Time division multiplexing target simulation method based on FPGA in a radar system

Abstract

The application discloses a time division multiplexing target simulation method based on FPGA in a radar system, and comprises the following steps: generating binomial code standard waveforms of each scattering point of a group target and linear frequency modulation signals of each scattering point of the group target; multiplying the binomial code standard waveforms of each scattering point and the linear frequency modulation signals of each scattering point in time to obtain modulated binomial code signals of each scattering point; selecting one of the linear frequency modulation signals of each scattering point and the modulated binomial code signals of each scattering point according to system working mode parameters to obtain modulated signals of each scattering point after mode selection; multiplying the modulated signals and corresponding echo amplitude parameters to obtain simulation data of each scattering point of the group target; and accumulating the simulation data to obtain single group target simulation data. The time division multiplexing technology is used for target simulation, so that the target simulation precision is ensured, and the number of group targets that can be simulated by a single FPGA is increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radar signal simulation, and more particularly to a time-division multiplexing target simulation method based on FPGA in a radar system. BACKGROUND

[0002] With the increasing complexity of modern radar system functions, the complexity and cost of field tests have increased significantly. Radar signal simulation technology, with its economy, flexibility and realism, has gradually become an indispensable means in the process of radar system design, analysis and performance testing, and is widely used in radar subsystem debugging, performance evaluation, analysis and debugging of radar system back stages under conditions that the radar front end does not have, and testing of radar overall performance and indicators.

[0003] The simulation objects of radar signal simulation are radar targets and environment, which include target echo, noise signal, clutter signal and interference. Existing researches on radar signal simulators at home and abroad mainly include two categories: one is radar signal simulation technology based on DSP, and the other is radar signal simulation technology based on FPGA. The implementation of radar signal simulation based on DSP has the advantages of high simulation accuracy and high flexibility, but in the scene where the system requires a large number of simulated beams, the processing speed of DSP is limited and cannot meet the system requirements. The implementation of radar signal simulation based on FPGA has the advantage of parallel processing, strong system real-time performance, and solves the beam limitation problem of DSP in radar signal simulation, and has great development potential in radar signal simulation.

[0004] However, when implementing radar signal simulation based on FPGA, the BRAM resources of FPGA will limit the number of simulated targets. How to reduce the FPGA resource occupation of single group target simulation while ensuring the simulation accuracy and improve the number of single-chip FPGA simulated group targets is a difficulty in current research. SUMMARY

[0005] An object of the present application is to provide a time-division multiplexing target simulation method based on FPGA in a radar system.

[0006] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0007] A time-division multiplexing target simulation method based on FPGA in a radar system, comprising the following steps:

[0008] According to the m-sequence feedback coefficient, the m-sequence order, the m-sequence initial sequence, the two-phase code window coefficient N1, the two-phase code window coefficient N2 and the delay parameters of each scattering point, the corresponding m-sequence is generated, and the two-phase code standard waveform of each scattering point of the group target is obtained after windowing;

[0009] According to the quadratic term coefficient, the linear term coefficient, the constant term coefficient and the delay parameter of each scattering point, phase accumulation calculation and sine and cosine signal generation are completed to obtain the linear frequency modulation signal of each scattering point of the group target;

[0010] The binary code standard waveform of each scattering point is multiplied by the linear frequency modulation signal of each scattering point in time to obtain the modulated binary code signal of each scattering point;

[0011] According to the system working mode parameter, one of the linear frequency modulation signal of each scattering point and the modulated binary code signal of each scattering point is selected to obtain the modulated signal of each scattering point after mode selection;

[0012] The modulated signal of each scattering point after mode selection is multiplied by the corresponding echo amplitude parameter to complete signal modulation and obtain the analog data of each scattering point of the group target;

[0013] The analog data of each scattering point is accumulated to obtain the analog data of a single group target.

[0014] Preferably, the analog data of each scattering point is accumulated to obtain the analog data of a single group target, further comprising

[0015] According to the sampling rate control parameter, the analog data of each scattering point is accumulated according to the sampling point and the sampling length is controlled to obtain the analog data of a single group target.

[0016] Preferably, the sampling rate control parameter is the integer part of the ratio of the system clock to the sampling rate f s .

[0017] Preferably, the sampling rate control parameter includes the number of system clock cycles maintained by the sampling point.

[0018] Preferably, the binary code standard waveform of each scattering point of the group target and the linear frequency modulation signal of each scattering point of the group target are obtained by time division multiplexing FGPA resources between different scattering points.

