Detection of LFM signals in low SNR based on STFT and wavelet denoising

In view of continuous time-frequency characteristic of linear frequency modulated (LFM) signals, a detection method based on Short-time Fourier transform (STFT) and wavelet denoising is proposed. Input signals are short-time Fourier transformed into coherent integration of frequency-shift sample sequences with complex envelopes, achieving a time-frequency curve which is to be processed by wavelet, in order to weaken the noise and to detect LFM signals effectively. The scheme remains available in quite a low signal-to-noise (SNR) with low complexity. Simulation results show its fine detection performance in -18dB condition, which meets the demand of electronic reconnaissance to a large extent.