[arm-allstar] PTT Delay idea

Tue Mar 5 21:42:13 EST 2019

John,

 We are using that board in our radio-less nodes that are about to be
released. You really need some kind of limiting/compression when you just
hook a mic to the CM1xx chip. It works very well. Anyone that is building
their own radio-less node should be aware of this. You either need to
reduce the level such that peaks do not clip or use some kind of
compression.

*73 Doug*

*WA3DSP*

*http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*

On Tue, Mar 5, 2019 at 1:52 PM "John Griffith via ARM-allstar" <
arm-allstar at hamvoip.org> wrote:

> 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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> > > >
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> > > >
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> > >
> >
> >
> >
>
>
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