Coherent Estimation of Three Positioning Measurements for Unknown Frequency-Hopping Signals in Passive Emitter Localization

Abstract

Due to the superior anti-interception performance and inherent security features, the wide applications of frequency-hopping (FH) signals bring a great challenge to the reconnaissance and monitoring of FH emitters. This paper addresses the problem of positioning measurement estimation for unknown FH signals in passive localization, considering the range migration (RM) and Doppler frequency migration (DFM) of the maneuvering target within the observation time. A coherent range difference (RD), range rate difference (RRD) and acceleration difference (AD) estimation algorithm based on scaled Fourier transform and scaled non-uniform fast Fourier transform is proposed. This method can effectively remove RM and random DFM effects regardless of varied carrier frequency and achieve the coherent estimation of RD, RRD and AD. The whole estimation process can be easily implemented by complex multiplications combined with fast Fourier transform (FFT) and inverse FFT operations without any brute-force searching procedure. Numerical experiments demonstrate that the anti-noise performance of the proposed method is superior to several representative methods and comparable to the optimal maximum likelihood estimator with a much lower computational cost.