[App_rpt-users] Jim and Ramesh (chan_voter and RPi)

Shane Morris edgecomberts at gmail.com
Thu Dec 27 15:06:28 EST 2012

Hi again,

Just did some quick research on the schematics of the Cubieboard and
the datasheet of the Allwinner A10 device - the EMAC for ethernet is
completely separate from the three on-chip USB that are routed out to
the two USB host and one USB-OTG port. So these are separate channels
for the communications in all cases, not one on-chip (and a poor one
at that) shared amongst at least three devices on the RPi.


On Fri, Dec 28, 2012 at 6:56 AM, Shane Morris <edgecomberts at gmail.com> wrote:
> Hi all,
> I was thinking, even though the RaspberryPi can't handle the audio
> stream from a URI due to the limitations of the USB bus, what is the
> ethernet performance like? I imagine it wouldn't be terribly good, due
> to the fact the ethernet swings off the USB, but hear me out...
> chan_voter is a module that communicates via ethernet, am I correct?
> It uses an RTCM connected over an ethernet bus to communicate the
> voice data around, and I can imagine, at a low codec rate like GSM or
> even Speex, throughput wouldn't be as excessive as raw sound data
> coming from a fob.
> So my proposal is, before Jim and Ramesh throw out the baby with the
> bathwater, and consign the RPi effort to the dust, why not take the
> work, which I believe involves getting Zaptel/ DAHDI to work with the
> RPi, and apply it to a purely chan_voter system? Yes, I know the
> chan_voter is dependant upon app_rpt, and in the future, someone,
> somewhere, is going to try to hook up a sound fob, and miserably
> complain it doesn't work, but we get the same questions about Asterisk
> 1.8 over and over too, right?
> The advantages here are manyfold - again, low power consumption comes
> into the game, everyone knows I personally need as low a power
> consumption as I can get. The fact the RTCM data (ie, VoIP over
> ethernet) is much more suited to the infrastructure on the RPi is a
> good thing here too. The fact that normal Asterisk just runs, and runs
> well, on RPi is another motivating factor - my friend Andrew is
> running his house PABX on an RPi running Asterisk 1.8 I believe, there
> is an image for this. And yes, simply the cool factor - who else can
> say they run their voting repeater system off something the size of a
> credit card, with all the proprietary, messy, rack mounted stuff out
> there?
> If Jim and Ramesh are unwilling, or unable, to help, due to the fact
> that the RPi is a bit of a letdown (I heard about the USB performance
> issues - ouch!), I would like to take their work, and apply it to a
> platform I think may have a bit better USB performance - its based on
> a Cortex-A8 (ARMv7) - the Cubieboard. For all you I/O junkies out
> there, what can YOU do with 96 I/Os? For $49, gets you something good,
> look it up, www.cubieboard.org - I got one for Christmas, and I
> thought it would be good for this. Its a Chinese Allwinnner A10
> device.
> Since I have gone beyond just simple URI systems since Jim introduced
> me to the RTCM, I would like to get this to work. I recognised the
> RTCM did something I was talking to Andrew about on the way home from
> Expedition in October of this year - "Wouldn't it be nice, Andrew, if
> we could have a voting system that allows us the flexibility to run an
> Expeditions communications in such a way that make it simply easy for
> us, and easy for the users?" Before, we've had users change channels
> in different places, this inevitably leads to confusion. With a
> chan_voter system, we can run the same UHF CB channel across the
> arena, and access it anywhere.
> Andrew had said to me "Shane, do you know how much such a system would
> cost...?" Yes, Andrew, I had the Simoco, and I bought the RTCM for
> $250 second hand ^.^ Sorry for being a smart-alec, I know you meant
> how much would a PROPRIETARY system cost us?
> Anyway, I hope I have Jim and Rameshes blessing on this one - they did
> some great work, and I know it must've been a letdown to find out the
> hardware simply wasn't up to the task. Believe me, this isn't the
> first story I've heard about the lacklustre I/O performance of the
> RPi, and it won't be the last. But by using their work on a much
> stronger (I hope!) platform that it still ARM Linux based, I hope to
> circumvent at least one problem with the RPi. And its only $11 more
> before shipping!
> Looks like I'm going to be reading the Allwinnner A10 device spec
> sheet now, huh? =)
> Thanks for putting up with my ramble everyone.
> Shane.

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