Earlier this week, Nokia released another firmware update for the N95. One key feature included in this release is the support for Assisted GPS (A-GPS) on the device. Assisted GPS works by combining the normal GPS satellite functionality with your cellular network connection. The end result is that you supposedly get faster, more accurate readings, while also using up less battery life.
But how accurate is GPS on the N95? Does this new firmware really make a difference? I’ve started doing some very unscientific experiments to find the answer and wanted to share some results.
The tests were done using Nokia’s Sports Tracker program with my N95. Sports Tracker works by recording your GPS position over time and using that information to display details about your speed, location, and distance travelled. One of the very cool features of this program is that it allows you to export your running routes and GPS data to a number of different formats including Google Earth.
I had a few workouts saved in Sports Tracker before the recent firmware update, and last night I went on the same run, but this time with the new firmware update. How did they compare?
The GPS route captured using the latest firmware definitely stays closer to the path than previously, however, the route also seems to zig zag a bit more than before. This can be critical if you’re using Sports Tracker to track distances as it can lead to inaccurate data.
For instance, I did a speed walk from my house to my friend’s house and I did the walk in 24 minutes. According to the map, the distance between the homes is 1.75 miles (2.82km). However, when I walked there using Sports Tracker, it said the distance was 2.18 miles (3.5km). This seemed like a huge difference, but when you compare the results on a map you can see why.
It seems that over time, the small zig zags in the GPS readings add up to big differences in distance, and also the average speed. According to Sports Tracker, I did the walk to my friend’s house at a pace of 5.4 mph (8.7 km/h), when in reality the pace was closer to 4.4 mph (7.1 km/h). So if you’re using the program to train or to accurately predict a workout, you should be cautious when examining the results.
What have other N95 owners experienced with the accuracy of their GPS data?