MEMO

TO:	FILE	DATE:	February 22, 2000
FROM:	GKP
SUBJECT:	REVISIONS TO RTK GPS WORK	PROJECT NO:	020205010
Upon completion of processing the RTK GPS files, 13 of them began work on creating the "CHECK SHOT COMPARISON" spreadsheet. I first notice point number 9 to have a couple of foot of error in the horizontal position. I deleted the shot thinking it was bad and over looked Kelly's notes. Later on still working in the spreadsheet I found check shots to monument 6,8 and 10 to have mulitple feet error in them. Now I had four control points, 6,8,9 and 10 with problems. Went back to TSOFFICE to review database.

Upon reviewing the database I found the same problem in it. I also found that Kelly had few check shots from day to day. I began re porcessing the dc-files one at a time. I coreected the here-position lat-long-height to the WGS 84 values derived from GPSURVEY so that I could publish them. During the reprocessing I checked each file for check points form one file to the next. Called Kelly to verifiy the few check shots he took. He confirmed only sparingly taking check shots because he was doing known-point int's on every point. I did find enough check shots to verify revisions I was about to make.

The first problem I found was Kelly had trouble collecting data for monument number 009. Point 009 would not pass the known-point init routine. Kelly tried three times before collecting the point again. The second attempt at collecting data at monument number 009 is point number 1275. Kelly also had trouble getting a known-point init for point 1275. Two or three attempts were made before the init routine finally gave heim a passing solution. Kelly never checked back into monument 009 again. Both 009 and 1275 miss the GPSURVEY position for monument number 009 by mulitple feet. This explains the first bad point I discarded in the spreadsheet.

I found the remaining problems in dc-file LUB012. Kelly set up on point 1275 and tied points 1439 through 1514. In this file he made three check shots to other control monuments, numbers 006,008 and 010. I found the vector meaurements from point 1275 to 006,008 and 010 to be withing hundredths of the GPSURVEY vector measurements. The realationships were correct but the starting position was wrong. I found no probelms with dc-file LUB013. I found one check point in this file and used it to verifiy my revisions to dc-file LUB0012.

I revised the database by removing points 9,1275 and points 1439 through 1514. I then calibrated the database to the GPSURVEY monument coordinates and found residual error of only 0.07 feet. I then started another project called REV012 under the 02020501 directory. I edited the dc-file with the GPSURVEY lat long and height formonument 009 (point 1275). I then calibrated the file using 1275 (009), 008,006 and 010. Residual error equaled 0.02 feet. I exported points 1439 through 1514 and imported them into the main database and check point 1515 from the LUB013 file to point 1490 of the LUB012 file and found 0.08 hundredths of error.

Revised dc file from 4700 done bye Leon Aylesworth. Leon's file had no problems in it but I had to correct the starting position with the GPSURVEY lat long and height so that I would get duplicate points. Leon's file was created in Lubbock by downloading Kelly's collector into a temporary project data base and then uploaded into Leon's TSC1. This file coul not be calibrated becuse Leon only took one check shot to another monument. I deleted the other control point positions in the TSC1 file becuse of their non-use.

GKP/gkp

\