Research Of Wideband Radar Signal Correlation System Based On Acousto-optic Processing

Coherent Optical processing applied optical Fourier Transforming to realize complex function. According to spatial optical modulator, two processed signal have been modulated by coherent optic, and correlated in frequency domain. So optical processing behaves wideband and high speed characteristics, it must be better than wideband digital processing in power and volume. In this thesis, a new space-integrating acousto-optic correlator was optimized, mainly discussed and simulated. And eventually the useful information’s extraction of wideband radar signal has achieved.The main contents of this thesis are as follows:Firstly, the application background and development status of wideband radar and AOP technology have been introduced.Secondly, this thesis simply described the classification of radar signals, while elaborated form of linear frequency modulation signal, the principle of pulse pressure and the impact of Doppler shift. And we also discussed the characteristics of the echo, the relationship of time delay and distance, speed and Doppler shift.Thirdly, based on acousto-optic interaction theory, the working principle of AOD, which is the most central part of the system, was described. We discussed several important parameters of AOD, and showed the amplitude expression of the diffraction light.Fourthly, the optical path structure part of space-integrating acousto-optic correlation system is optimized. We deduced the light intensity expression on the CCD, clearly explained why and how to use multi-line light intensity signals of the CCD to extract data by cross-correlation function. We also showed some specific data of devices parameters in the optical path based on actual situation. Frequency scale was simulated, and extends its functionality to frequency measurement. Meanwhile, we discussed the effect of angular deviation on system.Fifthly, the principle simulation of system was completed. We simulated the diffraction light cross-correlation results of single-frequency and wideband signals, then extracted the delay time and pulse width of radar echo signal and compared the results. We also analyzed the effect of different radar signal bandwidths and different speeds of target on the diffraction light cross-correlation results in some detail.