Based on Android does not / does not detect the correct location. Navigation does not work or does not work correctly. What to do and how to fix it?
Many users face the problem when phone or Android tablet starts to play up. It seems that nothing happened that could cause a malfunction, but it does not work as it should.
For example, the device has problems with the fact that it has ceased to determine its location either on tablet e or phone is not working properly navigation... This may be due to:
1st: Software glitch- i.e. the problem is a software failure
2nd: Hardware failure- i.e. the problem lies in the "hardware" (that is, it requires replacement or restoration of spare parts for the gadget)
However, do not rush to get upset - in 90% of cases with problems the operation of the function of location recognition, geolocation, determination of satellites, navigation, etc. smartphone a or Android tablet is to blame software glitch, which you can easily fix on your own.
We fix the software glitch:
Method 1. Quite simple - go to "settings" find there "Backup and reset" where you choose full reset settings with deletion of all data. Be careful, the use of this method is often effective, but it entails the removal of all photos, contacts, passwords, music, games, videos and, in general, all information stored on your smartphone e or tablet e. Therefore, first save everything you need by connecting the gadget to your computer. If this method does not suit you, or if the problem persists after it, see Method 2.
Method 2.
Based on solving network communication and reception problems phone s and tablets based on Android by introducing additional software. Utilities that control all processes inside gadgets. Today, there are quite a few of them, however, the fewer functions an application contains, the more, as a rule, it is effective. Best of all controls system functions, corrects, and fixes all possible settings and synchronization errors is a small and easy-to-use free utility for Android devices. You can download the application from Google Play and see its additional options in the description. After installing the application, all that remains is to launch it. Further, from you, in principle, nothing else is required. The application will completely take over the control of the device's functions. (By the way, among other things, the gadget will start charging 20% faster, and its performance will also significantly increase, which will affect the loading speed and operation of all applications, games, and the system as a whole. On average, after scanning, the system works on 50% faster.)
- Also, in order to achieve the maximum speed of data exchange over the Internet, it is recommended to install a high-speed browser on your Android device. Yandex Browser which you can download from Google Play.
Method 3.
Change of device software, or, as it is also called "Per firmware ". This method, as a rule, requires certain skills and is solved by contacting the Service Center. To independently carry out this task, you need to contact the manufacturer's website for your device, download the utilities and the firmware itself necessary for the firmware, and then reinstall it on your gadget.
If none of the methods brought results, unfortunately, you will have to contact the Service Center for repair of your tablet a or smartphone a.
Android phone or tablet does not / does not detect the correct location. Navigation does not work or does not work correctly. What to do and how to fix it?
On various sites and forums, questions are often raised, why the navigator does not determine the location? There can be many reasons for this malfunction.
If you turn on the navigator after an impressive movement (about 1000 kilometers), then it takes a long time for it to re-locate the satellites. If you remain motionless, this time may increase even more. In order for the navigator to show the location, he needs to "see" the sky. For more accurate positioning, the receiver needs to catch 4-5 satellites, in general, the more satellites, the more accurate the device will show the location.
Often, the reason that the navigator does not determine the location may be too dense buildings, dense trees, or, for example, the roof of a car. Another thing is that the signal may be too weak and insufficient to detect the location of the object where the device is installed.
If the navigator does not determine the location, the signal icon is crossed out, and if the signal is too weak, the signal indicator turns red.
Often, the device does not determine the location after flashing. The receiver can start connecting to satellites that are not visible to us, and therefore the device cannot automatically show the location. To load the correct almanac, you need to set the coordinates. There are two modes of how this can be done: automatic and manual. Automatic mode takes longer.
In manual mode, the country and city of location are independently selected and the receiver soon finds the correct satellites by itself. Why don't the devices catch satellites after updating the software from the official website? Often the reason lies in the opening of the wrong COM port or in the malfunction of the GPS antenna. The correct port can only be opened with the correct firmware, and if the wrong firmware version is loaded into the GPS navigator, it will malfunction or will not work at all.
