View Single Post
  #18   Report Post  
Old February 12th 08, 10:19 PM posted to uk.transport.london
Tom Anderson Tom Anderson is offline
external usenet poster
 
First recorded activity at LondonBanter: Oct 2003
Posts: 3,188
Default M25 Speed cameras

On Tue, 12 Feb 2008, Neil Williams wrote:

On Tue, 12 Feb 2008 05:02:55 -0800 (PST), Mizter T
wrote:

I've never really used a sat-nav system to compare true speeds with
indicated speeds, so I've never really been aware of the difference
between the 'true' speed I've been travelling at as opposed to the
'indicated' speed.


Be careful if you do use a sat-nav. If you're going up or downhill,
it will read slower because (so far as the satellites can see) you've
slowed down because your speed has a vertical component as well.


Unless your box is using the height it's inseparably calculated in
determining your speed!

If it was, it could tell you the gradient you're climbing, too.

tom

--
No hay banda