Method for source-controlled channel decoding by expanding the Viterbi algorithm

In Viterbi decoding of radio signals of the type calculating a metric increment ##EQU26## wherein .lambda..sub.k is calculated at time intervals indexed by k, i is a data bit position index, y is a received value, x is a coded bit of a predetermined sequence, and a is a fading factor, the improvement comprising:

• source-controlled channel coding wherein a metric addition B.sub.k is incorporated into the decoding according to the equation ##EQU27## where B.sub.k is a function of the quantity
• u.sub.k L.sub.k =log.sub.10 P(u.sub.k =+1)/P(u.sub.k =-1)!
• and
• if the channel is a binary symmetrical channel then
• B.sub.k =u.sub.k L.sub.k /L.sub.0k
• where
• L.sub.0k =log (1-P.sub.0k)/P.sub.0k !
• and P.sub.0k is the binary symmetrical channel error probability;
• and
• if the channel is a gaussian and fading channel then
• B.sub.k =u.sub.k L.sub.k / (E.sub.s /N.sub.0) log.sub.10 e!
• where E.sub.s /N.sub.0 is the channel signal-to-noise ratio and log .sub.10 e is approximately equal to 0.434.