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Voice operated transmit VOX enables the radio to transmit
when you speak without pressing the transmit buttons.
VOX can be built into the radio such as in Kenwood or some
Motorola or and external unit as used for Icom radios.
How VOX Works
VOX works by the electronics comparing the sound level received
by the Microphone against a trigger level which you have set
in the radio or VOX unit settings. Any noise can reach this
level and cause the radio to transmit so you have to be careful
that the Mic only picks up your voice and cannot pick up much
background noise.
VOX circuits are nowhere near as sophisticated as your own
ear and brain. While you can hear someone speaking with background
noise which is at a similar level to their voice, standing
by a noisy road for instance VOX circuits only hear all noise
and cannot specifically pick up human speech. They will trigger
easily from wind noise, and other background sounds if they
are at a similar level to your voice. Great care must be taken
to get the Mic near your mouth and shielded from background
noise.
There is also a slight delay from when you trigger VOX to
when the receiving radio responds. With this in mind you have
to take care you first syllable or word is not lost. Saying
VOX or ERR before you send your message will trigger the VOX
ready to pass your message.
Trigger Level
The VOX trigger level needs to be carefully adjusted too.
Simpler VOX systems only have three levels making them harder
to set whereas Kenwood has 10 preset levels and Icom is continuously
variable so you can change the trigger level very precisely.
VOX Earpiece Compatibility.
The earpiece or headset must have the Mic connected to the
VOX system at all times. This may seem obvious but most makes
of radio only connect the Mic when the transmit button is
pressed. Therefore the earpiece must be chosen as part of
the VOX system.
Other VOX features.
Kenwood radio probably have the best VOX features. The supplier
can set up the following features with most Kenwood radios.
Transmit Beep. A beep tells you that you have triggered VOX
and the radio is transmitting.
Transmit Lockout. If you are receiving a call your voice cannot
cause the radio to transmit.
VOX Level. 10 preset levels accessed from the side buttons.
www.wildtalk.com ©
2006
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VOX
