The problem, is that you cannot do a calibration fo a GPS since it will depend on the satellite constellation which change all day long even if you don’t move. So calibration of a GPS is a no no! If you use accurate GPS measurements, either baseline measurement, of PPP post processing (but you need a GPS slightly more expensive that the regular handheld ;-) ) you can have an accuracy of a few millimetres. So the std-dev should always be given explicitly for GPS.
Phil > On 11 Sep 2017, at 21:24 PM, Martin Sluka via Therion <[email protected]> > wrote: > > There is an application for Android Mobile Topographer (Pro). In Pro version > it is 15 EUR? > > It has many very interesting features to measure and use GPS including > calibration on known point etc. > > There is only one problem with this application. It has no automatic backup > of measured data. So only way around is export data to an available format > and save it manually. Topographer crashed on my Android tablet and I loose > all my GPS points. On other hand the uninstallation and new installation was > without any problem. Just to backup a folder with exports before. > > m.s. > >> 11. 9. 2017 v 20:53, Xavier Pennec via Therion <[email protected]>: >> >> One of the problem for a predefined accuracy of gps measures is that it >> really depends on each measurement. I usually use a stddev of 2 to 3 times >> the figure of merit (FOM) of the GPS averaging procedure for x and y >> coordinates and 4 to 5 times for the altitude. This can range from a few >> meters (this has to be on a plateau with no trees) to 50/100 m for >> measurements in forests with a few satellites only (there are also often >> reflections on cliffs that perturb the measure). >> >> Xavier >> >> Le 11-Sep-17 à 19:10, Benedikt Hallinger via Therion a écrit : >>> No, i meant the following: >>> >>> currently one has to give std-dev explicitely: >>> fix 1.2a 0.5 0.5 0.5 >>> >>> it would be nice to use instead: >>> fix 1.2a gps >>> where the term "gps" is some predefined accuracy, like in grade definition >>> >>> >>> Am 2017-09-11 10:08, schrieb Bruce Mutton via Therion: >>>> Benedikt wrote >>>>> The option to use "alias names" for fixes instead of directly numbers >>>>> would be good, this would allow to ship standards with therion and allow >>>>> the user to to define custom ones, just like in grade definitions. >>>> >>>> Not sure I understand correctly what you mean. >>>> >>>> We can make alias now, using equate. This is what I usually do for gps >>>> fixes. >>>> >>>> In a cave survey 'index data file'... >>>> centreline >>>> cs lat long >>>> fix gpsEntrance01 <lat> <long> <altitude> [<stderr> etc ] >>>> fix gpsEntrance02 <lat> <long> <altitude> >>>> etc >>>> >>>> equate gpsEntrance01 53@<survey1> >>>> equate gpsEntrance02 1@<survey14> >>>> equate gpsEntrance01 AliasNameCreatedByThisStatement >>>> endcentreline >>>> >>>> ie 53@<survey1>, gpsEntrance01 and AliasNameCreatedByThisStatement are all >>>> alias' of each other. They all refer to the same physical point. The last >>>> name is created by the equate statement, whereas the others all exist >>>> prior to the execution of the equate statements. >>>> >>>> Or were you meaning something different? >>>> >>>> Bruce >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> Therion mailing list >>>> [email protected] >>>> https://mailman.speleo.sk/listinfo/therion >>> >>> _______________________________________________ >>> Therion mailing list >>> [email protected] >>> https://mailman.speleo.sk/listinfo/therion >> >> -- >>> ------------------------- >>> Xavier Pennec >>> Senior Research Scientist / Directeur de recherche >>> Asclepios project-team, INRIA Sophia-Antipolis >>> 2004 Route des Lucioles, BP93 >>> F-06902 Sophia-Antipolis Cedex, France >>> +33 4 92 38 76 64 >>> +33 6 78 35 16 90 >>> http://www-sop.inria.fr/asclepios/ >>> ------------------------------- >> >> _______________________________________________ >> Therion mailing list >> [email protected] >> https://mailman.speleo.sk/listinfo/therion > > _______________________________________________ > Therion mailing list > [email protected] > https://mailman.speleo.sk/listinfo/therion _______________________________________________ Therion mailing list [email protected] https://mailman.speleo.sk/listinfo/therion
