The Research Of Pulse Compression For Weather Radars

This thesis discusses the techniques of pulse compression for weather radar,mainly studying coded waveforms and pulse compression filters with sidelobesuppression. In this paper, Baker code is used as the phase-coded waveform of pulsecompression for weather radar, and the inverse filter is used as compression filter andsidelobe suppression filter.Firstly, we introduce the detection theory of typical PD (Pulse Doppler) weatherradar, and analyze the characteristics of echoes in time and frequency domain. As aresult, the power spectrum of weather echoes is close to Gauss distribution. The echosignal for simple pulse weather radar is simulated.Secondly, with discussing Baker codes' time-frequency characteristics,ambiguity function, and auto correlation, Baker codes have a good correlation. A13-bit Baker code is used in the context, because of its large compression ratio andeasy implement. After analysis of pulse compression filter, the inverse filter is usedas compression filter for weather radar, because the match filter has high rangesidelobe level even with weight sidelobe suppression. By the way, the method ofspectrum estimation is discussed.Finally, the results from simulation and analysis of point targets, the ISL for theinverse filter improve with increasing Doppler shifts and declining with increasingSNR. At the same velocity and SNR, the IF×7 filter is better than other filter. And theresults from simulation of time-varying distributed targets show that, the match filterand IF×1 have high sidelobes, and IF×5 have a good result at power estimation, butnot at velocity and spectrum. However, the IF×7 does a good job of estimating boththe power and Doppler velocity at large gradient, which is the same as simple pulseoutput.