Low latency IP Audio streaming for remote base?

Discussion of internet radio linking, and other similar things.

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Low latency IP Audio streaming for remote base?

Postby Wowbagger » Wed Apr 28, 2010 8:12 am

I'm helping my club out on setting up Kids Day on the Air this June 19th. Unfortunately, the site we pretty much have to work from has a S7 noise floor, with interfering signals as high as -60dBm! - not exactly conducive to HF contacts. The plan is to operate a remote base for receive, somewhere with a lower noise floor, and just transmit from the site.

So the problem is "how to get audio from the remote base to the site?" One way would be to do an HF to VHF or UHF link, but that really requires a control operator at the remote base. The other would be to remote control the radio over the Internet via a secure tunnel - that moves the "control point" to the site and removes the need for a remote operator (also the remote site isn't transmitting). I've done a bit of playing around with Icecast2 + Ices2, but I really cannot get the latency below about 2 seconds here on my local network. That seems a bit high for 2 way communications, and I'd like to see if anybody else has a better suggestion for a solution.
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Re: Low latency IP Audio streaming for remote base?

Postby motorola_otaku » Wed Apr 28, 2010 10:31 am

I saw an ad for these guys in CQ yesterday but don't know a thing about them: http://www.glentekcorp.com/
Their solution to IP latency is to use a POTS line for audio back to the operator with the IP side handling radio control.

I don't guess the remote base site will be close enough to use point-point fixed devices, like Canopy?
And the sign says you got to have a membership card to get inside.

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Re: Low latency IP Audio streaming for remote base?

Postby Wowbagger » Wed Apr 28, 2010 11:12 am

motorola_otaku wrote:I saw an ad for these guys in CQ yesterday but don't know a thing about them: http://www.glentekcorp.com/
Their solution to IP latency is to use a POTS line for audio back to the operator with the IP side handling radio control.

I don't guess the remote base site will be close enough to use point-point fixed devices, like Canopy?


Not even close - no line of sight.

And POTS would be difficult given the circumstances.

This is a one-day event, not an on-going set up.
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Re: Low latency IP Audio streaming for remote base?

Postby Wowbagger » Thu Apr 29, 2010 9:46 am

Well, I've been doing a bit of experimentation, so I'll share:

Experiment #1: icecast2 + ices2 (http audio streaming)
Verdict: Unsatisfactory - buffering adds a minimum of 2 seconds latency. If the system is configured to use a low bitrate then it is even worse, as many clients insist upon buffering 64KB which is over a MINUTE of audio.

Experiment #2: Ekiga
Verdict: Possible - Low latency on LAN. However, will require registration of the radio with an Internet visible SIP server to set up the connection. I'll either have to use ekiga.net + insure the base SHALL NOT accept calls save from known sources OR use a private SIP on a non-standard port (:= difficult to do with standard clients). Also there needs to be a way to force Ekiga to accept the incoming call.

Future experiments:
MAST - RTP only server, no SIP needed. Requires JACK audio interface (grrr.)

Eliminated:
Echolink - pretty much Windows only, which rules it out.
IRLP - Requires Redhat, requires their audio interface board, hard to make a private link.
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Re: Low latency IP Audio streaming for remote base?

Postby kd5wyu » Thu Apr 29, 2010 1:26 pm

Any of your guys have a Kenwoody TS-480? It has some remote base capabilities that may do what you want.

http://www.kenwood.com/i/products/info/amateur/ts_480/pdf/TS-480_manual_E.pdf

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Re: Low latency IP Audio streaming for remote base?

Postby Wowbagger » Thu Apr 29, 2010 5:46 pm

Not that I am aware of: likely, the radios will be my IC7000, and a SDR5000 borrowed from work - Which one I use for receive and which one I use for transmit is still open for debate, but I am leaning toward the SDR doing RX at home and my 7000 doing TX.
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Re: Low latency IP Audio streaming for remote base?

Postby ve3nsv » Thu Apr 29, 2010 7:45 pm

Have you tried Skype yet? I have a friend who remoted am MP-1000 with ham radio deluxe and Skype with decent results.
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Re: Low latency IP Audio streaming for remote base?

Postby motorola_otaku » Thu Apr 29, 2010 9:37 pm

There's also Allstar (http://www.allstarlink.org) but I don't think you're going to like the latency with them either.
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Re: Low latency IP Audio streaming for remote base?

Postby Wowbagger » Fri Apr 30, 2010 8:01 am

I'm not sure Skype gives me anything Ekiga doesn't - both need a central server to set up the call, and at least with Ekiga I can think about running my own SIP server that I control access to.
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Re: Low latency IP Audio streaming for remote base?

Postby Wowbagger » Fri Apr 30, 2010 8:13 am

motorola_otaku wrote:There's also Allstar (http://www.allstarlink.org) but I don't think you're going to like the latency with them either.


Again, a bit heavy - I'd looked at Asterisk, but that's a lot to set up for one day.
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Re: Low latency IP Audio streaming for remote base?

Postby slimbob » Mon Apr 18, 2011 7:57 pm

Crossband repeat and ham radio deluxe =D
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Re: Low latency IP Audio streaming for remote base?

Postby Wowbagger » Sat Apr 23, 2011 9:46 pm

slimbob wrote:Crossband repeat and ham radio deluxe =D


Sorry, HRD has one failing from my perspective - it requires an invasive, stability robbing virus to be installed on your computer.
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Re: Low latency IP Audio streaming for remote base?

Postby smokeybehr » Tue Apr 26, 2011 3:13 am

Wowbagger wrote:
slimbob wrote:Crossband repeat and ham radio deluxe =D


Sorry, HRD has one failing from my perspective - it requires an invasive, stability robbing virus to be installed on your computer.


You mean Windows?
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Re: Low latency IP Audio streaming for remote base?

Postby KC8RYW » Tue Apr 26, 2011 4:05 pm

Who said IRLP needs to use their boards? :baby:

There's nothing that exciting about IRLP boards. Some LEDs, an 8870 for DTMF decoding (which is fed to the parallel port I/O lines), and some logic-level stuff for PTT and Aux outputs from the parallel port I/O lines.

The whole damn thing runs off of a bunch of binaries written in C, an open-source voice-conferencing program, BASH scripts, netcat, pgp, and cron jobs.

Take a look at the scripts sometime. Starting with the install script.

It's a giant kludge on wheels, but there's nothing stopping you from modifying it, other than perhaps Dave Cameron's IP rights. :ve4uo:

Interesting link: http://www.irlp.net/new-install/

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Re: Low latency IP Audio streaming for remote base?

Postby smokeybehr » Thu Apr 28, 2011 2:06 pm

I found a schematic for an IRLP interface board that I could easily fab up on a breadboard and transfer it to one of those breadboard PCBs. I just need to order the ICs from one of the usual sources, and whip it up for testing in an evening.
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