Hello I am developing a realtime gps tracker using this library
It gets data from GPS satellites in a period of time..if no gps results is received it then request from cell towers/wifi in a period of time also. My problem is..My gps location is fluctuating so bad. Here is a photo below:
Please if anyone there has used this library. Or can recommend to me how to ged rid of this fluctuations. Please help me out..Thanks
GPS can fluctuate when the device moves slowly or stands still.
Switching betweeen GPS and Network Location is not a good idea, (network will introduce jumps of e.g up to 1000m or eveen more)
If you have GPS always use GPS.
If fluctuations are caused by bad GPS signal, you can check the Location.getHoricontalAccuracy(): ignore the location if the value is > 30m and you are using GPS only.
If fluctuation is caused by slow movement or stand still, make sure this is the case and ask again for that specific topic, or search SO.
Related
I am working on gps tracking apps in android. Here is my code architecture:
BackgroundSyncService : A service class that is used for getting location update. Here GoogleApiClient is initialized and implements others Location related methods.
AppRunCheckerReceiver : A BroadcastReceiver class that will check if my BackgroundSyncService is running or not in a time interval. If it stopped then it start.
GpsEnableReceiver : A BroadcastReceiver it will fire if gps status changed. It will check if my BackgroundSyncService is running or not in a time interval. If it stopped then it start.
InternetConnectionStateReceiver : A BroadcastReceiver it will fire when internet status changed. It will check if my BackgroundSyncService is running or not in a time interval. If it is stopped, then it start.
In my BackgroundSyncService service I initialize the GoogleApiClient using this way:
public void setLocationLocationRequest() {
try {
googleApiClient = new GoogleApiClient.Builder(this).addConnectionCallbacks(this)
.addOnConnectionFailedListener(this).addApi(com.google.android.gms.location.LocationServices.API).build();
locationRequest = new LocationRequest();
locationRequest.setInterval(3000);
locationRequest.setFastestInterval(3000);
locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
googleApiClient.connect();
} catch (Exception e) {
}
Here accuricy is LocationRequest.PRIORITY_HIGH_ACCURACY and interval is
locationRequest.setInterval(3000)
here is the GoogleApiClient implementation code.
This application GPS info section contains Latitude longitude and Accuracy parameter
My Findings: in onLocationChanged(Location location) method I check the accuracy of Location object in this way : location.getAccuracy(). Here if accuracy is less than 50 meter, then I accept it.
In 85% of the cases it working like a charm. It sending me exact location from GPS. But in 15% cases, it sending me inaccurate location like more >300 meter.
The 15% device are low cost China brand mobile.
My Questions:
How can i make accuracy level near 99%. Is there any problem on my code architecture?
Does GPS accuracy depends on device configuration? if YES then what can I do for low configuration device?
How Uber, Go-JEK etc. ride sharing apps works for all device? Is they have extra coding for GPS only?
My application is for Bangladesh. Here internet is slow. Is it has negative impact on GPS accuracy?
Thanks in advance for this thread. And also sorry for bad english.
How can i make accuracy level near 99%. Is there any problem on my code architecture?
This is real life scenario. You cannot ensure that all the location providers will work as expected. You should ask for best available position.
a) Does GPS accuracy depends on device configuration?
YES. Some devices may have older GPS chipsets which can only track GPS signals (USA) since there are other positioning systems like Galileo (Europe), GLONASS (Russia), QZSS (Japan) and Beidou (China). The more the chipset support for these types the more chance you get to track more satellite hereby position fix. Also TTFF (time to first fix) depends on how many channels do the gps receiver has.
b) If YES then what can i do for low configuration device?
Since this is a hardware issue, you cannot do anything here. But other location sources can compensate the lack of GPS data such as AGPS (aided gps), wifi and cellular positioning. Also there are some paid options which provides a database to locate your device using wifi access points and cellids (they claim that they provide best solution on wifi but i m not sure as I dont use it. you can check it out http://combain.com). Wifi and cellid also depends on how many wifi access point and cell tower available around and how far they are (signal strength). If you need 50m accuracy, cellular positioning has nothing to do but wifi has a chance to get closer to this value.
