Re: Re: JMG - Collins Street Flyover

<[email protected]> 10/29/02 04:57pm >>>

On Tue, Oct 29, 2002 at 12:34:00PM +1100, Michael Walker wrote:

As to the suggestion of catering to enthusiasts (or even those
slightly interested), if they were serious they could consider setting
up web cams linked from their site to show one or many of their depots
bustling with trams going in and out. Or even better, webcams that
point out the windscreen of some of the trams so people who have lots
of time and bandwidth can play being a tram driver.

The prior may be practical, but have you any idea of what the cost of
beaming a live image back to a server would be? You'd either have to
cop the high cost of the mobile network, arrange some satellite
connection or send it somehow over RF (whether it be across a low
frequency like the ones they use for voice communication between depot
and trams, in which case they'd have dialup speeds or they could use
802.11b but they'd either be within hundreds of metres of the tram or
have line of sight to it).

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I don't recall claiming it to be practical!

However, since you ask 8^)...

802.11b although probably too complex could be an option on some parts of track given the linear nature of some of the streets with a suitably positioned directional antenna. I don't know how accurate some of the allegations of distance are, but many of the omnidirectional antennae are claiming distances in kilometres. Problems would be finding enough suitable postions, possibly hills and the like (the claims for 802.11b are that it will go through buildings with varying attenuation) will be problematic, and one could argue that the trams themselves would generate electrical interference. However, it would be one thing to point an antenna down the Port Melbourne tram line from Southbank depot, totally another trying to cover the length of the 86!

Currently Alphalink have just rolled out a wireless internet service for the inner northern suburbs (Carlton to Clifton Hill). From their website at http://www.alphalink.com.au/amain235.php , I would suspect that it is a 802.11 solution given the choice between 11Mb/s and 54MB/s. For $330 setup and $297 a year, it isn't a particularly expensive option for someone like a tram operator, especially once the coverage improves.

On the above basis, I daresay there are other possibilities that wouldn't break the bank, at least at proof of concept level.

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