Patent ID: 7286613

Claim:
A method of modulation of a carrier, in particular an RF carrier, in which two quadrature components I and Q are generated and a local frequency is vectorially modulated with these components, comprising: filtering the quadrature components I and Q around a zero frequency so as to create a small free frequency bands; inserting alternately into this small free frequency band, into the I and Q components, a low-frequency subcarrier sufficiently remote from the zero frequency so as not to engender any shift error of the continuous component and of a sufficiently low relative level with respect to that of the signal I and Q as not to disturb the latter; demodulating, a fraction of the vectorially modulated signal, in a synchronous manner with the same local frequency alternately cosine-wise and sine-wise; low-pass filtering the demodulated signal so as to extract the low-frequency subcarrier marred by a first set of amplitude and phase errors corresponding successively to a second set of amplitude and phase errors with which the signals I and Q are marred after the vector modulation; measuring said first set of amplitude and phase errors; and feedback correcting the two quadrature components I and Q to compensate for said second set of amplitude and phase errors.