The Institute for Space and Terrestrial Science

Ampex Corporation

Paul S Newby

Pasquale Leone

Dan E Bower

Wayne H Cannon

A simplified fast maximum likelihood decoder for (1-D) channels comprising a first stage decoder for detecting possible charge violations in a threshold decoded input signal, a second stage decoder for resolving charge violations detected in the first stage decoder by finding the most likely data pattern consistent with the charge constraint of the input signal, and an output shift register for generating corrected estimated decoded data in response to receiving control signals output from the second stage decoder.

Fast maximum likelihood decoder

A parallel sync circuit comprising a serial-to parallel converter for converting an input serial into a corresponding parallel signal, a phase detector for detecting possible phase of a sync word in the parallel signal and generating a phase signal responsive thereto, a sync word generator for receiving the phase signal and in response generating a phase shifted stored version of the sync word, and a correlator for comparing the parallel signal to the phase shifted stored version of the sync word and in the event of substantial identity therebetween generating an output signal for indicating detection of the sync word.

Parallel sync detection

The decision feedback decoder of the invention receives sequentially sampled values of a signal waveform corresponding to data bits transmitted by a channel. A magnitude comparator compares the sampled values to a threshold and based on each comparison it provides subsequent decisions determining the values of the corresponding data bits. A predetermined number of previous decisions are stored and applied to a first and a second threshold adjustment circuit. Each circuit adjusts the threshold depending on the respective values of the previous decisions, while the first circuit provides the adjustment based on an assumption that the next decision to be made will have a first signal value and the second circuit provides the adjustment based on an assumption that the next decision will have a second signal value. When that next decision becomes available, it is utilized to select the correct adjusted threshold value for the next comparison by the magnitude comparator.

Growing community of inventors

Toronto, Canada

Paul S Newby