Tuesday, March 14, 2017

Submitting corners to the NE PLSS using SurvCE raw files

If you are using Carlson SurvCE for your data collection then it’s pretty easy to get the data you need out of the raw file if you want to submit corners to the Section Corner Database.  There are just a few steps you need to take.

First, a quick examination of a SurvCE raw file.  Here’s a portion of a raw file of mine:

--User Defined: SSO-RichardsonCo
--Equipment: GRX1  SN:GRX1/S 665-00170
--Localization File: None
--Geoid Separation File: \DCFiles\NebKsMoArea.gsf
--GPS Scale: 1.00000000
--Scale Point not used
--Base Configuration by Previously Surveyed
--Point Used: 316
--Base Rod Hgt: 5.282
--Antenna Type: [SOKGRX1         NONE],RA0.0890m,SHMP0.0552m,L10.1101m,L20.1061m,--TPS p/n:01-090101-08
--Antenna Type: [SOKGRX1         NONE],RA0.0890m,SHMP0.0552m,L10.1101m,L20.1061m,--TPS p/n:01-090101-08
--RTK Method: CMR+, Device: Internal Satel
--Entered HR: 5.9055, Vertical
GPS,PN0284E09,LA40.030075609518,LN-95.351404448716,EL255.638283,--2 424
--GS,PN0284E09,N 35360.5788,E 134662.1040,EL932.4832,--2 424
--Valid Readings: 120 of 120
--Fixed Readings: 120 of 120
--Nor Min: 35360.5657  Max: 35360.5932
--Eas Min: 134662.0903  Max: 134662.1156
--Elv Min: 932.4576  Max: 932.5045
--Nor Avg: 35360.5788  SD: 0.0052
--Eas Avg: 134662.1040  SD: 0.0042
--Elv Avg: 932.4832  SD: 0.0103
--HRMS Avg: 0.0192 SD: 0.0001 Min: 0.0190 Max: 0.0199
--VRMS Avg: 0.0272 SD: 0.0005 Min: 0.0260 Max: 0.0283
--HDOP Avg: 0.6906  Min: 0.6812 Max: 0.6930
--VDOP Avg: 0.9796 Min: 0.9345 Max: 0.9925
--PDOP Avg: 1.1986 Min: 1.1564 Max: 1.2105
--Number of Satellites Avg: 17 Min: 17 Max: 18

As you can see, I record all the accuracy information that Carlson offers.  I record the number of readings, max / min / etc.  I maintain this “unedited” raw file for legal reasons but usually will process my raw files into what I call a “Packed” format which is what you need for submitting to the Online database.  Basically there are only a couple of things that need to be done:

  1. Convert the Elevation (in the line starting GPS) from the L1 Phase Center to the ground.
  2. Remove all extraneous lines so all you have is the Lat/Long/HAE.

Here is the process I use. I wrote a little program that takes the line reading LS,HR6.2667 (which is the L1 rod height) and subtracts that height from the elevation listed on the GPS line. For the GPS shot (Point 0284E09) the calculation would be the height above ellipsoid in meters (255.638283) minus the rod height (6.2667) in feet.

HAE = L1 – Rod, or HAE = 255.638283 - 1.910 = 253.7282.

If the base station (from the line that starts with BP,) has an accurate NAD83(11) position, then that is the only conversion necessary.

The program called “PackRaw.exe” does the computation above, and strips out all the unnecessary lines, leaving JUST the GPS shot. I’ve also supplied the QB64 basic source code PackRaw.bas if you want to see how the program is written.

This program is written in QB64 basic and is designed to be as small as possible. Put the executable in the same directory as your raw file because you have to type in the raw file name. The program creates a second file with the same name and adds “Pack” which is the stripped-down version of the raw file. As an example an input file named “RichCo.rw5” will create a file named “RichCoPack.rw5”

Running the program, the output for this raw file would look like this:

GPS,PN0284E09,LA40.030075609518,LN-95.351404448716,EL253.7282,--2 424

The program puts a “revised” rod height in (zero), and then leaves only the GPS shot. This is the basis for the file to submit.

I record all the accuracy data so my raw files get pretty large. I create a “Packed” file every couple of months and keep the unedited raw file for archive purposes.

Once you have a packed raw file run it through WinDMS-DDEG selecting conversion 15. The GPS, PN line structure is stripped off and leaving the Point, Latitude, Longitude, Height, Description. Verify the point number is the correct point ID and rename the text file to the requested format (LSnumber-Date-Frame.txt) and submit!

Hope this helps. If you spot a mistake or want more information let me know. If you have similar routines that you use with equipment other than Carlson let me know. Thanks.