The most accurate GPS navigators. Positioning by distances to satellites


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On approval of requirements for accuracy and methods for determining the coordinates of characteristic points of the boundaries of a land plot, as well as characteristic points of the contour of a building, structure or object of unfinished construction on a land plot

Pursuant to Part 7 of Article 38 and Part 10 of Article 41 Federal Law dated July 24, 2007 No. 221-FZ “On the State Real Estate Cadastre” (Collection of legislation Russian Federation, 2007,
No. 31, art. 4017; 2008, No. 30, art. 3597, Art. 3616; 2009, No. 1, Art. 19; No. 19, art. 2283; No. 29, art. 3582; No. 52, art. 6410, Art. 6419) order:

approve the attached requirements for the accuracy and methods of determining the coordinates of characteristic points of the boundaries of a land plot, as well as characteristic points of the contour of a building, structure or unfinished construction site on a land plot.

Minister E.S. Nabiullina

Approved

by order of the Ministry of Economic Development of Russia

from___________ No.___________

Requirements for the accuracy and methods of determining the coordinates of characteristic points of the boundaries of a land plot, as well as characteristic points of the contour of a building, structure or object of unfinished construction on a land plot

1. A characteristic point of the boundary of a land plot is the point at which the description of the boundary of the land plot changes and its division into parts.

A characteristic point of the contour of a building, structure or unfinished construction object on a land plot is the point at which the boundary of the contour of a building, structure or unfinished construction object changes its direction.

2. The location on the ground of characteristic points of the border of a land plot is described by their flat rectangular coordinates in the Gauss-Kruger projection, calculated in the coordinate system adopted for maintaining the state real estate cadastre.

The location of a building, structure or object of unfinished construction on a land plot is established by determining flat rectangular coordinates in the Gauss-Kruger projection of characteristic points of the contour of such a building, structure or object of unfinished construction in the coordinate system adopted for maintaining the state real estate cadastre.

3. The coordinates of characteristic points of the boundaries of land plots and characteristic points of the boundaries of the contour of a building, structure or object of unfinished construction on a land plot are determined by the following methods:

1) geodetic method (method of triangulation, polygonometry, trilateration, method of direct, back or combined serifs and other geodetic methods);

2) by the method of satellite geodetic measurements (determinations);

3) photogrammetric method;

4) cartometric method.

4. The identification of characteristic points of the boundary of a land plot on the ground with boundary signs is carried out at the request of the customer of cadastral work. The design of the boundary sign is determined by the contract. In the case of fixing characteristic points of the boundary of a land plot with boundary signs, their coordinates refer to the fixed (designated) centers of boundary signs.

5. The method of work to determine the coordinates of characteristic points is established by the cadastral engineer depending on the available initial information and the requirements for the accuracy of determining the coordinates of characteristic points adopted in this document.

6. The geodetic basis for determining the flat rectangular coordinates of characteristic points of the border of a land plot are points of the state geodetic network and points of reference boundary networks.

The geodetic basis for determining the flat rectangular coordinates of the characteristic points of the contour of a building, structure or object of unfinished construction are the characteristic points of the border of the land plot.

The SKP location of a characteristic point of the contour of a building, structure or object of unfinished construction is determined relative to the nearest characteristic point of the boundary of the land plot.

7. The SKP location of the characteristic point of the border of the land plot should not exceed the standard accuracy of determining the coordinates of the characteristic points of the boundaries of the land plots (Appendix No. 1).

8. The SKP location of a characteristic point of the contour of a building, structure or object of unfinished construction should not exceed the standard accuracy of determining the coordinates of characteristic points of the contour of a building, structure or object of unfinished construction:

for lands settlements- 1m;

for other lands – 5 m.

If the contour of a building, structure or unfinished construction object coincides with the boundary of a land plot, then the coordinates of the characteristic points of the contour of the building, structure or unfinished construction object are determined with the standard accuracy of determining the coordinates of the characteristic points of the boundaries of land plots.

If a building, structure or unfinished construction object is located on several land plots for which different standard accuracy is established, then the coordinates of the characteristic points of the outline of the building, structure or unfinished construction object are determined with an accuracy corresponding to the accuracy of determining the coordinates of the characteristic points of the outline of the building, structure or unfinished object construction with higher precision.

