On the implementation of a transciever to demodulate 384 MP3 satellite channels and remodulate them as 384 FDM stereo FM channels for cable distribution

We describe the implementation of a unique digital transceiver system. This system decodes up to 384 MP3 stereo audio signals received from a satellite downlink. It digitally remodulates the multiple sampled data signal sets as analog FDM signal composed of dbx [1] (noise reduction system) encoded FM stereo signals. The MP3 decoding is performed by 48 Analog Devices Blackfin Processors. The dbx encoding, system specific stereo FM modulation and re-sampling channelizer is performed in a single Xilinx Virtex-4 XC4VSX55 FPGA. The FPGA outputs a single sampled data stream of channelized FDM signal spanning approximately the 20-to-80 MHz frequency band. The emphasis of this paper is the tasks performed in the FPGA based modulator.