[cma-l] Streaming audio problem

Tue Nov 1 18:45:21 GMT 2011

Hi Phil,

I'm on the onelist too - but haven't put the question there as it's been 
very quiet for a while.

Yes, we're JFMG licensed for the link and have been since 2006. The schedule 
specified direction anetanna and that's what we have, 3 element Yagi's at 
each end. The antenna don't need to be CE marked, but the transmitter has to 
be. It is part of the JFMG agreement.

Ofcom had a report of interference to a radio ham and, when they did a site 
visit, they were the ones who saw the antenna was broken. It is on those 
grounds they want to come back and check it complies once the repairs have 
been carried out. The antenna was fixed yesterday, the transmitter is back 
on today and Ofcom will visit shortly, date to be arranged.

It was a temporary 'fix' so we're not looking at spending money on anything 
at this time. The FM link works fine for us when it's active, but maybe not 
for the radio ham. The old PC we had never had these issues, so we suspect 
we've not set something up properly. The router is prime suspect at present 
and we'll try swapping that out shortly.

In the meantime, the problem is solved by virtue of having the link back in 
service. Having said that, we could save a bob or three by taking the link 
out and using the ADSL at both sites. I should note that we are mono only, 
as in 'AM', so we don't pay for a stereo license on the link, which makes it 
a quarter of the stereo annual cost at £208.50. The shoutcast stream bit 
rate is low, 56 Kbps at 22.1Khz in mono.

I hadn't thought of using VLC, having tried Windows Media Player and Winamp 
and getting similar problems I took it that any media player would suffer in 
a similar fashion. Just to test this out I'm installing at rtight now (good 
job we have VNC installed) and will let it run overnight. Nobody on site so 
the listeners will hear the audio from the FM link. I'll see how that goes. 
Winamp fell over every few minutes and was forever showing the [Buffer: 0%] 
message. WMP would run for a couple of hours, then stop without warning.

If this stops/starts I'll try the Ping trick - although I'm probably going 
to put that in a batch file I can hide rather than leave a command prompt 
open.

Connecting anything to the NHS system is a big No. We've been warned not to 
even contemplate it. A bit daft as they have as dedicated microwave link 
between the two sites that was put in years ago.

Just to pick up on the ISP dropping the connection, the audio was being 
restarted due to silence of over 16 seconds every 2-3 minutes at times 
during the day, but not overnight and not when something else is connected, 
so there's a possibility that's the reason.

While I've been typing this, VLC has remained active for almost 18 minutes - 
hmmm. No, I didn't stay connected, so can't be that. I need a darkened room 
now.

Gordon

----- Original Message ----- 
From: "Phil Edmonds" <lists at philedmonds.info>
To: <cma-l at mailman.commedia.org.uk>; "Hospital Radio Discussion List" 
<hospitalradio at hospitalradio.dns2go.com>
Sent: Tuesday, November 01, 2011 5:13 PM
Subject: Re: [cma-l] Streaming audio problem

Hi Gordon,

I've took the liberty of including the "Hospital Radio Onelist" into
this reply as there will probably be some technically knowledgeable
people who subscribe to that list that aren't on the CMA mailing list.

See below for my comments

On 31/10/2011 20:19, Gordon Sharpe, TMCR 95.3 FM wrote:
> Guys, I have an issue with hospital radio, rather than community, but
> hope someone can help as it may solve another issue for me.
> */Trust AM/* serves the Bassetlaw (Worksop in N Notts, if you need to
> ask) and Doncaster hospitals. It's main base is Bassetlaw and from there
> there has been a Band 1 FM link for the last 6 years to feed audio to
> the remote hospital in Doncaster, a tad over 13 miles as the crow flies.
> Except it broke last week, the antenna fell apart. Thats been fixed but
> now Ofcom want to check the link transmitter and it could be a while
> before service can be restored.

That's interesting - in my experience of JFMG licenced "Programme Making
and Special Event" links Ofcom have not been interested in checking the
equipment - though they do often specify use of directional tx aerials
(I assume that any new kit would have to be CE type approved - but that
would only apply to the transmitter not the antenna?)
It would be interesting to know on what grounds they want to check the
link system before you can put it on-air - after all I assume you've
already paid the £800+ annual licence fee for the privilege.

> So, to try and make sure the patients could still listen I set up a PC
> to use Winamp to listen to streaming audio feed sent out from Bassetlaw
> using Shoutcast. It works fine for me at home, I could listen all day -
> and have done. Not so at the Doncaster studio though. It's been breaking
> up very badly, stop/start and sometimes showing [Buffer: 0%]
> I've read up about adjusting this that and the other settings and have
> tried just about everything I could find on the topic, it still does it.
> Except, when I connect via VNC to have a look at the log files or
> whatever. As long as there's a connection the stream remains stable. The
> stream is 'private' and had a password, which I took off to allow it to
> reconnect during these troubles. I often listen from home, to check that
> everything is up and running as I live in Doncaster too and can't hear
> the AM signal.

I'd try a different playback client - such as VLC.

Maybe TalkTalk do have some sort of traffic management in place which is
not seeing any upload traffic from your remote site - seems unlikely,
perhaps something on your local machine or router is dropping the
connection?

Try opening a Command Prompt Window (Start ->Run -> cmd) on the remote
end machine and running the following command:

ping -t google.com

this will run a continuous string of ping commands - which will keep the
connection live. This is a trick I use when using mobile broadband to
keep the connection open - as I find my provider often seems to 'drop'
my connection if I don't do anything for a few minutes.

> The router has already been set to a 'nailed up' connection, it's on
> TalkTalk Business. Checking the speed via ThinkBroadband.com says
> they're getting roughly 4.6 down and 0.7 up . I'm on a Virgin Cable 10Mb
> connection at home (9.6/1.0).
> I have a silence detector module running on the PC itself, it triggers
> after 16 seconds of silence. It kills Winamp and restarts it, taking it
> that the program itself has got stuck. Any blip in the meantime resets
> the counter, so the stop/start issue isn't always being detected. The
> resets are being logged at 4-5 per hour, except between 11pm and 7am
> when it seems to run smoothly ?
> I have had an active connection via VNC for the last hour and a half and
> the stream has remained up and stable during that time. Having noted the
> 11pm to 7am window when all runs with no problem I had suspected some
> sort of blocking by TalkTalk, but by having something else connected it
> sorts itself out...?
> Ideally I want to use the stream to feed the audio to the Doncaster
> studio 24/7, rather than have the FM link. OK, so the audio would be 40
> seconds behind real time but who's bothered about that when you're laid
> up in a hospital bed?

If you go down the replacing the FM link route I'd recommend not using
PC's and get a pair of Barix codecs (you'll recoup the cost in 1 year of
no JFMG licences) - though in my experiences it will drop occasionally
over ADSL links. Fine for non 24/7 purposes such as I have it in use
for. However cue Ian Hickling who I believe has had success doing this
on a 24/7 basis in Wales.

If both hospitals are the same NHS Trust you may be able to negotiate a
link over their LAN/WAN - I know of Chorley Hospital Radio and Roch
Valley Radio who do this - the former with Barix units the later with
more expensive Comrex codecs - but the principle is the same. I believe
Nick Beer at Westcountry Broadcast is your man who set-up Roch Valleys
system so give him a shout for some advice.

> I had planned to have a haircut later this week, I just hope I've got
> some left by then as this one has me puzzled.
> Any ideas?
> Gordon Sharpe, TMCR FM
>

Regards,
Phil Edmonds.

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