Pulse Doppler short-range radar signal processing simulation method based on multi-scattering-point model

Abstract

The invention belongs to the technical field of short-range radar signal processing, and provides a pulse Doppler short-range radar signal processing simulation method based on a multi-scattering-point model. The working process of a pulse Doppler system short-range radar is simulated on the basis of the short-range body target local irradiation radar detection condition, and a body target scattering source model capable of generating echoes is approximately constructed by using a multi-scattering-point structure; partial rigid body target reflection point echoes irradiated by the transmitted signal are calculated, and echo signals in the same range gate range are superposed to form a total echo signal of a body target; carrying out demodulation filtering processing on the echo signal containing noise, and then carrying out target detection by using frequency domain constant false alarm detection and time domain threshold detection so as to obtain target starting point information; according to the technical scheme provided by the invention, the influence of target surface details on the effective echo signal amplitude can be ensured, and meanwhile, the calculation efficiency of short-range radar signal simulation and target starting point information is considered.

Description

Technical Field

[0001] The invention belongs to the technical field of short-range radar signal processing, and in particular relates to a pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model. Background Art

[0002] Millimeter-wave short-range radar detectors are detectors that use electromagnetic waves with a wavelength between 1-10mm. They belong to the radar system in the shortwave (high frequency) frequency band. They have good short-range characteristics and are suitable for detecting short-range targets.

[0003] In the short-range detection environment, the working distance between the detector and the target can be compared with the geometric size of the target itself. At this time, when calculating the target echo, the reflecting target cannot be regarded as a point target like the long-range radar, but the reflecting target must be processed as a volume target. In the process of echo signal processing of the radar detector based on volume targets, it is usually necessary to divide the surface of the three-dimensional volume target into multiple two-dimensional facets and then calculate the target echo separately. Finally, the echo contribution of each area is combined to obtain the total echo signal of the three-dimensional volume target.

[0004] The size of each facet should be small enough to capture the details of the target surface, but the subsequent computational complexity and storage space requirements should also be considered when dividing the facets. Smaller facet sizes mean that more area units are required to cover the entire target surface, which significantly increases the computational complexity of the target echo signal calculation, thereby affecting the computational efficiency of the millimeter-wave short-range radar detector start-point simulation calculation.

[0005] In view of the above problems, it is necessary to consider simplifying the large number of grids of the body target in the illumination area of ​​the side-view short-range target detector into several scattering points, constructing a multi-scattering point model of the body target, improving the computational efficiency of the short-range detector starting point simulation while retaining the influence of the surface details of the body target on the echo signal amplitude, and ensuring the accuracy of the starting point simulation. Summary of the invention

[0006] The present invention aims to solve the problem raised in the background technology and proposes a pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model.

[0007] In order to achieve the purpose of the present invention, the present invention discloses a pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model, comprising the following steps:

[0008] Step S1, importing the target model, defining the simulated short-range detector transmission signal characteristic parameters, the detector and target intersection parameters and the pulse Doppler signal model, and recording the detector and target intersection parameters and the transmission signal carrier frequency into a multi-scattering point data file;

[0009] Step S2, simulating the radar transmission signal according to the pulse Doppler short-range radar transmission signal simulation model;

[0010] Step S3, setting the number of scattering points, at each moment, constructing a multi-scattering point model of the target according to the position information of each facet of the imported target model, and recording the position vector of each scattering point;

[0011] Step S4, accumulating the RCS values ​​of each facet that generates the same scattering point at each moment to obtain the total RCS value of the scattering point, and recording the characteristic data of each scattering point at each moment when the intersection condition between the detector and the target remains unchanged in the multi-scattering point data file;

[0012] Step S5, retaining the simulated radar signal characteristic parameters and the missile-target intersection parameters, resetting various types of simulation gain parameters, transmission pulse width, transceiver interval, pulse Doppler signal processing model and various signal processing model parameters, and reading the multi-scattering point data file generated in the above steps;