[0019] Preferably, the maximum value of the number of scattering points is set to be less than or equal to the sampling rate control parameter.

[0020] Preferably, the linear frequency modulation signal of each scattering point of the group target is obtained by completing phase accumulation calculation and sine and cosine signal generation according to the quadratic term coefficient, the linear term coefficient, the constant term coefficient and the delay parameter of each scattering point in the linear frequency modulation waveform simulation mode or the binary code waveform simulation mode.

[0021] Preferably, the number of echo amplitude parameters is consistent with the number of scattering points, and the echo amplitude parameter is set to 0 in the clock cycle without scattering points.

[0022] Preferably, the method further comprises analyzing, in MATLAB, the single group target simulation data processed by the pulse pressure and verifying the correctness and accuracy of the target simulation.

[0023] The beneficial effects of the present application are as follows:

[0024] The present application uses time division multiplexing technology for target simulation, time division multiplexing FGPA resources between different scattering points of a single group target, increases the number of single FGPA that can simulate group targets, improves the operation rate of target simulation, and has high real-time performance. BRIEF DESCRIPTION OF DRAWINGS

[0025] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0026] Figure 1 is a flowchart described in the embodiments of the present application.

[0027] Figure 2 is a schematic diagram of generating a two-fold interpolation binary code standard waveform described in the embodiments of the present application.

[0028] Figure 3 is a time division multiplexing schematic diagram of group target simulation described in the embodiments of the present application.

[0029] Figure 4 is a linear frequency modulation waveform target simulation result described in the embodiments of the present application.

[0030] Figure 5 is a linear frequency modulation waveform target simulation result and MATLAB simulation error result diagram described in the embodiments of the present application. DETAILED DESCRIPTION

[0031] In order to more clearly illustrate the present application, the preferred embodiments and the accompanying drawings are combined below. Figures 1-5 The present application is further described. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than limiting, and should not limit the protection scope of the present application.

[0032] The present application provides a time division multiplexing target simulation method based on FPGA in a radar system. In this example, Xilinx xc7vx690t chip is selected as the core device for target simulation, and MATLAB environment is used for simulation verification of the result.

[0033] Based on time division multiplexing technology, group target simulation of linear frequency modulation waveform and binary code waveform is realized. Among them, the sampling rate f s is controllable, the number of scattering points of a single group target is controllable, the maximum number of scattering points is less than or equal to the sampling rate control parameter, and the system clock is 240M.

[0034] As Figure 1 shown, is a flow chart of the embodiment, including each scattering point bi-phase code standard waveform and linear frequency modulation signal generation, modulating each scattering point bi-phase code standard waveform signal, after mode selection, multiplying the corresponding amplitude parameters, obtaining each scattering point simulation data. Finally, after accumulating each scattering point simulation data and sampling length control, single group target simulation data is obtained.

[0035] In this example, the target simulation method based on time division multiplexing technology includes the following steps:

[0036] Step (1) First, according to the m sequence feedback coefficient, the m sequence order, the m sequence initial sequence, the bi-phase code window coefficient N1, the bi-phase code window coefficient N2 and the scattering point delay parameter, the bi-phase code standard waveform signal of each scattering point is completed. The generation schematic diagram is shown in Figure 2 The imaginary part is 0 by default.

[0037] For single pulse signal, each dwell parameter remains unchanged. For pulse train signal, at the rising edge of each transmission pulse, the bi-phase code window coefficient N1, the bi-phase code window coefficient N2 and the scattering point delay parameter need to be updated, and the remaining parameters remain unchanged in each dwell.

[0038] Step (2) According to the quadratic term coefficient A2, the linear term coefficient A1 and the constant term coefficient A0 and the scattering point delay parameter, the phase accumulation calculation and the sine and cosine signal generation are completed to obtain the linear frequency modulation signal of each scattering point. Among them, the phase accumulation function is completed by code, and the function of sine and cosine signal generation is completed by using Xilinx IP core Cordic6.0 (single group target scattering point time division multiplexing). The single scattering point linear frequency modulation signal can be expressed as Wherein, the phase In the formula, N is the number of the current signal, the phase increment is 2A2N+A1, and the phase initial value is A0.

[0039] For single pulse signal, in a dwell, the phase increment is always changing and the phase offset is constant; for pulse train signal, in a transmission pulse period, the phase increment is always changing and the phase offset is constant, but the phase offset is different between each pulse period, that is, the phase accumulator needs to be cleared and the phase initial value needs to be switched at the moment of pulse arrival.

