A forward error correction system for heavily disturbed data transmission channels

This paper describes a new forward error correction system suitable for protected data transmission on heavily disturbed transmission channels, such as radio channels or dialled telephone lines. The system consists of two independent coding stages, one designed to combat random errors due to a binomial distribution and the other to correct the remaining bursts. This configuration adapts the system to channels, which contain random errors as well as bursts. In addition, a signal quality detector and a device designed for channel status measurements control the two coding stages in a way to achieve optimum adaption of the decoders to the actual channel disturbances. The channel status measurement makes a better use of the redundancy of the burst error correction stage. Furthermore, the system´s error detection characteristics avoid the delivery of data to the sink, which cannot be corrected with sufficient residual error probability with high security. Assuming a required residual error rate of Prest ¿ 10¿8, random errors with error rates up to Pist ¿ 10¿3 and bursts with lengths up to about 2900 bits are correctable.