Digital detector

DETAILED DESCRIPTION According to the present invention there is provided a digital detector to convert an audio frequency signal into a digital signal, characterized in that the detector comprises an Analog/Digital (A/D) converter for producing a first binary word (W.
sub.
o) corresponding tot he offset voltage of the detector, and a second binary word (W.
sub.
s) corresponding to each detected signal.
The digital detector further includes an offset voltage removal block in which the first binary word (W.
sub.
o), corresponding to the offset of the detector, is subtracted from each second binary word (W.
sub.
s), corresponding to each received signal, to provide a plurality of third binary words (W.
sub.
ss) representing modified signal symbols corresponding to each received signal.
The digital detector further includes a comparator for comparing each third binary word (W.
sub.
ss) with a set of predetermined decision levels to determine an output symbol, and a block for updating the set of predetermined decision levels responsive to changes in the received audio frequency signals as represented in changes in the third binary words (W.
sub.
ss).