Patent ID: 8396419

Claim:
A device for double frequency transposition, comprising at least one first amplification and/or filtering chain receiving a signal at a first frequency F RF , a first frequency mixer which carries out a first frequency transposition of said signal to a first intermediate frequency F FI1 and delivers said transposed signal to the input of a second amplification and/or filtering chain, a second frequency mixer which carries out a second transposition of the signal delivered by said second chain to a second intermediate frequency F FI2 and delivers said transposed signal to the input of a third amplification and/or filtering chain, a first fractional frequency synthesizer of loop band B adapted to produce a first synthesized frequency F OL1 at the input of said first mixer and a second integer or fractional frequency synthesizer adapted to produce a second synthesized frequency F OL2 at the input of said second mixer, and further comprising means for controlling the frequencies F OL1 , F OL2 of said first and second synthesizers, which are adapted to carry out the following steps: initializing the frequency F OL2 at a first given value F OL2,A , for a given pair of frequencies F RF , F FI2 , determining the frequency F OL1 with the aid of the following relations: if F RF >F OL1 and F FI1 <F OL2 , F RF =F OL1 +F OL2 −F FI2 (5), if F RF >F OL1 and F FI1 >F OL2 , F RF =F OL1 +F OL2 +F FI2 (6), if F RF <F OL1 and F FI1 >F OL2 , F RF =F OL1 −F OL2 −F FI2 (7), if F RF <F OL1 and F FI1 <F OL2 , F RF =F OL1 −F OL2 +F FI2 (8), if the value obtained for F OL1 lies in a frequency band of lower bound A·F REF −B·X and upper bound A·F REF +B·X, where A is a strictly positive integer and X is a given parameter, modifying the frequency F OL2 to a second value F OL2,B determined so that the difference in absolute value between F OL2,A and F OL2,B satisfies the following two conditions: | F OL2,B −F OL2,A |>AF REF +2 B·X | F OL2,B −F OL2,A |<AF REF −2 B·X and transmitting the frequency values F OL1 and F OL2 to said frequency synthesizers.