[Gps] Why Does Cold Start Take So Long?

[Winfried]

Hello

I know very little about how GPS works.

I noticed that after disabling GPS mode for a few days, even while standing on a street in the city, it can take several minutes for GPS to show my location, even after using GPS Status or GPS Test to reset and download A-GPS data over a 3G connection, and enabling Location in the Settings section.

Is that to be expected, or should I try something else?

FWIW, I use a Galaxy Nexus running CyanogeMod 11.

Thank you.

 

[Deleted User]

FWIW, that's been my experience as well (which is why I don't turn it off). I suspect it just takes it that long to re-establish a lock, but I could be wrong.

 

[tommo47]

Hello Winfried,

There are a number of articles available from a Google search 'how does GPS work' which you may find interesting eg. GPS

As RyanB said I don't think you are experiencing anything unusual. If my GPS has been inactive for a while it can take what seems to be a very long time for the first fix, although I reckon it's a bit like a watched kettle !! Depending on which article you read 12 to 20 minutes is possible in poor conditions.

Also bear in mind that a city street is not necessarily an ideal place to be for that first fix. If you are surrounded by tall buildings you will have a restricted view of the sky, and although A-GPS will preload your GPS receiver with those satellites nearest to you, your receiver still has to electronically 'see' and lock on to them.

Hope this helps.

 

[Goodspike]

You should have tried a stand alone GPS device from about 6-7 years ago. They would take forever, and then typically ask you about the date and time just to make sure they got it right. It could easily take over 5 minutes, particularly if you'd gone a long distance since turning the device off (e.g. fly from Seattle to Phoenix).