Wireless signal amplification system and a television signal decoder comprising one such system
A wireless signal amplification system including amplification apparatus ( 6 ) consisting of numerous different amplifiers ( 6 1 to 6 n ) which are distributed in an analogue processing chain ( 4 ). Also, a converter ( 12 ) for converting analogue signals into digital signals which, at input, are connected to the outlet of the analogue processing chain ( 4 ) and, at output, are connected to at least the gain control circuit ( 16 ) of the amplification apparatus ( 6 ) according to a value that is representative of a characteristic of the wireless signal ( 1 ). In this way, sampling of the wireless signal ( 1 ) by the converter ( 12 ) is optimized. The gain control circuit ( 16 ) establishes an average gain control signal ( 18 ), and also has, for each of the amplifiers ( 6 1 to 6 n ), a device for calculating an individual gain control signal ( 20 i to 20 n ) according to a transfer function (H 1 to H n ) which is specific to each amplifier and which is applied to the average gain control signal.
1. An amplification system for a wireless signal ( 1 ) comprising amplification means ( 6 ) consisting of a plurality of distinct amplifiers ( 6 1 to 6 n ) distributed within an analogue processing chain ( 4 ), and means ( 12 ) for converting analogue signals into digital signals linked at input, to the output of said analogue processing chain ( 4 ) and at output, at least, to means ( 16 ) of control of the gain of said amplification means ( 6 ) as a function of a value representative of a characteristic of said wireless signal ( 1 ) so as to optimize the sampling of said wireless signal ( 1 ) by said converting means ( 12 ), said control means ( 16 ) comprising means for establishing a mean gain control signal ( 18 ), characterized in that said control means ( 16 ) furthermore comprise, for each of said amplifiers ( 6 1 to 6 n ), means for calculating an individual gain control signal ( 20 1 to 20 n ) according to each amplifier's own transfer function (H 1 to H n ) applied to said mean gain control signal.
2. The amplification system as claimed in claim 1 , characterized in that the means for establishing said mean gain control signal ( 18 ) comprise means ( 26 ) of estimating the power of the wireless signal received ( 1 ) and means for determining a mean gain control signal dependent on the power of said wireless signal ( 1 ).
3. The amplification system as claimed in claim 1 , characterized in that said calculation means ( 20 1 to 20 n ) comprise for each amplifier ( 6 1 to 6 n ), a table ( 40 1 to 40 n ) defining the transfer function (H 1 to H n ) for going between the mean gain control signal and the individual gain control signal corresponding to said amplifier.
4. The amplification system as claimed in claim 3 , characterized in that said transfer functions (H 1 to H n ) define for each amplifier ( 6 1 to 6 n ), a succession of linear gains between the mean gain control signal and the individual gain control signals.
5. The amplification system as claimed in claim 1 , characterized in that said transfer functions (H 1 to H n ) are determined successively such that each of the amplifiers ( 6 1 to 6 n ) operates in a linear regime when the others are locked at their minimum linear gain, so that the overall gain of the amplification means ( 6 ) is a linear gain.
6. The amplification system as claimed in claim 1 , characterized in that at least one of said amplifiers ( 6 1 to 6 n ) forming said amplification means ( 6 ) has analogue control, the corresponding output of said control means ( 16 ) then being linked to the control input of this amplifier though digital/analogue conversion means ( 22 1 to 22 n ).
7. The amplification system as claimed in claim 1 , characterized in that at least one of said amplifiers ( 6 1 to 6 n ) forming said amplification means ( 6 ) has digital control, the corresponding output of said control means ( 16 ) then being linked directly to the control input of this amplifier.
8. A television signals decoder, characterized in that it comprises an amplification system as claimed in claim 1 .
9. The decoder as claimed in claim 8 , characterized in that it is adapted for decoding the signals coded according to the OFDM orthogonal frequency division multiplexing protocol.