The Coherent Processing And Compressed Sensing Method Of Chaotic Radar

Chaotic signal is a special kind of noisy signal, It has natural wideband characteristics. Therefore, the chaotic radar based on this signal has many incomparable advantages, such as the high resolution, flat power spectrum, low probability of intercept, strong anti-jamming ability, etc. But now, the chaotic signal is hard to achieve the time delay, so there is a problem of the coherent processing of echo signal which is caused by the fact that the matched filter is very difficult to realize for chaotic radar.Compressed sensing theory which can recover sparse signal by reconstruction algorithm has the potential to eliminate the use of matched filters and high-speed A / D sampling devices in radar. But the research literature for compressed sensing applied into the field of chaotic radar is few.This thesis focuses on the issues about the time delay of chaotic signal, the speed measurement of chaotic radar, the application of compressed sensing in chaotic radar, etc. And the main work is summarized as follows:(1) Study on the time-delay synchronication based on low-cost coherent radarGive the model of the time-delay synchronication based on the coherent chaotic system according to the synchronication theory. Through optimizing parameters, the output between the response system and the drive system reaches the time-delay synchronization. The algorithm realizes the state of the time delay for wideband chaotic signals in the analog domain by the synchronization character of chaos. It has three advantages:(a)The time- delay signal has little distortion;(b)It can achieve a greater delay;(c)The cost is low.(2) Study on the measurement of speed based on low-cost coherent radarBy the theoretical analysis, the radar echo signal is the time scale transformation signal of the transmitted signal. The time scale of transform coefficients contain the speed information. By constructing the time scale conversion system of the transmitting chaotic system and adjusting the time scale transformation coefficients, it could produce a series of time-scale transform chaotic signals. The speed information will be obtained through the way that these above signals will be associated processing with the echo signal. Simulation results show that the algorithm can simultaneously measure several targets even if the conditions of the echo signal to noise ratio is much lower.(3) Study on the compressed sensing theory applied into the imaging of the chaotic FM radarA kind of imaging algorithm on chaotic radar based on the theory of compressive sensing is proposed. Through a complete dictionary, the radar converts the detection of targets into a reconstruction issue of sparse signals in this comprehensive dictionary so that it can achieve imaging. Chaos FM signal and LFM signal separately constructs correlation measurement matrix. By calculating the eigenvalues of the two kind matrixs, verifying that the matrix which is constructed by the chaotic FM signal strictly meets restricted isometry property. Simulation results show that the compressed sensing imaging algorithm based on chaotic FM signal has high-precision、high-resolution advantages.