Forward error-correction for the aeronautical satellite communications channel

The effects of ocean-surface multipath on an L-band aeronautical satellite communications channel are examined. It shows that data messages transmitted over the channel exhibit unacceptably high error-rates under typical conditions. Channel characteristics and techniques for reducing the error-rate are discussed, leading to the choice of a diffuse threshold-decodable convolutional forward error-correcting code. Two implementations of coder/decoders for this code are described, one using standard IC logic, and the other a Z-80A microprocessor. Results of tests of the IC coder/decoder with noise, data error bursts, and a system simulator are quoted, which show that the codec performed as expected and is capable of reducing the error-rate to 0.000010 or better.