Field and equipment notes for ProMark2 GPS project on Saturday, September 4, 2004

My choice of tools and the place where I worked is based on what is available to me and easy to get to.  The fixed height tripods used for the base and the static sessions with the ProMark2 are Hixon poles that were custom built for me almost ten years ago.  They were used together with a short extension pole that originally came from Lo-Ink.  The rover pole is the typical SECO two meter RTK pole used with the SECO quick disconnect and a SECO bipod.  This is my original RTK rover pole but I had to replace the bipod with a SECO bipod I purchased about two years ago.  Since I am not signing surveys any more I have not put much effort into bubble maintenance lately.  They are close, but not perfect.

The base station is a SCA-12 GPS receiver part number 800087-04(3) serial number SW00163 that is owned by North Fork Surveying & Drafting.  The antenna is a Marine 4 L1 that was purchased with the SCA-12 with part number AT575-75W-TNCF-000-RG-36-NM with serial number 6771.  For the purposes of data processing I call it part number 103661.

The rover is a ProMark2 that was handed to me the week I came to work at Thales Navigation in September 2001.  It does not have an external serial number.  The internal serial number is 00003920896 with firmware rev 2.40  The sticker inside the battery compartment says part number 800470-07, serial number CH000550, and D/C 2801.  The ProMark2 antenna used is from the same vintage.  It does not have a Thales Navigation part number.  It shows part number AT575-189W-TNCF-000-RG-14-NM with serial number 5003 and DOW:  2/01  For the purposes of data processing I call it part number 110454.  This receiver ID is PS01.

For comparison purposes use the coordinates for BASE that were determined on a previous survey done with the ZXtreme and Ashtech Solutions.  The coordinates are NAD83(CORS96) the height was previously determined using Geoid99.

Latitude:  37° 21' 04.91604"N and Longitude: 121° 56' 04.94579"W with NAVD88 orthometric height of 20.265 meters

The SCA-12 was set up on BASE for all of the sessions.  The first file was recorded at a 10 second rate.  The second file was recorded at a 2 second rate.  The antenna height for both sessions is 2.190 meters.  Survey Control software in a Husky FS/2 was used to set up and configure the SCA-12.  Some combination of software/firmware problems keeps this antenna height from making it into Ashtech Solutions correctly.  When it gets into the processing software the height has been divided by ten.  Since I typically make antenna height errors when I am doing field work I have learned to check all antenna heights against my field notes.  You will find an antenna height error when I switched to the mag mount on my van for the kinematic session.

I was not able to download the SCA-12 to my WindowsXP Home Edition computer with Service Pack 2 using the download program version 2.75 nor version 2.60.  I also tried RCS Download version 3.20 without success.  It simply would not find the connection to the GPS receiver.  I used my old Windows98 SE computer with RCS Download to get the files from the SCA-12.  That worked on the first attempt.

I used Download version 2.75 on my WindowsXP computer to get the files from the ProMark2.

The first two files from the ProMark2 are static occupations of ROV2 with a vertical antenna height of 7.218 feet or 2.200 meters.

The third file from the ProMark2 is a Stop&Go session with a vertical antenna height of 6.890 feet or 2.100 meters.  I did not use the INI bar.  I did a long occupation on a Site named ZMAX to initialize the Stop&Go survey.

The fourth file from the ProMark2 is a kinematic session.  The initialization was on a Site named LOC3 that I observed as a control site at the end of the Stop&Go survey.  The antenna height on the initialization point was 6.890 feet (2.100 meters) but I failed to change the height when I switched to the mag mount on the van.  The antenna height for the kinematic points should be 6.200 feet or 1.890 meters.

From the time I turned the ProMark2 on just after 10 AM until I turned it off after the last session about five hours later I did not see an antenna short error message.  I did have loss of lock error messages on the kinematic session and you will find that many of the points on the kinematic session are duds.  This is not a big surprise to me based on past experience with all of my single frequency receivers.  It is very hard for me to get a kinematic survey right unless I do it in an Oklahoma wheat field.

The Stop&Go session has an extraordinary number of loss of lock indicators, particularly for SV3.  Some of it can be accounted for by environmental factors but the performance on SV3 was terrible.  I am very curious to know why SV3 gave such poor performance in the ProMark2 on Saturday.  The SCA-12 did not have significant problems with SV3.

When I got back to where the points were close together near the office building I started taking photos during the Stop&Go session.  By that time I had been up and down off my knees a lot scraping parking lot sealer off the nails.  My gimp leg was hurting, it was hot, and I was hungry.  What I am trying to say is that somehow I did not actually log all of the occupations.  I realized what I was doing after a while and went back to a couple of points where I think I forgot to press enter on START.  The photos will probably reveal some of my mistakes.  What I am trying to say is that you may want to also look at a trajectory of my Stop&Go session.  This also reveals the need to practice the procedures.  Reading how to do it is not the same as going outside to do it.  It has been several months since I did a Stop&Go survey with the ProMark2.  My field procedures were rusty.

The good news is that despite some poor data the Stop&Go session seemed to process very well.  The kinematic session was no worse than I expected.  I have not compared coordinates of the nails with the previous survey but the coordinate list is included with the data in the Labor04.zip file.  You will also find maps of all the points in the zip file.
