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

[dbromage@fang.omni.com.au (David Bromage)]

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