll of ships. These micro-movements also produce the Doppler effect, modulating the phase of the radar echo. This causes a time-varying Doppler modulation frequency and broadens the signal spectrum, manifesting as ghosting or defocusing at the locations of these targets in the SAR image. This type of motion distorts the phase history of the target echo, appearing as an out-of-focus signal in the SAR image. Consequently, existing detection methods are unable to detect and locate micro-moving targets. Summary of the Invention

[0003] In view of the above analysis, the present invention aims to provide an inversion positioning method for micro-motion targets based on multi-channel detection, so as to solve the problem that existing detection methods are unable to detect and locate micro-motion targets.

[0004] The purpose of the present invention is mainly achieved through the following technical solutions:

[0005] The present invention provides an inversion positioning method for a micro-motion target based on multi-channel detection, comprising the following steps:

[0006] Step 1: Remove the carrier frequency of the two sub-apertures and perform matched filtering in the fast time domain to obtain the echo signal;

[0007] Step 2: Compensate the echo signal for the additional Doppler centroid deviation caused by the azimuth deviation of the dual-channel antenna;

[0008] Step 3: Use the azimuth reference function to perform azimuth processing on the compensated echo signal convolution to obtain multiple imaging results;

[0009] Step 4: interpolate and register any two of the imaging results to obtain compensated imaging results to compensate for the phase error caused by the azimuth position deviation of the receiving aperture;

[0010] Step 5: Based on the compensated imaging result, obtain the micro-motion target energy, and determine the target position based on the micro-motion target energy.

[0011] Furthermore, in step 1, antenna No. 2 transmits, and the echo signal is received by antenna No. 1 and antenna No. 2 at the same time. The radar coordinate system (X, Y, Z) is established with antenna No. 2 as the origin. The origin is always fixed at the phase center of antenna No. 2. The SAR carrier moves along the positive direction of the X axis at a speed of V a flight;

[0012] Assume that the position of the target P in the radar coordinate system is (x0, y0, -h), and the flight speed of the SAR platform is (V a ,0,0), the phase center position of antenna No. 1 is (0,0,D a );

[0013] After removing the carrier frequency of the two sub-apertures and performing fast time matched filtering, the echo signal obtained is:

[0014]

[0015]

[0016] in, They represent the Doppler center frequency and modulation rate of the uniform rotation passive micro-interference echo received by the middle aperture respectively; λ is the wavelength of the radar transmission signal; j is an imaginary number; k is the signal modulation rate; R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; is the initial phase; t a For slow time; D a is the phase center distance between the two antennas of the dual-channel SAR system; B is the signal bandwidth; T p is the signal pulse width; c is the speed of light; t r Fast time; t a For J m (2kr) is the first kind of m-order Bessel function, where m is the order; θ(t a ) is the transformation angle.

[0017] Furthermore, in step 2, the echo signal is compensated for the additional Doppler centroid deviation caused by the azimuth deviation of the dual-channel antenna. The compensation function is:

[0018]

[0019] Where, j is an imaginary number; k is the signal modulation frequency; R0 is the distance from the radar to the target; t a D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X-axis.

[0020] Furthermore, in step 2, the compensation function C1(ta ) directly multiplied by J in step 1 p1 To compensate, J p2 The echo signal after compensation is unchanged:

[0021]

[0022]

[0023] in, represent the Doppler center frequency and modulation frequency of the uniform rotation passive micro-interference echo received by the middle aperture respectively; θ(t a ) is the transformation angle, λ is the wavelength of the radar transmission signal; j is an imaginary number; k is the signal modulation frequency; R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; is the initial phase D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X axis; B is the signal bandwidth; Tp is the signal pulse width; c is the speed of light; t r Fast time; t a is the slow time, Jm(2kr) is the first kind m-order Bessel function, and m is the order.

[0024] Furthermore, in step 3, the azimuth reference function is used Respectively with J p1 and J p2 Perform convolution processing and obtain the imaging result after convolution processing:

[0025]

[0026]

[0027] Among them, A3(t r ,t a ) is an additional modulation term; θ(t a ) is the transformation angle; λ is the wavelength of the radar transmission signal; j is an imaginary number; k is the signal modulation frequency; R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; is the initial phase; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X axis; B is the signal bandwidth; Tp is the signal pulse width; c is the speed of light; t r Fast time; t a For slow time, J m(2kr) is the first kind of m-order Bessel function, where m is the order; B d is the Doppler bandwidth of the echo signal.

