Compressed Sensing And Its Application In Parameters Estimation Of Wideband Array Signals

Array signal processing is one of the important parts of signal analysis and processing, which is widely used in communication, radar, sonar, chronometer and other areas of science and technology. One of the key problems to be solved array signals processing is parameter estimation, like the most attentioned problem:direction of arrival (DOA) of signal. With the fast development of communication technologies, many wide-band signals, such as spread-spectrum signal, frequency-hopping signal and linear frequency modulation (LFM) signal, are used more and more widely in communication systems. In addition, many signals, such as seismology wave is a kind of wide-band signal in nature. Currently, time-frequency method is widely used for DOA of wide-band array signals, but some disadvantages like selection of the correct time-frequency points exist in these methods. In addition, large-scale data processing is also a problem cause by tranditonal Nyquist sampling. So the research on wide-band array signal processing method becomes more and more vital.After the sparse decomposition of signals, a new theory called compressed sensing was present on 2006, which breaks the classical signal sampling rule and with many new advantages. If the signal is sparse on some domain, it's possible to be reconstructed based on far fewer random samples than required by tranditional Nyquist sampling rate. Based on the reaserches of compressed sensing, this paper applies it to wideband array signal parameters estimation problems, and presents a new way to frequency and DOA estimation of wideband LFM signals. The main work and contributions of the thesis as follows:1. Theory of compressed sensing was studied totally, from basic theory principle to the key points of compressed sensing, include:measurement matrix, sparse representation of signal and signal recovery algorithm.2. Several new methods based on compressed sensing are researched to estimate the frequency and DOA parameters of wideband LFM signals in array signal processing. Because the target parameter is sparse in the space of parameters, for example, single DOA of signal, our target is to find the DOA of signal source, so the only one direction is sparse in angle space, so it's possible to find the DOA by compressed sensing method. According to realization of compressed sensing, the measurement matrix, over-complete atom dictionary for signal sparse representation are constructed separately, a kind of recovery algorithm is selected, then the frequency and DOA parameters of LFM signal can be estimated. Experimental simulations show that the resolution is much higher than conventional methods (like STFD) in the case of lower samples situation.3. Single and multiple source DOA estimation of wideband LFM signal method based on compressed sensing was presented. To multi-source DO A problem, when the sources are disrelated or the relativity of the sources is very small, it's also feasible to use compressed sensing method to get a good estimation result under low samples situation.Using compressed sensing method to estimate parameters of wide-band array signal which avoid so many disadvantages, like the selection of the correct time-frequency points and performance cross-terms impact in time-frequency method, and large-scale data storage and transmission cause by traditional sampling way.