9. To determine the UPC location of a characteristic point, formulas are used that correspond to the methods for determining the coordinates of characteristic points.

10. Geodetic methods.

Calculation of the SCP location of characteristic points is carried out using software through which field materials are processed. In this case, a statement (extract) from the software is attached to the boundary plan.

When processing field materials without the use of software to determine the UPC location of a characteristic point, formulas for calculating the UPC are used that correspond to geodetic methods for determining the coordinates of characteristic points.

11. Method of satellite geodetic measurements.

Calculation of the SCP location of characteristic points is carried out using software through which satellite observation materials are processed. In this case, a statement (extract) from the software is attached to the boundary plan.

12. Cartometric and photogrammetric methods.

When determining the location of characteristic points combined with the contours of geographical objects depicted on a map (plan) or aerial photograph, the SKP is taken to be equal to Mt = K*M.

Where M is the denominator of the map or aerial photograph scale.

— for the photogrammetric method, K is taken equal to the graphic accuracy (for example, when determining the location of characteristic points from photographs - 0.0001 m);

— for the cartometric method:

— for populated areas K is taken equal to 0.0005 m;

- for agricultural and other lands
K is taken equal to 0.0007 m.

13. When restoring the boundary of a land plot on the ground based on information from the state real estate cadastre, the position of the characteristic points of the boundary of the land plot is determined with standard accuracy corresponding to the data presented in Appendix No. 1.

14. If adjacent land plots have different categories, then the common characteristic points of the boundaries of the land plots are determined with an accuracy corresponding to the accuracy of determining the coordinates of the land plot with higher accuracy.

15. At the request of the customer, the contract for cadastral work may provide for determining the location of characteristic points of the boundaries of the land plot and the contours of buildings, structures or unfinished construction objects with higher accuracy than established by this procedure. In this case, the determination of the coordinates of characteristic points of the boundaries of the land plot, the contours of buildings, structures or unfinished objects is carried out with the accuracy specified in the contract.

16. Based on the calculated coordinates of the characteristic points of the border of the land plot, a catalog of them is compiled, on the basis of which the area of ​​the land plot is calculated.

17. To calculate the maximum error in determining the area of ​​a land plot, the formula is used:

∆Р — maximum error in determining the area of ​​a land plot (sq.m);

M t — the maximum value of the mean square error of the location of characteristic points of the border of the land plot, calculated taking into account the technology and accuracy of the work (m);

R - land area (sq.m);

k— coefficient of elongation of the land plot, i.e. the ratio of the greatest length of a section to its smallest width.

Appendix No. 1

Standard accuracy of determining the coordinates of characteristic points of land boundaries

Item no. Category of land, area of ​​land plots Mean square error, (m)
1. Agricultural land
land area up to 1 hectare 0,2
land area up to 100 hectares
land area more than 100 hectares 2,5
2. Lands of settlements 0,2
3. Lands of industry, energy, transport, communications, radio broadcasting, television, computer science, lands supporting space activities, lands of defense, security and lands of other special purposes 0,5
4. Lands of specially protected natural territories and objects, lands of the forest fund, lands of the water fund and reserve lands 5,0

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Testing the accuracy of GPS receivers for mobile phones

During work on one project, we needed to find out the real (and not declared) accuracy of geopositioning for various smartphones.

For this purpose, a stationary receiver from Topcon was used, the readings of which were taken as a standard. The tested devices were located in the same place. After a cold start, an additional 2 minutes were kept for a more accurate determination of the coordinates.

The following devices took part in testing:

  • Fly IQ447 ($80);
  • Nokia Lumia 625 ($100);
  • Samsung Galaxy Tab 2;
  • Industrial Motorola smartphone TC-55 – ($1500);
  • Industrial smartphone Coppernic C-One ($1500);

It looked like this:


As a result, the results (the discrepancy between the coordinates of smartphones and the coordinates of a stationary receiver) were as follows:

  • Fly IQ447 (GPS) – 1-3 meters;
  • Coppernic C-One (GPS + GLONASS) – 2 meters;
  • Motorola TC-55 (GPS + GLONASS) – 6 meters;
  • Samsung Galaxy Tab 2 (GPS) – 8 meters;
  • Nokia Lumia 625 (GPS) – 30 meters.

Motorola was a little disappointed - for its price the results were expected to be better.

