Re: Signal at high speed (was: Re: [NSW] Guards & Mobile phones)

["Chris Downs" <cvdowns@ozemail.com.au>]

How significant is the Doppler effect in a train travelling at 83.3m/s
(300km/h) compared with the speed of radio waves 300,000,000m/s (approx 1.1
billion km/h)?

Maybe the speed of moving from one base station to another and loss of
signal strength has a greater effect?

Chris

David Bromage <dbromage@fang.omni.com.au> wrote in message
WsnV4.421$lX1.524033@news0.optus.net.au">news:WsnV4.421$lX1.524033@news0.optus.net.au...
> As a matter of interest, has anybody ever experienced problems with the
> signal dropping out at very high speeds (i.e. 250-300km/h)? You have to
> have been to Europe or Japan to answer this.
>
> Mobile phone networks were designed to accomodate moving handsets (e.g.
> in a car or train), but I don't think the designers ever envisaged the
> handsets moving at over 250km/h. There have been reports of the signal
> dropping out because of doppler shift effects.
>
> There were also reported to be some problem in the US when the X2000 was
> test run at 162mph (260km/h) with media on board.
>
> I wouldn't think that 300km/h would cause much of a problem at the
> frequencies used by mobile phones, but how sensitive are they? France and
> Japan are both talking about 350km/h running within a few years. I don't
> think 400km/h will be that far behind.
>
> Cheers
> David