[arm-allstar] Asterisk - Hum

[Eric Smyder]

Thanks for answering my inquiry, David.

The Pi3 is powered by the supply that came with it.  Is that supply
considered stable and clean enough?

The BF-888s is battery-powered.  The interface is the homebrew interface
following the USB FOB Simple Modification right in the DB shell.
https://hamvoip.org/hamradio/usb_fob_simple_modification/

The W3HZU repeater runs the DMK URI interface off the IBM PC in the video.

How would one begin to attack the problem if it is a ground loop?

thanks,

Eric
N3FIX


On Wed, Dec 13, 2017 at 10:27 PM, David McGough <kb4fxc at inttek.net> wrote:

>
> Hi Eric,
>
> You don't mention what type of interfaces you're using--like URI's,
> homebrew fobs, etc.???
>
> The noise heard on the HamVoIP system sounds like noise from a switching
> power supply and/or ground loop in the audio path.
>
> How are you powering the RPi3??  And, similarly for the BF888??
>
>
> 73, David KB4FXC
>
>
> On Wed, 13 Dec 2017, "Eric Smyder via arm-allstar" wrote:
>
> > Hello all:
> >
> > I've been experimenting with HAMVOIP, on a Pi3 at the home QTH with a
> > BF-888s as my radio.  It is a remarkably good system and easy to
> > configure.  However, I'm having an issue.  It is actually the same issue
> I
> > noticed on the W3HZU 6 meter repeater.
> >
> > The video links below exemplifies the issue.  When transmitting directly
> > from the repeater with the hand-mic the repeater sounds great.  When I
> > trigger the AllStarLink from Asterisk, or when the node makes an
> > announcement or identifies, there is a distinct tone or hum.  I get the
> > same thing on my Pi 3 at the house if I key the transmitter and speak
> into
> > the BF-888s.  It seems to be coming through the computer or being picked
> up
> > somewhere in the connections to the URI.  I have taken measures to shield
> > the wiring between the radio and the URI, but the hum is still there.
> >
> > At W3HZU 6m AllStarLink
> > https://photos.app.goo.gl/OtJn3aK2ZRCd6cPs2
> >
> > At the home QTH using the Pi3, where the hum is more noticeable.
> > https://photos.app.goo.gl/XsUC4on5t04LH6CS2
> >
> > Has anyone else noticed this and is there something I can do about it?
> >
> > Thanks,
> >
> > Eric
> > N3FIX
> > _______________________________________________
> >
> > arm-allstar mailing list
> > arm-allstar at hamvoip.org
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> >
> > Visit the BBB and RPi2/3 web page - http://hamvoip.org
> >
>
>