Receiver for multivalued digital signals

A receiver for multivalued digital signals, the voltage level of a received signal with respect to a reference level thereof signifying a logic value of said signal;

• said receiver comprising:
• comparator circuit means for comparing the voltage level of a received signal with a number of decision threshold voltage levels corresponding to respective logic values, and producing from such comparisons an output signal having a logic value corresponding to the logic value of the received signal;
• circuit means for regenerating said decision thresholds, such circuit means being coupled to said comparator circuit means to receive said output signal and derive therefrom a regenerated signal, said regenerated signal being at a voltage level equal to a decision threshold which corresponds to the logic value of said output signal;
• and
• adaptation circuit means for receiving said regenerated signal and said output signal and deriving therefrom an error signal corresponding to the difference therebetween;
• said adaptation circuit means comprising means for adjusting the decision thresholds generated by said decision threshold generating means in accordance with said error signal, so as to reduce the difference between said regenerated signal and said received signal;
• characterized in that said adaptation circuit means further comprises control means for classifying the output signal into one of at least two different categories on the basis of the logic value thereof, said control means being adapted to
• prevent said decision threshold adjusting means from reducing the decision thresholds when the regenerated signal is in a first of said categories;
• and
• prevent said decision threshold adjusting means from increasing the decision thresholds when the regenerated signal is in a second of said categories.