The reason that the navigator does not show the location can also be a malfunction of the almanac. This can happen if the device is stored without power, but after rebooting the almanac, the receiver will work stably. If this does not help, then you can still do a full factory reset.
It is also quite possible that the power amplifier has failed (in this case, it needs to be replaced) or mechanical damage to the device has occurred (shock, moisture), in which case it is necessary to carry out diagnostics. But, if, as a result, none of them appeared in the menu for determining the number of satellites, then, most likely, the problem with the navigator is quite serious and you need to contact the service center, which, as a rule, will conduct free diagnostics.
Now more and more mobile applications are becoming geo-dependent. Some simply do not make sense without knowing the user's location, others become more convenient with him. These are the so-called Location Based Services (LBS): navigators, forsquares, instagram with geotagged photos and even reminder apps that are triggered near a specific place, for example, near an office or a store.
For Yandex services and applications, we have created our own implementation of the location determination method without GPS - Yandex.Locator. It saves the user time and makes our apps a little bit smarter. In Navigator and Maps, it eliminates the need to enter the starting point of the route, even if you are in a covered parking lot. And when choosing a movie in the Movie Poster or a product in the mobile Market, it helps to immediately show where to find them in your area of the city. And, of course, when looking for cafes and ATMs - it allows you to show you the nearest ones, even when you are on the subway.
We opened the technology long ago as a free API. Today we want to tell you how it works.
Why without GPS and how else
Satellite navigation systems (GNSS), in our case GPS and GLONASS, are the most accurate geo-determination method today. The corresponding modules are found in almost all modern smartphones. But not always and not everywhere he can solve the problems of LBS.Firstly, the search for satellites sometimes takes several minutes, and there are situations in which the speed of determination is important even with a loss of accuracy. For example, when you need to build a preliminary route in the navigator or check in. Second, satellites are usually not "visible" indoors or underground. Thirdly, GPS modules are not found in every mobile phone or tablet, and they are almost absent in laptops. So LBS needs alternatives.
And, of course, there are alternatives - you can determine the location by the nearest GSM-towers, Wi-Fi networks, and even by the IP address. The accuracy of each of these methods is much worse than that of GPS. But if you combine them, they will give an acceptable quality together. At the same time, some disadvantages of one are neutralized by the capabilities of the other. GSM towers are almost everywhere, but Wi-Fi networks are not. At the same time, the detection accuracy is better over Wi-Fi. Therefore, the combined method is better in terms of completeness and accuracy than each separately. Less well known is the fact that two routers in different parts of a city may have the same MAC address. Combining GSM and Wi-Fi solves such collisions. These routers, most likely, will have towers with different identifiers nearby - after all, the probability of a match within a block is much less than on a city-wide basis.
There are several implementations of such a combined geo-determination method in the world. And it seems that the first question that all developers faced was - where to get information about the location of Wi-Fi networks and cell towers?
Base of network locations
In the buy-or-build dilemma, we ultimately opted for the latter. The main reason is that with your own data and algorithms it is much easier to control the quality of the result. Users of mobile Yandex.Maps helped us in collecting information.When we started developing Locator, there were already hundreds of thousands of people on the streets of cities with Yandex.Maps turned on in their phones. With the consent of the user, the application constantly transmits his GPS coordinates - Yandex.Traffic is built on the basis of this information. We thought that along with this, the application could mark which base station the phone is serviced in these coordinates, which Wi-Fi networks are visible (while, of course, without connecting to the networks themselves - so as not to create privacy risks).
A person does not need to do anything to participate in such crowdsourcing - just use the application. As with coordinates, data on the surrounding Wi-Fi networks and GSM stations are depersonalized. They practically do not "weigh" anything, and the battery from their transmission, accordingly, does not drain faster.
Thus, users began to help each other: 
Some, with a GPS receiver in their phone, find out the exact location of the networks and transmit the information to Yandex. Others, who do not have GPS-modules, send a list of networks that they see at the moment, and receive in response their approximate location on the map.
The database has been collected and is regularly updated. And here we are faced with the next problem.
