Automatic Gain Control (AGC) is a common tool for field recording, but it usually requires specific hardware such as voltage controlled amplifiers. In this paper, we address the problem of designing an AGC when none of this hardware is present, using an ubiquitous digitally controlled high end analog preamp. To do this, we have to overcome two problems: fixed gain steps and variable delay of the gain command. In order to propose an efficient solution, we will first study the effects of each of those two problems. Finally, a very simple digitally controlled automatic gain, but of high quality will be proposed, using only 10MIPS of processing power from our high end USB sound card.

Authors: Sturmel, Nicolas; Yu, Fusheng
Affiliations: Digigram S.A., Montbonnot Saint Martin, France; ENSEEIHT–INP, Toulouse, France(See document for exact affiliation information.)
AES Convention: 135 (October 2013) eBrief:125
Publication Date: October 16, 2013

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