Patent ID: 8275073

Claim:
A method for discriminating between phase-shift-key (PSK) modulation and frequency-shift-key (FSK) modulation in a received signal stream, comprising: receiving an analog signal stream with receive path circuitry; converting the analog signal stream to a digital signal stream; analyzing bit frequency for a plurality of bit segments within the digital signal stream to determine for a each bit segment a frequency (f max ) at which a maximum signal energy occurs within the bit segment; combining the maximum frequencies (f max ) to generate a bit frequency histogram for the bit frequency of the plurality of bit segments; determining that the digital signal stream includes PSK modulated signals if a number of frequency spikes in the bit frequency histogram is one, that the digital signal stream includes FSK modulated signals if a number of frequency spikes in the bit frequency histogram is greater than one, and that a PSK/FSK determination cannot be made if a number of frequency spikes is not determinable; and outputting PSK/FSK determination signals representing the results of the determining step.