| 摘要 |
For adaptively adjusting the gain in a modem receiver comprising two amplifiers (15, 19), the following steps are performed: for a buffer (21), a Hilbert filter (23), and an equalizer (27), a respective energy indicator (Pmax2, uavg2, xavg2) is generated from the signal samples in the respective delay line. Each energy indicator is compared to an associataed upper target level (4LU, 3LP, 1.19 LX), and for the equalizer also to an associated lower target level (0.84 LX). If necessary, a gain correction factor (S) initially set to 1.0 is modified to obtain an overall gain that keeps delay line energies within desired targets. Target comparisons are made so that excess energy in the buffer or Hilbert filter result in a rapid gain reduction whereas average equilizer energy is used for slow adaptations. After a gain change, all acquired samples in the delay lines are also multiplied by the correction factor (S) so that none is lost during gain acquisition. Gain is distributed between the two amplifiers in a swapping operation without modifying the adjusted overall gain.
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