Patent ID: 7805118

Claim:
A method for adjusting a receiving system in a satellite receiving installation, the method comprising: receiving, at an input of a receiving system, an external signal at a satellite frequency; generating, with a first oscillator, a first transposition signal at an oscillation frequency having a theoretical value and a real value different from the theoretical value; mixing the external signal and the first transposition signal with a first frequency mixer having a first input coupled to the input of the system, a second input receiving the first transposition signal, and an output delivering a first intermediate signal at a first intermediate frequency; generating, with a second oscillator, a second transposition signal at an oscillation frequency having a nominal value; mixing the first intermediate signal and the second transposition signal at a second frequency mixer having a first input coupled to the output of the first mixer for receiving the first intermediate signal, a second input receiving the second transposition signal, and an output delivering a signal at a second intermediate frequency; and controlling, with a microcontroller and with signals generated by only two oscillators, a real value of the oscillation frequency of the second transposition signal by: determining the nominal value of the oscillation frequency of the second transposition signal as a function of: (i) a given predetermined value of the frequency of the external signal, (ii) the theoretical value of the oscillation frequency of the first transposition signal, and (iii) a target value of the second intermediate frequency; controlling, via the microcontroller, the oscillation frequency of the second oscillator at the nominal value previously determined; detecting, with the microcontroller, a practical offset between the theoretical value and the real value of the oscillation frequency of the first oscillator, from an offset between the first intermediate frequency and the second intermediate frequency previously determined at an output of the receiving system; and correcting, with the microcontroller, the practical offset by changing the nominal value of the oscillation frequency of the second oscillator to a real value to cancel the offset determined at the output of the receiving system.