System for improving the performance at low signal-to-noise ratios of receivers with Viterbi decoders

摘要

The present invention includes a method and system for improving performance of a receiver at a low signal-to-noise ratio. According to a first aspect, an encoded signal is received. The encoded signal is decoded to recover information in the encoded signal. Next, a threshold is ascertained in response to the recovered information, the threshold indicating a maximum number of acceptable errors in the recovered information. It is determined if the errors in the recovered information are in excess of the ascertained threshold. Information is then extracted from the encoded signal without decoding. The extracted information is output when the errors in the recovered information are in excess of the ascertained threshold. In all other instances, the recovered information is output. According to a second aspect, recovered signal data is output, the recovered signal data being either the recovered information or the extracted information. Next, an encoding type of the recovered signal data is determined, the encoding type being feedforward encoding when the encoding is in a first state, and being feedback encoding when the encoding is in a second state. A data transformation is then performed, the data transformation adapted for performing conversion for a feedforward encoder when the encoding type is feedforward encoding, and adapted for performing conversion for a feedback encoder when the encoding type is feedback encoding.