"Moving" networks
Experience shows that the identifiers of cell towers are constantly changing - the number that was in the city center yesterday may be on the outskirts tomorrow. Wi-Fi routers can also move - along with their owners. And it turns out that with each move, you need to invalidate a noticeable part of the data.This is how we managed to solve the problems with moving both towers and routers at the same time. The user receives a request to determine the location along with data about which networks he sees. If the list of networks contains one that was seen in different parts of the city, the algorithm takes into account how many signals from it are accumulated in each district and the age of the latter. We call every dense accumulation of signals from a Wi-Fi network or cell tower a "cloud". The more signals there are in the cloud and the fresher they are, the more trustworthy it is. The answer will be the largest and freshest, respectively. And a cloud in which there are no signals for more than a month is considered obsolete - even if a more recent cloud has not appeared for this network in another area.
Cloud radius
Since the position is determined approximately, you cannot show a point - you need to draw a circle (after all, the radio signal is evenly distributed in all directions in the absence of interference). Although, if you look at the actual picture of the signals, most often it is an ellipse. After all, motorists use mobile Cards most of all. Their GPS tracks remain on the roads, and practically no signals are received from courtyards and, moreover, from buildings.
For the answer to be as accurate as possible, the radius of the circle must be as small as possible. If you just draw a circle around all the signal points of a particular network, the radius will be too large. Mate helped to reduce it. statistics. The signal density is subject to a normal distribution, that is, the three sigma rule applies. 99.7% of the points fall in the vicinity of this radius.
We decided to go further and experimentally selected a sigma factor that minimized the radius as much as possible, but retained acceptable accuracy. This was successful because in most cases the user sees several networks. That is, the areas “open” by decreasing the coefficient are most likely overlapped by other clouds.
Non-cloud signals
Unfortunately, not all GPS signals from users can be easily compiled into the clouds. It turned out that if you superimpose on the map all the signals of a single network, in addition to the "ellipses", it will contain points and lines. These are, accordingly, single signals that are very far from the accumulation of signals of the same network, and very long GPS tracks (i.e., chains of GPS signals).
"Loners" appear, for example, when a person moves on the subway. The phone loses contact with a cell at one station, and when it exits to another, it still thinks that it is being served by that cell. The Locator filters out such signals. In addition, we have set a minimum threshold for clouds so as not to rely on too few signal clusters.
Long GPS tracks appear, for example, when a person drives a car across the city. The phone “drags” the tower identifier from the beginning of the route and reports that it allegedly sees it all the way. It is known that base stations have a limited range, so the Locator also filters out such GPS tracks. Tracks, the length of which fits within the range of the tower, remain. They are usually seen in areas where there is little data. There they become a chain of small clouds.
We consider lone signals, small clouds and long tracks "noise". When the user sees one single network for which we know only such signals, he receives a response that the location could not be determined. We consider this to be more correct than to give a knowingly incorrect, according to our estimates, result.
When data was scarce, there was another difficulty with combining all signals into one cloud. It happened that the signals from the tower from one city also came from another. The presence in the identifiers of the GSM networks of the location area code - LAC (Location Area Code) helped us. Since towers with the same code should be located nearby according to the standard, the Locator began to give an underestimated weight to the clouds that were “in the wrong city” (ie among the clouds with a different LAC). 
Improving the definition accuracy ...
... over GSM networks
Once upon a time, applications only had access to information about one base station, although the phone most often sees several. After the Android platform appeared, applications were able to learn to see all of them (except for connection in the 3G standard, which allows only one cell tower to be recognized). The location began to be determined more accurately - no longer by one cloud, but by the aggregate of several. It turned out that for many clouds, you can use the same approach as for one. The radius is calculated from the root-mean-square deviation of the signals included in the set of clouds, and the center is calculated from the average of their coordinates.... over Wi-Fi networks
When a smartphone is within range of several Wi-Fi networks, it can report not only their list, but also the signal strength of each. We used the knowledge about this power to refine the center of the circle in which the user is located. We began to suspend imaginary springs to the centers of the observed clouds - the stronger the signal, the tighter. And their free ends are to connect. The point at which these springs are balanced is the refined center.
