The Design Of LFM Pulse Compression System

Pulse compression is one of the most important technologies in the radar signal procession。The pulse compression technology can resolve the contradictory between the distance and velocity resolutions in RADAR。This paper mainly discusses pulse compression and its design and realization。The project comes from a research job of a particular type of radar signal processor.In this subject, the pulse's repetition cycle is140μs , the A/D sampling frequency can achieve 120 MHz, compression ratio D be superior to 500, the ratio between main and side lobe is superior to 35dB, the target requires high and raised a very high demand of the compression system of processing speed and accuracy. Which way and the selection of optimization algorithm to choose will be the key to achieving this topic.The paper provided a brief overview on the pulse compression technology at first, then introduced the pulse compression, LFM pulse compression principle and FFT Fast Fourier Transform, and other basic theoretical knowledge. The paper analyzes the feature of the LFM signal characteristics and the principle of actualization, then processes to the point of the system design from the improved performance to meet the requirements of real-time according to the feature requirement. The paper discussed the method on the LFM pulse compression and given the composition of the program with the Computer Simulation, especially the components of the modular design.The pulse compression system is chosen the frequency pulse compression approach, the mismatch weighted filtering approach can increase the ratio of main and side lobe, ensure the system requirements of indicators.For the computer simulation, the result of the spectrum at where the echo signal s (t) uses a sampling of f s= 120MHz is exactly the same with the theoretical analysis, which verified that the 120MHZ sampling rate is feasible; the results of the computing simulation under FFT algorithm to the echo signal S (n) is fully consistent with the theoretical analysis; According to the in-phase component I(n) and quadrature component Q(n) which demodulated by S(n) the Filtering simulation results can be showed while the low pass filter and Haiming window weighted matched. The pulse width at -4dBτ0=27ns , the ratio between main and side lobe is -40dB, which Meet the requirements of indicators. Pulse compression system using computer simulation results validated the feasibility of the design plan.LFM pulse compression system design work have achieved the intended purpose.