View previous topic :: View next topic |
Author |
Message |
boyde Occasional Visitor
Joined: Dec 29, 2005 Posts: 9
|
Posted: Fri Dec 30, 2005 11:32 am Post subject: MPH out by about 7mph |
|
|
Not that it is really important, the speed on my tomtom go300 is about 7mph behind. How can I sought this? |
|
Back to top |
|
|
mikealder Pocket GPS Moderator
Joined: Jan 14, 2005 Posts: 19638 Location: Blackpool , Lancs
|
Posted: Fri Dec 30, 2005 11:37 am Post subject: |
|
|
What are you using to compare this to, if its the cars speedo then I would sugest the error is the speedo, (or incorrect size tyres etc), Note the GPS speed is at its most accurate on flat straight roads, is the 7MPH error at 70MPH indicated on the speedo? if so 10% is about all I would expect from a car speedo, thats your safety margin for not exceeding the limit - Mike |
|
Back to top |
|
|
peterc10 Frequent Visitor
Joined: Aug 21, 2005 Posts: 1761 Location: Kent, England
|
Posted: Fri Dec 30, 2005 1:24 pm Post subject: |
|
|
Mike's right - if you are doing a constant speed in a straightish line and on a flatish road it is your speedo not your sat nav that is wrong. |
|
Back to top |
|
|
Darren Frequent Visitor
Joined: 11/07/2002 14:36:40 Posts: 23848 Location: Hampshire, UK
|
Posted: Fri Dec 30, 2005 1:35 pm Post subject: |
|
|
Regulations require that vehicle speedometers are either 100% accurate or can read up to 10% over.
Consequently most speedo's will read somewhere between the two, often towards the 10% fast end.
Your GPS Speed is far more accurate assuming you are travelling at a constant speed. _________________ Darren Griffin |
|
Back to top |
|
|
mossman Regular Visitor
Joined: Dec 21, 2005 Posts: 90
|
Posted: Sat Dec 31, 2005 3:03 pm Post subject: |
|
|
Although I agree with the replies here (after all, the GPS data has to be a much more accurate way of computing speed), for me, it does take a huge leap of faith to start to disregard the speedo and use the GPS speed (even though I know that is is likely to be the more accurate). |
|
Back to top |
|
|
Adek Regular Visitor
Joined: Dec 01, 2005 Posts: 70 Location: UK
|
Posted: Sat Dec 31, 2005 3:23 pm Post subject: |
|
|
a traffic policeman explained to me that speedo's on the car are not all that accurate, as the tread on the tyre actually influences the reading you will get, and hence it will change with time as your tyres change.
There are other parameters which also influence its accuracy, so he explained to me that they re-calibrated their speedo's quite frequently on the patrol cars- I am not sure if this was the cars actual speedo they re-set or some further unit installed by the police.
anyway, the main difference I guess would be on the update speed of the GPS, - the car speedo will react very quckly to changes in the car speed, the gps will be slower I would think.
Adek |
|
Back to top |
|
|
Skippy Pocket GPS Verifier
Joined: 24/06/2003 00:22:12 Posts: 2946 Location: Escaped to the Antipodies! 36.83°S 174.75°E
|
Posted: Sat Dec 31, 2005 3:32 pm Post subject: Re: MPH out by about 7mph |
|
|
boyde wrote: | Not that it is really important, the speed on my tomtom go300 is about 7mph behind. How can I sought this? |
Fix the speedo on your car.
Car speedos have to read fast - you would feel pretty annoyed if it read too slow, wouldn't you. _________________ Gone fishing! |
|
Back to top |
|
|
|
Posted: Today Post subject: Pocket GPS Advertising |
|
|
We see you’re using an ad-blocker. We’re fine with that and won’t stop you visiting the site.
Have you considered making a donation towards website running costs?. Or you could disable your ad-blocker for this site. We think you’ll find our adverts are not overbearing!
|
|
Back to top |
|
|
|