[0028] Furthermore, in step 4, the compensation function C is used 12 (t a ) interpolates and registers the two complex images to compensate for the phase error caused by the position deviation of the receiving aperture. The compensation function C 12 (t a )for:

[0029]

[0030] Where j is the imaginary unit, k is the signal modulation frequency; R0 is the distance from the radar to the target; t a For slow time; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X-axis.

[0031] Furthermore, in step 5, the phases of the two images are extracted, and the interference phase is detected by setting a certain threshold phase to cancel the stationary target, and then the cancellation result is modulo-measured to obtain the energy of the slightly moving target.

[0032] Furthermore, in step 5, the stationary target is cancelled, and the result after cancellation is:

[0033]

[0034] Where j is the imaginary unit; k is the signal modulation frequency; R0 is the distance from the radar to the target; t a For slow time; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X-axis.

[0035] Furthermore, in step 5, the cancellation result is modulo-valued to obtain the micro-motion target energy:

[0036]

[0037] Among them, A3(t r ,t a ) is the additional modulation term; λ is the wavelength of the radar transmission signal; k is the signal modulation frequency; R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; D a is the phase center distance between the two antennas of the dual-channel SAR system; V ais the flight speed of the SAR carrier along the positive direction of the X axis; B is the signal bandwidth; c is the speed of light; t r Fast time; t a For slow time, J m (2kr) is the first kind of m-order Bessel function, where m is the order; B d is the Doppler bandwidth of the echo signal.

[0038] Furthermore, in step 5, after obtaining the energy of the micro-motion target, the maximum value of the slow-time micro-motion target energy is calculated, and the position of the maximum value is the position of the micro-motion target in the SAR image.

[0039] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0040] This method utilizes the variations in Doppler frequencies of echoes from different antennas to offset stationary targets and extract moving targets. The method also utilizes the relationship between the phase difference between two SAR images, the interferometric SAR system parameters, and the target motion parameters to derive target motion parameter information. The method is simple and highly operational, combining SAR's high-resolution imaging of ground targets with the detection of micro-moving targets. In subsequent engineering applications and practical applications, it can detect, locate, and track high-value targets, providing valuable information for on-site situation assessment, command, and control, and possessing significant significance for reconnaissance and on-site awareness.

[0041] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages will become apparent from the description or be understood through practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the embodiments of the description and the contents particularly pointed out in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0043] Figure 1 Schematic diagram of the process of the inversion positioning method of the present invention;

[0044] Figure 2 is a schematic diagram of a dual-channel SAR system of the present invention;

[0045] Figure 3 This is a schematic diagram of the imaging results of a ship and a micro-moving target according to the present invention;

[0046] Figure 4 Schematic diagram of the micro-motion target interference detection result of the present invention;

[0047] Figure 5 Schematic diagram of the repositioning result of the micro-movement target of the present invention. DETAILED DESCRIPTION

[0048] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0049] The present invention provides an inversion positioning method for a micro-motion target based on multi-channel detection, comprising the following steps:

[0050] Step 1: Remove the carrier frequency of the two sub-apertures and perform matched filtering in the fast time domain to obtain the echo signal;

[0051] Step 2: Compensate the echo signal for the additional Doppler centroid deviation caused by the azimuth deviation of the dual-channel antenna;

[0052] Step 3: Use the azimuth reference function to perform azimuth processing on the compensated echo signal convolution to obtain multiple imaging results;

[0053] Step 4: interpolate and register any two of the imaging results to obtain compensated imaging results to compensate for the phase error caused by the azimuth position deviation of the receiving aperture;

[0054] Step 5: Based on the obtained compensated imaging result, obtain the micro-motion target energy, and determine the target position based on the micro-motion target energy.

[0055] like Figure 1 As shown, the present invention first performs SAR imaging on the two echo signals respectively; then interpolates and aligns the two images; then extracts the phase of the two imaging results; by setting a certain threshold phase, the interference phase is detected, and if the interference phase exceeds the threshold phase, it is determined that the target exists.

