It's not exactly using the tracks, but Andrew has provided many
communications systems for rail networks using Radiax (R) radiating coaxial
cable laid alongside the rails. The cable has slots tuned for specific
bands such as VHF, cellular, GSM, or PCS, and has a tapered radiation loss
characteristic to give even signal strength along the line. Every so often
you put a repeater or network access point. Most of these systems have been
in underground metro tunnels, such as in Hong Kong where commuters talk on
their GSM phones through this network. However, it does get rather
expensive for a network hundreds of miles long, and the unusual propagation
and fade charateristics can limit the bandwidth.
Ralph
-----Original Message-----
From: Charlie Younghusband [mailto:[email protected]]
Sent: Wednesday, October 04, 2000 10:26 AM
To: Andreas Timm-Giel; [email protected]
Subject: Re: AW: Moving Targets
At $7 US/minute @ 64kbps, that's $420 /hr @ 64kbps or 6720 US $ / hr @
1Mbps.
Plus hw & ISP costs for down under. Yikes. Your research project could end
pretty quickly with an Inmarsat type solution.
Want a real research project? Find a way to send the signal through the
train
tracks. ;) Only way to really fix the tunnel problem!
Seriously though, I'd talk to some of the wireless providers in Australia.
Australia is quite advanced at digital wireless services, they might be all
over
an additional excuse to expand their east coast network where most Aussie
cities
are anyway.
Charlie
Also note that a 1Mbps downstream and a 56 upstream probably isn't a good
matchup (an offhand guess); even if you're doing 100% downloading of files,
your
upstream bandwidth could quickly become the bottleneck just with ACKs
assuming
normal windows TCP/IP. Something closer to a 10 to 1 ratio might be more
appropriate. Check some of the litterature regarding assymetry and TCP/IP.
Andreas Timm-Giel wrote:
Second problem for L- and
> S-band systems will be the prices for capacity on satellites (just as a
> reference: Inmarsat takes around US$ 7 / min for a 64 kbit/s link)
> >
> > Hi,
> >
> > I'm doing a research project about providing Internet access to moving
> > targets on the eastern seabord of Australia. In this case, the moving
> > targets are trains.
> >
> > We really need to provide around 1MB or so downstream, maybe 56k or so
> > uplink. I've been doing a lot of searching but facts seem to be hard
> > to come by.
> >--
Charlie Younghusband
Network Systems Engineering
Xiphos Technologies http://www.xiphos.ca/
514-848-9640 (f) 514-848-9644
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