Abstract
This paper considers the coherent integration problem for moving target detection using frequency agile (FA) radar, involving range cell migration (RCM) and the nonuniform phase fluctuations among different pulses caused by range-agile frequency (R-AF) coupling and velocity-time-agile frequency (V-T-AF) coupling. After the analysis of the term corresponding to the phase fluctuation caused by V-T-AF coupling, the term can be regarded as related to an equivalent non-uniform slow time, and nonuniform fast Fourier transform (NUFFT) could be the solution. So a fast coherent integration method combining Radon Fourier transform (RFT) and NUFFT based on low-rank approximation, i.e., Radon-NUFFT, is proposed. In this method, the RCM is solved by Radon algorithm via target trajectory searching, the non-uniform phase fluctuation caused by R-AF coupling is compensated by constructing a compensation item corresponding to the range and agile frequency. In addition, the compensation of the non-uniform phase fluctuation caused by V-T-AF coupling is converted into a problem of spectral analysis of non-uniform sampling complex-valued signal, which is solved by the NUFFT based on low rank approximation. Compared with the existing methods, the proposed method can realize the coherent integration for FA radar accurately and quickly. The effectiveness of the proposed method is verified by simulation experiments.
Highlights
In modern warfare, the capability of anti-jamming is critical to radar system for the survivability in battlefield
As the frequency variation range of the frequency agile (FA) radar is relatively small compared with the nominal frequency f 0, it can be seen from the form of tm = mTr (1 + cm ∆ f / f 0 ) that the sample points are approximately equispaced, so we adopt a nonuniform fast Fourier transform (NUFFT) algorithm based on low rank approximation.We first introduce the NUFFT algorithm based on low rank approximation, and the coherent integration method based on Radon-NUFFT is described in detail
We proposed a coherent integration method based on Radon-NUFFT for moving target detection using an FA radar
Summary
The capability of anti-jamming is critical to radar system for the survivability in battlefield. Radar that incorporate frequency agility, especially pulse-to-pulse carrier frequency agility, has the advantages of enhanced jam resistance and low probability of detection and interception [1]. Coherent integration is an effective anti-clutter technique for radar, and it enhances the capability of moving target detection since it provides the largest signal-to-noise (SNR) output in white Gauss noise. The existing coherent integration methods, such as Keystone transform [3], Radon Fourier transform (RFT) [4], sparse discrete fractional Fourier transform [5], discrete polynomial-phase transform [6] and Radon-Lv’s Distribution [7] are only applicable for conventional radar. Some methods have been proposed for coherent integration of Sensors 2020, 20, 2176; doi:10.3390/s20082176 www.mdpi.com/journal/sensors
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