Patent ID: 8050359

Claim:
A method for modulating an RF signal, comprising modulating an RF signal using frequency shift keying (FSK) modulation to define a plurality of symbols, said FSK modulation including transitioning an FSK tone between at least two different frequencies beginning at a transition start time; defining a guard period time interval during which samples of the FSK tone are not used for identifying said plurality of symbols, said guard period extending a predetermined duration from said transition start time; generating said FSK tone by using a sinusoidal waveform generator which determines a sinusoidal output sample value based on an input phase angle, and generates each said sample value by adding a delta phase angle to a previous said input phase angle; and performing operations in a phase domain to vary a frequency of said FSK tone in accordance with a predetermined rate of change, said operations including selectively varying said delta phase angle during said guard period to change said frequency of said FSK tone in accordance with a selected frequency transition profile.