[0040] Step (3) The standard waveform of each scattering point binary code output by step (1) is time-division multiplexed with the linear frequency modulation signal of each scattering point output by step (2) according to the scattering point pair Xilinx IP core Complex Multiplier 6.0, and multiplied to obtain the modulated binary code signal of each scattering point.

[0041] Step (4) According to the working mode, one signal is selected from the linear frequency modulation signal of each scattering point output by step (2) and the modulated binary code signal of each scattering point output by step (3) to obtain the modulated signal of each scattering point after mode selection.

[0042] Step (5) The signal of each scattering point after mode selection output by step (4) is time-division multiplexed with the echo amplitude parameter according to the scattering point pair Xilinx IP core Multiplier 12.0, and multiplied to obtain the analog data of each scattering point of the target. The number of echo amplitude parameters is consistent with the number of scattering points, and the echo amplitude parameter is set to 0 in the clock cycle without scattering points. The time-division multiplexing diagram of the scattering points is shown in Figure 3 , wherein, and A M respectively represent the modulated signal of the Nth sampling point of the Mth scattering point after mode selection and the amplitude parameter of the Mth scattering point.

[0043] Step (6) According to the sampling rate control parameter (the ratio of the system clock to the sampling rate f s downward rounding), the analog data of each scattering point output by step (5) is accumulated according to the sampling point, and the sampling length control is performed to obtain the analog data of a single target. The number of system clock cycles maintained by each sampling point of the single target analog data is the sampling rate control parameter, which realizes the function of simulating targets with different sampling rates, and facilitates subsequent beam forming and interleaving processing.

[0044] Step (7) In order to verify the correctness of the method, the signal output by the FPGA is output to a file, and then analyzed in MATLAB as shown in Figure 4 , and pulse pressure processing verifies the correctness and accuracy of target simulation. In addition, the data of target simulation generated by FGPA is compared with MATLAB simulation as shown in Figure 5 , and the amplitude error is controlled within ±1.

[0045] A specific embodiment,

[0046] A time-division multiplexing target simulation method based on FPGA in a radar system, comprising the following steps:

[0047] According to the m-sequence feedback coefficient, the m-sequence order, the m-sequence initial sequence, the two-phase code window coefficient N1, the two-phase code window coefficient N2 and the delay parameter of each scattering point, a corresponding m-sequence is generated, and a two-phase code standard waveform of each scattering point of the group target is obtained after windowing.

[0048] According to the quadratic term coefficient, the linear term coefficient, the constant term coefficient and the delay parameter of each scattering point, phase accumulation calculation and generation of sine and cosine signals are completed, and a linear frequency modulation signal of each scattering point of the group target is obtained.

[0049] The two-phase code standard waveform of each scattering point is multiplied by the linear frequency modulation signal of each scattering point in time division to obtain a modulated two-phase code signal of each scattering point.

[0050] For the linear frequency modulation signal of each scattering point and the modulated two-phase code signal of each scattering point, one of the signals is selected according to the system working mode parameter to obtain a modulated signal of each scattering point after mode selection.

[0051] The modulated signal of each scattering point after mode selection is multiplied by the corresponding echo amplitude parameter to complete the modulation of the signal, and analog data of each scattering point of the group target is obtained.

[0052] The analog data of each scattering point is accumulated to obtain analog data of a single group target.

[0053] Preferably, the analog data of each scattering point is accumulated to obtain analog data of a single group target, further comprising

[0054] According to the sampling rate control parameter, the analog data of each scattering point is accumulated according to the sampling points, and the sampling length control is performed to obtain analog data of a single group target.

[0055] Preferably, the sampling rate control parameter is the integer part of the ratio of the system clock to the sampling rate f s .

[0056] Preferably, the sampling rate control parameter includes the number of system clock cycles maintained by the sampling points.

[0057] Preferably, the two-phase code standard waveform of each scattering point of the group target and the linear frequency modulation signal of each scattering point of the group target further comprise time division multiplexing FGPA resources between different scattering points.

[0058] Preferably, the maximum value of the number of scattering points is set to be less than or equal to the sampling rate control parameter.

[0059] Preferably, the obtaining the linear frequency modulation signal of each scattering point of the group target further comprises: in the linear frequency modulation waveform simulation mode or the binomial waveform simulation mode, according to the quadratic coefficient, the linear coefficient, the constant coefficient and the delay parameter of each scattering point, completing phase accumulation calculation and generation of the sine and cosine signals to obtain the linear frequency modulation signal of each scattering point of the group target.