But most of all I was surprised Fly phone. For its price of 3,000 rubles, it turned out to be the most accurate; despite the fact that it does not have a Glonass receiver. We rechecked the results several times, but they always turned out to be excellent.

By the way, this phone- the only one who always and everywhere on an airplane from a cold start finds satellites and calculates coordinates. Despite the apparent good conditions reception, most other phones do not always find a signal from a sufficient number of satellites in flight - sometimes you can wait 20 minutes, but still not be able to determine the coordinates.

By the way, we initially did not want to take the coordinates of a point on a map (for example, Yandex) as a standard. We are aware of the possible discrepancies between maps and real coordinates. At our point at Yandex, the magnitude of this discrepancy was about 5 meters.

Pocket geolocation is quite common in Lately familiar. Now on all models modern phones there is a GPS system. But users often have questions about it. For example, they are interested in how to improve GPS reception on Android or iOS in order to receive more accurate location information or more conveniently play games that require detailed geolocation. Let's look at this problem and find out what can be done.

GPS is a system that allows a smartphone to use navigation applications and determine your location in order to build best option route to your destination. It is based on receiving data from satellites located in outer space.

Why do I need it?

GPS navigation is used by navigation applications. Together they help get to the right place without detailed study paper maps of the area and polling others on the topic “Where to go next and where to turn?”

The most famous free "Yandex.Maps" or "Yandex.Navigator", GoogleMaps and MapsMe. You can also find it on the Internet pirated version"Navitela". But the program may be from an old year. In this case, it can lead you onto non-existent roads and under “bricks”. In addition, the program may be infected with a virus. Then there is a chance that it will “break” the system of your smartphone, and you will have to change not only the navigator, but also the phone or at least its firmware.

Now the most common and modern models phones - these are IPhone based on IOS and phones that support a different system (“Android”). They use GPS in a more advanced form - A-GPS. This is a function that increases the speed of the application during cold and hot starts, due to other communication channels (WI-FI, cellular), and also increases positioning accuracy.

A situation where the phone cannot connect to new satellites when the application is turned on. In this case, it operates autonomously based on the data transmitted during the previous switching on by the satellites to which it was connected. Hot start - when the satellites immediately start working. They appear on the application screen or in a special tab for tracking their operation and data reception.

The first signal improvement option

Ways to improve GPS reception on Android or iOS, great amount. Let's look at the 3 most famous ones. The first and most in a simple way The way to strengthen the GPS signal is to enable the appropriate mode in the phone settings. To do this, we take the following steps:

  • Turn on GPS (geolocation) and go to the phone settings.
  • Find the "Geodata" section.
  • Choose top button"Mode".
  • A window called "Detection Method" opens.
  • Select the item "High accuracy".

The phone's performance will improve by enabling accuracy. At the same time, its operating time without recharging can decrease several times. The thing is that the turned on navigator will simply “eat up” the battery.

The second way to improve GPS reception on Android

The second option is more complicated. But it helps as often as the first one. You need to download an app to clear your GPS data. Once the satellite information is updated, the navigation system will work better than before. But this option may not be suitable for some phones due to incompatibility of the application and model, lack of space, etc.

The most difficult but reliable method

There is also a third, most difficult option solutions to the problem of how to improve GPS reception on Android. It is more suitable for computer geniuses. Its essence lies in altering the system file that controls the operation of the phone's GPS system. Let's figure it out in order:

