[arm-allstar] URI audio noise

[Doug Crompton]

Sam,

 Very interesting. I have always used pin 20 for ground when I wire next to the audio pins 21, 22.  I have not looked at the physical URI inside but I would guess maybe there is a poor contact to your pin 13. You might try ohm'ing that out. The shell should also be tied to the same point. While the schematic shows pin 13 as the shortest ground that is not representative of the real circuit. 
73 Doug
WA3DSP
http://www.crompton.com/hamradio


From: kj6qfs at gmail.com
Date: Sat, 1 Nov 2014 02:41:09 -0700
To: arm-allstar at hamvoip.org
Subject: Re: [arm-allstar] URI audio noise

You wouldn't believe it! I completely eliminated the noise by moving my ground from URI pin 13 to pin 20. The Schematic that DMK offers for the URI shows all Ground pins tied to a common ground point, so maybe this is specific to mine. Thanks Doug, and everyone else, for bearing with all the questions, hopefully some other newbie will find them helpful one day in a search. 73KJ6QFS
Sent from my iPhone
On Oct 31, 2014, at 6:15 PM, Doug Crompton <doug at crompton.com> wrote:




Sam,

 A scope would be real helpful in tracing this. It sounds like switching power supply noise. This could also come from a fan as many small fans used for rig cooling are actually AC fans with internal switchers. I have often seen this type of EMI and a RC filter works well in that case. About a 30-50 Ohm resistor in series and a 500-1000uf cap to ground on the 12V lead to the fan.

I don't think this is a normal thing with the URI or a large number of us would be seeing it on our systems. Something specific to your setup is causing it. With all of your tests I think I would rule out a ground loop or power supply to the BBB.
73 Doug
WA3DSP
http://www.crompton.com/hamradio


Date: Fri, 31 Oct 2014 14:06:54 -0700
From: kj6qfs at gmail.com
To: arm-allstar at hamvoip.org
Subject: [arm-allstar] URI audio noise

Hello again to all, I've interfaced a DMK URI to an RLC-4 Repeater controller. Everything works great, with the exception of the common "USB noise" (high-pitched whine, sounds like square wave) on both TX and RX audio from the URI. Here's the troubleshooting I did so far, to no avail.
*double-checked my grounding between the URI and controller. ( RLC-4 radio port pin 1 -> URI pin 13) *tried different USB cables between URI and BBB*tried powering BBB with mini-USB cable attached to charger-less laptop instead of my +5V wallwart*tried powering BBB with USB cigarette adapter plugged into controller's +12VDC supply*tried removing ethernet cable 
 Any tips/ideas would be greatly appreciated. Thanks!

KJ6QFS
Sam Skolfield


_______________________________________________

arm-allstar mailing list
arm-allstar at hamvoip.org
http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar

Visit the BBB web page - http://www.crompton.com/hamradio/BeagleBoneBlackAllstar/ 		 	   		  
_______________________________________________

arm-allstar mailing list
arm-allstar at hamvoip.org
http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar

Visit the BBB web page - http://www.crompton.com/hamradio/BeagleBoneBlackAllstar/
_______________________________________________

arm-allstar mailing list
arm-allstar at hamvoip.org
http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar

Visit the BBB web page - http://www.crompton.com/hamradio/BeagleBoneBlackAllstar/ 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.hamvoip.org/pipermail/arm-allstar/attachments/20141101/e72e8ad6/attachment-0001.html>