Telestra App Note

Working with Different Headsets on a Single Audio Channel (#113)

A common question that comes up as a requirement is the ability to support different headsets/helmets on a single audio channel. This can be achieved (when necessary - some headsets will work fine at the same gain level) by changing the software input or output gain of the channel to accommodate headset B over headset A. However, this involves using a Telestra web interface page and isn't always a practical solution. Is there an easier way to do it via a hardware switch or device?

Yes.

With the ACENet ACU2 audio device you have the ability to implement a hardware gain selector. This could be a switch selector or a special cable or just an Open vs. Closed circuit detection on the channel of the device. To do this you use the ControlIn3 input on the ACU2 AND you enable 'Alternate Gains’ in the Telestra web interface for the ACU2. Here is a summary of how it works:

To set this up you'll need to have a switch that connects to ControlIn3 (pins 13 and 14), as you read in the Users Guide. Once you've done that, there's two different ways to implement this.

The first is a simple switch, where the ControlIn is either open or closed

1. Go to the Telestra web interface --> ACENet
2. Select the ACU2 you want to use, then select the specific channel you want to use
3. In the "Alternate Gains" section, be sure to check the "Hardware selector" enable box
4. The "Standard Gain Settings" at the top of the page will get used when the switch is CLOSED
5. The gains at the bottom of the page will get used when the switch is OPEN, in this case "mic-power-enable3", "input-gain3", and "output-gain3"
6. Click submit and then the ACU2 channel will start to behave as described above

The other way is to implement this feature is with a multi-postion switch, that uses different resistances across the ControlInput.

1. Go to the Telestra web interface --> ACENet
2. Select the ACU2 you want to use, then select the specific channel you want to use
3. In the "Alternate Gains" section, be sure to check the "Hardware selector" enable box
4. The "Standard Gain Settings" at the top of the page will get used when the switch is as position 1
5. Gain set 1 in the "Alternate Gains" section will get used in position 2
6. Gain set 2 in the "Alternate Gains" section will get used in position 3
7. Gain set 3, at the bottom of the web page, will get used in position 4
8. Click submit and then the ACU2 channel will start to behave as described above

For more info on the ACU2 in general check out the ACU2 overview page.