GPS FORUM

Can anyone comment on the accuracy of GPS when it comes to measuring
speed?

My own GPS is a TomTom 300 and noted that there was some difference
between the speedo and the TomTom
--
John Bradbury

On Tue, 6 Sep 2005 14:50:12 +0100, John Bradbury wrote:

|
| Can anyone comment on the accuracy of GPS when it comes to measuring
| speed?
|
| My own GPS is a TomTom 300 and noted that there was some difference
| between the speedo and the TomTom

Car speedos under read by up to 10%.
GPS are accurate to about 1mph
The police measure speed as accurately as they can, and then give you the
odd mph leeway.

I have calibrated my speedo on a nice straight run against my GPS at every
10mph which gives me an extra 5-10% in every speed limit.

--
Dave Fawthrop
Intelligent Design? my knees say *not*.
Intelligent Design? my back says *not*.

In message , Dave Fawthrop
wrote

And only if travelling in a straight line at a constant speed.

--
Alan
mailto:news2me a 2003@amacleod.clara.co.uk

On Tue, 6 Sep 2005 15:57:35 +0100, Alan
wrote:

| In message , Dave Fawthrop
| wrote
| >On Tue, 6 Sep 2005 14:50:12 +0100, John Bradbury wrote:
| >
| >|
| >| Can anyone comment on the accuracy of GPS when it comes to measuring
| >| speed?
| >|
| >| My own GPS is a TomTom 300 and noted that there was some difference
| >| between the speedo and the TomTom
| >
| >Car speedos under read by up to 10%.
| >GPS are accurate to about 1mph
|
| And only if travelling in a straight line at a constant speed.

You clipped the bit where I said that :-(

--
Dave Fawthrop
Intelligent Design? my knees say *not*.
Intelligent Design? my back says *not*.

In an earlier contribution to this discussion,
Alan wrote:


. . and on a level road - because the GPS will only measure the
*horizontal* component of the velocity - although youd have to be going up
or down quite a steep hill to make any significant difference. [I guess that
if you were going fast enough down a 1 in 3 for the 6% GPS speed error to be
significant, accuracy would be the least of your worries!]
--
Cheers,
Set Square

Please reply to newsgroup. Reply address is invalid.

Dave Fawthrop wrote : |

:
: Car speedos under read by up to 10%.

:I think you meant over read..............ie when you are doing 70 mph car
speedo will read approx 77 mph.

Mark

John Bradbury wrote in message
news:Mmbk8iAU6ZHDFAtH@j-brad.com...
My TomTom Go says Im going 3 mph slower than my car speedo, this is a
constant 3 mph what ever speed Im actually going at.

--
Regards,
David
<><
Please reply to News Group

On Tue, 06 Sep 2005 20:03:08 GMT, Mark wrote:

|
| Dave Fawthrop wrote : |
|
| :
| : Car speedos under read by up to 10%.
|
| :I think you meant over read..............ie when you are doing 70 mph car
| speedo will read approx 77 mph.

Yes

--
Dave Fawthrop
Intelligent Design? my knees say *not*.
Intelligent Design? my back says *not*.