[arm-allstar] URI audio noise

[Doug Crompton]

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/ 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.hamvoip.org/pipermail/arm-allstar/attachments/20141031/04521849/attachment.html>