The resulting quality
First, a few words about how we assess the quality of our solution. As already mentioned, from users who have a GPS module in their devices, Latitude receives both coordinates and a list of networks that devices see. To assess the quality, he first determines the approximate location, focusing only on these networks. And then it checks whether the true coordinates from the user fall within the circle suggested by the Locator.
Using this technique, we got the following numbers:
- for 83% of requests per day, the location was determined correctly - the GPS coordinates of the device fell into the area named by the Locator
- 14% of signals - with an error:
- 7% - error less than 100 meters
- 5.6% - from 100 meters to several kilometers
- 1.4% - Locator is wrong by city
- the remaining 3% of requests receive a response "Location not found"
Can you get better quality? Yes. The advantage of the method is that with a certain maturity of the algorithms, it is enough just to collect more data in order to determine the location more accurately. And this is easy enough, because the number of Wi-Fi networks is growing, and the number of users of our applications is growing.
But there are technological limits:
- if the phone reports only about one GSM tower - the minimum radius will be several hundred meters in the city, and several kilometers outside the city
- if the phone sees several towers, the center can be determined more accurately, but the radius can hardly be reduced
- if a Wi-Fi network is visible - the minimum radius will be 10 meters
The amount of computation
To respond quickly to a user, you need to prepare the entire response in advance, or at least a significant part. Every night, a cluster based on our YAMR distributed computing system aggregates signals received up to yesterday, receiving "clouds" ready for response. At the moment of request, the Locator only needs to combine them correctly. So terabytes of "raw signals" were compressed to 1.5-2 GB of ready answers, which can easily fit into memory. And preparation of the response almost always fits into 1 ms, and each server in the cluster can withstand 10 thousand RPS.And so that the duration of the daily calculation does not grow linearly with the growth of the history of GPS signals, we have achieved the "additivity" of the clouds. Now it is enough to store only a few indicators for each cloud, and there is no need to re-process the entire old history every day.
It turns out to be ineffective to prepare a more complete answer. If you cluster each combination of networks into a separate cloud, you get a combinatorial explosion. The volume of ready-made answers grows by several orders of magnitude, and if the networks overlap, even more calculations are needed to prepare the answer.
Analogs
Location services without GPS, as we have already said, are not only available from Yandex. Developers can contact a commercial provider (such as Altergeo in Russia and Skyhook Wireless in the world), or use the API of a mobile platform or browser.In general, such a database can be assembled in three ways:
- go around cities of interest by car, scanning networks, and then periodically go around again to update the database
- create a mass mobile application (for example, Yandex.Maps)
- create a mobile platform (like iOS or Android)
The main purpose of a GPS tracker is to determine coordinates. But it happens that the tracking beacon does not cope with this function. Why do these problems arise and how can they be resolved?
The principle of determining coordinates using a tracker
At the first start, it is also called "cold start", it takes the tracker up to 15 minutes to establish communication with satellites, determine the coordinates and download the data on the location of all satellites, so that in the future this process occurs faster. Our devices have a built-in AGPS function that allows you to determine the coordinates much faster, in a few seconds. Usually, a beacon uses a GPS antenna to receive coordinates from satellites every second. If the object on which the tracker is installed falls into an area where the signal from the satellite is not received, is shielded, the device can switch to orientation via the GSM network, that is, cell towers. In this case, the accuracy of determining the coordinates is an order of magnitude lower.
Receiving coordinates from satellites or towers, the tracking beacon then transmits them to a mobile device via a cellular service or to a computer connected to the Internet via a server. This is how it works. The problem can arise not only at the stage of obtaining location data, but also at the stage of transferring this information, if there is no coverage or Internet connection.
Possible problems and solutions
People who monitor the performance of a tracking beacon have to periodically face the following problems:
- it is not possible to determine the coordinates by satellites, the device transmits zero coordinates;
- unable to determine the coordinates of the towers;
- received coordinates are not transmitted;
- the error exceeds the permissible value.
