A hybrid LVD-HAF method of quadratic frequency-modulated signals

This paper describes a novel algorithm for estimating the parameters of a quadratic frequency modulated (QFM) signal under low signal to noise ratio (SNR). The proposed method combines the frequency domain method called Lv's Distribution and the time domain method called high order ambiguity function (HAF) to improve the estimation performance. The algorithm is following two stage approaches. First, the phase differentiation is applied on the observed QFM signal to produce a linear frequency signal (LFM). Second, the parameters of LFM are estimated by the LVD, which is simple and can be easily implemented using the complex multiplication. The main significance of the LVD is to convert a 1-D LFM into a 2-D single-frequency signal. Through simulations and analyses, we verify the effectiveness of the Hybrid LVD-HAF algorithm.