  1. You need to extract the GPS.CONF file located in the system/etc/gps/conf folder via special programs, which give access to system files. Then we move it to internal memory phone or SD card so that you can open it on your computer later.
  2. Changing GPS.CONF settings is done through the Notepad++ program on a regular PC. The phone is connected to the computer via a standard USB cable.
  3. Next, you need to change the settings of the NTP server, which is used to synchronize time. They usually say something like this - north-america.pool.ntp.org. The entry needs to be rewritten - ru.pool.ntp.org or europe.pool.ntp.org. As a result, it should look like this: NTP_SERVER=ru.pool.ntp.org.
  4. It would also be a good idea to add additional servers without making any changes to them: XTRA_SERVER_1=http://xtra1.gpsonextra.net/xtra.bin, XTRA_SERVER_2=http://xtra2.gpsonextra.net/xtra.bin, XTRA_SERVER_3=http ://xtra3.gpsonextra.net/xtra.bin.
  5. Next, you need to decide whether the GPS receiver will use WI-FI to strengthen the signal. When entering the ENABLE_WIPER= parameter, you must enter a number that will allow (1) or prohibit (0) use wireless connection. For example, ENABLE_WIPER=1.
  6. The next parameter is connection speed and data accuracy. There your choice is as follows: INTERMEDIATE_POS=0<—— (точно, но медленно) или INTERMEDIATE_POS=1 <—— (не точно, но быстро).
  7. In the type of data transfer use, knowledgeable people advise installing User Plane, which is responsible for the wide transfer of subscriber data. Then DEFAULT_USER_PLANE=TRUE is written in the program line.
  8. The accuracy of GPS data is monitored through the INTERMEDIATE_POS= parameter, in the line of which you can set whether to take into account all data without exception, or to remove errors. If you put 0 (zero) after the "=" sign, then the geolocation will take into account everything it finds, and if it is 100, 300, 1000, 5000, it will remove errors. Programmers recommend setting it to 0. But if you want to try, you can use error removal.
  9. The use of the A-GPS function, as mentioned above, is supported or automatically enabled on all modern devices. But if you still want the function to work, then in the A-GPS activation line you need to set DEFAULT_AGPS_ENABLE=TRUE.
  10. The final version of the file needs to be saved and transferred to the phone, and then rebooted.

An important point: if you don’t want to do all this yourself for various reasons, for example, laziness, fear of breaking something in the system, etc., then you can find the GPS.CONF file with the parameters you need and simply copy it to your smartphone. All that remains is to restart the phone and use the improved GPS.

Why doesn't GPS work on Android yet?

There are other reasons for the problem. It happens that GPS on Android does not work at all (does not turn on, does not search for satellites, etc.). Resetting the system to factory settings can help resolve this problem. This is done through the phone settings. In addition, the gadget can be reflashed or given to service center employees, who will “dig” into the electronics and correct the defect.

Don't you like that the GPS on your Android takes too long to "search for and acquire satellites"? The location accuracy is worse than 10 meters? Did you think that “this is how GPS actually works”? Nothing like this. Your GPS can provide an accuracy of +-5 meters, or even more accurately. And I will tell you how to achieve this. And no more “patches” or third-party and “gemorrhagic” in the use of “GPS utilities that speed up the search for satellites and increase accuracy.” Everything you need is in your device. The manufacturer simply enters “medium-light” “calibrations” there - naturally, he won’t calibrate each phone individually. And where is the manufacturer? In China, but you need to calibrate where you actually use it. The instructions below were collected by me from different sources in parts and checked, except for the part “ensuring maximum accuracy,” which I will check later and make an addition, but even without it, time “ Cold start" GPS, after rebooting the phone, it was possible to bring it to less than 20 seconds, instead of 1-2 minutes before calibration. At the same time, the capture of the first satellites occurs in less than 3-4 seconds, and “GPS capture” (localization by satellites, when the “GPS search” stops blinking and the body switches to working on satellites) - less than 10 seconds (sometimes up to 40 seconds, but less often - depending on the accuracy of your smart watch and satellite visibility).
To decide which one you prefer, you can read impressions of both methods here:. I personally recommend the “native GPS calibration method” (described below) - it gives the same results, and in my opinion is much preferable and easier to use.
It should be noted that with the help of the program described here: the speed of activation from the “cold” state is still a little faster. but it’s more dangerous, and due to its “deep penetration into the Android GPS system”, it can “throw down” the calibrations of its “native system”, which are discussed below. Plus, everything that needs to be done with its help, before each turn on, the GPS makes the startup using it really slower than in the option outlined in this note.


Added 08/30/2013. Before starting calibration, look at this note and follow the procedures described in it: . This is especially true if you have serious problems with GPS, such as “it holds the satellites very poorly” and the “lock” “falls” at the slightest weakening of the signal, plus after that, the GPS will “hold” more satellites at the same time, which will improve both stability and accuracy . Without these procedures, I could not “bring the GPS back to normal” under JB 4.1.1 Cink King. Then perform calibration according to the method. outlined below in this note.