Instead of the expected coordinates, the device can send a message without coordinates. Some models begin to determine and transmit coordinates only after they receive the command to start work. Make sure that you have given such a command and that the settings allow the determination of satellite coordinates and the AGPS function, which accelerates the determination of coordinates, is enabled.
The beacon can determine coordinates that are slightly shifted relative to real ones, if the signal is shielded (for example, when being near high-rise buildings). In this case, you can try again outdoors. Another possible cause of the problem is incorrect orientation of the device: the tracker should be directed with the screws upwards, and if this is not possible, then there should be no metal obstacles in front of the device at a distance of less than 40 cm.
If coordinates are not determined by base stations (towers), first of all, you also need to check whether this is allowed by the tracker settings. Then check the Internet access settings, their compliance with the settings of the mobile operator, the availability of coverage, and the features of the tariff plan. If there is a connection, the device may not receive a signal from the nearby towers, since they were recently commissioned and have not yet had time to be indexed. The same problem occurs when the operator renames towers: the tracker does not recognize them. This often happens when the operator brings new towers into service.
Inaccurate coordinate display
The accuracy of determining the coordinates depends on many factors: the model of the tracker, the method of determining the location (by GPS or GSM signal), the area where monitoring is carried out. For a satellite signal (GPS + GLONASS), the error is 5–15 m, for a signal from base stations (GSM) it increases to 150–500 m, and in rural areas, where towers are distant from each other for considerable distances, the error can reach 5 km ... Possible reasons for low accuracy:
- determination of coordinates from the satellite is not allowed (you need to check the settings);
- the signal from the satellite does not pass, and the device receives the signal from the towers. This happens when the tracker is incorrectly oriented, used indoors, surrounded by high-rise buildings, in the thick of trees or in mountainous areas;
- the tracker is receiving a signal from an insufficient number of satellites.
Usually, their number is deliberately limited in the settings to save battery life: the more satellites the tracker interacts with, the faster it discharges (searching for new satellites takes time). If such settings negatively affect the accuracy of position determination, you should increase the minimum number of satellites from which a signal is received.
It is not only the number of satellites within sight of the tracker that matters, but also their location. If they are all concentrated on one side of the beacon, the accuracy will be lower, and if the satellites evenly surround the tracker on all sides, the positioning accuracy will be significantly improved.
In most cases, problems with determining coordinates are not a symptom of a malfunctioning tracking beacon. They lie either in the wrong settings and are easily solved by changing them, or in objective reasons that are temporary, situational (signal shielding, lack of coverage).
Information on many Yandex services depends on the user's location. For example, the Yandex home page displays the local weather forecast, billboard, and traffic jams in your city. The location is also taken into account in the search results: if you are looking for a gym, Yandex will show you the nearest sports clubs.
If you have blocked your location from being determined, a link will appear in the search results. Results nearby... You can click it to allow access to your location and get more accurate results for your request.
You can change the settings for accessing a location using the Access to location instructions.
- How to set a city manually
- How to reset city settings
- How to prevent location determination
How Yandex determines my city
Yandex can determine the location of your device in several ways:
- By IP address
By default, the city in which a device connected to the Internet is located is determined by the IP address of that device.
Situations are possible when the same IP address is used in different cities. Then a location set correctly for one user will be incorrectly determined for another user.
- With LBS technology
LBS technology (Location-based service) allows you to determine a more accurate location of the device:
- Wi-Fi hotspots. When the device's Wi-Fi adapter is turned on, it periodically checks the signal strength of nearby networks. The approximate location of a device can be determined if there is at least one Wi-Fi network whose location Yandex knows about. For example, it might be a Wi-Fi hotspot at a nearby café.
- By cell of the cellular network. The location of a mobile device is determined using the Cell ID (Cell ID) within which the device is located.
The resulting coordinates are matched against our database of the location of Wi-Fi hotspots and cells.
Note. Yandex.Maps users helped to create the database. With the help of the built-in Yandex.Locator technology, the Yandex.Maps mobile application, with the consent of the user, constantly transmits the GPS coordinates of the device and determines which base station serves the phone in these coordinates, which Wi-Fi networks are visible.
