| 摘要 |
The invention provides an automatic gain control system that is implemented by digital hardware. The digital hardware determines the range of a set of digital data values, and then examines each digital data value in a sequence. An index counter increments a sample count index i each time a new digital data value is examined and determines the absolute value of the i<th >digital data value. The digital hardware also counts both the number j of digital data values that exceed a high percentage value of the range, and the number k of digital data values that are less than a low percentage value of the range as the digital hardware runs through the sequence. If the digital hardware determines that a digital data value is greater than the high percentage value, the ratio j/i exceeds a first threshold value, and the gain level is not set to the lowest gain level, then the gain is decreased. If the digital hardware determines that a digital data value is less than the low percentage value, the ratio k/i exceeds a second threshold value, a predetermined interval of time has elapsed, and the gain level is not set to the highest gain level, then the gain is increased.
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