[0013] Step S6: The echo signal received by the receiver is often accompanied by interference, and suppression interference is used to implement interference signal simulation;

[0014] Step S7, under the new gain condition and signal processing model, the echo signal simulation mathematical model calculates the echo signal values ​​contributed by different scattering points at each moment, adds interference to the echo values ​​at each moment, and accumulates the effective echo contributions of each scattering point within the range gate to complete the echo signal simulation of the volume target;

[0015] Step S8, mixing the effective echo signal with the local oscillator signal, and obtaining a Doppler signal carrying target information after filtering;

[0016] Step S9, perform time domain threshold detection and frequency domain constant false alarm detection on the Doppler signal. If the target is detected in both the time domain and the frequency domain, start the short-range target detector and calculate the starting point information of the target location. Otherwise, enter the next moment and start from step S7 to execute the calculation of the simulation steps in sequence.

[0017] Further, in step S1 or S5, the simulated short-range radar signal characteristic parameters include: RF pulse amplitude, transmission signal carrier frequency, transmission signal power, transmission signal beam inclination, beam width, beam effective range, pulse repetition period, transmit-receive interval, random pulse position modulation duty cycle, pseudo code symbol width, pseudo code sequence length, transmission pulse width and reception pulse width; the detector and target intersection parameters include: simulated target speed, detector speed, target offset relative to the detector center, target offset azimuth, start time to the detector plane, stop time through the detector plane and attitude angle of the short-range radar detector and the target; the pulse Doppler signal model includes: equal-width and equal-period pulse Doppler signal model, random pulse position pulse Doppler signal model and pseudo code phase modulation pulse Doppler signal model.

[0018] Further, in step S2, the simulation mathematical model of the equal-width and equal-period pulse Doppler short-range radar transmission signal is:

[0019]

[0020] The mathematical model for the simulation of the random pulse Doppler short-range radar transmission signal is:

[0021]

[0022] The mathematical model for simulating the transmission signal of pseudo-code phase-modulated pulse Doppler short-range radar is:

[0023]

[0024] Where A is the RF pulse amplitude; ω0 is the carrier frequency of the transmitted signal; The width is τ M pulse; t is time; δ(t) is the Dirichlet function; T M is the pulse repetition period; N is the number of pulses; N i is a random variable uniformly distributed in [0, T0]; define T0 / T M is the random pulse position modulation duty cycle, usually 0.3-0.6; M(t)=±1 is the bipolar code corresponding to the M sequence.

[0025] Furthermore, in step S3, the position vector of each scattering source in the scattering point model is obtained by clustering the centroid position vector of the surface element model according to the distance;

[0026] In step S4, the characteristic data of each scattering point includes: RCS of each scattering point, slant distance of each scattering point, approach speed of each scattering point and detector, coordinates of each scattering point and the farthest distance between the target irradiated unit and the short-range detector;

[0027] In step S5, the simulation gain parameters include: antenna system input impedance, antenna gain, transmission power peak, system loss coefficient, range gate selection loss, Doppler gain and video gain; the signal processing model parameters include: receiving pulse width, random pulse position modulation duty cycle, pseudo code symbol width and pseudo code sequence length.

[0028] Further, in step S6, the mathematical model of the suppressed noise amplitude modulation interference signal simulation is:

[0029] J(t)=(U j +u n (t))cos(ω0t)

[0030] Where ω0 is the center frequency of the noise amplitude modulation signal, which is equal to the carrier frequency of the transmitted signal; U j Indicates the interference signal amplitude, u n (t) is the variance Noise with mean 0, t is time;

[0031] In step S7, the mathematical model of the echo signal simulation is:

[0032]

[0033] Where ω0 is the carrier frequency of the transmitted signal; The width is τ M pulse; t is time; δ(t) is the Dirichlet function; T M is the pulse repetition period; N is the number of pulses; τ i is the delay of the echo signal of the i-th scattering point relative to the transmitted signal; ω di It is the Doppler angular frequency generated by the motion of the target scattering point relative to the short-range detector.

