CN-119716768-B - Anti-foil-strip interference method for LFMCW millimeter-wave fuze based on FPGA

Abstract

The invention relates to an anti-foil-strip interference method for an LFMCW millimeter-wave fuse based on an FPGA (field programmable gate array), which aims to solve the problem that the existing millimeter-wave fuse can have failure modes such as premature burst under the condition of foil-strip interference. The method comprises the steps of firstly sampling a received difference frequency echo signal, completing analog-to-digital conversion, synchronously controlling two paths of collected signals through synchronous pulses and performing FIFO buffer, then performing FIR digital filtering, calculating a polarization ratio average value of output signals, judging whether foil interference is detected at the moment, performing oblique projection polarization filtering processing on one path of signals if the foil interference is detected, then completing spectrum analysis, outputting distance information of an effective target, and directly performing spectrum analysis if the foil interference is not detected, so as to obtain the distance information of the target. Finally, the range of the distance is judged, and when the target is within the fixed range of the fuze detection system, an execution level signal is output.

Inventors

• ZHOU LIN
• LIU JINGPING

Assignees

• 南京理工大学

Dates

Publication Date

20260512

Application Date

20230928

Claims (1)

1. 1. The anti-foil-strip interference method for the LFMCW millimeter-wave fuze based on the FPGA is characterized by comprising the following steps: 1) AD acquisition data output Sampling two paths of difference frequency echo signals of a horizontal polarization channel and a vertical polarization channel by using an ADC (analog-digital converter), and finishing analog-digital conversion; 2) Synchronous pulse Synchronous control is carried out on the two paths of collected echo signals by using synchronous pulses; 3) FIFO buffer and FIR digital filtering Performing FIFO (first in first out) buffer storage on two paths of echo signals controlled by synchronous pulses, and then finishing the design of a filter by using FIRIP cores; 4) Polarization identification, comprising the steps of: 4.1 Using) Calculating the polarization ratio of the ith echo signal in the step 3), wherein a HH and a HV represent the amplitudes of two paths of echo signals, i=1, 2. 4.2 After the polarization ratios of the N echo signals are respectively calculated, calculating the average value of the N echo signals, judging whether the average value is larger than a judgment threshold value of the average value of the polarization ratios, and adopting the step 4.1) to calculate the average value of the polarization ratios of the aircraft as the judgment threshold value of the average value of the polarization ratios; 4.3 When the average value of the polarization ratio of the echo signals is smaller than or equal to a judging threshold value, judging that the foil interference exists, performing processing of inhibiting the foil interference signals, and entering a step 5; 5) The oblique projection polarization filtering comprises the following steps: 5.1 Using the echo signal with foil interference determined by polarization recognition as an input signal, wherein the input signal is the echo signal of a dual-polarized fuze, and firstly, carrying out polarization parameter estimation on the polarization angle gamma J and the polarization angle phase difference phi J of the echo signal to determine the polarization state of the foil: φ J ＝arg[E JV (t)]-arg[E JH (t)] Wherein E JV (t) represents the echo signal amplitude of the vertical polarization channel, E JH (t) represents the echo signal amplitude of the horizontal polarization channel, arg [ g ] represents the phase angle of the acquired signal; for the polarization state of an airplane target, the polarization state of the airplane target needs to be determined in advance, and the calculation mode is the same as that of the foil strip in the step 5.1), so that an airplane polarization angle gamma S and an airplane polarization angle phase difference phi S are obtained; 5.2 Calculating an oblique projection operator according to the polarization parameters estimated in the step 5.1) by the following formula: Wherein [ g ] T represents the transposed operation of the matrix, [ g ] H represents the conjugate transpose of the matrix, S represents the polarized subspace of the aircraft signal, J represents the polarized subspace of the foil signal, E SJ is the oblique projection operator, An orthogonal projection operator of the J orthogonal complement space, wherein I is an identity matrix; 5.3 Multiplying the oblique projection operator in the step 5.2) with the input signal of any polarization channel to obtain a target echo signal after the interference of foil strips is inhibited; 6) FFT conversion Invoking an FFT IP core to convert the echo signal processed in the step 4.3 or the step5 from a time domain signal to a frequency domain signal; 7) Distance estimation detonation control The frequency domain signal obtained in the step 6) is an effective target echo signal after the foil interference is restrained, and for the LFMCW millimeter wave fuze, the target distance is calculated by using the spectral line sequence number corresponding to the spectral peak value through the following steps: wherein, F beat_up and F beat_down are respectively the difference frequency signal frequencies of the upper and lower sweep frequency segments of the moving object, c is the speed of light, T M is the modulation period of the LFMCW signal, and DeltaF M is the modulation bandwidth of the LFMCW signal; and outputting an execution level signal when the target is in the fixed distance range of the LFMCW millimeter wave fuze detection system.

