2010
12.04

On a recent trip to Asia, I carried my Droid, and although there was CDMA service in the countries I visited, I didn’t really need or want to use it.

But I did want to use my GPS capability, and after much fiddling, I was able to use Droid as a scrolling map GPS.

The first thing you need to know about GPS on Droid is that the GPS function is married to the CDMA radio in some obtuse fashion, and one must apparently start the GPS with all radios (CDMA (phone transceiver) and GPS receiver) on, until a position is obtained, and then you can turn the CDMA off, either by entering Airplane mode or by turning it off with a tweaker app, like Advanced Settings. This much is well documented.

A catharsis that I had one day, standing under an open sky, with all GPS and CDMA enabled, waiting for GPS to find satellites, was when I turned off “Data Enabled” under “Wireless and Networks” -> “Mobile Networks”. I always have “Data Roaming” turned off, but turning off “Data Enabled” made the GPS suddenly find several satellites. Since the whole point was to make GPS work without network, it didn’t harm anything, and it did really help.

Also, turn off “use wireless networks” under “Location and Security”. Can’t use it without coverage, turn it off.

In order to have a scrolling map, I used Maverick, and Mobile Atlas Creator. I down-loaded about 5 different zoom levels, you wouldn’t need all levels, of Google Maps, which worked really well. Of course, no turn-by turn, but I was able to navigate and record tracks and waypoints, even with the limited numbers imposed by the free version of Maverick. I intend to buy it, it seems worth the 5 Euros.

Backing up a little:
On day one after my arrival, the GPS got satellites, found position, and worked well with Maverick. A couple of days later, however, it refused to find satellites, and when Maverick was open, it showed 5000-some miles to local land marks, which suggested that it was assuming a point in the US as its starting point. For a while, I fiddled around and googled, trying to figure out how to move the starting point, which has been part of the procedure with my previous Garmin and Magellan handheld GPS receivers. I never did see a way to do this, but I think that the strategy of “assisted” GPS, as found in Android, is to forego that step by using CDMA base stations to guess the starting point. The “starting point” is important in a short time between power-off and position-reporting GPS, because if the GPS knows where it is, it can estimate which satellites it can expect to receive by consulting ephemerides. It’s also not clear that the Droid GPS saves state which survives power off and/or battery change, because it is designed to have the “assisted” part.

But unchecking “Data Enabled”, “Data Roaming” and “Use Wireless Networks” seems to give the Droid a leg-up on doing “no-coverage” GPS.

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