Distributed Automatic Volume Control (DAVC) (SIP)

The Distributed Automatic Volume Control (DAVC) is an algorithm which is using one or more microphones ("AVC Source") to measure the ambient audio/noise level, and adjusts the loudspeaker output level of the PA amplifier ("AVC Receiver") according to the ambient audio level.

The AVC Source is the input device with the listening microphone used for measuring the ambient noise level. This is typically an EINS-1, but any Turbine Device with microphone can be used.
The AVC Receiver is the output device that is used for playing audio, typically an ENA amplifier, or a PA Interface such as a TKIS-kit or TKIE-kit.

DAVC is not operating while audio is actively playing at the AVC Receiver. With the default configuration, it needs minimum 100ms of silence to be able to adjust the gain by 1dB. This should work just fine with normal speech, but AVC will not adjust while playing constant music.

Software requirements

The Distributed Automatic Volume Control (DAVC) is supported as from:
- Turbine firmware v. 4.11

Configuration

AVC Source

The AVC Source is the input device with the listening microphone used for measuring the ambient noise level. This is typically an EINS-1, but any Turbine Device with microphone can be used.

Log in to the web interface of the AVC Source, and enable Advanced Configuration. Select Sip Configuration > DAVC:

AVC Receiver

The AVC Receiver is the output device that is used for playing audio, typically an ENA amplifier, or a PA Interface such as a TKIS-kit or TKIE-kit.

To configure the DAVC, log in to the web interface of the AVC Source or AVC Receiver, and select Sip Configuration > DAVC Settings:

Distributed Automatic Volume Control (AVC) Configuration:

Enable Distributed AVC: Activated DAVC when checked
Device is AVC Receiver: This device is a "AVC Receiver"
Device is AVC Source: This device is a "AVC Source" (listening microphone)
Master Volume [-40 - 2] dB: Sets the base gain when the "AVC Receiver" is an ENA Amplifier. Set a low base gain when using "Positive Mode", and a high base gain when using "Negative Mode".
Enable AVC Algorithm: The AVC Algorithm must be enabled either on all AVC Sources or on all AVC Receivers

AVC Algorithm (visible only when Enable AVC Algorithm is checked):

Adjustment Mode:
- Positive Mode: Gain adjustment is from zero at AVC threshold level and adjusted positive. AVC Receiver should have a low base gain.
- Negative Mode: Gain adjustment is from zero at AVC max level and adjusted with negative gain downwards. AVC Receiver should have a high base gain.
Lower Threshold [-95 - 0 dB]: The microphone signal level where AVC starts to work. Below this level no adjustment is done, and Audio Receivers should work on default base gain
Upper Threshold [-95 - 0 dB]: The microphone signal level where AVC stops to work. Above this level, no adjustment is done. The difference between upper and lower threshold also defines the working range for AVC gain adjustments. In negative AVC mode this also defined the ambient level where configured base output gain is reached (offset adjustment is zero)
Attack Rate [0.1 - 200 dB/sec]: This determines how quickly the AVC adjusts gain on raising ambient audio level
Decay Rate [0.1 - 200 dB/sec]: This determines how quickly the AVC adjusts gain on falling ambient audio level
Hysteresis [0.00 - 6.00 dB]: Hysteresis around previous set ambient audio level before doing adjustments
Far-End Lockout Time [0.0 - 1.0 sec]: When playing audio in AVC Zone (far-end-signal) all AVC adjustments are locked. When there is a pause in far-end-signal, adjustment commences after this lockout-time

AVC Source Devices (available only when Device is AVC Receiver is checked):

Source Selection Strategy: The AVC Receiver will receive ambient audio levels or Gain adjust values from a number of AVC Sources. This configures the selection strategy for final gain adjusts on AVC Receiver.
- The different settings are: Highest, Average, Average Mid. "Average" requires two or more AVC Sources. "Average Mid" will remove high and low values if more than 4 AVC sources, and average rest.

Source Directory Number: The directory Number of the remote microphone devices
Audio Channels: Which audio channel(s) on this device should be effected by signals from the remote AVC Source

AVC Receiver Configuration (available only when Device is AVC Source is checked):

Enter the IP Address of the "AVC Receiver" and a descriptive name. Press "+" to add, then Save.

Host name is not supported, only IP Address. Due to this, the AVC Receiver should have static IP address

On the AVC Receiver, AudioData UDP port 5035 must be enabled in the Firewall

If your AVC receiver is a TKIS-2 or TKIS-2 based device (IP Loudspeaker), you must disable the inbuilt AVC from the Audio Settings tab

Example Configuration

In this example one channel of an ENA Amplifier is used in one zone, and the other channel is used in another zone. There is one EINS-1 in each zone, measuring the ambient noise level in the zone. The EINS-1 with directory number 123 must be configured to adjust the channel 1 output of the ENA Amplifier, while the EINS-1 with directory number 124 must adjust channel 2.

ENA Amplifier configuration

The ENA Amplifier is configured to be the Audio Receiver. Adjustment Mode is set to "Negative", and the two TKIS units are configured to adjust the associated channel of the ENA Amplifier.

EINS-1 configuration

Both EINS-1 units must be configured to report ambient noise level to the ENA Amplifier at IP 10.9.8.117: