A manual for users of Magellan MSTAR software



Introduction


From the year 1996 dates the program MSTAR from Magellan. It was developed for Windows 3.1 and Windows 95. So do not be surprised when things look a bit like the old times. But in the intervening years the laws of mathematics and physics are not changed. Some more things are invented and discovered but the principles this software uses (and all arithmagic) are still valid.
First: where to get MSTAR?
Goto the ftp site of
ftp://ftp.ashtech.com/
and find the directory 'software'. In there are a lot of nice thing available. We go for MSTAR and Rinex folders. The MSTAR software is distributed on 7 virtual floppy disks (a leftover from the times before the CD-ROM was invented). Get them all downloaded.

Follow the instructions in the readme file and install the software.
Because MSTAR started as dedicted software being a part of the hardware (all in one buy) the normal files to input are in a special proprietairy format. Later the support for data in RINEX files was added.
Further: there is a big Y2K bug. And that is serious because date/time stamps are essential in all calculations.

Rinex solution

Although Rinex files can be inputted in NSTAR the results are wrong. This is a result of the Y2K bug. The way to go is: use the special converter for Rinex files. Be carefull to use Rinex files that 'belong' to one another. There is no check on that. The program outputs a single file in proprietary format (.car) containing everything. So you need the obs-files and the nav-files. Maybe even the best ephemeris files you can get (from IGS for instance on http://igscb.jpl.nasa.gov/components/prods_cb.html )
So you end up with a file for the rover and one for the base station.

Base stations

Somehow the program cannot distill the position of the base station from the (Rinex) file of station observations. So you have to make for each station you use a so called point file. We use ETRS89 for the positions of European EUREF stations. But when you use WGS84 the differences between the used ellipsiods is minimal.
The way to go is:

Launch MSTAR.

Open a new session. The name does not matter because you will not save it.
The Configuration window will appear. Click Session Options.
Click I/O Grid/Datum. Put check marks in the Geodetic and HAE boxes.
Click Set Datum.
Click Transformation then select Mododensky from the list.
Click Datum Name then select World Geodetic System 1984 from the list.
Click Ok or Close buttons until you get get back to the Configuration window.
Click Control Point. Input the lat/lon of Delft. This being:
N 51 g 59 m 10.02191 s E 4 g 23 m 15.30289 s Height 74.359
Set the Range, Bearing, and Height values on the right to all zero. Click Close.
Click Session Options.
Click I/O Grid Datum. Put a check mark in the ECEF (WGS-84) box.
Click OK or Close buttons to return to the Configuration window.
Click Control Point. You should now see the xyz coordinates for Delft.
You can save it in a file for later use.

Check

The position of DELFT station is:
N 51 degrees 59 minutes 10.02191 seconds
E 4 degrees 23 minutes 15.30289 seconds
74.359 meters above ellipsoid
and this should translate to:
X 3924687.7079 meters
Y 301132.7690 meters
Z 5001910.7697 meters
After rounding off, they are identical to:
X3924687.708 Y301132.769 Z5001910.770
When you check these results with the CC40 calculator (downloadable at RDNAP ) you will find this is correct.

Ronald J. van der Kamp

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