Yes, when I’d started again, that were the easiest approach I think:
Just align my station with known reference point.
But that still leaves open how to interpret reference coordinates.
Looked in the definitions of ntrip and RTCM - for vain.
Closest information I could get:
‘Discrepancy between points with NTRIP and local base station - RTK / PPK configuration - Emlid Community Forum’
A local plate fixed datum comes along for the ride and the coordinates don’t change, that’s why CORS normally use them.
All over our communities places, including Stefal’s recommendations, they say:
“for precision, collect 24 hrs, get 'em postrocessed and align to local official plate fixed system”.
OK, could have registered with SAPOS (the German official service), paid them 20€ p.a. and get my data processed to ETRS89/DREF91 (R2016) - without understanding what’s going on.
Or as I did before, run my Antenna with LFPS ntrip (part of SAPOS, 20 € p.a. already registerd) and get an average (see some posts above).
With my survey stick running on LFPS ntrip (i.e. ETRS89/DREF91 (R2016) as I suppose) I checked that BayernAtlas DOP where roughly OK at ~10cm, as far as one can match ground features.
This match to official maps is what I wanna have in the end.
Just received my postprocessed ITRF2020 coordinates from my yesterday 24hr-record and converted them to ETRS89/DREF91 (R2016) - as I hope:
...$ echo 4015871.3006 872670.2865 4862126.2068 2025.54 | cs2cs -d 8 +init=epsg:9988 +to +init=epsg:10284
12.26006092 49.98424037 605.43964324 2025.54
When I compare those coordinates whith what I’d exprect from earlier LFPS tests, this matches expectations as close as 22 mm (green line at the bottom).
Raw ITRF2020 as supplied from rgp.ign.fr (top blue line) and the plain WGS84 (which is quite close to it - second line) are more than a meter off.
Without proper epoch, we are still > 30 cm off (second last line)
label | lat | lon | alt | d lat ° | d lon° | d mm lat/lon/diag
Thus, I dare to odd that I figured it out.
Lets go test it.