| Abstract: | An implementation of a 16 state, rate 8/9 six-dimensional (6-D) 8PSK rotationally invariant trellis decoder for use in a concatenated codec is described. The concatenated codec allows transmission of STM-1 signals (at the 155.52 Mb/s information rate) over a 72 MHz satellite transponder. The inner trellis decoder is used with an outer (255,239) RS block decoder. The trellis decoder operates at 165.93 Mb/s and currently has an implementation loss of only 0.2 dB. The concatenated codec achieves a bit error ratio of 10?10 at an Eb/N0 of 8.2 dB (assuming an ideal modem and AWGN channel). Details are given of many Viterbi decoding ‘tricks’ that were used in order to implement the main functions of the decoder on two 10,000 gate equivalent CMOS programmable gate arrays. |
