GPS

I once bought a Garmin eTrex VentureHC (the cheapest one available at that time in the store), and since then I have been using it to mark the coordinates of points. Actually, I don't use it for anything else, the built-in card is bad there, you can't write new ones there. Its accuracy, according to Yandex, is 15 meters.
About accuracy. 0.5 m for cheap civilian vehicles is unrealistic, you need professional geodetic devices of the appropriate cost. Smartphones and tablets can further improve positioning accuracy by using the cellular network signal. Where it is not there, alas, it does not immediately determine the coordinates.

If you believe the data of the unit itself, the error in open terrain is from 3 to 5 m. There is much more in the forest. Yes, the unit is eTrex, I don't remember the exact brand.

In general, I don't really understand why such accuracy is necessary. If you need to search for something on the ground, put a point and a parallel placemark on the ground.That is, you can use GPS to find a place, but you can specify it using the actual placemark. I sometimes do this with trap lines when there are few visual landmarks, such as a vast swamp...

Accuracy is required for creating a map. I can find nests by sight, even without marking them, which is very risky to do where all sorts of people are wandering around. In general, apparently, as I suspected, Pan Stepova and that time brazenly shaved. You will have to take up the tape measure, fishing line and compass again.

That's it, I get it: Pan had a gadget from the future: https://hitech.vesti.ru/article/680651/

That's it, I get it: Pan had a gadget from the future: https://hitech.vesti.ru/article/680651/

Almost comprehensive information: https://ru.wikipedia.org/wiki/GPS
From my own experience: under excellent reception conditions (8-12 satellites are visible and captured by the device), the accuracy of household receivers is about 5 meters.

In my communication with pan, I referred to Pedivikia and other sources, but he claimed (five years ago) that the local information was outdated, and now almost centimeter accuracy is available in household appliances. I know that there is a certain method that provides something similar using the signal not only from satellites, but also from some ground-based base stations. But this is clearly not what is used in smartphones and tablets. And we hardly have such stations.

But it is still strange why it was so godless for him to lie, in those days he was still not infected with the Maidan of the brain, and was quite adequate.

Garmin Oregon G450. I bought it for 700 bucks. The accuracy is 1.2 m. I put light traps in the evening and tags in the Garmin, in the morning it brings them to them without any problems or errors.

Garmin etrex 30. Despite my efforts, I couldn't get any clear figures on errors and technical characteristics-neither in terms of positioning accuracy, speed, atmospheric pressure, etc. - either from technical support or on specialized forums. Everything was limited to the same sacred "3-5 meters" in ideal conditions (a spherical horse in a vacuum is exactly the case)) and comments a la household appliance, th you finally want. The device shows the error based on its own estimates, but how they relate to reality, I do not know. If you're interested, the person here also tried to find out something: http://nuvi.ru/forum/forum26/topic15947/
In general, a useful device for hiking, but in the forest, for example, especially after a rainstorm, you can not dream of any 5 meters. I have one difficult place, four times (at different times) there I put a dot, and always with an average - a karst log, on one side a high wall, a forest-a spread of about 20 meters. This is useful for orientation, including in the mountains, with poor visibility, etc. But for your mapping, I'm afraid it's a bit rough.
I didn't use smartphones - they quickly sit down and drown in rivers. But they are an order of magnitude superior to Garmin in the speed of map rendering and ease of use of the large screen, I can't say anything about accuracy.
In other words, if you have a relatively small stationary site, you can set up a network of some permanent landmarks on the ground - stakes, poles, markers, etc.and link to them during observations - you need a familiar surveyor with a theodolite. This is if you have many years of observations in one place - the effort to set up the network will be significant.
The tape measure can be replaced with a laser rangefinder, this should greatly facilitate the process. There are artisanal modifications of mass-produced models that allow you to measure horizontal and vertical angles in addition to distance - Google: DistoX2, used, for example, for topography in caves and other inconvenient cases. But the price of the kit, I think, is now 500 bucks. You need to calibrate it periodically. I'm not the owner, unfortunately.

some kind of ground-based base stations.

... cellular network

... cellular network

No.
Special geodesics: http://www.rusgeocom.ru/gps-priemniki-dlja-rezhima-rtk

Wow, this means you also need to buy a base station

Wow, that means you need to buy a base station too

Yes, or pay for connecting to existing ones:
http://www.rusgeocom.ru/set-referentsnykh-bazovykh-stantsiy

This, probably due to A-GPS, will not work for us.

This is because Garmin is in no hurry to introduce new powerful processors, etc.

And what kind of maps are there that make a 5-meter margin of error important? On kilometers and then don't care...

If the nests were located at a distance of at least 1 km from each other, I would agree with you. But the reality is different.

You, ENO, do not be offended, but try to think about the meaning of the question I asked )
Once again: how large are maps supposed to display information about points?

This post was edited by kovyl - 13.03.2018 18: 26

In the digital age, apart from complex interactive methods, the map scale is only linear, which can only be displayed on the map itself and in no other way. Therefore, your question cannot be answered here. However, the distance between the sockets must be measured with an accuracy of at least 0.5 m. We are talking about very compact areas (200 - 1000 sq. m.), where the relative position of points must be transmitted correctly to the database.

