A Novel Real-Scene Echoes Signals Physical Simulator of Doppler Weather Radar

The calibration and quantitative performance test of receiver system is indispensable and the echo signals are needed during the development, debugging, routine maintenance and repair of the Doppler weather radar. Traditionally, the real meteorological targets echoes are used for the receiver as a test signals in the filed test. But this method is high cost, complicated process and long period. And it is difficult for quantitative test because the parameters of meteorological targets are uncontrollable. Currently,a point frequency which was not having the characteristics of the weather rather than a spectrum signal was generated from the universal signal generators or from the special test instruments manufactured by some manufacturers. So this signal could be used for doing calibration that verifies the system hardware technical performance through measuring the technical parameters of the system channel, but could not be applied to the terminal algorithm verification and dynamic test. To avoid these defects, this paper presents a simple, quick and economic method for developing the hardware and software of the real-scene echoes signals simulator system. The parameters of the simulation weather phenomena are set through the simulator's Human-Computer Interface, and then the parameters are calculated to obtain a complex spectrum that was composed by the random phase spectrum and the random Doppler power spectrum which is Gaussian distribution and contains Gaussian White noise. The IQ signals that correspond to the signals of the receiver's I channel and Q channel are produced from complex spectrum by Inverse Fourier transform, respectively. Through IQ modulation and pulse modulation, a analog Intermediate Frequency (IF) signal was generated by the IQ signals. The IF signal can be directly added to the IF receiver front-end, or connected to RF front-end by up-conversion to RF signal for the weather radar receiver system quantitative test and the terminal algorithm verification. The experiment results on dual polarization Doppler weather radar WSR-98D/XD show that the simulator not only can successfully simulate a great diversity of signals which approximated to the real weather echoes signals, for instance, precipitation, blizzard, hailstone, front, hurricane, tornado, clear air, but also can simulate the complex environmental noise that close to the radar actual work condition. Some echoes of the extreme weather phenomenal which were hardly received or never occurred in the test field can be used for improving the performance of the Doppler weather radar. And the Ultimate performance of radar receiver was obtained through quantitative test and analysis. The simulator systematic error was in the precision requirements of the WSR-98D/XD system.