CN102565763A

CN102565763A - Adaptive clutter suppression moving-target signal processing technology and realizing method

Info

Publication number: CN102565763A
Application number: CN2011104099332A
Authority: CN
Inventors: 潘瑞云
Original assignee: 724th Research Institute of CSIC
Current assignee: 724th Research Institute of CSIC
Priority date: 2011-12-12
Filing date: 2011-12-12
Publication date: 2012-07-11

Abstract

The invention relates to an adaptive clutter suppression moving-target signal processing method, which is mainly applicable to moving-target signal detection in a clutter environment in the field of radar detection. The adaptive clutter suppression moving-target signal processing method comprises processing flows as follows: firstly, dynamically matching pulse-pressed signals; carrying out primary compensation processing on the signals and sending the processed signals into narrow-band filter sets; respectively carrying out distance unit constant false-alarm processing on the signals output by each filter set, and obtaining a detecting result by selecting large output; and calculating an FIR (Finite Impulse Response) coefficient which uses a speed center as a main peak of a filter by using a given movement speed of a target which is focused on, and changing the coefficient of the filter in a adaptive manner. With the adoption of the method disclosed by the invention, the clutter is restrained obviously, the signal to noise ratio of the movement target is improved through the adaptive method, so that the signal detection performance is finally improved. Furthermore, application of VHDL (VHSIC Hardware Description Language) in FPGA (Field Programmable Gate Array) is completely realized. The method disclosed by the invention has wide application prospect in fields such as the radar detection.

Description

A kind of self-adapting clutter suppresses moving-target signal processing technology and implementation method

Technical field

The present invention relates to a kind of self-adapting clutter and suppress moving-target signal processing technology and implementation method.Belong to the moving target signal processing technology in the clutter environment of radar detection field, adopt the adaptive narrow-band bank of filters in the input that realizes the advanced capabilities radar detection system.

Background technology

In the echo signal detection and parameter estimation of radar-probing system, need to survey various flights, motion and standstill target, but not only contain echoed signal in the radar reception signal from moving target, also have from atural object, sexual intercourse and interference echo signal.Radar-probing system need be from than detecting target the much better than clutter of object, will it be designed to a system with the complete Adaptive matching of object, realized the effective detection to target.The present invention is exactly to be the Optimum Matching of moving target with System Signal Processing.

At present existing under clutter and interference environment to the technology of target detection; Generally be to adopt the filtering method that carries out clutter and interference based on the fixed form of FFT method; Because it can not effectively mate with the target spectrum characteristic, thereby can not obtain high performance clutter and jamming performance.

For ease of realizing adaptive process, use FIR as narrow band filter among the present invention: can be according to special requirement, adopt than FFT and more effectively obtain filter characteristic with flexible design method more; Can design different bank of filters respectively, tackle different clutter velocity distribution flexibly; Being not limited to arteries and veins group number, must not be 2 integral number power; Through the corresponding filter coefficient of real-time calculating object, adaptively changing filter characteristic.

Summary of the invention

The object of the present invention is to provide a kind of based on the clutter inhibition technology of Adaptive matching and the method that in FPGA, realizes; Main functional modules is to use cancellation techniques and narrow band filter group to constitute; Self-adaptation adjustment filter coefficient; Thereby realize inhibition to clutter, finally reach improve the moving target letter assorted make an uproar than purpose.

Carry out Dynamic matching according to the signal of clutter improvement factor after with pulse pressure; Main flow process is that the signal that exceeds the signal Processing dynamic range is carried out amplitude limiting processing; But its IQ signal amplitude relativeness is kept; Can the full coherent characteristic of signal not impacted, guarantee the doppler characterization of moving-target, realized the requirement of amplitude limit in the signal Processing and coherent.

Utilize the Doppler frequency spectrum characteristic of reflecting object different, through offseting processing and FIR narrow band filter group it is suppressed for noise signal.For the moving target of paying close attention to; Calculate FIR filter coefficient adaptively through the movement velocity that feeds back to corresponding to this speed; And moving target can not be affected, and has improved the signal to noise ratio (S/N ratio) of moving target, thereby improves the ability that detects moving target.

The present invention realizes on the VPX hardware platform based on FPGA, adopts the VHDL language programming, has realized this Processing Algorithm and has been applied to engineering reality.

The present invention compared with prior art; Its remarkable advantage is: adopt the FIR wave filter to form the narrow band filter group; Can more effectively suppress fixed clutter and slow motion clutter, in complex environment, detect moving target more easily, and calculate from crossing adaptometer.And its Project Realization is simple, on based on the hardware platform of FPGA, can realize real-time processing.This method has that real-time is good, clutter suppresses good effectiveness, and its proposition and Project Realization are of very high actual application value in the radar detection field.

