Automatic Gain Control (AGC)

Automatic Gain Control (AGC) is a feature of the Zenitel IP devices. The purpose of the AGC feature is to try to maintain a constant microphone signal level, despite variations in the speech level because the talker is at a distance from the intercom station, or talking with a low voice. The AGC feature is providing more amplification to weak signals and less amplification to strong signals thus maintaining a constant signal amplitude level at the output.

The AGC feature is to be used with caution and in special conditions where the talker may be operating in varying distances deviating from the nominal talker distance to the station. The Turbine intercoms TxIV+ with camera (iMX8 processor), Desktop and IP Flush Master (iMX6 processor) has a fixed, not-configurable AGC enabled

IC-Edge mode

Log in to the Edge Controller, and navigate to Edge Controller > System Configuration > Call and Audio, and enable/disable "AGC" per device:

Enabling AGC in an IC-Edge system

SIP and ICX-AlphaCom mode

Log in to the Zenitel IP device.

• SIP mode: Navigate to SIP Configuration > Audio Settings, and enable "Automatic Gain Control (AGC)"
• ICX-AlphaCom mode: Navigate to Advanced ICX-AlphaCom > Audio Settings, and enable "Automatic Gain Control (AGC)"

Enabling AGC on a device in SIP or ICX-AlphaCom mode (screenshot from firmware 7 and later)

Some additional settings are available in Advanced Configuration mode. Navigate to Audio Settings > Audio signal processing:

Advanced AGC settings (screenshot from firmware 7 and later)

• Enable AGC: Enable/disable the AGC component which brings the microphone signal to an appropriate range
• AGC mode: Algorithm type. Use "Digital SW AGC" for the majority of use cases. "Analouge HW AGC" is available only on Turbine devices using analogue microphone. "Analogue HW AGC" should basically be used for "Push to Talk"/"Talk back" applications and not in Open Duplex modes
  • Digital SW AGC
  • Analouge HW AGC (noisy profile)
  • Analouge HW AGC (quiet profile)
• AGC gain profile: The target signal gain level. "Standard" shall aim to keep a "nominal voice signal level" at approx -23 dBFS. The other options will target increasingly higher signal levels. Use with caution.
  • Standard
  • Moderate
  • High
  • Very high
• AGC speed: Attack and decay rates of the algorithm.
  • Slow
  • Fast