The Research & Realization Of Software Radio Receive System

In my design, signal is processed directly with software method based on software radio idea, which realizes the AM signal demodulation. The definition of Software Radio (SR) is that the signal is digitalized after antenna, make all processes programmable and make all processes be disposed by software. But with the limitation of performance of A/D and process speed of processor, the more effective method-SDR (Software-defined Radio) emerges, that is to say, SDR reserves the analog part of high frequency. The analog part of SDR includs mixing and magnification of signal from antenna. In my system, input signal from antenna is filtered and magnified and then digitalized.My system can receive the signal frequency from OMHZ to 30MHZ. The system can be divided into 2 parts - analog radio frequency processing part and digital processing pat. Analog radio frequency processing part mainly finishes filtering and magnifying signal from antenna. Digital processing part mainly finishes demodulation, which is made of A/D, D/A, DSP, FPGA. FPGA is the main process unity, and DSP is the main control unity. The peripheral interface is made of PCI interface and USB interface. The key technique of that is:1 Timing control of two ADCs;2 Realization of DDS in FPGA;3 Realization of CIC filter in FPGA;4 Realization of HB filter in FPGA;5 Driver program design of PCI interface chip;6 Firmware of DSP design of USB interface chip;7 Boot of the whole systemAt last, the complete SW signal decoding form OMHZ to 30MHZ and communication between DSP and personal computer through PCI interface and USB interface.