Design Of The Platform For Processing IF Signal Based On Software Radio

The traditional radio receivers rely on the hardware strongly, and the flexibilityto different communication systems and adaptability to different communicationsignals are bad. The appearance of the SDR (Software-Defined Radio) results inreceiver's renovation. The essential idea of the SDR is to establish a universalhardware platform where the A/D converter is moved as closely as possible to theantenna and the radio functions are accomplished by software as much as possible.Due to the limitation of the device, it is impossible to sample RF signal directly now.So sampling wideband IF signal is a feasible method.This paper places emphasis on the processing technology of the wideband IFsignal. Firstly, the fundamentals including the Sampling theory, Digital DownConverter, Multi-rate signal processing technology and Quadrature Demodulation,which are concerned by IF signal processing, are introduced. And the IF signalprocessing platform was established based on the high-speed and high-precision A/Dconverter AD6644 and the programmable digital down converter AD6620 and thehigh performance DSP TMS320C6416. Secondly, the circuit design and hardwareimplementation of the platform was accomplished, the initial program of theAD6620 was designed and a fast method of the DSP flow of signal transfer andprocessing was came up with. Finally, the demodulation of AM, FM and FSK wasaccomplished on this platform by programming the AD6620 on-line and loading thecorresponding DSP algorithm and the demodulation results were analyzed.The IF signal processing platform designed in this paper is universal andflexible, and embodies the spirit of the SDR. It provides an ideal experimentplatform for the farther study of the SDR and an implementation method for theproduction of the SDR receiver sample.