| With the fast development of digital technology, the new generation weather radar(CINRAD) based on digital signal processing has formed a net in china from the last century90’s, which greatly improved our forcast ability for disaster weather. While the pace of economic construction and national defense construction accelerate, a more real-time and accurate weather forecast is always required. Weather radar plays an important role in weather forecast, it is the most effective ways for monitoring and forecasting sudden disaster weather.Weather radar always use rectangular pulse transmitting electromagnetic waves for meteorological observation in a single frequency.The observation results show that,there are different scattering degrees between different radar wave’s lengths for meteorological targets,and there is a defect while radar detect different sizes precipitation particles and weather system in a single frequency.The laboratory attempt to develop a new type weather radar has step frequency modulation.lt will be used in meteorological sounding, to investigat the wideband radar significance for different sizes precipitation particles and weather systems.The multi-channel digital receiver technology has developed very well in the field of civil aviation and military.Because of hardware limitations,it is not realistic to design a reciver for proceeing wideband signal directly.The solution is splitting the bandwidth into several receiving channels, and each channel has down-conversion process to produce I/Q quadrature signals independently. In the end, the digital reciver synthesize all channels to form the wideband baseband signals.The paper is responsible for designing a4-channels digital wideband digital receiver.It include the receiver design of digital intermediate frequency sampling circuit, design of multi channel signal conversion, data storage design for baseband signal and hardware realization.The paper describes digital down conversion process in detail, and design CIC filter, HB filter and FIR filter in FPGA(Field-Programmable Gate Array), it use Matlab and Modelsim as simulation tools to simulat all designs, and design a high capacity rapid FIFO as buffer memory for baseband signal.In the end, the paper structure the hardware platform for digital receiver.Theory and board level verification proved that the multi channel digital receiver can satisfy wideband receiver requirements for step frequency modulation radar used for weather forcast. |
