Will J2ME Location Based API work without GPS?can you gave me example ?
Depends on the device implementation!
On many devices you can specify the behaviour during accessing the Location API. (Nokia s40 lets you search for bluetooth gps devices e.g.)
If the location API is able to use data like cellID, LAC, ... (if you specify low accuracy criteria) depends on the device implementation and even if your operator lets you use those values. ( http://www.easywms.com/easywms/?q=en/node/3589 )
Many devices do have the API on board even if they are not equipped with gps functionality.
I believe it will work, but it will be less accurate because it has to use the cell towers to determine location, not GPS.
Well, the call will work, but how will it know where you are?
See the discussion at Oracle, which says:
"To discover the location of the
device, LBS must use real-time
positioning methods. Accuracy depends
on the method used."
In the United States, to provide semi-accurate tracking data for the 911 emergency system, all phones must be able to be located within a few hundred feet. It's done by triangulating distance from the nearest three or so towers.
GPS simply makes that (existing) data more accurate.
Related
I want to make an Android app that needs locations accurate to about 1m or less.
Is the "Fused Location Manager API" good enough, or can GPS never be this accurate, regardless if fused with other Sensors?
If so, does anybody know a way to get more accurate locations on a smartphone?
Thank you!
For Getting more accuracy in Android phones was not recommended due to battery/data consumption. If it not an issue means you can use below code
Integer gpsFreqInMillis = 1000;
Integer gpsFreqInDistance = 1; // in meters
locationManager.addGpsStatusListener(this);
locationManager.requestLocationUpdates(gpsFreqInMillis, gpsFreqInDistance, criteria, this, null);
There has been a previous discussion about whether the Fused Location Provider is a good choice (the answer to that question was yes). You can find that post here: Is Fused Location Provider good choice?
Perhaps this is what you are looking for: Android's most accurate Location API
Hopefully this helps!
For GPS 3m is max see https://gis.stackexchange.com/questions/43617/what-is-the-maximum-theoretical-accuracy-of-gps It wont get any better than that. And that is outside and away from any buildings.
All other sensors are less accurate. Maybe you can get some better accuracy if you take multiple measurements over time and average them (works only with a still device).
You can get very good results with wifi rtt (which is not strictly a sensor) https://www.gpsworld.com/how-to-achieve-1-meter-accuracy-in-android/ which is used by Fused Location Provider
I'm developing an app that tracks walks, bicycle rides, car rides etc. I need precise info, so I basically would like to use only GPS. Still most sources I found recommend using Googles fused API e.g. for power saving reasons, so I went for the fused API.
Now once in a while (once or twice a month) I get one freak value among thousands of good ones. a few of them I got near railway stations, where the freak value is at another railway station, several kilometers away, so I assume it is a wrong interpreted WiFi based position.
Here's one example, where I ride my bicycle from the river towards the main railway station located east of the river. Once I arrive at the main station, I get no position for 126 s (I asked for every 10 sec, so I probably lost the GPS signal), and then suddenly I get a freak GPS value at another railway station 3450m away on the other side of the river. The reported accuracy for the freak value is 20 m.
The problem is that I cannot easily identify and filter these freak values.
Calling currentLocation.getProvider() always returns "fused", which is not very helpful.
Also Location.getAccuracy() returns typical values below 100m.
So today I filter based on evaluating speed combined with unrealistic changes in bearing, but I'm afraid I might also discard good samples in the process.
I scanned a lot of Stackoverflow, but strangely enough I didn't find any relevant answers yet.
I now feel like moving to the old framework location API and use GPS based data only. But is that really necessary, or does anybody have an idea how to avoid getting the freak values, or alternatively how to easily identify and discard all wifi based positions?
And will using the framework location API have bad battery life as a result?
I'm new to android programing. I know how to get a position of a user in outdoor environment using GPS.
But i'm faced with a problem to find the location of a person inside a building where you don't have GPS available.
