| This paper mainly studies the hybrid-coded signal waveform designing and signal processing。Waveform designing is one of the key technologies of radar system. It affects directly the characters of the system, such as resolution, precision, clutter rejection and anti-jamming. In recent years, with the development of digital processing technology,it is possible for the new type of detecting technology and radar waveform agile. Because the shortcomings of conventional radar waveform modes, we need to study a new waveform mode which has rich code resources and good detection performance.Firstly, this paper based on classical theory of radar, such as resolution, pulse compression technology, Doppler sensitivity and so on. This paper summarizes the performance of the traditional radar waveforms, researches on Hybrid coding signal design domain in recent years, as well as existing waveforms of Hybrid coding signal. It analyzes the properties of Hybrid coding signal, advantages and disadvantages by means of digital simulation.On this basis, the author choose a new waveform model named random sequence LFM, and analyses its various signal characteristics through digital simulation, including spectral distribution, pulse compression, Doppler sensitivity and cross-correlation properties. Through the study, it found that it’s not practical to use conventional pulse compression method to a random sequence LFM, and the detection performance is defective.In order to play/find the potential of random sequence LFM, this paper further studied and proposed two new special processing methods, which are sequence rearrangement and Subsection accumulation &erase. through digital processing to make up for the defects of random sequence LFM.Sequence rearrangement processing method with reference to Chirp Scaling Imaging algorithm of synthetic aperture radar, in which eliminates range moving of ground Echo by using the frequency domain correction. we introduce CS algorithm in processing random sequence LFM, moving symbol sequence position in frequency domain before the signal pulse compression, and reconstructing the random sequence of linear FM signal as a standard sequence linear frequency modulated signal, then do the pulse(compression) processing, thus effectively reducing the side lobes of pulse compression, and improving the detection capabilities.Subsection accumulation &erase reference to early inverse synthetic aperture radar processing methods, through Subsection processing to improve the Doppler adaptability, then according to the segmented signal pulse pressure distribution characteristics after adding eliminate poor handling, dramatically reducing the sequences cross-correlation, and making the random sequence has a higher linear FM signal practicality.In addition, this paper also proposes a signal processing method by using multispecimen pulse compression. With the improving of digital signal processing ability, using a plurality of signal samples and the corresponding processing method to processing the pulse compression, then fusion processing the results of collected signals, give full play to the advantages of each mode to obtain optimal detection performance.We designed a hardware-in-the-loop simulation system,to prove the Performance of random sequence LFM by experiment. The results show the random sequence LFM has excellence detect Performance by Sequence reconstruction and subsection accumulation &erase algorithms.Lastly, the full paper is concluded, and forecasts the application prospect of random sequence LFM in the waveform agile and detection technology of new type detection technology. The result of this paper has certain significance in the technology of radar waveform design. |
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