Below in conjunction with accompanying drawing the present invention is described in further detail.

Description of drawings

Fig. 1 is a workflow diagram of the present invention;

Fig. 2 is a FIR bank of filters spectrogram of the present invention;

Fig. 3 is VHDL program realization flow figure of the present invention.

Embodiment

The present invention is based on cancellation techniques, FIR narrow band filter group and CFAR detection and accomplish clutter and suppress and moving object detection, the practical implementation step does, referring to accompanying drawing 1:

Carrying out Dynamic matching according to noise grade and the moving-target handling property signal after to pulse pressure handles;

1, offsets processing;

2, handle through FIR narrow band filter group;

3, respectively each channel signal being carried out range unit logarithm CFAR handles;

4, follow the tracks of the velocity to moving target that provides through monitoring, calculate the FIR wave filter of corresponding speed, signal selects big output in the lump after CFAR is handled and 4..

In use the principle of FIR Filter Design group is: the main lobe of each narrow band filter should be evenly distributed on zero and in signal repetition frequency (0-Fr), cover, to such an extent as to do not lose the target that is in any Doppler frequency (except zero Doppler); The characteristic that guarantees wave filter according to the overall system parameter meets the demands, and generally needs to consider improvement factor, main lobe width, notch depth etc.; Usually all to add once or twice before the narrow band filter and offset, need make fine setting to the FIR coefficient in order to make entire process device frequency response output keep smooth; To keep very dark recess near the zero-frequency.

FIR Filter Design method:

1), according to radar period, antenna bearingt beam angle, signal emission repetition frequency, confirm coherent pulse number in the half-wave bundle.The exponent number of FIR wave filter must lack than coherent pulse number in the half-wave bundle, otherwise the wave beam internal object can lose, and causes moving-target to improve performance and weakens.

2), according to radar improvement factor decision wave filter principal subsidiary lobe ratio, and, the position of wave filter main peak in Fr confirmed according to Doppler frequency.

3), ripple best uniform approximatioss such as employing, dull in the design passband, stopband is for waiting Chebyshev's weighting low-pass filter of ripple.Designing desirable wave filter amplitude function according to 1,2 principle is Hd (w), finds the solution the approximation problem such as best uniform such as ripple such as grade here through Lei Mizi (Remez) algorithm, obtains the unit-sample response Hg (w) of wave filter, has both obtained the FIR filter coefficient.

4), through offseting the wave filter output frequency response out-of-flatness of processing, through to each wave filter amplitude fine setting, and to 3) in the low-pass filter that produces carry out moving on the frequency spectrum, obtain a narrow band filter group.

Each bank of filters frequency spectrum corresponding shown in accompanying drawing 28 rank FIR bank of filters, dotted line is the whole frequency response curve of bank of filters, solid line is a filter frequency.

This method is handled on based on the signal processing platform of FPGA in real time.The function of total system adopts VHDL language to write, and is finally accomplished by FPGA.The VHDL program adopts top-down tree form, and the whole VHDL program structure of system is shown in accompanying drawing 3.Total system is operated under the 128MHz clock.

Suppress moving target processing successful Application type three-dimensional radar detection system based on self-adapting clutter; This method can be adaptively with fixed clutter and slowly motion clutter inhibition; And guarantee that moving target do not suffer a loss, guarantee follow-up parameter measurement precision effectively.

Claims

1. a self-adapting clutter suppresses the moving-target signal processing method; It is characterized in that: adopt based on the narrow band filter group of FIR wave filter and cancellation techniques and realize, realize to the signal to noise ratio (S/N ratio) lifting of moving target with to the inhibition of clutter through adaptive algorithm to the inhibition of clutter with to the coherent accumulation of moving target.This method is strengthened the further inhibition to zero-speed target and microinching target through the appropriate design filter coefficient, eliminates atural object, sexual intercourse, sea clutter and chaff interference etc. to a greater extent, increases the monitoring capability to moving target.

2. realize that the described self-adapting clutter inhibition of claim 1 moving target processing is based on the disposal system that adopts the VHDL language programming to realize on the hardware platform of FPGA for one kind; It is characterized in that: signal is carried out Dynamic matching; Again signal is carried out once the filtering of slake FIR bank of filters, ask the CFAR of mould logarithmetics to handle the signal of each bank of filters.Simultaneously with the reference value of the signal in the zero-speed passage as bank of filters coefficient and CFAR thresholding.