*italic font The points necessary to achieve generally theoretically possible accuracy are highlighted. Italics may be omitted, this will slightly reduce the accuracy (actually 2 times), and will not affect the “cold start” speed.
**Before the procedure, find out the code for the engineering menu of your device - you will need it.

  1. GPS accuracy, and especially the speed of “capture after a cold start,” greatly depend on the accuracy of the time setting on your device. Usually, in the “Date and Time” settings, “synchronize time over the network” is set. I had it too. But as it turned out, the device uses the operator’s cellular signal to set the time, which in some cases can give time setting accuracy worse than + - several minutes, and in my case (Kiev, Life operator) it gave a difference from real time of as much as 3 seconds. In general, feces, and not “exact time signals”. There is also the option to “determine the time using GPS,” but if you don’t live in a village, then this will consume a lot of battery, and will be of little use - neither in an apartment, nor on the subway, nor in a minibus, nor in the office... Well, you get the idea.
    Therefore, let us first take care of setting the most accurate possible time. To do this, I installed the free ClockSync program, from here: https://play.google.com/store/apps/details?id=ru.org.amip.ClockSync&hl=ru, you can also get it from here: http://4pda. ru/forum/index.php?showtopic=171610 . You can also use the technique that I described here: - it does not require installing additional programs, but it does require manual editing of several system configuration files.
    Next, we decide on the reference exact time server that we will use. It is important that it be as close to you as possible and that the ping time to it be minimal. To begin with, the addresses of the “pools” - for Ukraine this is ua.pool.ntp.org, for Russia ru.pool.ntp.org. If you are in another country, look here: http://www.pool.ntp.org/ru/.
    Now we launch the terminal, and in it the command “ping ua.pool.ntp.org”, and look at the response time. We do this 10 times - each time it will contact a random “pool” server, and usually a different one. Even for Ukraine, the “response” time for different servers ranges from 5 to 60ms (on land), let alone Russia with its size. Accordingly, we write down the IP address of the server whose response time is minimal. We will use it.
    Launch the installed ClockSync program, Menu > settings. The first item is "NTP server". Enter the selected IP address there. Next, check the “automatic synchronization” box, then select “Interval”. The smaller the interval, the more often the synchronization will take place, and this means “a little traffic and a lot of battery”, on the other hand, my device “goes away” by as much as 160-180 milliseconds in 3 hours... I settled on 3 hours for now. Next "Precise interval" checkbox - you don't have to check it - it will save the battery a little, I personally checked it. "High precision mode" - check it, especially since synchronization will sometimes take place through cellular data transmission at a very unstable speed (you don't have to check it - the accuracy will drop, but Battery consumption will be significantly reduced during synchronization.) We also set “detect time zone”
    Exit the settings menu, click “menu”, and select “synchronize” - how much your device is “past time” can be seen on the screen. Yes, in the settings menu after a day you can see how fast/late your device’s clock is per day (my Fly IQ 450 is 9.21 seconds per day).
    PS automatic time synchronization is only possible on a “rooted” device. If you are not rooted, there is a “manual mode” in the program, but the accuracy will not be the same.
    Note - added later. There is also a second way to accurately synchronize time, without installing an additional program, I described it here:. After comparing the results, I chose this method, but it requires some editing of the configuration files.
    It is also advisable, if you have a rooted device, to edit the /system/etc/gps.conf file. Namely, in the first line, after “NTP_SERVER=", replace the “default” one indicated there with a more suitable one for your country - for example, for Ukraine at ua.pool.ntp.org, or even with a previously defined IP address, but this will less universal and sometimes fraught with failures if a specific server does not work, so ua.pool.ntp.org is more universal, but the IP address in this field can further speed up the initial cold start. Editing can be done using "Root Explorer".
    Over time we figured it out. Further.
  2. Let's go to the phone settings. Location. We mark the items: “By network coordinates”, “GPS satellites”, “Auxiliary data”, “AGPS”, the rest is “to taste”. Now go to the "EPO Settings" item. Turn off "EPO" during calibration. Everybody is here.
