A Study Of Implement Methods Of Ambiguity Resolution In Weather Radar

Weather radar is a major means for atmospheric monitoring, But for a certain repetition frequency, when the wavelength of weather radar is short, the range and velocity ambiguity problems can exist at the same time. The ambiguous problems would make the parameters obtained by spectrum estimation inaccurate, but also cause radar hard to observe and forecast the special meteorological phenomena. In view of these problems, some practice methods of ambiguity resolution of the weather radar signal processing mainly be discussed. The major contents are outlined as follows:1. The echo characteristic of weather radar has been discussed. The simulation of a Gauss model of echo is constructed, and meantime the two algorithms commonly used for spectral moment estimation in engineering project are given, a method called Pulse Pair Processing in time domain and a method of Fast Fourier Transformation in frequency domain, and the performance of two methods of spectral moment estimation is given by simulation, meantime the radar echo figures are given out.2. Some methods of the velocity ambiguity have been discussed in detail. The distinguishing method of the velocity ambiguity is made out. some methods of the velocity ambiguity are given out, including a software method, a Dual PRF method and a method called three PRF, which a common method of Dual PRF to extend the velocity range in engineering project is mainly discussed. But due to some points of the velocity ambiguity after the Dual PRF processing, combined with simulation analysis, and a new formula is given out through modifying the original velocity estimation formula, and the new velocity estimation formula really solves the velocity ambiguity in a certain range.3. A series of discussions and study of some methods of the weather radar signal processing to eliminate the distance ambiguity have been clarified. T[-he principle of the random phase coding method to eliminate the range ambiguity is discussed, and there are some problems when the method is applied to the engineering project. In view of the problems, a better performance method of SZ-2 phase coding is given out, and some relevant technical of SZ-2 phase coding method are mainly studied, including SZ(8/64) phase coding, the design of FIR band stop filter and the ground clutter suppression processing technology when eliminating the range ambiguity and other problems, and meantime the processing is simulated. Compared with the suppression performances of the time domain method of four order IIR high-pass elliptic filter, the frequency domain method of Gaussian model adaptive processing has a good result. Finally the performances of SZ-2 phase coding are introduced.Based on the realization of the common processing of weather radar, the extended velocity method of Dual PRF and SZ-2 phase coding are applied in range-velocity ambiguity resolution, and then are realized in the DSP by programming, and from the experimental results, it can conclude that the two methods have a good effect on range-velocity ambiguity resolution.