Abstract: A communications system includes 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 has initial and final instantaneous frequency. The chirp signal is controlled from an in-phase control signal and a quadrature-phase control signal to have, in a complex plane, constant amplitude and instantaneous phase. The instantaneous frequency is defined by the speed the instantaneous phase is changed in the complex plane by the in-phase and quadrature-phase control signals; the instantaneous frequency is linearly changed between initial and instantaneous frequencies over the whole duration of the chirp signal; the initial and final instantaneous phases of the chirp signal are identical.

Abstract: System for converting a radiofrequency signal SRX so as to recover encoded information carried by the signal SRX, includes generating elements arranged to generate a signal SLO, mixing elements (3) arranged to generate a signal SRX-LO by mixing the signal SRX with the signal SLO, an analog/digital converter arranged to convert the signal SRXLO into a digital signal SRX-LO-Num, a device generating an error correction digital signal SCor, the device being arranged so that the signal SCor reflects the phase gap between the phase of the signal SLO and a phase setpoint, the phase setpoint being the phase of an ideal signal S0, ideal for recovering the encoded information carried by the signal SRX, combining elements arranged to generate the signal S0?-Num by combining the signal SRX-LO-Num with the signal SCor. A system for converting a digital signal so as to send a radiofrequency analog signal carrying the information of the digital signal is also described.

Abstract: A communications system includes 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 has initial and final instantaneous frequency. The chirp signal is controlled from an in-phase control signal and a quadrature-phase control signal to have, in a complex plane, constant amplitude and instantaneous phase. The instantaneous frequency is defined by the speed the instantaneous phase is changed in the complex plane by the in-phase and quadrature-phase control signals; the instantaneous frequency is linearly changed between initial and instantaneous frequencies over the whole duration of the chirp signal; the initial and final instantaneous phases of the chirp signal are identical.

Abstract: System for converting a radiofrequency signal SRX so as to recover encoded information carried by the signal SRX, includes generating elements arranged to generate a signal SLO, mixing elements (3) arranged to generate a signal SRX-LO by mixing the signal SRX with the signal SLO, an analog/digital converter arranged to convert the signal SRXLO into a digital signal SRX-LO-Num, a device generating an error correction digital signal SCor, the device being arranged so that the signal SCor reflects the phase gap between the phase of the signal SLO and a phase setpoint, the phase setpoint being the phase of an ideal signal S0, ideal for recovering the encoded information carried by the signal SRX, combining elements arranged to generate the signal S0?Num by combining the signal SRX-LO-Num with the signal SCor. A system for converting a digital signal so as to send a radiofrequency analog signal carrying the information of the digital signal is also described.