[Elecraft] [K3] VOX on the K3 - Smooth Voice Controller

[Wright, Robert]

Thanks Lyle for the good explanation.  And, Rich, yes, I found CONFIG:TX MON in the PDF manual.  (It was not in my printed manual.)  Mine is set to Normal.

So the VOX PTT to voice delay is an artifact of the DSP filtering delays.  And the difference I was hearing (and remember of the Smooth Voice Controller) is the difference between the 10-15mSec and 85mSec.

So let me reword my original comments:  It would be really neat if the K3 had a setting for 85mSec or so of voice delay on the VOX.  The current 10-15mSec is better than zero but still does not approach the really smooth VOXing achieved by the A&A box at 85mSec or so.

Love my K3 even if it doesn't have 85mSec.  This is just frosting on the VOX.  :-)

73, Bob N7ZO

-----Original Message-----
From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Lyle Johnson
Sent: Thursday, February 21, 2013 10:19 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] [K3] VOX on the K3 - Smooth Voice Controller

The DSP Tx audio filtering adds a delay of 10 to 15 msec (I don't remember the exact value off the top of my head) but the VOX detector is before the filtering.  The net result is that very little, if any, of the first syllable is clipped when using VOX.

The monitor is derived from the 15 kHz IF within the DSP, which only happen when the radio is in transmit, so you can hear if any syllable truncation is occurring and adjust things accordingly. There is an menu option to bypass the 15 kHz IF demodulation for monitoring and just pass the audio through, but this is bypassed when you adjust mic gain or clipping so you can hear the effect of the adjustment.

73,

Lyle KK7P

---------------------------------------------

Eric, 

Interesting and neat.  I should have expected you were already on top of this.  :-)

 I just went back to the K3 and played with it a bit.  Just by listening, the monitor delay seems to be the same whether I have VOX enabled or not.  This is just the normal acceptable delay I have come to expect in the K3's monitor.

The Smooth Voice Controller had a nominal 85mSec delay (QST article April 1992 pg. 42) and, if I recall correctly, seemed much more noticeable than what I am hearing in the K3.  Eric, can you comment on the amount of delay used for the K3 VOXing? (Saves me setting up for a measurement.)   Does the monitor come before that delay?  Am I hearing, in the monitor, what is being transmitted (relative to the PTT-voice timing and first syllable cut-off)?

Thanks, Bob N7ZO


-----Original Message-----
From: Eric Swartz - WA6HHQ, Elecraft [mailto:eric at elecraft.com] 
Sent: Thursday, February 21, 2013 8:49 AM
To: Wright, Robert
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] [K3] VOX on the K3 - Smooth Voice Controller

This is -exactly- what we do in the DSP for the K3's VOX to eliminate any cutting off of the first syllable. You can talk normally without that 'Ahh' at the beginning of sentences to avoid loss of info ;-)

73,

Eric
elecraft.com

On 2/21/2013 8:07 AM, Wright, Robert wrote:
> I used to have a box from A&A Engineering called a Smooth Voice Controller.  It was a VOXer with a short audio delay line (bucket brigade IC) to allow the PTT to get to the radio before your first syllable.  The result was no clipping at the beginning of each phrase.  The only downside was that monitoring yourself with headphones was tricky with the delay.  But the VOX results were very good.
>
> I've always thought that this concept would be a great improvement to the K3's VOX and could be done readily in the DSP.  It could be a menu setting with the voice delay variable from 0 (normal operation) to some fixed amount.  It would only need to be enabled when VOX was on.
>
> 73, Bob N7ZO
>
>