Research Of IF Sampling Receiver Technology

Lightning can make a powerful destruction by its great current, very high temperature, strong blast and strong electromagnetic radiation in suddenly, so it caused great harm to country property and people's security. Lightning detection digital receiving which finding the direction of lightning according to the positioning algorithm by the lightning signal it received can play a great role in reducing the country and people's property losses and lightning preventive.This paper according to the general design requirement of the lightning detection system, implementing digital down converte (DDC), array calibrate and SDRAM controller in IF sampling receiver. Firstly, we research the principle of the DDC in this system, according to the maximum output width of each part, controlling the data width reasonably, completing the implementation of 8 channels DDC in FPGA with less resource. After that, in the main of resolving the amplitude-phase errors of the array elements, we studied the algorithm of array calibration, according to the envelope of sinusoidal signal is constant, we add a module to judge whether envelope is constant in order to resist the external interference. At last, according to the timing require of the SDRAM control commands completing the design of the SDRAM interface in FPGA. We proved DDC and array calibration meeting the system requirement by analysed the results of DDC and array calibration in Matlab. The commands of reading and writing SDRAM simulated by Modelsim verify the accuracy of the interface design. The whole system is working well in experiment, the experiment result prove the correctness of our design.