A Design Of Deinterleaver In QAM Demodulation Chip

The techonology of convolutional interleaving and deinterleaving is an important addition to the Reed-Soloman coding and decoding system. When continual erupting errors happen in the channel, sometimes may go beyond the error correcting range, it's necessary to use the technology of interleaving and deinterleaving to disperse the errors so that the RS decoder can work well.This paper is to design and implement a RS(204,188)-oriented convolutional deinterleaver, which complies with the DVB-C standard. The digital demodulation system in the DVB-C was firstly introduced in this paper, secondly the principle and methods of interleaving, then some hardware implementation of convolutional interleaving and deinterleaving were presented and comared as well, finally a good design method was given. A RS(204,188)-oriented convolutional deinterleaver, which comlies with the DVB-C standard, convolutional depth equals 12, cell depth equals 17, was presented. This convolutional deinterleaver uses the method of RAM whole block cycle shifting which unifies the SRAM address. Because of the using of single port SRAM, the circuit area is saved. Furthermore a controlling method of reading and writing data of the SRAM speeds up the deinterleaver. In this paper hardware description language was used to design the deinterleaver, then the circuit passed the simulation and verification. The simulation result showed the convolutional deinterleaver presented in this paper, combined with RS decoder, can decode the bit stream according with the DVB-C standard, and can be applied in the set-top boxes of HDTV and so on.