Parameters estimation of LFM signals based on STTFD

The accurate estimation of the center frequency and the chirp rate of a linear frequency- modulated (LFM) signal palys an important role in radar signal processing. The WVD transform can show the characteristic of the center frequency and the chirp rate of a LFM signal, but the cross-terms of signals deteriorates the precision of the estimation of the center frequency and the chirp rate. So, in order to estimate those parameters of the LFM signals better, this paper proposes a new method based on the scaling transform in time-frequency distribution plane (STTFD) for the parameters estimation of the LFM signals, by which the frequency of each LFM signal in time-frequency plane changes from the linear distribution along the time axis to the constant distribution along the time axis, then the coupling effect between the signal time and the correlation function delay can be removed and the center frequencies and the chirp rates of the LFM signals can be accurately estimated by the peak value locations of accumulated signals realized by the Fourier transform with respect to the time domain. At the same time, the analysis of the characteristic of STTFD is given in detail. Finally, the simulated result shows that the method proposed in this paper can effectively weaken the effect of the cross-terms and accurately estimate the center frequencies and the chirp rates of the LFM signals.