Why is it taking so long to find a fix?
There can be several reasons reasons for this.
- New location - if you are at a new location after a long flight, the GPS on your phone can take a while to reorient itself. Try running GPSLogger at high frequency until it does find a location.
- Interference - there may be structures nearby blocking your signal.
- Mid flight - if you are in a commercial aircraft, you are probably traveling too fast for your phone's hardware to keep up with the GPS signals.
The gist of a phone using GPS is that it needs to know where every satellite in the GPS constellation is and it usually
wants to use your data connection to do this. The GPS satellites do broadcast this information at different intervals;
specifically, each satellite broadcasts almanac data and ephemeris data.
The almanac is not very precise and gives a rough overview of the constellation and their positions over the next few months.
A GPS receiver can use this to get a rough idea of where it is and which satellites to select. When a phone has been off
for a long time, or suddenly shifted to a new location, it needs to reacquire almanac data.
The ephemeris data is more precise; it is broadcast more frequently and goes stale quite quickly. It's only once a GPS
receiver has its almanac data that it knows to look for the ephemeris data. Once the phone has both of these pieces of information,
it can then figure out where it is. This process can take around 12 minutes and is known to be very flaky; any interference
or interruption in the process means that the GPS receiver in the phone needs to start over. The satellites only broadcast at
Because it takes so long, to assist with this, many mobile operators deploy aGPS servers;
these servers have already downloaded the almanac and ephemeris data and your phone can download it from them at a faster rate then
from the satellites. But it does mean that your phone has to be on a familiar network. Being on roaming or with a restricted
data plan will prevent this from happening.
All in all, there are a lot of factors at play. The problem could be anything from missing almanacs to data to hardware. GPSLogger simply waits for the OS to be ready with its information.
It's not accurate!
It all comes down to your hardware, settings and environment. The accuracy is only as good as your phone's GPS chip.
Some phones may have 4 meter accuracies, some have 500 meters. Also, using GPS satellites will give you better accuracy but take a longer time; using network location will give worse accuracy but is quicker. You may also want to check your environment, as there can be inaccuracy due to clouds, buildings, sunspots, alien invasion, etc.
My time interval has passed, but no point was logged
There are two possible reasons for this.
- The GPS will have attempted to find its location and given up after a while. This means that Android OS will not have given a location to GPSLogger
- The accuracy was below your Accuracy filter settings, or the distance was below your Distance filter settings, so GPSLogger didn't log it.
You can try setting a Retry interval in which GPSLogger can wait for a more accurate point to show up and then use it.
How do I remove the notification?
Unfortunately, and annoyingly, the notification needs to stay there. Android 4.x has become very restrictive and will kill foreground services that don't show notifications. There is also
no way to work around this as there
was in the past. This also means that more applications will start to ask for notification area space, it may get quite crowded soon. At the same time, this is with good reason;
the user should know that a foreground service is running and consuming resources, however no means has been provided to allow it to be dismissed.
It's using the wrong timezone, can you make it use my timezone?
The standard when logging points is to use UTC. Since this is the standard, it would be wrong to use the the local time zone. Instead, it is the responsibility of the software you use the log file on (Google Earth, GeoSetter, etc.) to adjust for your timezone.
Any application that deals with GPX or KML files will have a setting that allows you to specify your own timezone.
Where is the file being logged? How do I get to it?
You can connect your phone to your computer and mount the SD card, then copy the
file from the GPSLogger folder. That's the default folder, but you can change it in the settings. Note that while your SD card is mounted, GPSLogger can't write to the
card, since it's in use. To view it on the phone itself, if you have a file explorer, then you can go to /sdcard/GPSlogger > Long
press file > Open as > Text
I've changed the settings, but it's still showing/using the old settings
If the app is logging, and you make changes to the settings, the changes will
take effect after the next point is logged. This means that if you've set
your interval as 1 hour, you have a long wait ahead of you. If you want the
changes to take effect immediately, then stop logging and start it again so that
the changes are refreshed.
What do the various settings mean? (Accuracy, retry interval for accuracy, etc)
- Time before logging - How long to wait after a point has been logged to try logging again.
- Distance filter - When a point is available, the app will check to ensure that this much distance exists between the previous and current points. If it isn't this distance, the point is discarded.
- Accuracy filter - When a point is available, the app will check to ensure that this point has a minimum accuracy specified. If it does not match the specified accuracy, the point is discarded. This is useful if you are inside a building for a while.
- Time interval for accuracy - When searching for a point, the app can continue searching for this many seconds until it finds a point that meets the accuracy and distance filter criteria above.
How do I make it last longer?
Mainly, turn wifi off, turn mobile data off, turn background synchronization off, turn bluetooth off. If you turn data off, you'll probably want to inject aGPS data regularly, there are apps that can do it for you.
You can also try going into airplane mode which turns many things off. When it comes to choosing between location sources - GPS vs network - GPS will be more battery hungry while network location is easier on the battery.
I see the Android GPS icon active between the intervals I've set, why is that?
It's how the Android OS has implemented its GPS system. When you say you want a
point every 60 seconds (for example), that's actually a suggestion rather than an
imperative, and so the time interval between GPS points is never guaranteed.
GPSLogger has logic that checks the time difference, though, and will make sure
that at least 60 seconds have passed before logging again.
Why can't I remove the notification?
As of newer versions of Android, removing the notification will cause the service to be killed. As a result, the notification now needs to stay there.
You may have seen a recent increase in the number of apps that need to sit in the notification bar for the same reason - to perform background services without being killed.
Why haven't you developed XYZ feature?
I work on GPSLogger in my spare time and I don't always have the time or resources to implement a feature. However, GPSLogger is open source. You are encouraged to contribute or get someone else to contribute a feature.
How is this different from other logging apps?
It's meant to be more battery efficient. A lot of other apps, such as MyTracks,
usually go with the assumption that you have a data connection available and your
routes won't be very long. They use CPU wakelocks and log points extremely frequently with high accuracy.
The aim of GPSLogger is to log points and stay quiet.
How does this integrate with Tasker/Llama or other automation frameworks?
If your automation app can send intents, you can send intents to GPSLogger to get it to perform a few actions.
For example, in Tasker, create a new action under Misc > Send Intent.
immediatestart:true (others below)
These are the extras you can send to GPSLogger:
immediatestart - (true/false) Start logging immediately
immediatestop - (true/false) Stop logging
logonce - (true/false) Log a single point and stop
setnextpointdescription - (text) Sets the annotation text to use for the next point logged
settimebeforelogging - (number) Sets preference for time before logging option
setdistancebeforelogging - (number) Sets preference for distance before logging option
setkeepbetweenfix - (true/false) Sets preference whether to keep GPS on between fixes
setretrytime - (number) Sets preference for retry time
setabsolutetimeout - (number) Sets preference for absolute timeout
You can also invoke the Start and Stop shortcuts that GPSLogger comes with.
What are some recommended settings to save battery life?
From location providers, choose only network and passive. Preferring to use network (cell towers) over GPS saves more battery. You will also save more battery life if you keep the interval between points to about 60 seconds or more. Note that any option to save on battery life will not guarantee accuracy.
How can I define a preset file with my own values?
Many people distribute GPSLogger to other people along with phones, with some preset values. If you create a file at either
/sdcard/gpslogger.properties, then GPSLogger will read this file each time it loads and apply those settings to the application.
For example, in the file you can put
accuracy_before_logging=42 and that will reset the Accuracy Filter to 42 meters each time the application starts. There are many properties that can be applied and you can glean a full list here.
The most common examples of properties would be
opengts_* for OpenGTS settings,
smtp_* for email settings.