[0034] Furthermore, the Doppler angular frequency generated by the motion of the target scattering point relative to the short-range detector is:

[0035]

[0036] Where V ri is the relative motion speed between the scattering point i and the detector; is the angle between the scattering point i and the detector line of sight and the relative velocity vector between the two; λ is the beam wavelength, Among them, F t is the carrier frequency of the transmitted signal;

[0037] Parameter k in the mathematical model of echo signal simulation i is a coefficient including the scattering point RCS, the transmitted signal power, and the radar distance factor. Its relationship with the power at the entrance of the receiving antenna is:

[0038]

[0039] In the formula, G t is the antenna gain; λ is the beam wavelength; r i is the scattering point slant distance of scattering point i; P t is the transmitted signal power; R is the input impedance of the antenna system; is the radar cross section of scattering point i.

[0040] Further, in step S7, the effective echo contribution of each scattering point within the range gate is accumulated, including the following steps:

[0041] S71, calculating the effective time range of the range gate as [t1, t2] based on the current simulation pulse sequence number, pulse repetition period, receiving pulse width, transmitting pulse width and receiving and transmitting interval;

[0042] S72, obtain within the effective time range of the range gate with step length t0 sampling points;

[0043] S73, calculate the delay of the echo signal of the scattering point relative to the transmission signal according to the relative distance Ri_abs between the scattering point i and the short-range detector Where C is the speed of light 3×10 8 m / s;

[0044] S74, traverse the sampling points within the effective time range of the range gate, and the time corresponding to the sampling point sequence number Num is times=Num×t0;

[0045] S75. If times is within the time range [t3, t4] of the echo signal generated by the scattering point i, it is considered that the target echo generated by the scattering point i is within the range of the range gate, and the echo contribution is valid. The echo contribution value of the scattering point is calculated according to the echo signal simulation mathematical model;

[0046] S76, accumulating the echo contribution values ​​of the scattering points that generate effective echoes to obtain the total echo simulation signal of each sampling point.

[0047] Further, in step S71, the time lower limit t1 of the effective time range of the range gate is:

[0048] t1=NT M +Tri

[0049] Where N is the simulation pulse number; T M is the pulse repetition period; Tri is the transmit / receive interval; the lower limit t2 is:

[0050] t2=t1+taot

[0051] Wherein, taot is the receiving pulse width.

[0052] In step S75, the lower limit t3 of the time range of the echo signal generated by the scattering point i is:

[0053] t3=NT M +delay_time

[0054] The lower time limit t4 is:

[0055] t4=NT M +tao0+delay_timei

[0056] Where, N is the simulation pulse number; T M is the pulse repetition period; tao0 is the transmit pulse width; delay_timei is the delay of the echo signal of scattering point i relative to the transmit signal.

[0057] Furthermore, in step S8, the filtering process is implemented by a second-order low-pass filter, and its mathematical model is:

[0058]

[0059] Where x0(t) is the filter output value at the current moment; x i (t) is the echo signal value of the input filter at the current moment; t0 is the signal sampling step; f c is the cut-off frequency; γ is the damping ratio, and the best effect is achieved when the value is 0.707.

[0060] Further, in step S9, the specific process of time domain threshold detection is: setting the time domain threshold K and the number of pulse detection N1, if there are N1 consecutive sample values ​​in the Doppler signal output by the filter exceeding the threshold K, it is considered that the target is detected in the time domain;

[0061] In step S9, the specific process of frequency domain constant false alarm detection is: set the false alarm probability and the number of consecutive threshold points in the frequency domain N2, take 64 sample points forward from the current moment as the starting point, perform Fourier transform on these 64 data to obtain the frequency domain amplitude-frequency response waveform of the data in the sliding window, perform unit average constant false alarm detection based on the amplitude-frequency response waveform at the current moment, and if N2 consecutive sliding windows detect the presence of the target, it is considered that the frequency domain detects the presence of the target.

