Tuner of the type having zero intermediate frequency and corresponding control process

• US 20020003586A1
• Filed: 04/05/2001
• Published: 01/10/2002
• Est. Priority Date: 04/21/2000
• Status: Active Grant

• Current Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Paillardet, Frederic, Busson, Pierre, Jouffre, Pierre-Olivier
• Granted Patent: US 7,106,808 B2
• Time in Patent Office: Days
• US Class Current: 348/731
• CPC Class Codes: H03G 3/3068 Circuits generating control signals for both R.F. and I.F. stages
• CPC Class Codes: H03G 3/3089 Control of digital or coded signals

Abstract

A tuner includes an analog block, a digital block, and an analog/digital conversion stage connected therebetween. The analog block includes a first attenuator/controlled-gain amplifier stage connected upstream to a frequency transposition stage. The overall mean power of the entire signal received by the tuner is calculated during a phase of initialization. This overall calculated power is compared in the digital block with a first predetermined reference value corresponding to a maximum power desired at a predetermined location of the analog block. The gain of the first attenuator/amplifier stage is adjusted to minimize the deviation between the overall calculated power and the reference value. In a phase of normal operation, one of the channels of the signal received is selected, with the gain of the first attenuator/ amplifier stage being fixed.

Claims

1. Process for controlling a tuner of the type having zero intermediate frequency, comprising an analog block (BAN) containing a first attenuator/controlled-gain amplifier stage connected upstream of a frequency transposition stage containing baseband filtering means, and a digital block (BNM) connected to the analog block by an analog/digital conversion stage, characterized in that it comprises a phase of initialization in which the overall mean power of the entire signal received by the tuner is calculated (20), this overall calculated power is compared in the digital block with a first predetermined reference value corresponding to a maximum power desired at a predetermined location of the analog block and the gain of the first attenuator/amplifier stage (ETA1) is adjusted so as to minimize the deviation between the overall calculated power and the said reference value, and a phase of normal operation in which, the gain of the first attenuator/amplifier stage being fixed, one of the channels of the signal received is selected (24).

2. Process according to claim 1, characterized in that, the analog block of the tuner furthermore containing a second controlled-gain amplifier stage (AGC1, AGC2) connected downstream of the baseband filtering means, the mean power of the selected channel is calculated (25) in the phase of normal operation, this calculated mean channel power is compared in the digital block with a second predetermined reference value corresponding to a maximum channel power desired at the input of the analog/digital conversion stage and the gain of the second amplifier stage is adjusted so as to minimize the deviation between the calculated channel power and the said second reference value.

3. Process according to claim 1 or 2, characterized in that the overall mean power of the entire signal received by the tuner is calculated on the basis of the signal available between the output of the first attenuator/amplifier stage (ETAL) and the input of the frequency transposition stage (MX1, MX2).

4. Process according to claim 1, 2 or 3, characterized in that the calculation of the overall mean power of the entire signal received is performed in the digital block (BNM).

5. Tuning device of the type having zero intermediate frequency comprising a signal input (ESO), an analog block (BAN) containing a first attenuator/controlled-gain amplifier stage (ETAL) connected between the signal input and a frequency transposition stage containing baseband filtering means, and a digital block (BNM) connected to the analog block by an analog/digital conversion stage, characterized in that it comprises

a controllable means of signal routing (MUX1), incorporated into the analog block, possessing an input terminal (BE) connected to the signal input, a first output terminal (BS1) connected to the input of the baseband filtering means (FBB1, FBB2), a second output terminal (BS2) connected directly to the input of the analog/digital conversion stage (CAN1, CAN2),

first means of calculation (MCL, FIR1), connected to the second output terminal of the routing means, and able to calculate the overall mean power of the entire signal received by the tuner,

first means of comparison (ADD1), incorporated into the digital block, and able to compare this overall calculated power with a first predetermined reference value corresponding to a maximum power desired at a predetermined location of the analog block,

first means of adjustment (TB1) able to adjust the gain of the first attenuator/amplifier stage as a function of the result of the said comparison, and

means of control (MCM) able in a phase of initialization, to control the routing means in such a way as to connect their input terminal to their second output terminal, so as to minimize the deviation between the overall calculated power and the said first reference value, and in a phase of normal operation in the course of which a channel of the signal received is selected, to control the routing means in such a way as to connect their input terminal to their first output terminal, the gain of the first attenuator/amplifier stage being fixed.

6. Device according to claim 5, characterized in that the analog block of the tuner furthermore contains a second controlled-gain amplifier stage (AGC1, AGC2) connected downstream of the baseband filtering means, and in that the tuner also comprises

second means of calculation (MCL), connected to the output of the baseband filtering means (FBB1, FBB2), and able to calculate in the phase of normal operation the mean power of the selected channel,

second means of comparison (ADD2), incorporated into the digital block, and able to compare this mean calculated channel power with a second predetermined reference value corresponding to a maximum channel power desired at the input of the analog/digital conversion stage, and second means of adjustment (TB2) able to adjust the gain of the second amplifier stage so as to minimize the deviation between the calculated channel power and said second reference value.

7. Device according to claim 5 or 6, characterized in that the signal routing means (MUX1) are disposed between the output of the first attenuator/amplifier stage (ETA1) and the input of the frequency transposition stage (MX1, MX2).

8. Device according to claim 5, 6 or 7, characterized in that the digital block incorporates the first means of calculation (MCL).

9. Device according to one of claims 5 to 7, characterized in that it is embodied entirely in integrated fashion on a semiconductor substrate.

10. Receiver of satellite digital television signals, characterized in that it comprises a tuning device (TZ) as defined in one of claims 5 to 9.