Using VOX mode on the PC

This article is written for: Zello Work Zello Friends & Family.

VOX feature is only available on the PC and Android apps. 

The purpose of VOX mode is to allow you communicating without using a keyboard at all, which could be very useful sometimes although it might require some upfront configuration. You can switch between PTT and VOX modes on the fly using the hotkeys.

Turning VOX mode on

Before you can use VOX you should turn it on and probably tweak some settings. Go to Tools > Options>VOX. Check the box to Turn on VOX for handsfree :

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Click OK. Now it’s enabled and you can close the settings. However if you start speaking now nothing would happen. This is because in order to keep the flexibility you can switch on the fly between push-to-talk and VOX modes.

Using VOX

To activate VOX use Handsfree keyboard shortcut (Ctrl + F7 unless you re-assigned it) or click a small button with the lock icon on the main screen:

 

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When VOX is active, this button turns red:

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Now when you say something it’ll start transmitting it automatically. When transmission is active the left side of the button turns red too (same way as it does when you use push-to-talk):

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Clicking the lock icon again, pushing F7 or Ctrl + F7 switches it back to the push-to-talk mode.

Tweaking VOX settings

It’s possible that VOX didn’t work perfectly with default settings – picked up every tiny sound or the opposite – didn’t react even to loud voice. It happens because every sound card and environment is different and it’s hard to configure algorithm parameters automatically. Here comes the new VOX tab in the options:

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You’ve got four parameters to play with. Here is what they do:

Activation threshold – allows you to set the sound level above which the transmission starts. If you need to increase the sensitivity move the slider left and vice versa.
De-activation threshold – sets the sound level below which the transmission stops. It can’t exceed Activation threshold and usually should be quite a bit lower.

Please note that the decibels (dB) scale is logarithmic and 20dB on the scale corresponds to 10x difference in signal levels so adjust carefully.

The good news is that you rarely need to modify Trigger time or Relaxation time but if you really want to here is the explanation.

Trigger time (in milliseconds) – sets a typical reaction time of the algorithm. In order to skip very short sound impulses (such as mouse clicks) VOX filters out the sounds, which are shorter than trigger time set in this parameter. Increasing it makes VOX slower to respond, which helps to reduce unwanted transmissions but also proportionally increases transmission delay.
Relaxation time (in milliseconds)– is the counterpart to the Trigger time. It sets a typical time the algorithm takes to switch off. The parameter should be high enough to allow you the normal pauses between words without splitting the message.

The convenient way to play with the Settings is to activate VOX first (using “echo” as your guinea pig), and then open VOX settings. Using that approach you can try any new combination by pressing Apply without leaving the settings screen (hotkeys doesn’t work when Options is active).

If, after playing with it, you disable VOX in settings, Handsfree hotkey works as a simple transmission toggle.