  3. Launching Google Earth , In the settings, we switch it to show coordinates in the format of degrees and fractions. We are looking for a place nearby where we will carry out calibration. It should be a fairly open place, such as a square. We select the point where we will stand during calibration (select signs to stand exactly at it later), point the cursor at it, and write down the shown coordinates to the last digit. The preparation is over - let's go "to the field" :) with the phone.
  4. If you used p3- we stand EXACTLY at the point we previously selected. Launch "root explorer", go to the /data/misc folder, delete the mtkgps.dat file. We download the latest AGPS data - for example, through the GPS Status program (menu>tools>AGPS Data>Download). We check the time, for example with the ClockSync program (we check it several times, look at the typical deviation, and then click synchronize - how to use the program and where to get it - see earlier in the article on time calibration). Go to the engineering menu, LocationBasedServices, select “GPS” in the menu, and press the “GPS” button (the inscription on it will change from OFF to ON). Go to "View". We wait until the “fix” appears (the GPS indicator stops blinking), and then for at least another 2 minutes. Then click RefPosition, and in the windows that appear, enter the coordinates previously written out from Google Earth for the point where you are calibrating (there will be zeros there). Click "OK". Go to the View screen again, and wait after the "fix" for at least 2x minutes, preferably 5 minutes. We go back to the engineering menu. If step 3 was not performed, simply choose any fairly open place. Taking out- don’t even try to do the calibration on the balcony or “from the window” - you’ll only make it worse.
  5. ****Before calibration, you can also check the correct choice of SIM card for AGPS - if your cellular operator is “glitchy”, and there are two cards and two operators, then you can choose a less buggy one, this, if “buggy” was selected, can significantly speed up the operation of GPS, ATO and “revive” a “completely broken GPS” procedure is described at the very end of the note.
  6. Go to the "Engineering Menu"(for my FLY IQ 450 and many Chinese clones, this is the code *#*#3646633#*#*, which we dial where you usually dial the phone number when calling, you may have a different one). Find "YGPS location" and launch it. Hold your phone vertically.
  7. Go to the Information tab. Click the "Full" button.
  8. Go to the "Satellites" tab, wait for at least 5 satellites to appear (preferably more - I had 11 of them when setting up), and after they “appear and turn green”, wait at least another 2 minutes, holding the device motionless (it can be longer - it won’t be worse - only better ). This is the initial calibration. It took me about 3 minutes, but for some devices, according to reviews, it can take up to half an hour.
  9. Go to Information", click "Cold". Continue as in point 8. Repeat point 9 3 times. More is possible.
  10. Back to Information. Click "Warm". further as in paragraph 8. There is no need to repeat it anymore.
  11. Back to Information". Click "Hot". Continue as in step 8.
  12. If you followed step 3, go to the engineering menu, select the "LocationBasedService" item, go to the "View" tab (remember to activate GPS as described in step 4), and wait until the maximum satellites are determined. Minimum 7, better more (the more, the more accurate the calibration), and after the maximum is determined, wait another 2 minutes. Then go to the tab GPS, and click "RefPosition". You will have two numbers, from the one you previously recorded using Google Earth, they will most likely differ in thousandths. Correct both to those that you wrote down earlier in step 3. Click "OK". Now go to the GPS tab and wait for 5 minutes holding the phone motionless. Here in this place - the longer the better. The GPS program, having received real coordinates, compares them with those that it “obtains” and makes corrections. clarifying them. Below in the window you will see a “process” counter and data that changes from time to time.
  13. Exit the engineering menu and reboot the phone.
  14. All. We rejoice in the fast and accurate GPS.
After completely following the instructions, the real accuracy of determining the position (calculated from google earth and not the one shown by the GPS itself) was ~2.3-2.5 meters (GPS showed an accuracy of 5-6 meters in the status), with 9 satellites “visible”, and 8 meters (GPS showed an accuracy of 10.5 meters in the status) with 7 satellites visible - the satellites move and do not happen from time to time in the sense of day to day.

