Hans Mayer <[email protected]> writes: > On 17.12.25 01:10, Greg Troxel wrote:
> Yes I am in Austria and it is EGNOS. But where do I choose it ? GNSS receivers generally can generally enable or disable SBAS. >> After that, if you are using a dynamic datum (Egnos TRF, ITRFnn, WGS84), >> or a static datum on the wrong plate (NAD83 in EU), then you need to >> bring positions to a common epoch to compare them. > > Uploading the file I used the button ITRF because this sounds for me logical > > * The epoch will be the same as the GPS data. > * A UTM zone will be calculated from the longitude. UTM and ITRF don't really have anything to do with each other. ITRFxxxx current epoch (you continue to leave out details that might batter) should be consistent with whatever EGNOS is using and with autonomous GPS, more or less. >>> The most interesting question is "what is the distance?" The maximum is >>> about 80 cm ( 2,6 ft ) >> I don't find that super interesting because I don't expect accurate >> answers from averaging GPS. > > You are right, it's completely irrelevant what’s the position of the > antenna on my house. I didn't say that. > But you know, we all are striving for maxims: higher, deeper, faster, > further > And in this case "closer to a narrower area" I know that many do, and if you are, then you will need to understand things better to succeed. The first step is to be clear about reference frames and epochs and not compare data with a non-matching CRS. If you are comparing points in ITRF "epoch of data" from multiple years ago and now, and the observed location is fixed to the Eurasian plate, you should be transforming the positions to a common epoch. I am unclear on [ceurasian plate motion; the North American plate near me is more or less 2-3 cm/y (as expreesed in ITRF).
