1. A decoder for decoding a stream of received convolutionally encoded data, which may be corrupted by noise, having a predetermined plurality of possible states and an arbitrary predetermined code rate, comprising an input terminal capable of receiving the stream of convolutionally encoded data; first means connected to said input terminal capable of both (a) effecting the availability of at least a first and a second inverted and noninverted sample of the analog waveform received at said input terminal, each of said samples being separated by a time interval which corresponds to the data rate of the received signal and said first sample corresponds to the most recently received sample, and (b) computing likelihood functions represented by analog voltage signals for all possible transitions into each state of the convolutional code which has a plurality of possible states, said first means selectively using the inverted and noninverted analog waveforms of said first and second samples and the analog voltage signal representative of the most recently computed most probable likelihood function for each of said plurality of possible states for computing said likelihood functions; second means connected to said first means capable of temporarily storing the most recently computed analog voltage signal generated by said first means representative of the most probable likelihood function for each state for subsequent use by said first means for computing the likelihood functions for each possible transition during the next time interval; third means connected to the output of said first means for comparing the analog voltage signals representative of the likelihood functions associated with each state and generating an output signal indicating the most probable transition into each state of said plurality of possible states; and fourth means responsive to the output of said third means for storing the most likely data sequence into each state over a predetermined length and for producing at an output terminal thereof a stream of data corresponding to the decoded data.