Complete Communications Engineering

Automatic Gain Control

Automatic Gain Control (AGC) is used keep a constant recording volume regardless of the input signal level. AGC is typically one of the last Voice Quality Enhancement (VQE) blocks of the transmit path of the microphone signal. A wide dynamic range of input speech levels can be difficult and tiresome to the listener on the far-end.  AGC is implemented to resolve this issue.

automatic gain control diagram

The gain by which to achieve a constant recording level is determined by monitoring the voice activity state and the peak levels of the input signal.  When talkers speak too softly or are located a far distance away, then the signal will be amplified.  When the talkers speak too loudly or are located close to the microphone, then the signal will be attenuated.

Automatic Gain Control Software Features

Automatic Gain Control Applications


supported platforms

VOCAL’s optimized Gain Control software is available for the following platforms. Please contact us for specific Gain Control supported platforms.

ProcessorsOperating Systems
  • Texas Instruments – C6xx (TMS320C62x, TMS320C64x, TMS320C645x, TMS320C66x, TMS320C67x), DaVinci, OMAP, C5xx (TMS320C54x, TMS320C55x)
  • Analog Devices – Blackfin, ADSP-21xx, TigerSHARC, SHARC
  • PowerPC, PowerQUICC
  • MIPS – MIPS32, MIPS64, MIPS4Kc
  • ARM – ARM7, ARM9, ARM9E, ARM10E, ARM11, StrongARM, ARMCortex-A8/A9/A15/A3x/A5x/A7x, Cortex-M3/M4/M7/M33
  • Intel / AMD – x86, x64 (both 32 and 64 bit modes)
  • Linux, uClinux, BSD, Unix
  • Microsoft Windows ACM / RTC / CE / Mobile
  • Apple iOS / iPhone / iPad & MacOS
  • Google Android
  • Green Hills Integrity
  • Micrium μCOS
  • Symbian
  • Wind River VxWorks
  • eCOS / eCOSPro

More Information