Description

Anti-foil-strip interference method for LFMCW millimeter-wave fuze based on FPGA Technical Field The invention belongs to the technical field of fuse anti-interference, and particularly relates to an anti-foil-strip interference method for an LFMCW millimeter-wave fuse based on an FPGA. Background The radio fuse serving as a proximity fuse has the advantages of being long in detection distance, high in ranging accuracy, high in target recognition rate and the like, in order to improve the accuracy of the proximity fuse, the application frequency band of the radio fuse gradually develops towards the millimeter wave direction in recent years, and failure modes such as premature burst and the like are extremely easy to occur under foil interference of the millimeter wave fuse, the performance of the missile-borne fuse is greatly influenced by the occurrence of the foil interference, and therefore, the capability of improving the anti-foil interference of the millimeter wave fuse is highly needed. At present, the technology of resisting the interference of foil strips can be roughly divided into six types, namely (1) an identification method based on waveform characteristics of echo signals, (2) an identification method based on time domain characteristics of echo signals, (3) an identification method based on frequency domain characteristics of echo signals, (4) an identification method based on Doppler characteristics of echo signals, (5) an identification method based on polarization domain information and (6) an identification method based on compound guidance. The polarization characteristic reflects the inherent physical property of the target, more target information can be provided for the fuze, and the identification and interference suppression capability of the fuze can be further improved by utilizing the polarization characteristic difference of the target and the interference. However, in the existing research of anti-foil-strip interference by using polarization information, only the situation that the target and the foil-strip interference are respectively in the fuze detection range is considered, and the implementation verification of hardware is lacked. Disclosure of Invention In order to solve the influence of the current foil interference on the LFMCW millimeter-wave fuse, the invention provides an anti-foil interference method for the LFMCW millimeter-wave fuse based on an FPGA. The technical scheme for solving the problems is as follows: the anti-foil-strip interference method for the LFMCW millimeter-wave fuze based on the FPGA is characterized by comprising the following steps: 1) AD acquisition data output Sampling two paths of difference frequency echo signals of a horizontal polarization channel and a vertical polarization channel by using an ADC (analog-digital converter), and finishing analog-digital conversion; 2) Synchronous pulse Synchronous control is carried out on the two paths of collected echo signals by using synchronous pulses; 3) FIFO buffer and FIR digital filtering Performing FIFO buffer memory on two paths of echo signals controlled by synchronous pulse, and then completing the design of a filter by using an FIR IP core; 4) Polarization identification 4.1 Using)Calculating the polarization ratio of the ith echo signal in the step 3), wherein a HH and a HV represent the amplitudes of two paths of echo signals, i=1, 2. 4.2 After the polarization ratios of N echo signals are respectively calculated, calculating the average value of the N echo signals, judging whether the average value is larger than a discrimination threshold value of the average value of the polarization ratios, wherein the threshold values of different aircraft targets are different, and the average value of the polarization ratios of the aircraft is required to be determined in advance in actual application, wherein the calculation mode is consistent with that of the step 4.1), and the average value is used as the discrimination threshold value of the average value of the polarization ratios; 4.3 When the average value of the polarization ratio of the echo signals is smaller than or equal to a judging threshold value, judging that the foil interference exists, and processing the foil interference signal to be suppressed, entering a step 5; 5) Oblique projection polarization filtering 5.1 Using the echo signal with foil interference determined by polarization recognition as an input signal, wherein the input signal is the echo signal of a dual-polarized fuze, and firstly, carrying out polarization parameter estimation on the polarization angle gamma J and the polarization angle phase difference phi J of the echo signal to determine the polarization state of the foil: φJ＝arg[EJV(t)]-arg[EJH(t)] Wherein E JV (t) represents the echo signal amplitude of the vertical polarization channel, E JH (t) represents the echo signal amplitude of the horizontal polarization channel, arg [ g ] represents the phase ang