[K3] VOX on the K3 - Smooth Voice Controller

[Robert Wright]

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

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[Eric Swartz - WA6HHQ]

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
>
>
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[Robert Wright]

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:[hidden email]]
Sent: Thursday, February 21, 2013 8:49 AM
To: Wright, Robert
Cc: [hidden email]
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
>
>
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[Richard Fjeld]

Just a note to say that I recall the monitor delay is adjustable in the Config menu.

Rich, n0ce

  ----- Original Message -----
  From: Wright, Robert
  To: [hidden email]
  Cc: [hidden email]
  Sent: Thursday, February 21, 2013 11:35 AM
  Subject: Re: [Elecraft] [K3] VOX on the K3 - Smooth Voice Controller


  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:[hidden email]]
  Sent: Thursday, February 21, 2013 8:49 AM
  To: Wright, Robert
  Cc: [hidden email]
  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
  >
  >
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[Lyle Johnson]

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
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[Robert Wright]

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: [hidden email] [mailto:[hidden email]] On Behalf Of Lyle Johnson
Sent: Thursday, February 21, 2013 10:19 AM
To: [hidden email]
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:[hidden email]]
Sent: Thursday, February 21, 2013 8:49 AM
To: Wright, Robert
Cc: [hidden email]
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
>
>
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[Robert Wright]

Ray,

Right, but you'd never be aware of the delay unless the monitor was turned on.

73, Bob N7ZO


-----Original Message-----
From: Ray Sills [mailto:[hidden email]]
Sent: Thursday, February 21, 2013 11:57 AM
To: Wright, Robert
Subject: Re: [Elecraft] [K3] VOX on the K3 - Smooth Voice Controller

Hi Bob:

I don't know what the delay interval is... but remember: sound travels about 1000 feet per second, so a 1 millisecond delay is what you encounter when the sound source is 1 foot from you.  85 milliseconds is what you would experience from a source 85 feet away.
Most of the time, we are not bothered by delays of 30 milliseconds or less.

73 de Ray
K2ULR

On Feb 21, 2013, at 12:35 PM, Wright, Robert wrote:

> 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:[hidden email]]
> Sent: Thursday, February 21, 2013 8:49 AM
> To: Wright, Robert
> Cc: [hidden email]
> 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

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[Jim Brown-10]

On 2/21/2013 10:39 AM, Wright, Robert wrote:
> The DSP Tx audio filtering adds a delay of 10 to 15 msec

I'm not a DSP programmer, but we started using DSP extensively in pro
audio nearly 20 years ago, so as system designers, we had to learn a lot
about how it behaves. It's helps to remember that ANY DSP takes time.
Each A/D and D/A conversion takes time. The time difference between
input and output is called "latency," and is a function of the
processor, data formats, bandwidths, and rates, the processing
algorithms, the need to minimize distortions of various sorts, and, to
some extent, the skill of the programmer.

Delay can also be added at any point in the signal chain to accomplish
things like the technique described to improve VOX action.  Another use
is improving response time for peak limiting -- the main signal path has
a bit of delay added before the limiting block, but the detector and
control to the limiting block are un-delayed (or have no intentional
delay).

The human brain has varying sensitivity to delay, depending on many
factors. Most of us are not bothered by hearing a copy of our own speech
delayed less than about 10 msec; increase that delay to more than about
50 msec and we have trouble talking.  Most sound system professionals
have heard even the best announcers slow down and stop talking when
confronted with 100 msec of delay, which is what happens when the talker
is 120 ft or so from the speakers in a big sound system.

73, Jim K9YC

.
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