Technology can, and will, go wrong - I have a witnessed max speed shown on TOM TOM of over 700mph (yes over seven hundred mph)!
The A38 around Burton is nice and straight . . . . . . sanity was restored by a re-boot.
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He should be done for drunk driving instead: from his own admission.
"I'm wasted in taxis," he said."
:-)
madf
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I don't know what is the maximum speed a GPS will record but I've seen a genuine 499 miles/h on my Garmin - in a 737 over France.
JS
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I have a Garmin Foretrex 101 which is a jogger's unit [ I use it for timing trains actually! ] and it will record up to 999mph. I would imagine most of the sat nav versions are similarly capable of recording the same speed - the manual should say what the upper limit is.
Incidently, like in the case above, I have had a corrupt signal when it didn't log on to the satellites properly on two occasions [ in both cases while re-aquiring after a loss of signal caused by a bridge ] and I have as a result clocked London commuter trains apparantly doing 319mph and 442mph (!).
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Didn't Top Gear prove (using a TVR) that if you can do about 160MPH a Gatso cannot record this.
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Muggy
How do you get it to work at all in a train? Mine fails to acquire any signal at all in Virgin Pendolinos (alu body may be a factor), little better in Silverlink's 321 emu. Not tried it in the new 350 Desiro yet.
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This is a bit off topic but you asked so I guess I ought to answer! :-)
It will work on any train in the UK except all variants of Voyagers [ 220s, 221s, 222s ] and Desiros [ 350s, 444s, 450s; I have yet to test it on a 185 ], in these cases the windows have a coating which blocks the signals from being received [ despite the use made of GPS devices by some blind / partly sighted people - possible interesting Disability Access Act stuff looming here! ].
In the case of the Pendolinos, it will not work in the cabin, but it will work if you stand in the doorway vestibules; I am not sure if this is down to the ridiclously small size of the cabin windows or if they are coated - probably a combination of both. I need to test it further to be certain.
However, in all cases where the GPS will work it is important to keep the device close to a window as it will require "line of sight" to four satellites in order to lock on and after that it needs at least three satellites to maintain the "lock" - drop to two and the "weak signal" kicks in and it loses the connection.
Location is also a factor - where the line is in a cutting or around tall buildings a signal is very difficult on any stock. Out in the open, there should generally be no problems, but large numbers of trees close to the line - especially in summer - will block the signal [ the water in the leaves is the problem here ].
I have also found that although in theory the GPS satellites are evenly distributed across the sky, at times only eight are above the horizon for a given location and it can be worth moving from one side of the train to another to see if the signal is any better.
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Sorry - forgot to add [ and I can't find an editing function! ] the GPS will not work in Junipers [ 334s, 458s, 460s ] either.
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GPS can screw up
My Garmin E Trex legend clocked a max of 730 and a distance travelled in excess of 700miles in an afternoon on foot in Thornthwaite forest (Keswick)
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Took a GPS receiver with me on a flight in the US - with 200mph tailwinds at 30,000 feet the GPS spat out a ground speed of over 700mph.
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