This post was edited by ENO-03/15/2018 21: 56

Is such precision really important? At what distance can the nests be located from each other? After all, 0.5 m is only! 1% of 50m... You will agree that few instruments can provide such an error when measuring at such distances. I believe that 1% is quite an acceptable margin of error. If so, then it is better to measure the distances between closely located nests with a tape measure or a rangefinder. Between distant ones, the accuracy of the tourist GPS is enough. By God, you're not marking up a construction site )

This post was edited by kovyl - 18.03.2018 23: 20

And here 50 m? Have you seen the area figures I mentioned? There the entire plot of 50 m will lie.

Well, if the entire plot of 50m will fall, then you should not build a garden. Roulette will always be more accurate than GPS and much cheaper.

But many orders of magnitude more hemorrhoid.

Hello! Initially, I took latitude and longitude coordinates for marking moth fishing points using an additional function in the car recorder. Then using a special navigation app in your mobile phone, and sometimes using satellite maps with jps navigation. What was my surprise when, when overlaying these data, the discrepancy was sometimes about a kilometer!
Has anyone ever encountered such a problem? It seems that the data is deliberately distorted or one of the sources is inaccurate. Well, okay, if a few meters, but not a few hundred.. In one of the cases, my fishing point, according to various sources, "floats away" from Khakassia to the Kemerovo region!

Hello! Initially, I took latitude and longitude coordinates for marking moth fishing points using an additional function in the car recorder. Then using a special navigation app in your mobile phone, and sometimes using satellite maps with jps navigation. What was my surprise when, when overlaying these data, the discrepancy was sometimes about a kilometer!
Has anyone ever encountered such a problem? It seems that the data is deliberately distorted or one of the sources is inaccurate. Well, okay, if a few meters, but not a few hundred.. In one of the cases, my fishing point, according to various sources, "floats away" from Khakassia to the Kemerovo region!

I assume that the phone tends to determine the location primarily by the signal from the base stations. The less they are in its line of sight, the more accuracy "floats".

I assume that the phone tends to determine the location primarily by the signal from the base stations. The less they are in its line of sight, the more accuracy "floats".

Yes, it may well be that this is the case. It was at this point that there was no cellular connection (taiga, mountains), and the coordinates were given from satellite. I will now use electronic maps with coordinates to put down points. But how much can you trust them? In this category, participants write that 5-15 m. If so, no problem.

The accuracy of determining coordinates using GPS in general and in principle is not a constant value, and even more so in relation to maps. Maximum accuracy is provided by geodesic-class military devices, each of which has its own secure communication channel with satellites with ID codes, carried out on at least 8 subchannels, and receives undistorted data from satellites (at least in the United States), with a high frequency in real time, using data from correcting ground stations of the system WAAS is the PPS (Precise Positioning Service) mode. The data received by the receiver is processed according to a special algorithm with multiple repetitions to reduce the resulting error and is very accurately linked to highly accurate electronic maps in four coordinates (3 plane and height), for which the receiver needs to see at least 4 satellites (out of 24 available), and in reality for high accuracy - at least 8 mi. This mode is usually not available to civilian users, although I once dealt with it in Florida - the actual positioning error was less than 20 inches (50 cm). But this is in Florida, which is flat as a table and packed with essential equipment. For civilian users, as a rule, only the SPS (Standard Positioning Service) service is available. The data transmitted over it is deliberately distorted if a special mode is enabled on the satellite, the smallest for the United States and noticeably larger for other regions (for obvious reasons). Algorithms for receiving and processing data are much less advanced, although now many civilian receivers have 8 subchannels and are able to increase the accuracy of calculations with increasing time on them. Most civilian receivers also use not very accurate maps and intricate algorithms for linking to them (depending on the application). In some cases, for higher accuracy, it is better to disable linking, if possible, but then it is difficult to visually assess the accuracy. In addition, when networks are available, they are used as corrective services instead of WAAS, but the adjustment is quite rough. In the United States, the actual error under ideal reception conditions is 3-5m, and in other regions it is always more (possibly, except for Z.Europe, where I have little experience). Also, different instruments may use different coordinate systems and output data in different formats, which can and often does lead to confusion. In addition to all this, the positioning accuracy always depends on the number of visible satellites, the signal from which can be processed, the number of re-reflections from the surrounding terrain elements (on flat terrain, the accuracy is much higher, all other things being equal), the state of the atmosphere and many other factors, and all errors are summed up. Therefore, in remote areas with difficult terrain, GPS anchoring, if at all possible, often does not give better results than manual anchoring using linear landmarks on a good map. However, a very precise binding only makes sense for some special purposes, and can almost always be replaced by a description. For example, if you want to return to a place and find, for example, a line of specific traps that you left behind (and not just a station), it is absolutely necessary to create a description of the line in terms of directions and distances (for example, in steps) from the starting point, and also link this point with a description, adding coordinates that take a long and then link it to the map and use the existing link. It is also highly desirable to supplement the description with placemarks on the terrain (feeds, etc.). Moreover, depending on the time after which you will return, you need to choose different landmarks (grass grows, rivers become shallow, etc.) and types and methods of setting placemarks.