Its the Battery Stupid....?

Having an extrernal bluetooth GPS puck for your cellphone is IMHO a no brainer IMHO. Adding a Bluetooth halo to your field data collection has a number of interesting advantages and complexities.

I too am interested in the embedded GPS chip sets in the Android population and their configurations. Autonomous GPS relying only on L1 and SA off with good geometry should provide a RMS error of 1.5 to 3 meters depending upon its internal smarts and its calculative latency. A WASS corrected GPS solution could improve on the same condition to a RMS of 0.5 to 1.0 meters. But performance will vary with smarts of the GPS device particularly when geometry is poorer. In any case, Leszek Pawlowicz's AndroGeoid is a blog that will likely provide a constant stream of quality insight to geo-android issues and topis...   He has been at hand-held geo-toolings for a bit... for posts/articles on GIS, GPS, Google Maps/Earth, neogeography and more, visit my other site: Free Geography Tools.

Why Use An External Bluetooth GPS Receiver With An Android Phone?

Published in android os, bluetooth and gps. 0 Comments

Google’s specification for an “official” Android unit, that allow it to use Google’s logo and have access to the Android Market, includes a requirement for a built-in GPS receiver. That’s why the new line of Archos Android tablets need their own app marketplace – they don’t come with GPS receivers. So if Android phones come with GPS, why bother with an external Bluetooth GPS receiver, especially when it will cost you extra? Here are a few good reasons:

4. Using an external Bluetooth GPS position instead of the built-in GPS can extend the battery life of your Android unit.

In a previous post, I looked at the battery drain from GPS, Bluetooth, WiFi, and cellular. The built-in GPS had the biggest power requirements by far; in comparison, turning Bluetooth on had virtually no effect on battery life. I just ran some additional comparison tests on battery life for the Droid X using internal GPS with Bluetooth off  vs. external Bluetooth GPS. The unit was in Airplane mode in both cases, to eliminate cellular/WiFi power drain. I used the TrekBuddy map app, which lets you choose between the internal GPS and an external Bluetooth GPS as the GPS position source. Approximate battery life is given in hours, based on the time to drop from 100% battery to 60% battery. For one set of tests, the display was turned off; for the second, the display was left on continuously at 50% brightness.

	Display off	Display on (50%)
Bluetooth GPS	20.2	9.1
Internal GPS	11	5.7

Results are pretty dramatic – switching from the internal GPS to an external Bluetooth GPS cuts almost doubles battery life when the display is off. Even with the display on, the battery life with the external Bluetooth GPS is actually comparable to some stand-alone GPS units. For example, battery life for the Magellan Triton or deLorme PN-40 units with two AA batteries is often a bit less than 10 hours under normal use. If you remember to turn off the display when you don’t need it, you could easily get 15+ hours of continuous use by switching over to an external Bluetooth GPS.

5. An external Bluetooth GPS is cheaper than a spare battery.

External Bluetooth GPS units aren’t free, but they don’t have to be terribly expensive. Basic models like my Holux M-1000 (which works great with my Droid X), or the Globalsat BT-359 run less than $45, which is the cost of a standard OEM spare battery for my Droid X. My Holux will run for 16 hours on a charge, which is just about the same time you can run the Android phone before it needs recharging as well.