On 02/02/2016 16:57, NY wrote:
"The Natural Philosopher" wrote in message
...
If you have GPS on so you don't have to wait 5 mins until it has
worked out where it is.

If you have quickfix enabled they take a few seconds even from cold.

What's quickfix? Sounds intriguing.


GPS tends to be accurate to about 5m or less these days.
They usually have at least 12 channel receivers so they can get good
accuracy if they can see enough sky.

My Android phone (Samsung Galaxy S2) takes a very variable length of
time to get a fix. I have an app called GPS Status installed which shows
the number of satellites in view and indicates whether or not they are
supplying information that enables a fix to be calculated. It also
downloads S-GPS information from the internet (assuming there is
mobile/wifi coverage) which helps to give a quicker fix - I think it
supplies the "almanack" information which is only transmitted from the
satellites every few minutes.

That is "quickfix".
It should enable the GPS to find the satellites in seconds as it knows
which to look for and doesn't need to download the data from them to
know their precise position in space.


But even with this I can find that from cold it can take from a couple
of seconds to tens of minutes to get a fix - usually if I get fed up of
waiting, a reboot of the phone will help.

That sounds like cr@p software. A reboot shouldn't really change
anything if the software is working correctly.


And GPS Status shows a maximum of about 10 satellites out in the open,
whereas some newer phones can see many more, and I'm sure this allows
them to get a quicker fix and/or to give a more accurate location. The
best precision is reported to be about 10 m, and usually it is more like
20-50 m.


It may be time to get a newer phone, both to give a faster processor and
a better GPS.

My Sony S3 has a 24 channel chip AFAIK.
In doors it is currently using 14 of them and has an accuracy of about
9m. Outdoors where it gets a better view I expect it to be better.


I'd keep GPS and wifi or mobile internet turned on all the time, but
both drain the battery: even with them turned off, I'm lucky if the
battery will last all day. If I'm going anywhere that wifi or GPS are
essential (eg tracking a long walk) I use a large external battery that
keeps the phone charged. It doesn't help that I live in a weak mobile
phone area so my phone winds its gain up to maximum to search for a
mobile phone signal to check for incoming calls/texts: if I spend the
day in a large town, the battery lasts a *lots* longer than if I'm at
home, all other things being the same; the only difference seems to be
mobile signal strength, as reported on the phone's Settings | Battery
graph.

Mine turns the GPS on every few minutes and takes a fix, the battery
lasts about 3 days before I charge it. It says about 60% remaining by then.