Application Name: GPS Averaging
Description: Logs and averages multiple GPS positions to improve position measurement accuracy
Publisher’s website: GPS Averaging
Version/date reviewed: v. 0.9 / 10-17-10
Phone/OS: Droid X / Android 2.2
GPS determines position by analyzing signals from GPS satellites to figure out how far away they are. These satellites are in orbits that put them about 12,000 miles above the Earth’s surface, which can make their signal faint (and noisy) by the time they reach your Android unit. This noise can introduce some error into the calculated GPS position – the GPS receiver can have some difficulty analyzing a noisy signal. If the noise is random, you can improve accuracy a bit by averaging multiple position measurements, and that’s what the GPS Averaging app does.
Figure 1: When you start up the program, it fires up the GPS; when a position is obtained, the “Start averaging” button is enabled. Press that to start averaging …
Figure 2: Display will show current position, and averaged position, along with the number of measurements. Degree-minute display only, unfortunately; wish the Babylonians had never come up with that system. When you’re done, press “Stop averaging” to stop the process.
The “shake the phone” tip might work if you’re in a wooded area with limited sky visibility, but I doubt it will help in open-sky situations
Figure 3: Once completed, the average position will be displayed, and you’ll have the option of showing that position in Google Maps (Map button), creating a GPX file for that location (Export button), or sending the position to an app of your choice, like a Notepad app …
Figure 4: Fortunately, the exported data gives the location in decimal degrees as well as degree-minutes. Way too many decimal places, though – it should round off to no more than the sixth decimal place, and you’ll be lucky to get five decimal places of accuracy
Keep in mind that this only helps with position inaccuracy based on a noisy GPS signal; it won’t help with other important factors like satellite geometry, ionosphere effects, etc.. See my previous posts on improving GPS accuracy for help with this. Since most built-in Android GPS receivers don’t have the WAAS system used to reduce position error, GPS Averaging will only help a little if those position errors are large. But GPS Averaging does work if you use an external Bluetooth GPS receiver, which does usually have that WAAS system capability.
Trying to “Send” the data to the Springpad note-taking application didn’t work; it interpreted the exported data as a search command. But since it worked fine with every other app I tried, I’m guessing this is a Springpad issue.
You may get a bit of improved accuracy by using GPS Averaging, but it’s hard to quantify how much improvement you’ll see. It’s likely to be small, especially with a typical Android phone’s built-in GPS, since those aren’t capable of high accuracy to begin with. With an external Bluetooth GPS, it may be a bit more useful, but you still shouldn’t expect a huge improvement in accuracy. And you should keep other factors that can degrade GPS accuracy in mind.