PS If you are also going to use the program described here: then please note that you need to calibrate after installing it. And if it is uninstalled, calibrate it again - it resets the calibration data during uninstallation, and the GPS again begins to “search for satellites for several minutes.” Loading its “acceleration” data does not SEEM to affect the calibration, but it also makes no sense - the difference in speed is “within the limits of statistical error.” But it seems that the real accuracy is a little better, with freshly downloaded data (by 20 percent, but also within the statistical error in essence). Also keep in mind that the downloaded data from the above program quickly becomes outdated, and after a day or two, on the contrary, it will slow down the GPS and reduce accuracy (compared to a simply normally calibrated native one using the method described above in this article). Plus, I took it down nafik :) Bo, firstly, is not needed, and secondly, with it you can get “GPS which does not determine anything” if you forgot to download new data. Even if you clicked the “reset downloaded data” button and do not launch the program itself. At least this happened to me once - I didn’t check the rake again.

PPS There are rumors on the net that “turning on EPO data” (specific GPS data for MTK chips), which gives some acceleration of the “cold start”, reduces the number of “captured satellites”. This is unlikely. The number of captured satellites is determined by their “number overhead at the moment” and their height above the horizon (in the city, those above the horizon are usually not visible). But still, when calibrating it is better to turn it off. And use only if you are traveling to a place where the Internet may not be available. Then it will give you a real launch acceleration (it downloads data a month in advance). In a normal situation, it is better to use only AGPS - its data is fresher, and therefore more accurate, so the “start” speed with it is typically higher.

PPPS Below is “reference information” for those who received a device with a completely non-working GPS. It’s worth checking it - the reason may be that you have something different from the following listed in your settings:

In the engineering menu, in the LocationbasedService item, in the AGP tab S:

Enable A-GPS, MSB, User Profile, SLP Template - GOOGLE, supl.google.com, 7275, TLS Enable, RRLP, IMSI, K-Value must be enabled.
Horizontal Accuracy - 22, Vertical Accuracy - 0, Location Age - 0, Delay - 0. Location Estimate is selected.
*********Selecting a SIM card for AGPS
Go to the NET tab - select - click look at the map (Map tab), the address where you are located, or close to it, should appear there. We do the same with . We compare what is more accurate to your real position, and on the AGPS tab select your preferred SIM card.
On the AGPS tab, click
Yes, if any of the things listed in this PS differed from the settings of your device, or if you changed the SIM card to which you have AGPS attached, you need to perform a new calibration.

PS About the influence of clock accuracy on the GPS cold start time.

From the “inconvenient place” - a balcony, everything on top is covered with concrete, a courtyard-well - houses on 4 sides, the sky is “a piece from above”, 4 satellites are barely visible (then you can barely see 3, and the 4th one appears and disappears). the phone was calibrated according to the method outlined above (before calibration, there was no capture at all under these conditions). The clock “lags” by ~160ms (2 hours have passed since the clock was calibrated by the ClockSync program). Cold start time ~250-300 sec. After forced time calibration by the ClockSync program, the “cold start” time is ~100 seconds. However, these are the conditions. in which GPS usually does not work at all, but clearly illustrates the influence of clock accuracy on the “cold start” time.

PPS To force the loading of AGPS data, for example, if you are far from the place where they were downloaded - for example, you went 200 kilometers for fishing/vacation, etc., and the AGPS data downloaded at home has become irrelevant, which can negatively affect the “cold start” time.

You can use the GPS Status program from here: https://play.google.com/store/apps/details?id=com.eclipsim.gpsstatus2&hl=ru. Launch this program. At the bottom left under the “coordinate circle” is the age of the AGPS data in hours. Click Menu > Tools > A-GPS Data. Then "download".


The accuracy of GPS measurements varies from 1 centimeter to more than 15 meters, depending on the equipment used, data processing techniques and other factors. In addition, the accuracy of the data obtained is influenced by your experience and knowledge of the basics of working with GPS systems.

Remember that the accuracy of determining plan coordinates when using GPS usually 2-5 higher than altitude, regardless of location on the Earth's surface. If you are using equipment and software(software), which gives an accuracy of horizontal coordinates of about 1 cm, then the accuracy in height will be 2-5 cm. This can become a decisive factor when you use equipment with an accuracy of horizontal coordinates of about 2-5 meters. In this case, the accuracy of determining the height may be worse than tens of meters.

In this section you will find information on how to get the highest possible accuracy from your GPS equipment.

Equipment

The choice of equipment directly depends on the accuracy you need to obtain.

C/A code receivers

Information about the status of all satellites is included in the almanac transmitted to each satellite. Almanac data is updated daily and transmitted from each satellite approximately every 12.5 minutes.

If your GPS receiver has received an almanac that contains information that a satellite is “unhealthy,” the receiver will not track or receive data from the inoperative satellite until the almanac is updated. Even if the satellite returns to working condition, then the receiver will begin to use its data only after the corresponding information appears in the new almanac. The GPS receiver automatically monitors these changes and makes updates as needed.

