How to most accurately determine the location of an Android device?

Question

I'm building an app that should be able to report the users exact location. There is only a need for a single location, ie I don't need to track the device continuously.

I want the location to be as accurate as possible, and it's okay to wait a short while for the location to be determined (max 1-2 minutes).

I've been looking at FusedLocationProviderClient.getLastLocation() , but since I want the location to be as accurate and updated as possible it doesn't fit my needs.

So I started looking at using FusedLocationProviderClient.requestLocationUpdates() instead, and it seems like a better choice.

But I'm not sure how to best configure my LocationRequest to get as good accuracy as possible. For instance, would it be better to use setNumUpdates() so that I only receive a single update and use that as my location, or should I receive multiple updates in hopes of getting better accuracy (GPS locking to more satellites for example)? I'm thinking that if I use the second approach, I could look at the value of getAccuracy() from each location update and only keep the one with the highest accuracy. The downside is that if the device is moving and I keep receiving updates for a minute or so, the first location could have the highest accuracy, but since it's a minute old it's not accurate any more.

As stated above, I need just a single highly accurate location and it's okay for the app to wait 1-2 minutes for it if needed. What would be the best approach in this kind of scenario?

Answer 1

First, make sure the accurate location is turned on. look at Settings.Secure.LOCATION_MODE_HIGH_ACCURACY It has a noticeable advantage over only using GPS. Then listen for the location for a while and calculate the result you get to find out the best location. You can also detect if the user is moving if the number differs a lot or by using Activity Recognition API . It shouldn't be very hard to write this calculate function to get the best result.

I'm not sure about this but I really don't think waiting more than a few seconds gives you an advantage. to be sure you can simply alter this time and watch the result.

Answer 2

You might want to use LocationManager. In my experience FusedLocation will indeed appear to lock faster but may not be as accurate overall, or at least for a while. I have an app that also requires pretty accurate coordinates. My default is to use a LocationManager based approach but users can switch to a FusedLocation provider if they want faster locking (like when indoors).

This is a good overview https://developer.android.com/guide/topics/location/strategies

For the provider when requesting updates I'd use LocationManager.GPS_PROVIDER. It will take longer to lock since it will wait for satellites and not use Wifi or other towers. But you said that's OK. Something along these lines

LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, YourLocationListener);

Once you start getting location updates via your listener's onLocationChanged() you can start to inspect the location for accuracy, movement from last location change, etc. to try and evaluate if the GPS receiver is still settling in on a location. Once you are satisfied with the quality of the fix you can stop receiving location updates ( locationManager.removeUpdates(YourLocationListener) ) and then run your logic that needs the location. The link I provided has good info about this too.