I can handle the coding part but i need an idea in how to use compass, accelerometer, and gyroscope data or any other sensor data except GPS to get the current position of the user inside the building after you pass the compass, accelerometer, and gyroscope data to the server. Here consider that the inside of the building is mapped.
Sorry if this is a stupid question.
It sounds like you intend to perform inertial navigation using accelerometer data based on the last good GPS fix. I think you'll find this is not feasible on a mobile phone. Accelerometers used in inertial navigation -- for example, in aircraft -- have to be extremely accurate and highly calibrated to minimize errors. Even then, all inertial systems drift over time. With the relatively low accuracy of a phone, these errors will accumulate quite rapidly and render your position solution unusable very quickly.
Without GPS, most phones can still give you a rough position estimate using cell-site multilateration. This is nowhere near as accurate as a GPS fix, but it's better than nothing.
See also this excellent discussion of indoor locationing (inertial navigation is mentioned there too):
Android accelerometer accuracy (Inertial navigation)
Indoor locationing is quite difficult, if not impossible today.
What works is mounting Low energy Blue Tooth "Beacons" at multiple places in the building,
and use that as info. (see ios Beacons) (But you have to manage that yourself, relation between beaconID and location inside bulding).
With compass, accelerometre and gyroscope you will not have (much) success:
In this Google Tech Talk video it is quite detailed explained why a gyro / accelerometer (relaive) navigation cannot work because the slight inaccuracies accumulate within 2 or 3 seconds so strong that you cannot use the result. This is cause by the double integration, see video at 23:30.
Private WLAN (inside your building) triangulation can work, but not inside an (limited) phone which does not give you the info which WLANs are vissible, at which strength.
What remains the already build it GSM-Cell or Wlan location in your smart phone for indoor usage.
There is one further approach:
Evaluating the magnet fields of an building.
This can work, and at least one company works on that, but you have to calibrate that for each building.
But this is more a reasearch topic, than a well known technic.
Further info
My Algorithm to Calculate Position of Smartphone - GPS and Sensors
I would like to detect location of bluetooth enabled devices automatically using bluetooth accesspoints. Is it possible? If so, how can I do it?
Bluetooth devices have unique MAC addresses so I think this would be possible but has a number of constraints:
You would want the devices to be either discoverable, or to have already paired with them
Bluetooth devices don't tend to be screwed to the ceiling like enterprise access points, or tethered to a phoneline like their domestic counterparts.
The range of bluetooth is typically less than WiFi, which will potentially increase the difficulty in accurate localisation.
No such database already exists to my knowledge.
You can get the signal strength information you'd need to do this from BlueZ on Linux, so I assume similar is possible on other platforms. It's then a question of building a database of measured signal strengths at known location to "map" an area. With this database an unknown set of signal strengths can be matched to a large radius, by just using the set of all known positions of all of the devices seen. With that knowledge you could either:
Triangulate properly if you actually know locations of individual devices
or:
See which location in your database, within the trivially calculated radius best matches the strengths you are measuring on the device currently.
Hi
I'm working with google maps api in both javascript and java on respectively a pc and android. There's probably a difference, but I've been looking around in the documentation for a max number of markers that is a good idea to put on the map, to not have a system crash. It's probably a lot smaller on android, but I really have no idea of an estimate is it 25 - 100 - 1000?
So that's why I'm asking you. What is the maximum number of markers on a map that the user system can handle on pc and android? I know that it depends on the individual system, but I also bet that there are some guidelines I'm not aware of, that I can follow to optimize the user friendliness of my applications.
thanks
From the Google documentation
There is no limit to the number of
markers or path vertices supported by
the Google Static Maps API. However
Static Maps API URLs can be a maximum
of approximately 2,000 characters
which constrains the number of markers
and path vertices that can be
specified based on the number of
decimal places used when specifying
each latitude/longitude pair.
However, you should consider whether your application is overloading the users ability to select from so many markers. Ideally, your application should be doing the filtering for them and only showing a few simple, well spaced choices to allow for big thumbs on the touchscreen.
I would suggest that you use a zoom level manager after reading this article that describes one.