Garmin GPS 18 under dash with Uniden BCT-15

[zuzu]

Per my previous post, I finally got a deal on eBay for $75 for a Garmin GPS 18 PC, which uses DB-9 serial to connect to the Uniden BCT-15 scanner and a cigarette lighter adapter for power from the 12v / 13.8 vDC of a vehicle's auxiliary line through a voltage regulator out to the 5v that the GPS puck expects.

I used "industrial strength" Velcro discs, one adhered to the magnetic underside of the GPS receiver puck and the other to the top of the cowl for the instrument panel -- in other words, hidden underneath the dash top.

However, the BCT-15 doesn't seem to detect satellites right away. Is the dash of the car interfering too much with hearing the GPS signal? Or is there just some setting in the BCT-15 that I need to configure first to recognize it? The Garmin GPS 18 PC definitely outputs the NEMA 0183 coding of GPS information required by the BCT-15.

 

[zuzu]

Nevermind, the BCT-15 will read "GPS Connected" after a minute (or two) out driving in the open sky. (As opposed to the 15 seconds stated on the Garmin data sheet.) Tree canopy overhead (plus being stowed under the vinyl dash) apparently causes too much interference.

However, it will connect, even hidden under the dash (and furthermore under the glass of the windshield) as long as it has open sky above.

The GPS really is a wonderfully automating feature enhancement for the scanner radio if you use one in your vehicle. Adding an additional cigarette lighter port to accommodate the voltage transformer and 1amp fuse of the cigarette lighter adapter included with the Garmin GPS 18 PC wasn't any more difficult than adding a power line for the scanner. In fact, they're sharing the same tap on the accessory line in my setup.

(I had considered that the GPS could run directly off the battery, like the clock and radio settings do, since it only consumes 50mA, and in this way it wouldn't have to "reconnect" every time the car starts. But I was too paranoid about my battery running down.)

 

[zuzu]

However, the BCT-15 doesn't seem to detect satellites right away. Is the dash of the car interfering too much with hearing the GPS signal? Or is there just some setting in the BCT-15 that I need to configure first to recognize it? The Garmin GPS 18 PC definitely outputs the NEMA 0183 coding of GPS information required by the BCT-15.

Actually, this summed up really well all the GPS features that the Uniden scanners (e.g. BCT-15, BCD996T) include:
http://wiki.radioreference.com/index.php/Uniden_Scanner_GPS_Features

The GPS really is a wonderfully automating feature enhancement for the scanner radio if you use one in your vehicle.

Specifically I was referring to Location Based Scanning, but everything else is really nice too.