Although your GPS receiver typically does not use the signal from an unhealthy satellite, you may not want to take this into account for prediction purposes when planning GPS measurements. In this case, you can use the information from the “unhealthy” satellite or ignore the “healthy” satellite. If you ignored the indication that the satellite is “unhealthy”, then the satellite planning software will assume that the satellite is “healthy”. If you ignored the indication that the companion is “unhealthy” in the software base station, the message will be ignored and the satellite data will be written to the base file.

Availability of satellites in GPS “constellations”

The GPS receiver by default receives information from all satellites. This means that they are used in all calculations (provided they are “healthy”). Some Trimble GPS receivers allow you to disable healthy satellites. After this, the receiver will not receive signals from these satellites.

Attention! You are unlikely to ever need to disable healthy satellites. This can be useful, for example, for scientific tasks, to “force” the receiver to work with a certain configuration of the GPS satellite constellation.

The accuracy value of measuring the distance from the satellite to the user (URA or User Range Accuracy)

The user distance accuracy (URA) value is included in satellite signal. This value characterizes the accuracy of measurements from a particular satellite. The URA for each spacecraft is typically displayed on the receiver (4000 series) or controller (TSC1) screen. If the URA value is greater than 30, then most likely the Selective Access (S/A) mode was activated on the satellite.

Antenna location

Satellite GPS signal can be received from any direction. For getting best result, the antenna must be installed in an area with the most open part of the sky (right up to the horizon). A small amount of water or snow does not affect the quality of signal reception. Metal surfaces, buildings, dense tree canopies, etc. block the signal. Powerful transmitters (especially in the microwave range) can distort the GPS signal. During operation, you should try to avoid areas through which focused microwave radiation passes or areas located near powerful radars emitting radio frequencies close to multiples of the L1 signal frequency (1575 MHz).

The base station antenna must be placed in places with the most open horizon. If, for example, the base station is located in a heavily built-up area, then a mobile receiver can capture a satellite invisible from the base station. In this case, this satellite cannot be used when performing differential correction, since simultaneous observations from 2 GPS receivers. It is much more difficult to create ideal observing conditions for a mobile receiver. Try to ensure that the sky is as open as possible when shooting. Do not stand near tall buildings. When working in the forest, try to place the antenna a meter or two above the treetops.

Remember how many times you swore at an innocent navigator, finding yourself on the wrong exit, on the highway instead of an understudy, on an unfamiliar sofa with your face covered in toothpaste... Well, okay, in the latter case, the navigator has nothing to do with it. But if you think about it, the device is not always to blame for other wrong turns.

Birmingham, England

The software in a navigator or smartphone works with GPS chips, in which nothing has changed for years. And in satellites that have been circling in orbit for decades, nothing can be changed at all. And yet the American corporation Broadcom intends to change the existing order of things.

An interchange passing through a high-rise building. Osaka, Japan

At the ION GNSS+ conference in Portland, a prototype of a commercially mass-producible BCM47755 GPS chip with an accuracy limit of 30 cm instead of the current 5 m was presented!

Shanghai, China

Among other things, the chip consumes half as much energy (smartphone owners open champagne!) and does not get confused in the palisade of high-rise buildings. Broadcom representatives claim that some smartphone models that will go on sale in 2018 will be equipped with the new chip. But here’s the annoyance: they don’t say which ones.

Swindon, UK

Any receiver satellite navigation, whether American GPS, Russian GLONASS, European Galileo or Japanese QZSS, works approximately the same: it calculates its location from a signal about the exact location of three or more satellites, using different data, for example, the time it takes for the signal to travel between the satellite and the receiver.

Springfield, Virginia, USA

Why are new GPS chips being launched now? Firstly, Broadcom has mastered the production of processors on 28-nanometer architecture. And secondly, the constellation of new generation navigation satellites has increased. There is more than one format for transmitting data by satellites. Standard precision L1 signals have been in use for quite some time, but now the more powerful and broadband L5 signal has come to their aid. According to Broadcom, even with limited sky visibility in large cities, GPS devices simultaneously “see” six to seven satellites, and this is quite enough for the new high-precision chips to work.


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