aGPS: Only Great When Supported
Otherwise, you’re better off using plain ol’ GPS.
I learnt this the hard way yesterday when I decided to take the Touch HD out for a navigational spin. Having TomTom all set up and running, I wanted to see if the lag issue (which will be discussed in another article) was as bas as some claim it was. What I found out instead was totally unexpected.
Firstly, the Touch HD took quite a while to find a lock on the satellites. Granted it was from a cold start but even with the GPS data downloaded? Maybe it was due to the weather. The clouds were dark and overcast. That could have been a factor.
Apparently that was not the only issue. Once fixed, the Touch HD would lose it’s signal for about 2-3 seconds before locking on again for about 1-2 seconds and then losing it again. This cycle kept going on and on and on, whether the car was stationary or moving.
So I setup TomTom on the X500 which I had with me and surprise, surprise, it locked on to the satellites and stayed locked on. The Touch HD still was having mood swings.
Sure they have different chips: the Glofiish X500 sporting a SiRF STAR III chipset while Touch HD packed Qualcomm’s. But that was not the cause of it.
The main reason for the flaky behavior of the Touch HD GPS was that I had enabled aGPS on it (which was off by default and for good measure if I might add). When aGPS is turned on, it relies on data from your carrier to fix your position. So if your carrier did not have those data, as in my case with T-Mobile USA, aGPS is just a glorified feature on your device.
To confirm this, I turned off aGPS and voila, no more flaky fix. It locked on and stayed locked on for the rest of the journey.
So folks, do check if your carrier supports aGPS before turning it on. It’ll save you a whole lot of trouble.
To find out more about GPS vs. aGPS, head on over to this WMExperts’ article.
Related posts
If you enjoyed this post, please consider to leave a comment or subscribe to the feed and get future articles delivered to your feed reader.
Very good article and full description of the problem. Actually more helpful than expert XDA sites.
I have the Eten Glofish X500 loaded up with TomTom GPS and it always works like a charm.
Great explanation of the problem with the aGPS.
Good to know glad I read this. Really helpful to know.