Carlson Software Forum

I've been a Trimble user for as long as I've been using GPS equipment. Honestly I don't use RTK much, more of a static control type of guy. That being said, I'm trying to learn a little about the way Carslon GPS handles GPS information.

I beleive with the Trimble TSCs, RTK information is being stored as dXDYDZ ECEF WGS84 vectors. On the fly the data collector can modify the calibration or related data and generate new coordinates for points surveyed. Often I pull the DC file into TGO and end up doing my calibration there ... I don't technically have 'points', I have vectors. Not baselines, vectors. An LSA program like StarNet can read the DC file, and work with the vectors just as if they were derived from a static post-processed baseline.

An RTK GPS shot in a Trimble TSC DC file


I'm trying to learn SurvNet and now turning my attention to its capabilities in the GPS area. Unlike StarNet bringing in a DC file, I'm not seeing SurvNet able to bring in an .rw5 file (with respect to RTK data). My sample .rw5 file of RTK seems to show just a coordinate value being stored, hence, SurvNet could not wind up with a vector if it read the file. Can someone help me understand if I am understanding correctly? If so I think the GPS part of an .rw5 file needs to be adjusted to include this raw information (store the observable).

An .RW5 file of a GPS RTK shot, contrastable to the file shown above.

GPS,PN102,LA33.523580973615,LN-116.175862410863,EL286.688363,--
--GS,PN102,N 2262605.8833,E 6546605.8624,EL1039.6732,--
--HRMS:0.043, VRMS:0.152, STATUS:FIXED, SATS:8, PDOP:2.2

If in SurvCE GPS, you update your 'localization', which I'm assuming is the same as Trimble's calibration, does that automatically cause all the previously collected data to update?

Is the Lat/Lon being stored as the means to detemine the 'vector' from the base ... if so, what happens if I update the base position, will the Lat/Lon update as well?

To continue my question and clarify...

Testing using data collector files of simple RTK work:
I've tested bringing in a Trimble DC file into SurvNet and viola vectors!
I've tested bringing in a SurvCE .rw5 file (could not accept through GPS input) and no vectors.

I've also read up on SurvCE GPS and to the best of my understanding, re-localizations are possible. I'm thinking you're stuck to a datum and then it is using the lat/lon's generated to transform to whatever system you're trying to fit.

Are there no raw vectors to bring into an LSA progrm like SurvNet or StarNet? Is this good data being thrown away?

Speaking with a manufacturer, I'm hearing that their unit could be scripted to store the vector information, for later download from the head unit. I think a much better option, if it doesn't exist, would be to have the DC store this information for all GPS units. I'm sure most people using RTK never think of the raw, like most people using .crd files, but that is just dissapointing, not the way it should be. A modern surveyor should have a working knowledge of LSA and apply it in their daily work, IMNSHO.

Rich,

I participated in the SURVNET w/ GPS webinar last year and posted the question of RTK vectors from the SURVCE .RW5 file format. At that time, you could not bring them (SURVCE RTK) via the .RW5 file as there was no actual vector data. The suggested work around was import your RTK-derived coordinates and assign realistic standard errors to them. This seems to be a rather tedious process.

Would be nice if you could bring in a .crd file of the points with the accuracy stored as a note or RTK Vector data.

I am currently on SURVCE 2.07 and 2008 Survey Standalone.

Matt

Thanks for your comments Matt.

I would respectfully respond to whomever suggested the work-around that calling it a work-around would be a misnomer. The vectors are the measurment, the coordinates are not. Bringing the coordinates in, even with the Q1 & Q2 values as weighting, severly constrains the capabilities of the adjustment software. I would be much more likely to bring in a published control value from which measurments are made with positional uncertainty, something we're very likely to do now with the change in NGS control format.

The vector data is available at the time of measurement, it needs to be stored so that it can be brought in as it is done when importing a Trimble DC file. Hopefully it can be seen that this is a limitation that will keep people from using SurvCE GPS, and that it will be corrected.