Many radio circuits require a push-to-talk signal to transmit, but
more and more receivers do not provide a CAS ("carrier activated switch")
signal that can be used to interface to these radio circuits.
Conventional voice-activated switching does not work well in these
applications because the transmit path is not activated quickly enough
to avoid chopping or garbling the first syllables of a message.
The NHRC-VOX combines a de-bounced, re-timed audio signal detector and
an audio delay long enough to allow the radio circuit to be established
before the audio is sent, preventing the loss of the first few syllables
of the message.
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