Loading patent…
AssigneeThomson-CSF
InventorsYvon Fouche, Jean-Bernard Rault, Tristan de Couasnon, Raoul Monnier
Estimating the term…
The present invention relates to a method of realigning the local oscillators of a receiver, as well as a device for implementing the method. In a receiver with a high frequency/intermediate frequency translation oscillator, an intermediate frequency/baseband translation oscillator, and a sampling oscillator receiving a signal modulated by at least one circuit for inverse fast Fourier transform FFT.sup.-1 computation according to a multicarrier modulation of OFDM (Orthogonal Frequency Division Multiplexing) type with addition of a transition interval at the start of each transmission interval. The spectrum of the signal has two master lines with a fixed frequency difference between them. The method is characterized by the following steps: (1) determination of the start of a transmission interval; (2) determination of the position of the two master lines; and (3) computation of the variation of the phases of these two lines as a function of time, and exploitation of the result to set the frequency of the sampling oscillator and of the intermediate frequency baseband translation oscillator. The invention will find particular application to digital television.
Method of realigning the oscillators of a receiver comprising a high frequency/intermediate frequency translation oscillator, an intermediate frequency/baseband translation oscillator, and a sampling oscillator receiving a signal modulated according to multicarrier modulation of OFDM (Orthogonal Frequency Division Multiplexing) type using inverse fast Fourier transform FFT.sup.-1 computation the spectrum of the said signal comprising two master spectral lines having a fixed frequency difference between them, the method comprising computation of the variation of the phase of the two spectral lines as a function of time with the aid of fast Fourier transform on reception, then said oscillators being frequency adjustable and setting the frequency of the sampling oscillator and the frequency of at least one of the other two oscillators according to the result of said computations.
Dependencies are inferred from the claim text.