[0056] In step 1 above, if Figure 2 As shown, R0 is the distance from the radar to the target, the target rotation radius is r, r<<R o , the speed is ω, the initial phase is t a For slow time, D a is the phase center distance between the two antennas of the dual-channel SAR system. Antenna No. 2 transmits, and the echo signal is received by antenna No. 1 and antenna No. 2 at the same time. The radar coordinate system (X, Y, Z) is established with antenna No. 2 as the origin. The origin is always fixed on the phase center of antenna No. 2. The SAR carrier moves along the positive direction of the X axis at a speed of V a flight;

[0057] Assume that the position of the target P in the radar coordinate system is (x0, y0, -h), and the flight speed of the SAR platform is (V a ,0,0), the phase center position of antenna No. 1 is (0,0,D a ); The two sub-apertures are orthogonally demodulated to remove the carrier frequency, and matched filtering is performed in the fast time domain through a matched filter, and the obtained echo signal is:

[0058]

[0059]

[0060] in, represent the Doppler center frequency and modulation frequency of the uniform rotation passive micro-interference echo received by the middle aperture respectively; θ(t a ) is the transformation angle, λ is the wavelength of the radar transmission signal; j is an imaginary number; k is the signal modulation frequency; B is the signal bandwidth; Tp is the signal pulse width; c is the speed of light; t r For fast time, t a For slow time, J m (2kr) is the m-th order Bessel function of the first kind, where m is the order.

[0061] In step 2 above, due to the azimuth deviation between the dual-channel antennas, additional Doppler centroid deviation is caused, so compensation is required. The compensation function is as follows:

[0062]

[0063] Where, j is an imaginary number; k is the signal modulation frequency; R0 is the distance from the radar to the target; t a For slow time; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X-axis.

[0064] Using the compensation function C1(t a ) is directly multiplied by Jp1 in the previous step for compensation, and Jp2 remains unchanged. The specific compensation process is:

[0065]

[0066] That is, the echo signal of antenna 1 after compensation is:

[0067]

[0068]

[0069] in, represent the Doppler center frequency and modulation frequency of the uniform rotation passive micro-interference echo received by the middle aperture respectively; θ(t a ) is the transformation angle, λ is the wavelength of the radar transmission signal; j is an imaginary number; k is the signal modulation frequency; R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; is the initial phase; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X axis; B is the signal bandwidth; Tp is the signal pulse width; c is the speed of light; t r For fast time, t a is the slow time, m is a constant, J m is the Jacobian matrix.

[0070] In step 3 above, the azimuth reference function is:

[0071]

[0072] Using the above azimuth phase reference function and J p1 and J p2 Perform convolution processing to obtain imaging results

[0073]

[0074]

[0075] Among them, A3(t r ,t a ) is an additional modulation term, which reflects the effect of the additional phase term on the expansion and blurring of the image, but does not affect the peak position of the interference; θ(t a ) is the transformation angle; λ is the wavelength of the radar transmission signal; j is an imaginary number; k is the signal modulation frequency; R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; is the initial phase; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X axis; B is the signal bandwidth; c is the speed of light; t r Fast time; t a For slow time, J m (2kr) is the first kind of m-order Bessel function, where m is the order; B d is the Doppler bandwidth of the echo signal.

[0076] In step 4 above, the two complex images are interpolated and registered using the following compensation function to compensate for the phase error caused by the azimuth position deviation of the receiving aperture.

[0077] Specifically, after imaging processing, since the receiving aperture has an azimuth position deviation, it is necessary to compensate for the phase error caused by this position deviation before performing ground clutter cancellation.

[0078] The compensation function is shown below:

[0079]

[0080] Using the compensation function C 12 (t a ) multiplied by I P1 , the result is approximately equal to I P2 The specific calculation process is as follows:

[0081]

[0082]

[0083] I p1 (t r ,t a )*C 12 (t a )≈I p2 (t r ,t a )

[0084] It should be noted that in the above calculation process, x0=V a *t a .

[0085] Where, The term actually corresponds to the compensation function Compensation function C1(t a ) is because the time domain linear term corresponds to the frequency domain shift, so compensation is performed to align the center. However, the image obtained after imaging is a dual time domain image. Therefore, the phase before compensation corresponds to the phase error caused by the antenna aperture, which can be seen to be independent of the starting position x0 of the target point; where j is the imaginary unit, k is the signal modulation frequency; R0 is the distance from the radar to the target; t a For slow time; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X-axis.

