Viterbi decoder for digital packet signals

Abstract

An adaptive trellis decoder seamlessly switches between multiple input signal formats. The trellis decoder employs a code sequence detection system, described in the context of an exemplary Viterbi decoding system, that detects codes in an input interleaved packet data signal. The code sequence detection system also reduces the delay (latency) between the input of encoded data and the output of decoded data. The code sequence detection system provides branch metric values in response to the input interleaved packet data signal which exhibits one of a plurality of signal formats, e.g., partial response and normal formats. A Viterbi decoder decodes the packet data signal to produce a decoded output in response to the branch metric values which include a substantially replicated value associated with one of the formats. The Viterbi decoder includes a comparison network that provides decision data in response to branch metric values associated with the trellis encoded data packets. The decision data is organized by trellis state and by data packet and is associated with trellis state transitions. A traceback network provides decoded data in response to the organized decision data.