Radar moving target long-time phase-coherent accumulation detecting method based on RFRAF

Abstract

The invention relates to a radar moving target long-time phase-coherent accumulation detecting method based on an RFRAF, and belongs to the technical field of radar signal processing and detection. The method comprises the following steps that (1) radar echo data are demodulated, pulsed and compressed in the distance direction, and pulse accumulation is completed; (2) parameters are initialized; (3) the RFRAT is adopted to compensate distance and Doppler migration, and then long-time interpulse phase-coherent accumulation is completed: (4) the parameters are transversely searched, an RFRAT domain detecting unit map is constructed, and constant false alarm detection is conducted; (5) target moving parameters are estimated, and moving trace points are output. The advantages of the ambiguity function and fractional order Flourier transformation are synthesized, high order phase signals of a target generated in the moving process can be flexibly matched and accumulated, the distance and Doppler migration are compensated, accumulation and gain of a radar to complex moving target signals are improved, the capacity of detecting weak moving targets in strong clutters is possessed, the moving trace points of the target can be acquired, and popularization and application value are achieved.

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 long-term coherent accumulation detection method for radar moving targets based on Radon-fractional ambiguity functions, which can be used for radar detection of weak moving targets in complex environments deal with. 2. Background technology [0002] As the main electronic information equipment, radar is responsible for important tasks such as information acquisition and precision guidance in modern warfare. In recent years, the emergence of low-altitude / ultra-low-altitude penetration, anti-radiation missiles (Anti Radar Missile, ARM), comprehensive electronic countermeasures (Electronic Counter Measures, ECM) and stealth targets have greatly weakened the ability of radar to detect targets, and have The living environment of radar presents serious challenges. In particular, stealth weapons and equipment (such as stea...

AI Technical Summary

Problems solved by technology

At present, the long-term coherent accumulation mainly faces the following two problems: on the one hand, due to the continuous improvement of the radar range resolution and the high-speed movement of the target, the target echo envelope moves between different pulse periods during the long-term accumulation. It is called the distance migration effect (Across Range Walk, ARU), which causes the target energy to disperse in the distance direction, and it is necessary to perform echo distance migration compensation before detection; on the other hand, during long-term coherent accumulation, due to the instability of the engine Or the complex environment makes the target echo produce high-order phase, which has time-varying characteristics. For example, the thrust change of rockets and missiles during flight causes the jerk (jerk) to produce more than two high-order phases. For target detection under sea conditions, the target is bumped with the sea surface, and the echo produces high-order terms. At this time, the target energy will spread in the Doppler dimension, and the frequency will span multiple Doppler units, which is called Doppler migration. Effect (Doppler Frequency Migration, DFM), reducing the coherent accumulation gain

[0004] In order to solve the problem of distance migration, the 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 performance and can not obtain better envelope alignment; the Keystone transform method relies on the Doppler ambiguity of the target echo; the Radon-Fourier Transform method (Radon-Fourier Transform, RFT) searches the parameter space The method of target parameters solves the problem of coupling range migration and phase modulation, but it assumes that the target moves at a uniform speed

For Doppler migration compensation, existing methods include De-chirp method, Chirp-Fourier transform method, Fractional Fourier Transform (FRactional Fourier Transform, FRFT), Fractional Ambiguity Function (FRactional Ambiguity Function, FRAF), etc., but the compensation performance is limited by the 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

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