Signal Processing For Time Spreading Channel

Higher capabilities were put forward for homing because of dispersive channels. More and more interest has been attracted by the wideband processing for its versatile, high gain, high resolution and powerful ability of anti-interference compared with the narrow band processing. Based on the theories of Time-Frequency Analysis(TFA) and Wideband Correlation Processing(WCP), this dissertation is devoted to the study of wideband signal processing in multipath ocean environment in a systematic and all-round way. The main contributions are as follows:1. The concepts and properties of wideband signal and Time-Frequency Analysis are introduced. The mode of wideband point-target echoes is presented. WCP and Wideband Ambiguity Function(WAF) is pointed out emphatically.2. Detection of two important dispersive channels resulted with multipath and the reverberation power was studied in theory and simulations. Two approaches to improve the robustness of the detector, each based on a different theirs distortion mechanism. One is based on the modeling as time spreading distortion(TSD) channel whose optimum detector is replica correlation integration(RCI).The second approach is the segmented replica correlator(SRC) for fast fading distortion(FFD).3. Two kinds of typical wideband signal, Line Frequency Modulation(LFM) signal and Hyperbola Frequency Modulation(HFM) signal, is analyzed qualitatively with WAF. Then the author obtain Doppler tolerant signal and time-scale combine resolution signal.4. The Doppler is estimated by Wigner Hough Transform(WHT).The multipath delay is obtained by a so-called "instantaneous time-frequency correlation function " proposed in this paper. The proposed method is characterized by the stronger robustness of additive Gaussian noise and the lower computational cost.