GPS MPH and Location Accuracy on 412gw

[Jagmanmick]

Does anyone know the accuracy of the GPS unit. Been checking speedo readings against the display and note that the GPS reading is a couple of MPH lower than indicated speedo reading. As speedo's cannot read lower than your true speed was wondering if the GPS readout is accurate!

 

[Nigel]

Average GPS speed over 1 hour should be well within 1mph accuracy.
If you are looking at it over just 10 seconds then it could be way out due to local reception issues.

The speedometer must read higher than real speed when it departs the factory and it is also affected by tyre pressure, tyre model, tyre temperature etc, so you should expect what you are seeing, it is normal for the car speedometer to over read by 2-5mph.

 

[BJB]

Usually the GPS reading is 3mph lower than the speedo.This also shows on Sat Nav units.

 

[Nextbase Support]

The calculation of speed is based upon GPS position and hence distance travelled over time taken.

This is a complicated algorithm and there may indeed be some discrepancy between devices, as it is a calculated speed, not an actual speed as measured by your road wheels. In our tests, once multiple satellites have been located the speed is accurate to within 5%. Normally however, this is still MORE than your speedometer will display, as vehicle manufacturers always tend to be optimistic in their display of speed.

The location should be accurate, the Map should confirm this when you play the files back.

 

[Jagmanmick]

Thanks for the info Tiffany.
I have noticed when parked the location does vary slightly, presume this is due to the number of satellites the GPS unit can see.

 

[Sabe]

I think it's hardware and software issue, my gps navigator shows true speed(verified) but i have one designated gps speedometer that shows 2 to 5 km lower speed all the time making hole device unusable. GPS location is never accurate when you move, that's why all car navi softwares use so called 'magnet' option, that magnet keeps your position indicator on the road even if there is errors which is convenient when you are driving, some navis can disable magnet if you choose walking mode. That magnet mode may also give people false sense of gps accuracy.

 

[Nextbase Support]

There isn't a hardware or software fault: the difficulty with video recordings displaying speed is it will naturally take time to perform the calculation and display the updated speed.

This means the speed displayed is for a fraction of a second ago, that is true for any device.

When accelerating to decelerating this is most noticeable as the differences in the calculated distance over time is changing at a greater rate.