Patent ID: 8406275

Claim:
A communications system including a modulator for generating a chirp signal aimed at spreading the frequency spectrum of an information signal over a specified spectral bandwidth of a communications channel, the chirp signal having an initial instantaneous frequency and a different final instantaneous frequency, the modulator being characterized in that it comprises: means for controlling the chirp signal from an in-phase control signal and a quadrature-phase control signal that define together, in a complex plane, over a whole duration of the chirp signal, a constant amplitude and an instantaneous phase for the chirp signal; and further characterized in that the modulator is arranged so that: an instantaneous frequency is derived from the speed at which the instantaneous phase is changed in the complex plane by the in-phase control signal and the quadrature-phase control signal; the instantaneous frequency is linearly changed between the initial instantaneous frequency and the final instantaneous frequency; initial and final instantaneous phases of the chirp signal are identical.