[0086] In step 5 above, the phases of the two images are extracted, and the interference phase is detected by setting a certain threshold phase to cancel the stationary target. That is, the two images are subtracted and canceled, and then the cancellation result is modulo (see the following formula) to obtain the energy of the slightly moving target;

[0087]

[0088] Take the modulus value of the cancellation result to obtain the micro-motion target energy:

[0089]

[0090] Among them, A3(t r ,t a ) is the additional modulation term; λ is the wavelength of the radar transmission signal; k is the signal modulation frequency; R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X axis; B is the signal bandwidth; c is the speed of light; t r Fast time; t a For slow time, J m (2kr) is the first kind of m-order Bessel function, where m is the order; B d is the Doppler bandwidth of the echo signal.

[0091] After obtaining the energy of the micro-motion target, the maximum value of the micro-motion target energy is calculated, and the position of the maximum value is the position of the micro-motion target in the SAR image.

[0092] In one embodiment, through digital simulation, a ship is selected as an imaging target, wherein the ship warning radar has micro-motion target characteristics, and the simulation parameters used are shown in Table 1.

[0093] Table 1 Simulation parameters of micro-motion target

[0094]

[0095] According to the above simulation parameters, the ship target imaging results are as follows: Figure 3 As shown in Figure 2, we can see that the ship target can be well imaged and the outline of the ship is clear. At the same time, during the accumulation time, the radar rotation causes obvious Doppler stripes, such as Figure 3 As shown in the white circle.

[0096] The method provided by the present invention is used to perform dual-channel image interference cancellation, and to detect micro-movement targets based on the detection threshold, and to extract micro-movement target results such as Figure 4 According to the relationship between the dual-channel interferometric phase and the rotation parameters, the relocation of the rotating radar target is realized, and the results are shown in Figure 5 As shown in the figure, when the SNR is better than 15dB, the corresponding target positioning accuracy can reach 1 / 15 of the beam width, and is better than 0.5° when the beam width is less than 7°.

[0097] In summary, the method of the present invention can utilize the changes in the Doppler frequency of echoes from different antennas to offset stationary targets and extract moving targets. Target motion parameter information is derived by utilizing the relationship between the phase difference between two SAR images, the interferometric SAR system parameters, and the target motion parameters. The method of the present invention is simple and highly operational, combining SAR's high-resolution imaging of ground targets with its micro-motion target detection capabilities. In subsequent engineering transformation and practical applications, it can detect, locate, and track high-value targets, providing useful information for on-site situation assessment, command, and control, and is of great significance for reconnaissance and on-site perception.

[0098] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for inversion positioning of micro-motion targets based on multi-channel detection, characterized in that: The steps include: Step 1: Remove the carrier frequency of the two sub-apertures and perform matched filtering in the fast time domain to obtain the echo signal; In step 1, antenna No. 2 transmits, and the echo signal is received by antenna No. 1 and antenna No. 2 at the same time. The radar coordinate system (X, Y, Z) is established with antenna No. 2 as the origin. The origin is always fixed on the phase center of antenna No.

2. The SAR carrier moves along the positive direction of the X axis at a speed of V a flight; Assume that the position of the target P in the radar coordinate system is (x0, y0, -h), and the flight speed of the SAR platform is (V a ,0,0), the phase center position of antenna No. 1 is (0,0,D a ); The two sub-apertures are de-carriered and processed by fast time matched filtering, and the resulting echo signal is: in, They represent the Doppler center frequency and modulation frequency of the uniform rotation passive micro-interference echo received by the middle aperture respectively; λ is the wavelength of the radar transmission signal; j is an imaginary number; k is the signal modulation frequency; θ(t a ) is the transformation angle, R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; is the initial phase; t a For slow time; D a is the phase center distance between the two antennas of the dual-channel SAR system; B is the signal bandwidth; Tp is the signal pulse width; c is the speed of light; t r For fast time; J m (2kr) is the first kind m-order Bessel function, where m is the order; Step 2: Compensate the echo signal for the additional Doppler centroid deviation caused by the azimuth deviation of the dual-channel antenna; Step 3: Use the azimuth reference function to perform azimuth processing on the compensated echo signal convolution to obtain multiple imaging results; Step 4: interpolate and register any two of the imaging results to obtain compensated imaging results to compensate for the phase error caused by the azimuth position deviation of the receiving aperture; Step 5: Based on the obtained compensated imaging result, obtain the micro-motion target energy, and determine the target position based on the micro-motion target energy.

