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Automatic Gain Control for Voice Compression Algorithms Disclosure Number: IPCOM000061780D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09

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McDonald, BS [+details]


The software automatic gain control (AGC) method is described to maximize the signal-to-noise ratio of the digital signal processing code by minimizing the fixed-point calculation error. The features that the software implementation has included 1) look ahead, 2) overhang, 3) silence detection and, 4) separate tracking and normalization gain factors. The AGC being used is a peak detection type. The "energy" of the signal is tracked by multiplying each sample by a tracking gain. If the resulting number exceeds a preset maximum, the tracking gain is reduced very quickly. If the resulting number is in the operating region, the gain is not changed. If the resulting number is below the operating range, the gain is increased slowly.