[0062] Compared with the prior art, the significant progress of the present invention is as follows: 1) in view of the low computational efficiency and large number of related parameters of the millimeter-wave short-range radar detector when simulating the starting point of a body target, a multi-scattering point target model is constructed to describe the scattering source position of the body target, and on the basis of preserving the intersection parameters of the short-range detector and the target, some parameters are allowed to be changed to realize the rapid calculation of the starting point simulation of the body target under different gain and model conditions; 2) in the application method of the range gate in the simulation process of the effective echo of the body target, a method of first dividing the range gate and then calculating the echo signal value of each sampling point in the range gate is adopted, which improves the simulation efficiency of the effective echo signal compared with the method of first realizing the body target echo calculation and then determining the effective echo samples in the range gate; 3) in view of the characteristics of discrete storage of each waveform data in the simulation process, a second-order difference equation is adopted to realize the filter function, which reduces the filter's requirement on the number of input data and overcomes the difficulty of having no accurate mathematical model to describe its Doppler signal after filtering the echo signal after adding interference.

[0063] In order to more clearly illustrate the functional characteristics and structural parameters of the present invention, further description is given below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0065] Figure 1 The present invention is a flow chart of a pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model. DETAILED DESCRIPTION

[0066] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0067] like Figure 1 As shown, a pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model includes the following steps:

[0068] S1. Import the target model, define the simulated radar detector signal characteristic parameters, the detector and target intersection parameters and the pulse Doppler signal model, and record the detector and target intersection parameters and the transmission signal carrier frequency into the multi-scattering point data file;

[0069] S2. simulating radar transmission signals according to a pulse Doppler short-range radar detector transmission signal simulation model;

[0070] S3, setting the number of scattering points, at each moment, constructing a multi-scattering point model of the target according to the position information of each facet of the imported target model, and recording the position vector of each scattering point;

[0071] S4, accumulating the RCS values ​​of each facet generating the same scattering point at each moment to obtain the total RCS value of the scattering point, and recording the characteristic data of each scattering point at each moment when the intersection condition between the short-range radar and the target remains unchanged in the multi-scattering point data file;

[0072] S5, retaining the simulated radar signal characteristic parameters and the detector and target intersection parameters, resetting various types of simulation gain parameters, transmission pulse width, transmit-receive interval, pulse Doppler signal processing model and various signal processing model parameters, and reading the multi-scattering point data file generated in the above steps;

[0073] S6. The echo signal received by the receiver is often accompanied by interference. Taking suppression interference as an example, interference signal simulation is realized;

[0074] S7. Under the new gain condition and signal processing model, the echo signal simulation mathematical model calculates the echo signal values ​​contributed by different scattering points at each moment, adds interference to the echo values ​​at each moment, and accumulates the effective echo contributions of each scattering point within the range gate to complete the echo signal simulation of the volume target;

[0075] S8, mixing the effective echo signal with the local oscillator signal, and obtaining a Doppler signal carrying target information after filtering;

[0076] S9, perform time domain threshold detection and frequency domain constant false alarm detection on the Doppler signal. If the target is detected in both the time domain and the frequency domain, start the short-range radar detector and calculate the starting point information of the target location. Otherwise, enter the next moment and start from step (7) to execute the calculation of the simulation steps in sequence.

[0077] In a preferred embodiment of the present invention, in step S1 or S5, the simulated short-range radar signal characteristic parameters include: radio frequency pulse amplitude, transmission signal carrier frequency, transmission signal power, transmission signal beam inclination, beam width, beam range, pulse repetition period, transmit-receive interval, random pulse position modulation duty cycle, pseudo code symbol width, pseudo code sequence length, transmission pulse width and reception pulse width; the detector and target intersection parameters include: simulated target speed, detector speed, target offset relative to the detector center, target offset azimuth, start time to the detector plane, stop time passing the detector plane and attitude angle of the short-range radar detector and the target; the pulse Doppler signal model includes: equal width and equal period pulse Doppler signal model, random pulse position pulse Doppler signal model and pseudo code phase modulation pulse Doppler signal model.

