Research Of SWR Demodulation Arithmetic And Design Of Digital IF Receiver

In this design, signal is processed directly with software method based on software radio (SWR) idea. Software radio is an innovation in communication field. Radio systems are undergoing the revolution from hardware radios to software radios. Software Radio is an opening system structure, the basic platform of which is composed of modularized and standardized hardware units through bus connection. It can implement radio communication functions through software load.In this paper, the conception of SWR is introduced, and the structure of digital IF receiver system is discussed including its core technology. Demodulation arithmetic of several sorts of signals are researched and simulated with MATLAB tools. Especially, BFSK signal demodulation arithmetic is researched. Demodulation is realized through comparison of magnitude values of two signals in frequency field. The results show that bit-error-rate is less than 8.3e-4 when SNR is over 2dB. The arithmetic is simulated and optimized in C code in the environment of CCS (C6000) on the base of simulation in the environment of MATLAB. Time consumption reduces 22.84% after optimization.The structure of digital IF receiver system in this design is based on DSP + CPLD + PCI bridge. The whole system design includes hardware and software parts. In the design, IF signals (10.7MHz) are digitalized, digital down converted and demodulated. In the end, the IF signals are transmitted to PC through DMA of PCI bridge. Frequency spectrum analysis and result display are completed by application program in PC.