Losing ICN 630 GPS signal...

Mojo · Posted: Wed Dec 22, 2004 12:23 pm Post subject: Losing ICN 630 GPS signal...

I have a strange problem. My ICN 630 loses cannot get a GPS fix in my car when I have it in the centre of the windscreen practically sitting on the dashboard. If I move it upwards towards the rear view mirror or along the windscreen towards the right (drivers side) the GPS signal returns until I practically get a full signal when it's almost at the door/windscreen pillar. Anyone know why this is happening? What could be interfering with the signal? I don't have a heated front windscreen.

Darren · Posted: Wed Dec 22, 2004 12:38 pm Post subject:

What car do you have? Sounds very much like you have one with an athermic coating on the windscreen to block heat but this also has a side effect of degrading the GPS signal.

Most PSA vehicles (Citroen, Peugeot, Renault) have these coatings as do some Italian vehicles e.g. Alfa Romeo.

The coatings often do not extend the the far edges of the screen and they normally leave a clear section behind the rear view mirror to alolow the use of Toll Tag devices etc.

Your only options are to mount where you can get a signal or use an external antenna or re-radiating antenna, see here.
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Darren Griffin

Mojo · Posted: Wed Dec 22, 2004 11:33 pm Post subject:

Ah, well I do have an Alfa 156. How does athermic coating work then? I only have to move the GPS a few cms from the centre to get a signal. It's almost full strengh if I put it in front my the driver's cockpit, but it's distracting there, so I leave it at the far right hand side of the driver by the door/windscreen pillar and it's fine there.

Darren · Posted: Thu Dec 23, 2004 12:59 pm Post subject:

Athermic coatings are an anti-glare layer, how they work I have no idea but I do know that they as they block solar radiation they have the unwanted side effect of degrading the already pretty weak signal from the GPSV's 25,000 miles above.

The simplest solution would be to buy the accessory external antenna for the iCN630, this has a magnetic base and mounts outside. You can then position the unit on the dash whereever you wish.
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Darren Griffin

DavidW · Posted: Thu Dec 23, 2004 4:27 pm Post subject:

The athermic windscreen most likely has a metallic based coating or layer in the glass. Not only will that reflect infra-red radiation (the whole point of it), it also affects the RF permeability of the screen.

David

Dave · Posted: Fri Dec 24, 2004 5:22 pm Post subject:

Correct, they do have a metallic coating inside the screen, a very thin layer not visible.

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