[arm-allstar] PTT Delay idea

[David McGough]

John,

What is your audio input source? Can you turn the input level up some 
before the SMM2167--that's probably the simplest solution??


73, David KB4FXC

On Sun, 6 Oct 2019, "John Griffith via ARM-allstar" wrote:

> I've been trying to integrate one of these SSM2167 boards into my repeater
> now.
> I can't figure out how to completely defeat the noise gate however. On low
> level transmissions off the network, the audio cuts out. 
> I need to defeat the noise gate while maintaining the gain. Also I need to
> find a schematic of the little red board itself, not just the chip so I
> know how to tailor it to my needs. I found that 50K resistor for R1 works
> for the compression ratio I need, and I've tried all different values for R2
> including the no more than the recommended 5K (1mV) threshold, but I can't
> detect a difference in the noise gate.  Any documentation would be great and
> appreciated.
> 
> John
> N7OKN
> n7okn.com
> 
> 
> 
> >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
> 
> 
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