Some study results from 2009 [3]
3G iPhone w/ A-GPS ~ 8 meters
3G iPhone w/ wifi ~ 74 meters
3G iPhone w/ Cellular positioning ~ 600 meters
How Uber, Go-JEK etc. ride sharing apps works for all device? Is they have extra coding for GPS only?
They may have specific Location strategies but it will based on using other sources during GPS outage.
My application is for Bangladesh. Here internet is slow. Is it has negative impact on GPS accuracy?
Other answers claims that internet is not related to GPS. Yes it is true it is not related to GPS but location. AGPS uses internet to fetch 3 types of data (Satellite signals, almanac and ephemeris) which assist GPS to provide position fix faster. If ephemeris and almanac are outdated or the device moved several hundred km from the previous position fix then it is called cold start and takes around 12-15min without AGPS.
Fused location provider already knows how to provide best solution with these configurations, so you should bless it.
References:
[1] http://gpssystems.net/agps/
[2] http://gpsinformation.net/main/almanac.txt
[3]
https://communityhealthmaps.nlm.nih.gov/2014/07/07/how-accurate-is-the-gps-on-my-smart-phone-part-2/
First, (and second)
How can I make accuracy level near 99%. Is there any problem on my code architecture?
Does GPS accuracy depends on device configuration? If YES then what can I do for low configuration device?
Both - device configuration and code architecture, are important here. If you are already at an 85% success rate, the code architecture is alright I think.
As far as GPS goes, line-of-sight is an important factor when it comes to device configurations and accuracy.
Although a low cost mobile could return an accurate location with a clear line-of-sight. You can try running 2 cycles more/waiting to attain higher accuracy.
In a worst case scenario and for what its worth, you can also try retrieving location using the LocationManager and GPS provider technique which works as a fallback in the 15% just to compare and ensure you are using the most accurate location you can get.
Location Strategies put it as
In most cases, you'll get better battery performance, as well as more
appropriate accuracy, by using the Location Services API.
How Uber, Go-JEK etc. ride sharing apps works for all device? Is they have extra coding for GPS only?
They do work but not always with highest of accuracy for locations received within the app. If there are any location hacks for us developers, we need to find them, maybe a 5th page google search result :) or benefit from the open source environment. For me, best practices and android repo links suffice. You have already followed posts like Receive location updates
My application is for Bangladesh. Here Internet is slow. Is it has negative impact on GPS accuracy?
No relation between Internet and LocationManager + GPS_PROVIDER
Some resources say getLastKnownLocation() merely gives a location of some previous app's Location Change Listener.
But one thing I feel is missing from the conversation -- if the phone has GPS enabled, isn't this GPS tracking/updating as the phone moves? So if I call getLastKnownLocation(), isn't it getting the current GPS from the phone's constantly-updated GPS?
If so, then why do people warn against using it / accuse it of potentially getting a "stale" location? If the GPS is being tracked / updated, and getLastKnownLocation() makes a one-time grab of it's current position, what makes getLastKnownLocation() bad?
What am I mistaken about the Locations service or GPS?
The documentation says: Returns a Location indicating the data from the last known location fix obtained from the given provider.
Also, about the "out of date location": This can be done without starting the provider. Note that this location could be out-of-date, for example if the device was turned off and moved to another location. ("This" refers to getting the last known location).
Also, taken from LocationProvider docs:
Each provider has a set of criteria under which it may be used; for example, some providers require GPS hardware and visibility to a number of satellites; others require the use of the cellular radio, or access to a specific carrier's network, or to the internet. They may also have different battery consumption characteristics or monetary costs to the user.
if the phone has GPS enabled, isn't this GPS tracking/updating as the phone moves?
