[arm-allstar] PTT Delay idea

Tue Mar 5 13:46:59 EST 2019

Perfect. Looks like from the documentation, that increasing the value of the  AVG capacitor increases the recovery time without affecting the fixed 30 ms attack time. That's actually what I was looking for. I think I'll order one and a project box to put it in. Impressive that that chip will amplify signals all the way to 1MHz.

In the meantime, is there a way within the programming of app_rpt to send a short tone or noise burst then the PTT signal on every key-up?

-----Original Message-----
From: David McGough <kb4fxc at inttek.net> 
Sent: Tuesday, March 5, 2019 11:02 AM
To: john at qso.com
Cc: arm-allstar at hamvoip.org
Subject: RE: [arm-allstar] PTT Delay idea

Okay....I think this board (or a similar one) will solve your ALC issues.  
I haven't measured the actual dynamics of this board, with the supplied component values.  These values could be adjusted to allow wide modification of all the various parameters, or course.  I would guess the attack is under 1mS and release maybe 100mS. I know on a radioless node, with a electret mic attached and without this board, you can easily pop-your-P's, even with the levels set low. With this board, no spattering at all!!!

Here is a datasheet for the SSM2167 chip:

https://www.analog.com/media/en/technical-documentation/data-sheets/ssm2167.pdf

73, David KB4FXC

On Tue, 5 Mar 2019 john at qso.com wrote:

> I'll look into that. Thank you. Right now I have one of those old cassette tape recorders in record mode / monitor mode. 
> What's the recovery time in the ebay unit?  I see adjustments for the
other vectors.  Also as far as what Doug mentioned, I think I'll wait for that, although another board project seems inviting.  I'm using ALC on the transmitter because my finger is always on the volume control turning people up and down.  Why not? It's my repeater after all ðŸ˜Š
> 
> To answer an earlier question, I have a URI connected to a Motorola
Quantar powered by a Pi from Doug's image.
> 
> 
> -----Original Message-----
> 
> John,
> 
> Have a look at this nifty little compressor/limiter board. I'm using
them now for solving mic audio issues and they work GREAT!
> 
> They should work just as well for RX audio, after adjusting the levels.
> 
> 
> https://www.ebay.com/itm/332468614881
> 
> 
> 
> 73, David KB4FXC
> 
> 
> 
> 
> On Tue, 5 Mar 2019, "John Griffith via ARM-allstar" wrote:
> 
> > Well then that answers that. I can wait. Thank you. 
> > 
> > Right now, my wife's voice on the ID'er is over deviated the first 
> > 200 ms as my leveler's attack time is slow, But at the same time 
> > recovery is slow so that normal conversation afterwards doesn't 
> > sound compressed like a commercial broadcast AM radio signal does.
> > 
> > The network I'm on encourages people to hold the mike key down a 
> > full second before they talk so that all the entire network can key 
> > in order not to cut off their first words. It's an issue.  There's 
> > usually plenty of time to knock the leveler down before PTT. Was 
> > wanting to take advantage of that time.  Sounds like your update 
> > will make this moot.
> > 
> > Oh, ALC is automatic level control. 
> > 
> > Again, thank you for all you do.
> > 
> > -----Original Message-----
> > From: ARM-allstar <arm-allstar-bounces at hamvoip.org> On Behalf Of 
> > "Doug Crompton via ARM-allstar"
> > Sent: Tuesday, March 05, 2019 12:00 AM
> > To: ARM Allstar <arm-allstar at hamvoip.org>
> > Cc: Doug Crompton <wa3dsp at gmail.com>
> > Subject: Re: [arm-allstar] PTT Delay idea
> > 
> > John,
> > 
> >  I think you contradict yourself because you want audio to level 
> > before PTT but you tell people to hold PTT for a few seconds before 
> > they talk. That does not make sense. Then there would be carrier 
> > without audio. What is this ALC? A good audio limiter/compressor 
> > should be almost instantaneous in response. Are your levels really 
> > that wacky? Perhaps the users need to set their levels better! You 
> > could delay PTT any amount you want with a rather simple circuit but 
> > remember you are cutting off the beginning of the transmission by that amount.
> > 
> > On a side note we will be introducing a new channel driver later 
> > this year that will allow you to use a SW limiter/compressor with custom settings.
> > 
> > 
> > *73 Doug*
> > 
> > *WA3DSP*
> > 
> > *http://www.crompton.com/hamradio 
> > <http://www.crompton.com/hamradio>*
> > 
> > On Mon, Mar 4, 2019 at 7:50 PM "John Griffith via ARM-allstar" < 
> > arm-allstar at hamvoip.org> wrote:
> > 
> > > I was wondering if there's a way to delay PTT for 200 milliseconds 
> > > (but
> > not
> > > the audio stream) so that my ALC can properly level out before 
> > > anything
> > is
> > > heard on the repeater?  The people on the repeater network I'm on 
> > > are pretty good about holding the key down for a second or 2 
> > > before talking, so it would be a big deal.
> > >
> > > Another option I was thinking about would to have a tone or white 
> > > noise
> > or
> > > anything really.. keep the ALC circuit busy and leveled during 
> > > times of non-transmit.  Anyone have an idea?  I already have a 
> > > burst of noise at
> > the
> > > very beginning of the repeater ID, I would just want that to be 
> > > during
> > the
> > > 200ms.
> > >
> > > John
> > > N7OKN
> > >
> > > _______________________________________________
> > >
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> > > ARM-allstar at hamvoip.org
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> > >
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> > >
> > _______________________________________________
> > 
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> > 
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> > 
> > _______________________________________________
> > 
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> > ARM-allstar at hamvoip.org
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> > 
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> > 
> 
> 
> 