Based On Fractional Fourier Transform Amplitude Linear Fm Signal Detection

As a new outlooking field, the research of linear Frequency Modulation(LFM) signal with time-varying amplitude is being paid more and more attentions, and is carried through with all kinds of means recently.Based on the preceeding research done by others, the detection and parameter estimation of the time-varying amplitude LFM signals using the Fractional Fourier Transform(FRFT) is focused in this dissertation, and the main contributions are:1. The detect method based on FRFT is explored, the grad-search method is used to simplify the peak detection in the fractional Fourier domains with no accuracy degradation.2. The Ozaktas's algorithm of the FRFT requires the dimensional normalization and it's effect on the paramer estimation of the LFM signal is studied , a relationship before and after the normalization is developed ,and how apply the algorithm with practical discrete signal is now settled.3. In order to suppress the interference induced by strong signals on the detection and estimation of weak signals, a signal separation technique in the fractional Fourier domain is further devised that will provide significant improvements in terms of detection performance and estimation precisions.4. The theoretical analysis about the properties of the detect method is provided, and the property feature of the output signal-noise ratio(SNR_out) is derived. The validity of the detect method is also verified by simulation results.