| With the development of wireless communication technology, sorts of certain pulse waveform are often used to meet specific needs in radar technology. But in the field of weather radar, waveform change less. This paper is designed to adopt step frequency signal to solve the velocity ambiguity problem in Doppler weather radar, devises a receiver part for step frequency signal, including a RF module and intermediate frequency echo signal processing platform.First of all, this paper tells the reasons why velocity and range ambiguity exist in Doppler radar, and the researches on these aspects at both home and abroad. Secondly, we introduce the principle of using step frequency signal to solve Doppler radar ambiguity problem and the pulse compression technique. Meanwhile, various receiver modules are designed respectively to accept step frequency signal, and their properties are simulated, such as receiver bandwidth, VSWR and so on. Furthermore, we excogitate a IF signal processing platform based on software radio, and write procedures of frequency mixing, filtering, PPP(Pulse Pair Processor) algorithm and FFT(Fast Fourier Transform) algorithm via VC++. In addition, we analyze several factors, such as initial phase, A/D truncation error and frequency stability, and their influence on the performance and precision of signal processing platform.On the basis of the theory and analysis about how the step frequency signal achieves the solution of the velocity ambiguity, step frequency signal can solve Doppler radar velocity ambiguity problem. But the performance indexes of the RF front part in receiver are only evaluated by computer simulation, they also need actual verification. Digital echo signal intermediate frequency processing platform also need further inspection for actual effect with simulated meteorological echo signal or real echo signal. |
