On Mon, 16 Aug 2004 08:37:24 -1000, Ken Brown wrote:
>If the TX audio were digitized and then delayed, it would be possible
>for the VOX to turn on the transmitter after the beginning of a word,
For at least several decades, the designers of studio/broadcast quality
devices like compressors and limiters have used "feed forward"
techniques, whereby the audio path is delayed by a few ms but un-
delayed audio goes to the gain reduction element that provides the
limiting. This alllows the limiting to be very transparent -- the gain is
reduced a fraction of a ms before the peak hits it, so there is no
overshoot.
The very small delays needed to make VOX work without clipping
leading edges would not be a problem in ham applications. The entire
audio signal is still there, but is simply transmitted a 5-10 ms later, from
beginning to end.
Jim Brown K9YC
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