Quote: Originally Posted by Dragorus

Hey all.....I am an installer for GPS systems here in NJ......What you need to be as accurate as possible is an external antenna magnetic mount for your car.....That would be the best and a 12 channel WAAS enabled receiver.....All those usb through the glass receivers suk.....They sell kits for this......I would try to get at least a 8-12 channel GPS receiver.....And make sure it is waas enabled all this will ensure you are being tracked at 10 foot radius......Hope this helps...Also Street atlas has been working awsomely with my 12 channel gps external antenna magnetic roof mount......It always "Snaps to road" even thought it isn't an included feature....Because I am being tracked at 10 foot radius.
The usb Earthmate is a 12 channel WAAS enabled receiver even though everyone here keeps saying it's no good. And "through the glass" should have no effect on the signal as long as you have an otherwise unobstructed view of the sky. Glass or plastic won't affect the signal, only metal. An external roof mount antenna is better only because that is the highest point of the car.
And you still need to be receiving the correction signals from one of the two WAAS satellites to get the increased accuracy. Since these satellites are geostationary (over the equator), they may be blocked if you don't have a clear view of the horizon. WAAS corrections are only available for North America.