T2 Base File

[Jim Campi]

Gentlemen,

Yesterday I completed a 4 hour RTK survey with the T2 set up on an autonomous position. The recording interval on the T2 was 30 seconds.

At the end the day, my tech disassembled the base and left the T2 on for approximately 5 minutes. The unit was moved about 200 yards over the course of the 5 minute interval.

My intention was to send the base file to DPOS for corrections and update the LS coordinates. What impact, if any, will moving the T2 have on the base file and is there anything I can do if this is a problem? Can I delete the last 5 minutes of data points?

 

[Matt Johnson]

.jps files can be trimmed with Justin Link and with JPS2RIN. JPS2RIN would create rinex files so they would have to go to OPUS for processing if you use it. DPOS is limited to .jps files. I would be surprised if you would get good results submitting the file to DPOS with the bad data included but you could also try it to see if those epochs get discarded.

 

[Jim Campi]

Thanks Matt. I don't use Justin Link but have it installed. Do I import the jps file, export to txt, edit and reimport? Is there a way to edit the file directly?

 

[Matt Johnson]

You need to import the jps file, right click on its recordset and select properties and then you can edit the observation time. After that use the "Export to JPS" option:

 

[Jim Campi]

Thanks Matt,

That's precisely what I did after getting into the software.

The file size is 1.2 GB. 30 sec recording interval on the T2 for about 3.5 hours. I trimmed 10 minutes off the total time and it cut the file size in half to 588 KB.

4.8% drop in recording time resulted in a 51% decrease in file size after exporting to jps. Does that sound right?

 

[Shawn Billings]

Jim,
I'd be curious to know if you might have inadvertently changed the recording interval. It could be, too, that Justin Link isn't writing all of the data to the new file. The jps file contains a lot of data that isn't necessarily satellite observation data. For instance, tilt and orientation values are stored for each epoch. RTK rover files also include the RTCM correction data. I've not used this feature of Justin Link before, so these are just guesses on my part as to why you might see a decrease in size.

 

[Matt Johnson]

I see the same thing why I trim a file, it appears that when it is exported with JustinLink only GPS and GLONNASS observations are exported. Observations from WAAS, Galileo and Compass look like they aren't exported.