[0078] In a preferred embodiment of the present invention, in step S2, the simulation mathematical model of the equal-width and equal-period pulse Doppler short-range radar transmission signal is:

[0079]

[0080] The mathematical model for the simulation of the random pulse Doppler short-range radar transmission signal is:

[0081]

[0082] The mathematical model for simulating the transmission signal of pseudo-code phase-modulated pulse Doppler short-range radar is:

[0083]

[0084] Where A is the RF pulse amplitude; ω0 is the carrier frequency of the transmitted signal; The width is τ M pulse; t is time; δ(t) is the Dirichlet function; T M is the pulse repetition period; N is the number of pulses; N i is a random variable uniformly distributed in [0, T0]; define T0 / T M is the random pulse position modulation duty cycle, usually 0.3-0.6; M(t)=±1 is the bipolar code corresponding to the M sequence.

[0085] In a preferred embodiment of the present invention, in step S3, the position vector of each scattering source in the scattering point model is obtained by clustering the centroid position vector of the panel model according to the distance.

[0086] In a preferred embodiment of the present invention, in step S4, the characteristic data of each scattering point includes: the RCS of each scattering point, the slant distance of each scattering point, the approach speed of each scattering point to the detector, the coordinates of each scattering point and the farthest distance between the target irradiated unit and the short-range detector.

[0087] In a preferred embodiment of the present invention, in step S5, the simulation gain parameters include: antenna system input impedance, antenna gain, transmission power peak, system loss coefficient, range gate selection loss, Doppler gain and video gain; the signal processing model parameters include: receiving pulse width, random pulse position modulation duty cycle, pseudo code symbol width and pseudo code sequence length.

[0088] In a preferred embodiment of the present invention, in step S6, the mathematical model for simulating the suppressed noise amplitude modulation interference signal is:

[0089] J(t)=(U j +u n (t))cos(ω0t)

[0090] Where ω0 is the center frequency of the noise amplitude modulation signal, which is equal to the carrier frequency of the transmitted signal; U j Indicates the interference signal amplitude; u n (t) is the variance Noise with mean 0; t is time.

[0091] In a preferred embodiment of the present invention, in step S7, the echo signal simulation mathematical model is:

[0092]

[0093] Where ω0 is the carrier frequency of the transmitted signal; The width is τ M pulse; t is time; δ(t) is the Dirichlet function; T M is the pulse repetition period; N is the number of pulses; τ i is the delay of the echo signal of the i-th scattering point relative to the transmitted signal; ω di The Doppler angular frequency generated by the target scattering point relative to the short-range radar movement:

[0094]

[0095] Among them, V ri is the relative motion speed between the scattering point i and the detector; is the angle between the scattering point i and the detector line of sight and the relative velocity vector between the two; λ is the beam wavelength, where F t k is the carrier frequency of the transmitted signal; i is a coefficient including the scattering point RCS, the transmitted signal power, and the radar distance factor. Its relationship with the power at the entrance of the receiving antenna is:

[0096]

[0097] Among them, G t is the antenna gain; λ is the beam wavelength; r i is the scattering point slant distance of scattering point i; P t is the transmitted signal power; R is the input impedance of the antenna system; is the radar cross section of scattering point i.

