Stabilized GPS

morgan shared this question 6 months ago
Answered

Please explain or provide a link to the user manual that explains what this is.


thank you

Replies (5)

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This method is used for accurate placement of points - Locus Map records a group of locations obtained from the phone location sensors (GNSS etc.) and then calculates the average that is the closest to the actual location. Originally this feature was provided by an abandoned third-party add-on GPS Averaging.

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when and why would you use it? Isn't regular gps with 12+ locked sats accurate to like like 30 feet?

thanks Michael

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For example for placing a geocache.

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Don't forget that it's important not to move while creating the stabilized point ๐Ÿ˜Ž

When/you you would use the feature? Whenever you want to record a point with as high precision as possible, e.g. to add an survey point to OpenStreetMap or an object where precision is security relevant like a gully/hole or bivouac box that is often hidden below snow. Please consider the displayed accuracy of the GPS signal is surprisingly often way higher than the actual accuracy โ€“ just try for yourself as sketched below โ€“ and this is not only true when conditions are demanding for satellite signal position fix (thick clouds, heavy rain, dense forest, few visible sattelites due to high & dense buildings or narrow deep valley, mountains made of ore with high metal concentration,...), but for bad conditions, then the effect is much stronger.


If you want to try for yourself how reliable displayed accuracy is, one quick & easy way it is to change Locus settings to record also the raw NMEA data (did I say I love search feature in settings? ๐Ÿ˜‰), lay down your mobile for e.g. 1 minute and start track recording & memorize displayed accuracy while recording, stop recording, delete the recorded track within Locus, open the NMEA file e.g. in JOSM or any other tool, and measure the distance between recorded points. I just did on my terrace, the conditions were not at all demanding for satellite signals (see above), displayed accurracy 10-11m, recorded points distance 38m. In bad conditions, I had several times hundreds of meters deviation despite displayed one was only ~15m. Exactly this type of short term disturbances (every passing truck modifies the signal, the satellites are moving with ~30000km/h etc.) can be compensated to a certain degree by the feature "GPS averaging" / "stabilized GPS", but also that shows an accurracy that is "only" true for that moment & device, but not "universally" true. Why? Because your GPS receiver may have a slight bias, while another device may have the opposite bias. Because the satellites now have a different setting than tomorrow. Because the atmosphere is now different than tomorrow or in 6 months. To see this long term effect, for some time period, repeatedly go to a precisely defined point e.g. a bench below an big tree that now (beginning of spring) has no leafs but in a few weeks will have dense leafs. Depending on what you wanna see, also go when conditions for exact gps fix are bad. Each time you're there, record a "stabilized GPS" point and write down the displayed accuracy. After some weeks you'll likely have a cloud of points scattered much wider than the displayed accuracy. You could now average these points again to increase precision. And you could do the whole game with several devices of different manufacturers. And over a longer period of time. Etc.

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Great explanation...thanks

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