| 摘要 |
The method comprises the measuring of the power of the digital signal by the first measuring means (MM1) after an analogue-digital conversion (CAN) and the controlling of the gain on the basis of the measured power according to a predetermined law by the control means (MC) connected to the amplifiers control logic (ACTL) for controlling the gains (G1,G2) of two amplifiers with gain control (AGC1,AGC2) in the main branch of the tuner (TN). The method also comprises the measuring of the power of the analogue signal by the second measuring means (MM2) picked up between the input amplifier stage (AGC1) and the first stage of frequency transposition, that is the first mixer (MX1), or immediately after the mixer, the comparing of the measured power to a predetermined power threshold (SSE) in a manner to obtain the first binary information, and the adjusting of the law for controlling the gain on the basis of binary control values obtained from the first binary information by a bistable (BSC) connected to a filter (FN). If the measured power is greater than the threshold value (SSE), the law of control is modified, and in other cases it is left unchanged. The tuner (TN) is of the double-conversion type and comprises the second-stage transposition or mixing (MX2) connected downstream of the first-stage transposition or mixing (MX1), and two stages of amplification (AGC1,AGC2), where the law of the gain control comprises the first adjustment of gain (G1) of the input amplification stage and the second adjustment of gain (G2) of the second amplification stage. The modification of the law of control comprises a supplementary decrease of the gain (G1) and an increase of the gain (G2). The analogue block (BAN) comprises the amplifiers with gain control (AGC1,AGC2) and two stages of frequency transposition or mixing (MX1,MX2), and is connected to the digital block (BNM) by the analogue-digital conversion stage (CAN). The analogue block also comprises a comparator (CMP) for comparing the measured power with the threshold value (SSE) and delivers the first binary information. The comparator (CMP) functions on the basis of hysteresis. A receiver of terrestrial digital signals is claimed and comprises the tuner as specified.
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