Patent ID: 7729440

Claim:
A method of transmitting digital data, the data comprising a series of data items each having either a first value or a second value and exhibiting a rate T, using a frequency modulator to modulate as a function of the data, a central carrier frequency f 0 at a first frequency value f 0 +¼T representing one of the first value and the second value and/or a second frequency value f 0 −¼T representing the other of the first value and the second value, the method comprising: modulating, using the frequency modulator, the central carrier frequency f 0 from one of the first and second frequency values representing the value of one of the data items in the series to the other of the first and second frequency values representing the value of the next data item in the series during a time interval T; and wherein the modulating is performed via successive frequency stages in each of which successive frequency stages the frequency is modulated to have a different respective frequency value, and at the end of the time interval T the frequency attains the other of the first and second frequency values.