[0098] In a preferred embodiment of the present invention, in step S7, the effective echo contribution of each scattering point within the range gate is accumulated, including the following steps:

[0099] S71, calculating the effective time range of the range gate as [t1, t2] based on the current simulation pulse sequence number, pulse repetition period, receiving pulse width, transmitting pulse width and receiving and transmitting interval;

[0100] S72, obtain within the effective time range of the range gate with step length t0 sampling points;

[0101] S73, calculate the delay of the echo signal of the scattering point relative to the transmission signal according to the relative distance Ri_abs between the scattering point i and the short-range detector Where C is the speed of light 3×10 8 m / s;

[0102] S74, traverse the sampling points within the effective time range of the range gate, and the time corresponding to the sampling point sequence number Num is times=Num×t0;

[0103] S75. If times is within the time range [t3, t4] of the echo signal generated by the scattering point i, it is considered that the target echo generated by the scattering point i is within the range of the range gate, and the echo contribution is valid. The echo contribution value of the scattering point is calculated according to the echo signal simulation mathematical model;

[0104] S76, accumulating the echo contribution values ​​of the scattering points that generate effective echoes to obtain the total echo simulation signal of each sampling point.

[0105] In a preferred embodiment of the present invention, in step S71, the lower time limit t1 of the effective time range of the range gate is:

[0106] t1=NT M +Tri

[0107] Where N is the simulation pulse number; T M is the pulse repetition period; Tri is the transmit / receive interval; the lower limit t2 is:

[0108] t2=t1+taot

[0109] Wherein, taot is the receiving pulse width.

[0110] In a preferred embodiment of the present invention, in step S75, the lower limit t3 of the time range of the echo signal generated by the scattering point i is:

[0111] t3=NT M +delay_time

[0112] The lower time limit t4 is:

[0113] t4=NT M +tao0+delay_timei

[0114] Where N is the simulation pulse number; T M is the pulse repetition period; tao0 is the transmit pulse width; delay_timei is the delay of the echo signal of scattering point i relative to the transmit signal.

[0115] In a preferred embodiment of the present invention, in step S8, the filtering process is implemented by a second-order low-pass filter, and its mathematical model is:

[0116]

[0117] Among them, x0(t) is the filter output value at the current moment; x i (t) is the echo signal value of the input filter at the current moment; t0 is the signal sampling step; f c is the cut-off frequency; γ is the damping ratio, and the best effect is achieved when the value is 0.707.

[0118] In a preferred embodiment of the present invention, in step S9, the specific process of time domain threshold detection is: setting the time domain threshold K and the number of pulse detections N1, if there are N1 consecutive sample values ​​in the Doppler signal output by the filter that exceed the threshold K, it is considered that the target is detected in the time domain.

[0119] In a preferred embodiment of the present invention, in step S9, the specific process of frequency domain constant false alarm detection is: setting the false alarm probability and the number of points N2 that continuously cross the threshold in the frequency domain, taking the current moment as the starting point and intercepting 64 sample points forward, performing Fourier transform on these 64 data to obtain the frequency domain amplitude-frequency response waveform of the data in the sliding window, performing unit average constant false alarm detection based on the amplitude-frequency response waveform at the current moment, and if N2 consecutive sliding windows all detect the presence of the target, it is considered that the frequency domain detects the presence of the target.

[0120] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0121] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model, characterized in that: The following steps are involved: Step S1, importing the target model, defining the simulated short-range detector transmission signal characteristic parameters, the detector and target intersection parameters and the pulse Doppler signal model, and recording the detector and target intersection parameters and the transmission signal carrier frequency into a multi-scattering point data file; Step S2, simulating the radar transmission signal according to the pulse Doppler short-range radar transmission signal simulation model; Step S3, setting the number of scattering points, at each moment, constructing a multi-scattering point model of the target according to the position information of each facet of the imported target model, and recording the position vector of each scattering point; Step S4, accumulating the RCS values ​​of each facet that generates the same scattering point at each moment to obtain the total RCS value of the scattering point, and recording the characteristic data of each scattering point at each moment when the intersection condition between the detector and the target remains unchanged in the multi-scattering point data file; Step S5, retaining the simulated radar signal characteristic parameters and the detector and target intersection parameters, resetting various types of simulation gain parameters, transmission pulse width, transmit-receive interval, pulse Doppler signal processing model and various signal processing model parameters, and reading the multi-scattering point data file generated in the above steps; Step S6: The echo signal received by the receiver is often accompanied by interference, and suppression interference is used to implement interference signal simulation; Step S7, under the new gain condition and signal processing model, the echo signal simulation mathematical model calculates the echo signal values ​​contributed by different scattering points at each moment, adds interference to the echo values ​​at each moment, and accumulates the effective echo contributions of each scattering point within the range gate to complete the echo signal simulation of the volume target; Step S8, mixing the effective echo signal with the local oscillator signal, and filtering to obtain a Doppler signal carrying target information; Step S9, perform time domain threshold detection and frequency domain constant false alarm detection on the Doppler signal. If the target is detected in both the time domain and the frequency domain, start the short-range target detector and calculate the starting point information of the target location. Otherwise, enter the next moment and start from step S7 to execute the calculation of the simulation steps in sequence.