2. The inversion positioning method for micro-motion targets based on multi-channel detection according to claim 1 is characterized in that: In step 2, the echo signal is compensated for the additional Doppler centroid deviation caused by the azimuth deviation of the dual-channel antenna, and the compensation function is: Where, j is an imaginary number; k is the signal modulation frequency; R0 is the distance from the radar to the target; t a For slow time; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X-axis.

3. The inversion positioning method for micro-motion targets based on multi-channel detection according to claim 2 is characterized in that: In step 2, the compensation function C1(t a ) directly multiplied by J in step 1 p1 To compensate, J p2 The echo signal after compensation is unchanged: in, represent the Doppler center frequency and modulation frequency of the uniform rotation passive micro-interference echo received by the middle aperture respectively; θ(t a ) is the transformation angle, λ is the wavelength of the radar transmission signal; j is an imaginary number; k is the signal modulation frequency; R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; is the initial phase; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X axis; B is the signal bandwidth; T p is the signal pulse width; c is the speed of light; t r Fast time; t a For slow time, J m (2kr) is the m-th order Bessel function of the first kind, where m is the order.

4. The inversion positioning method for micro-motion targets based on multi-channel detection according to claim 3 is characterized in that: In step 3, the azimuth reference function is used Respectively with J p1 and J p2 Perform convolution processing and obtain the imaging result after convolution processing: Among them, A3(t r ,t a ) is an additional modulation term; θ(t a ) is the transformation angle; λ is the wavelength of the radar transmission signal; j is an imaginary number; k is the signal modulation frequency; R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; is the initial phase; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X axis; B is the signal bandwidth; c is the speed of light; t r Fast time; t a For slow time, J m (2kr) is the first kind of m-order Bessel function, where m is the order; B d is the Doppler bandwidth of the echo signal.

5. The inversion positioning method for micro-motion targets based on multi-channel detection according to claim 4 is characterized in that: In step 4, the compensation function C is used 12 (t a ) interpolates and registers the two complex images to compensate for the phase error caused by the position deviation of the receiving aperture. The compensation function C 12 (t a )for: Where j is the imaginary unit, k is the signal modulation frequency; R0 is the distance from the radar to the target; t a For slow time; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X-axis.

6. The inversion positioning method for micro-motion targets based on multi-channel detection according to claim 5 is characterized in that: In step 5, the phases of the two images are extracted, and the interference phase is detected by setting a certain threshold phase to cancel the stationary target. Then, the cancellation result is modulo-measured to obtain the energy of the slightly moving target.

7. The inversion positioning method for micro-motion targets based on multi-channel detection according to claim 6 is characterized in that: In step 5, the stationary target is cancelled, and the result after cancellation is: Where j is the imaginary unit; k is the signal modulation frequency; R0 is the distance from the radar to the target; t a For slow time; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X-axis.

8. The inversion positioning method for micro-motion targets based on multi-channel detection according to claim 7 is characterized in that: In step 5, the cancellation result is modulo-valued to obtain the micro-motion target energy: Among them, A3(t r ,t a ) is the additional modulation term; λ is the wavelength of the radar transmission signal; k is the signal modulation frequency; R0 is the distance from the radar to the target; r is the target rotation radius; r<<R o ;ω is the rotation speed; D a is the phase center distance between the two antennas of the dual-channel SAR system; V a is the flight speed of the SAR carrier along the positive direction of the X axis; B is the signal bandwidth; c is the speed of light; t r Fast time; t a For slow time, J m (2kr) is the first kind of m-order Bessel function, where m is the order; B d is the Doppler bandwidth of the echo signal.

9. The inversion positioning method for micro-motion targets based on multi-channel detection according to claim 8, characterized in that: In step 5, after obtaining the slightly moving target energy, the maximum value of the slightly moving target energy is obtained, and the position of the maximum value is the position of the slightly moving target in the SAR image.

Images