Variable multi-threshold detection for 0.3-GMSK

A method of detecting a plurality of bits of a sampled baseband signal using variable multi-thresholds in a receiver of a communication system with GMSK modulation in its transmitter, comprising the steps of:

• sampling said baseband signal to generate said sampled baseband signal with a predetermined number of samples per bit;
• providing at least 2 previous bits relative to said plurality of bits;
• integrating a plurality of samples within said plurality of present bits to generate a sum corresponding to said plurality of present bits;
• estimating a phase offset of said sampled baseband signal based on said at least 2 previous bits;
• generating a binary decision value representative of said at least 2 previous bits;
• selecting a threshold from a plurality of groups of multi-thresholds based on said phase offset and the binary decision values of said at least two (2) previous bits;
• comparing said sum with said threshold selected to determine a binary decision value representative of said plurality of present bits;
• delaying said binary decision value representative of said plurality of present bits after comparing for selecting the next threshold for the next bit.

A variable multi-threshold circuit for a sampled baseband signal in the receiver of a communication system using GMSK modulation with BT between 0.2 and 0.5 in the transmitter, comprising:

• integrate/dump means for accumulating a predetermined number of samples of said sampled signal to generate a sum for a present bit;
• means for providing a predetermined number of previous bits relative to said present bit;
• digital processing means for generating an estimated phase offset based on said predetermined number of previous bits;
• means coupled to said digital processing means for generating a binary value representative of said predetermined number of previous bits;
• level selector means for selecting a threshold from a plurality of groups of multi-thresholds based on said estimated phase offset and the binary value of said predetermined number of previous bits;
• compare means for comparing the sum from said integrate/dump means with said threshold selected from said level selector means to generate a binary value of either one of "0" or "1" for said present bit;
• and
• delay means for delaying said binary value representative of said present bit from said compare means to be used by said level selector means to determine a next threshold for a next bit.