2. The pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model according to claim 1 is characterized in that: In step S1 or S5, the simulated short-range radar signal characteristic parameters include: radio frequency pulse amplitude, transmission signal carrier frequency, transmission signal power, transmission signal beam inclination, beam width, beam effective range, pulse repetition period, transmit-receive interval, random pulse position modulation duty cycle, pseudo code symbol width, pseudo code sequence length, transmission pulse width and reception pulse width; the detector and target intersection parameters include: simulated target speed, detector speed, target offset relative to the detector center, target offset azimuth, start time to the detector plane, stop time passing the detector plane and attitude angle of the short-range radar detector and the target; the pulse Doppler signal model includes: equal width and equal period pulse Doppler signal model, random pulse position pulse Doppler signal model and pseudo code phase modulation pulse Doppler signal model.

3. The pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model according to claim 2 is characterized in that: In step S2, the simulation mathematical model of the equal-width and equal-period pulse Doppler short-range radar transmission signal is: The mathematical model for the simulation of the random pulse Doppler short-range radar transmission signal is: The mathematical model for simulating the transmission signal of pseudo-code phase-modulated pulse Doppler short-range radar is: Where A is the RF pulse amplitude; ω0 is the carrier frequency of the transmitted signal; The width is τ M pulse; t is time; δ(t) is the Dirichlet function; T M is the pulse repetition period; N is the number of pulses; N i is a random variable uniformly distributed in [0, T0]; define T0 / T M is the random pulse position modulation duty cycle, usually 0.3-0.6; M(t)=±1 is the bipolar code corresponding to the M sequence.

4. The pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model according to claim 1 is characterized in that: In step S3, the position vector of each scattering source in the scattering point model is obtained by clustering the centroid position vector of the surface element model according to the distance; In step S4, the characteristic data of each scattering point includes: RCS of each scattering point, slant distance of each scattering point, approach speed of each scattering point and detector, coordinates of each scattering point and the farthest distance between the target irradiated unit and the short-range detector; In step S5, the simulation gain parameters include: antenna system input impedance, antenna gain, transmission power peak, system loss coefficient, range gate selection loss, Doppler gain and video gain; the signal processing model parameters include: receiving pulse width, random pulse position modulation duty cycle, pseudo code symbol width and pseudo code sequence length.

5. The pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model according to claim 1 is characterized in that: In step S6, the mathematical model of the suppressed noise amplitude modulation interference signal simulation is: J(t)=(U j +u n (t))cos(ω0t) Where ω0 is the center frequency of the noise amplitude modulation signal, which is equal to the carrier frequency of the transmitted signal; U j Indicates the interference signal amplitude, u n (t) is the variance Noise with mean 0, t is time; In step S7, the mathematical model of the echo signal simulation is: Where ω0 is the carrier frequency of the transmitted signal; The width is τ M pulse; t is time; δ(t) is the Dirichlet function; T M is the pulse repetition period; N is the number of pulses; τ i is the delay of the echo signal of the i-th scattering point relative to the transmitted signal; ω di It is the Doppler angular frequency generated by the motion of the target scattering point relative to the short-range detector.

