Montana Department of Transportation

Trimble Pathfinder Community Base Station(CBS) Global Positioning System (GPS) Files

Montana Department of Transportation(MDT) in Helena operates a CBS, logging data files 24 hours a day 7 days a week. (subject to change for maintenance)

These files, used for differentially correcting rover positions, are available, free of charge through MDT's FTP site. The root directory for the files is GPSFILES with each day as its own subdirectory.

Specifics on the Base Station:
Reference Positions:

Latitude	46 35' 20.4183" N
Longitude	111 59' 32.7047" W
Altitude HAE (M)	1233.820
Elevation Mask:	0
PDOP Mask:	6
SNR Mask:	6
Synced Measurements:	5 second intervals
Receiver:	12 Channel Maxwell
Antenna	Compact L1 with Groundplane
Software:
Receiver	Firmware v3.08
Workstation	PFCBS v2.33

Specifics on the Base Station Files:
Rinex Files are now available as of June 1998. They are the *.Nav and *.Obs files under the Rinex subdirectory. Trimble files are in self extracting, compressed,Standard Storage Format(SSF) one hour blocks. If you need data in a different format, have trouble with the files or have any questions about the gps file please contact:

John O'Mara

Phone: 406.444.6307

Email:

The data is available no later than 3½ hours after collection. The files are named via the station letter, year, month, day, GMT hour naming convention with .exe extension. For example: Data collected on April 19, 1996 during 4:00PM - 5:00PM(GMT) would be A6041916.EXE.

These files will be available on the server for approximately 60 days. The files will then be deleted from the server.