[0060] Preferably, the number of echo amplitude parameters is consistent with the number of scattering points, and the echo amplitude parameter is set to 0 in the clock cycle without the scattering point.

[0061] Preferably, the method further comprises analyzing the pulse pressure processing of the single group target simulation data in MATLAB and verifying the correctness and accuracy of the target simulation.

[0062] The application discloses a time division multiplexing target simulation method based on FPGA, realizes group target simulation of linear frequency modulation waveforms and binomial waveforms, minimizes FPGA resource occupation when the number of simulated group targets is certain, and the realization process is as follows: firstly, binomial standard waveforms and linear frequency modulation signals of each scattering point of a group target are generated, then the binomial standard waveforms of each scattering point are multiplied with corresponding linear frequency modulation signals in time division mode, then the signals after mode selection are multiplied with corresponding echo amplitude parameters to complete signal modulation, and simulation data of each scattering point of the group target is obtained. Finally, the simulation data of each scattering point is accumulated to obtain single group target simulation data. The application utilizes time division multiplexing technology to simulate targets, time division multiplexes FPGA resources between different scattering points of a single group target, increases the number of group targets that can be simulated by a single FPGA while ensuring simulation accuracy.

[0063] Obviously, the above embodiments of the application are only examples for clearly illustrating the application, and are not intended to limit the implementation modes of the application. For those skilled in the art, on the basis of the above description, other different forms of changes or modifications can be made, and it is impossible to enumerate all the implementation modes here. Any changes or modifications that belong to the technical solutions of the application and are derived from the obvious changes or modifications are still within the protection scope of the application.

Claims

1. A time division multiplexed target simulation method based on FPGA in a radar system, characterized by, The method comprises the following steps: According to the m-sequence feedback coefficient, the m-sequence order, the m-sequence initial sequence, the two-phase code window coefficient N1, the two-phase code window coefficient N2 and the delay parameter of each scattering point, the corresponding m-sequence is generated, and the single group target each scattering point two-phase code standard waveform is obtained after windowing; According to the quadratic term coefficient, the linear term coefficient, the constant term coefficient and the delay parameter of each scattering point, the phase accumulation calculation and the generation of the sine and cosine signals are completed, and the single group target each scattering point linear frequency modulation signal is obtained; The two-phase code standard waveform of each scattering point is multiplied by the linear frequency modulation signal of each scattering point in time, and the modulated two-phase code signal of each scattering point is obtained; For the linear frequency modulation signal of each scattering point and the modulated two-phase code signal of each scattering point, according to the working mode parameter of the target simulation in the radar system, one of the signals is selected, and the modulated signal of each scattering point after mode selection is obtained; The modulated signal of each scattering point after mode selection is multiplied by the corresponding echo amplitude parameter to complete the modulation of the signal, and the simulation data of each scattering point of the single group target is obtained; The simulation data of each scattering point is accumulated to obtain the simulation data of the single group target; The simulation data of each scattering point is accumulated to obtain the simulation data of the single group target, further comprising According to the sampling rate control parameter, the simulation data of each scattering point is accumulated according to the sampling points, and the sampling length control is performed, and the simulation data of the single group target is obtained; The sampling rate control parameter is the integer part of the ratio of the system clock to the sampling rate . The sampling rate control parameter comprises the number of system clock cycles maintained by the sampling points. The single group target each scattering point two-phase code standard waveform and the single group target each scattering point linear frequency modulation signal further comprise time division multiplexing FGPA resources between different scattering points.

2. The method of claim 1, wherein, The maximum value of the number of scattering points is set to be less than or equal to the sampling rate control parameter.

3. The method of claim 1, wherein, The single group target each scattering point linear frequency modulation signal further comprises, in the linear frequency modulation waveform simulation mode or the two-phase code waveform simulation mode, according to the quadratic term coefficient, the linear term coefficient, the constant term coefficient and the delay parameter of each scattering point, completing the phase accumulation calculation and the generation of the sine and cosine signals, and obtaining the single group target each scattering point linear frequency modulation signal.

4. The method of claim 1, wherein, The number of echo amplitude parameters is consistent with the number of scattering points, and the echo amplitude parameter is set to 0 in the clock cycle without scattering points.

5. The method of claim 1, wherein, The method further comprises analyzing in MATLAB, pulse compression processing the single group target simulation data and verifying the correctness and precision of the target simulation.

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