6. The pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model according to claim 5 is characterized in that: The Doppler angular frequency generated by the target scattering point moving relative to the short-range detector is: Where V ri is the relative speed between the scattering point i and the detector; θ i is the angle between the scattering point i and the detector line of sight and the relative velocity vector between the two; λ is the beam wavelength, where F t is the carrier frequency of the transmitted signal; Parameter k in the mathematical model of echo signal simulation i is a coefficient including the scattering point RCS, the transmitted signal power, and the radar distance factor. Its relationship with the power at the entrance of the receiving antenna is: In the formula, G t is the antenna gain; λ is the beam wavelength; r i is the scattering point slant distance of scattering point i; P t is the transmitted signal power; R is the input impedance of the antenna system; is the radar cross section of scattering point i.

7. The pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model according to claim 1 is characterized in that: In step S7, effective echo contributions of each scattering point within the range gate are accumulated, including the following steps: S71, calculating the effective time range of the range gate as [t1, t2] based on the current simulation pulse sequence number, pulse repetition period, receiving pulse width, transmitting pulse width and receiving and transmitting interval; S72, obtain within the effective time range of the range gate with step length t0 sampling points; S73, calculate the delay of the echo signal of the scattering point relative to the transmission signal according to the relative distance Ri_abs between the scattering point i and the short-range detector Where C is the speed of light 3×10 8 m / s; S74, traverse the sampling points within the effective time range of the range gate, and the time corresponding to the sampling point sequence number Num is times=Num×t0; S75. If times is within the time range [t3, t4] of the echo signal generated by the scattering point i, it is considered that the target echo generated by the scattering point i is within the range of the range gate, and the echo contribution is valid. The echo contribution value of the scattering point is calculated according to the echo signal simulation mathematical model; S76, accumulating the echo contribution values ​​of the scattering points that generate effective echoes to obtain the total echo simulation signal of each sampling point.

8. The pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model according to claim 7 is characterized in that: In step S71, the lower time limit t1 of the effective time range of the range gate is: t1=NT M +Three Where N is the simulation pulse number; T M is the pulse repetition period; Tri is the transmit / receive interval; the lower limit t2 is: t2=t1+taot Wherein, taot is the receiving pulse width. In step S75, the lower limit t3 of the time range of the echo signal generated by the scattering point i is: t3=NT M +delay_timei The lower time limit t4 is: t4=NT M +tao0+delay_timei Where, N is the simulation pulse number; T M is the pulse repetition period; tao0 is the transmit pulse width; delay_timei is the delay of the echo signal of scattering point i relative to the transmit signal.

9. The pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model according to claim 1, characterized in that: In step S8, the filtering process is implemented by a second-order low-pass filter, and its mathematical model is: Where x0(t) is the filter output value at the current moment; x i (t) is the echo signal value of the input filter at the current moment; t0 is the signal sampling step; f c is the cut-off frequency; γ is the damping ratio, and the best effect is achieved when the value is 0.

707.

10. The pulse Doppler short-range radar signal processing simulation method based on a multi-scattering point model according to claim 1, characterized in that: In step S9, the specific process of time domain threshold detection is as follows: setting the time domain threshold K and the number of pulse detections N1, if there are N1 consecutive sample values ​​in the Doppler signal output by the filter that exceed the threshold K, it is considered that the target is detected in the time domain; In step S9, the specific process of frequency domain constant false alarm detection is: set the false alarm probability and the number of consecutive threshold points in the frequency domain N2, take 64 sample points forward from the current moment as the starting point, perform Fourier transform on these 64 data to obtain the frequency domain amplitude-frequency response waveform of the data in the sliding window, perform unit average constant false alarm detection based on the amplitude-frequency response waveform at the current moment, and if N2 consecutive sliding windows detect the presence of the target, it is considered that the frequency domain detects the presence of the target.

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