Radar moving target radon-fractional Fourier transform long-time phase-coherent accumulation detection method

Abstract

The invention relates to a radar moving target Radon-fractional Fourier transform (RFRFT) long-time phase-coherent accumulation detection method, and belongs to the technical field of radar signal processing and detection. The radar moving target Radon-fractional Fourier transform long-time phase-coherent accumulation detection method includes steps of 1), performing range demodulation and pulse pressure for radar echo to complete intra-pulse accumulation; 2), initializing parameters; 3), completing long-time inter-pulse phase-coherent accumulation by RFRFT compensation distance and Doppler frequency migration; 4), traversing all search parameters and creating a distance-RFRFT domain detection unit graph; 5), performing constant false alarm rate detection for the detection unit graph; and 6), estimating movement parameters of a target and outputting movement point traces. The radar moving target Radon-fractional Fourier transform long-time phase-coherent accumulation detection method has the advantages that amplitude information and phase information of the echo of the moving target are simultaneously utilized for long-time phase-coherent accumulation, the distance and the Doppler frequency migration in a long-time accumulation procedure are compensated, background clutter and noise are effectively suppressed, an accumulation gain is increased, dim moving targets in the heavy cluster can be detected, the movement point traces of the target can be acquired, and the method has popularization and application value.

Description

1. Technical field [0001] The invention belongs to the technical field of radar signal processing and detection. More specifically, the invention relates to a radar moving target Radon-fractional Fourier transform long-term coherent accumulation detection method, which can be used for radar detection of weak moving targets in complex environments deal with. 2. Background technology [0002] With the development of science and technology, especially the continuous development of high-speed targets and the increasing maturity of stealth technology, robust and effective radar moving target detection has always been a difficult problem in the field of radar signal processing. Research on signal processing to improve the ability of radar to detect weak moving targets method is important. The complexity of target detection not only comes from the target itself, but also is affected by the increasingly complex electromagnetic environment and clutter background. There are many type...

AI Technical Summary

Problems solved by technology

Commonly used non-coherent accumulation methods include envelope interpolation displacement compensation method, dynamic programming method, maximum likelihood method, Hough transform method, etc. Non-coherent accumulation has no strict coherent requirements for the system, and is relatively simple in engineering implementation. However, its signal accumulation efficiency and signal-to-noise (noise) ratio improvement are significantly lower than the coherent accumulation method, which is not suitable for the detection of weak moving targets in complex environments.

Coherent accumulation technology uses the motion characteristics of the target and Doppler information to obtain higher accumulation gain, but at present, long-term coherent accumulation mainly faces the following two problems: on the one hand, due to the continuous improvement of radar distance resolution and The high-speed movement of the target, when accumulated for a long time, the target echo envelope walks between different pulse periods, which is called the distance migration effect (Across Range Walk, ARU), which makes the target energy disperse in the distance direction. The traditional distance-based The moving target detection (Moving Target Detection, MTD) method of the unit can no longer effectively adapt to the detection of this type of target, and it is necessary to perform echo distance migration compensation before detection; on the other hand, during long-term coherent accumulation, the uniform acceleration of the target Motion or high-order motion will cause the echo phase to change, so that the radar echo signal has time-varying characteristics and appears in the form of high-order phase. The Doppler frequency of the target will span multiple Doppler units, which is called Doppler migration Effect (Doppler Frequency Migration, DFM), which makes the target energy dispersed in the frequency domain, reducing the coherent accumulation gain

In addition, for high-speed moving targets, the distance and Doppler frequency will still change greatly in a short accumulation time, and the distance and Doppler migration will also occur, which will affect the accumulation effect

[0005] For range migration compensation, existing methods include envelope correlation methods (such as cross-correlation method, minimum entropy method, spectral peak tracking method, etc.), but in the case of low signal-to-noise (noise) ratio, due to the adjacent echo correlation Poor and unable to obtain a better envelope alignment effect; the Keystone transform method relies on the Doppler ambiguity of the target echo; the Radon-Fourier Transform method (Radon-Fourier Transform, RFT) through the joint search of the target in the parameter space The parameter method solves the coupling problem of distance migration and phase modulation, but it assumes that the target moves at a uniform speed, and the algorithm complexity is high

For Doppler migration compensation, existing methods include De-chirp method, Chirp-Fourier transform method, polynomial phase method and fractional Fourier transform method (FRactional Fourier Transform, FRFT), etc., but the compensation performance is poor. Limited by estimated signal length

At present, there are few long-term coherent accumulation methods that can compensate for range and Doppler migration at the same time, and the accumulation gain is often affected by the signal-to-noise (noise) ratio, which is not suitable for signal processing in complex clutter background environments

The above problems limit the practical application of the long-term coherent accumulation method for weak moving targets at long distances or high-speed and high-maneuvering targets

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