Well, it is, but not constantly. This has to do with battery consumption, if the phone was constantly updating the GPS location, the battery life would suffer a lot. The GPS location is usually updated when some app requests it. But even that request is not guaranteed to succeed. For example, suppose your going into a tunnel. Some application requests to update the GPS coordinates right before entering the tunnel and it succeeds. Now, you've entered the tunnel, which is 5km long. Most probably your device won't be able to get a GPS fix from the tunnel, so for the next 5km (at least) getLastKnownLocation() will return an outdated value, since the devices last known location was at the entrance of the tunnel.
What you could do is explicitly request to update the GPS location, that however might take some time and there are no guarantees that it will succeed.
You have the assumption "if the phone has GPS enabled, isn't this GPS tracking/updating as the phone moves". This assumption is incorrect. The GPS functionality takes up a lot of battery life so it should be used sparingly and almost certainly not all the time.
Id like to narrow down the location of a phone to the cm or less than a foot (nothing creepy I promise :). Say there was a room full of people I would like 1 user to be able to look though an augmented reality view on their phone to find another user.
Only problem is the location data, I know gps is probably out since I think its only accurate to 10-15 meters? Could you do something with the wifi points, ie have a couple and measure ping time between them to work out location? Or does this technology already exist? Thanks C
Android provides basically two location provider :
GPS
Network
GPS is the most accurate source which you don't want to use and it's slow.
Network location provider is false but less accurate than gps.
So the only hope is GPS.
Hi i am working on a real time location tracking application where i have used Fused Location provider Api. I was able to get the location updates when the device is moving. But i was also able to get the location updates even if the device is stationary on a table when i am indoor. So I have calculated the distance between the last location and the current location triggered in Onlocationchanged event and checked whether the distance is less than 30 metres, to know the device is actually moving. But sometimes the distance i get is greater than 400 metres (indoor/Device is Stationary). How Can i ignore the onlocationchange event when i am indoor? Any suggestions are appreciated.Thanks in advance.
Unfortunately I don't believe there's much you can do about it.
The reason you see those updates with great changes it's because indoors, you won't get a GPS lock, so the device is relying on cell tower and WiFi hotspot triangulation to determine your location, and something around 200m to 1km is the best you'll get with this kind of technology.
A possible attempt to hack-around it would be to:
check the source and precision of the location update
use the activity recognition API to guess if the device really moved
but both are a hack, around the technology limitation and might not be as reliable.
I am using LocationManager to get the values of Latitude and Longitude of a user. These values are updated regularly to a database and find out the distance between two users basing on the stored Latitude and Longitude values.
Now,onLocationchanged() called very slow,some times get fast.while i'm waiting long time to proceed next process.When i 'm in indoor the Location search is very slow..
Is there any solution to this prob.pls give me a guide and example.
Please Accept My question as soon as give me a solution.
If you use network location provider, you will get location faster, but it will be less accurate (100-500m).
OTOH, GPS provider will be more accurate (10-20m) but it will take more time to acquire location as device needs to acquire GPS satellite signals. Sometimes it's not even possible to acquire signals, especially if indoor or beneath thick trees.
Well there are there types of GPS starts :
COLD start: takes a lot of time. The old GPS (satellite/time) data is practically useless.
WARM start : is when the GPS device remembers its last calculated position, almanac used, and UTC Time, but not which satellites were in view. You get the fix fairly fast.
HOT start : is when the GPS device remembers its last calculated position and the satellites in view, the almanac used (information about all the satellites in the constellation), the UTC Time and makes an attempt to lock onto the same satellites and calculate a new position based upon the previous information.
To emulate the warm start case all you have to do is connect to the SUPL network, which provides assistance data. Even cold starts can be converted to a warm start. To make sure that SUPL networks are available, make sure you are connected to the internet. In indoor cases no satellites are visible so getting an exact fix is tough without any assistance data. At least 3 satellites should be visible. Again SUPL networks come to the rescue.
Note that, various GPS chipset have different performances/algorithms and the triangulation time depends on the SUPL networks provided by your Network provider.
You can here more about this here
Good starting point is blog/project by Reto Meier:
http://code.google.com/p/android-protips-location/