Satnav

[Blodders02]

I have an AvensisTR and the satnav is sometimes unable to locate itself. Can you help?

[Raistlin]

Try on of these or move...

[Blodders02]

Is that a genuine Toyota part or do they stock it at Halfords?

[dew66]

David,

For any GPS receiver to correctly locate it position, the receiver has to simultaneously receive the signals from at least 4 satellites (although in some circumstances 3 will do for some receivers but then without the GPS giving elevation information).

The satellites themselves are spread all over the sky and all appear to be slowly moving. So the car GPS antenna has to have a wide angle of operation.

If the line-of sight-to any one of the 4 is blocked then the GPS will be unable to determine the location.

In most situations, in open country, there will be reception from typically 8 or more satellites so blockage in some signal directions (eg from trees or occasional buildings) is ok, but in built up areas blockage caused by buildings can be significant and widespread.

And no point in considering GPS operation at all when inside a garage, tunnel or similar.

The use of the "tongue in cheek" satellite dish would be no good because the dish functions as a narrow beamwidth device - very good only for one satellite direction but no good for the other satellites.

Does this throw any light on your GPS inability?

[Blodders02]

Thanks for that. I can't see any blockage to the GPS reciviver it's as if come thing is interfering with it. I was wondering if it could be rebooted or reset.

Regards

Dave