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Utah County GPS Base Station Technical Information

Receiver Type : Trimble Navigation, Ltd., 12 channel Everest-based PATHFINDER GPS Community Base Station (CBS)

Measurement Type : Synchronized

Measurement Rate : 5 seconds

Elevation Mask : 5 degrees Antenna Phase Center LAT 40 deg 08 min 58.9724 sec LON 111 deg 39 min 30.9310 sec ALT 1373.259 Meters HAE Datum WGS 84 Accuracy: +/- 2cm.

This site provides downloadable GPS base files in Trimble SSF format recorded over the past twelve months. Old SSF files are moved off the site and archived. The files are collected continuously each day, and new SSF files are uploaded to the County's ftp site hourly. RINEX files are available upon request and are uploaded to the ftp site as needed.

The only manipulation of the data collected by this CBS prior to uploading it is the use of PKWARE PKZIP file compression software to conserve disk space and to lessen file download times. The files are stored in a self-extracting EXE format.

The antenna for this station was positioned by the Utah County Surveyor's Office using three Trimble 4000SSE survey-grade GPS receivers occupying B-order HARN stations, and a Trimble 4000SSI survey-grade receiver occupying the CBS antenna location. The files from this CBS can be used for mapping-grade differential corrections within roughly a 300 mile radius of the station.

The station is housed in the County's Central Dispatch Utah County Security Centerfacility in the Utah County Security Center in Spanish Fork. The antenna is positioned atop the Center's telecommunications tower adjacent to the building. The data logging computer at the station is a 50 MHz 486 running MS-DOS 6.0 and PFCBS v2.23 software. It is connected to the Center's Novell LAN and the data is transferred to the County's ftp site each hour.

The method used to transfer data to the ftp site employs software called Map Assist 3.10A from Microtest, Inc., and a transfer program written in C by one of the County's computer programmers.

  • When the data logger is booted, it attaches to the Novell LAN, loads Map Assist Host, and launches PFCBS. Map Assist Host allows the local hard drive of the data logger to be published on the LAN as a network-mountable drive.
  • A second PC, also attached to the LAN, runs the transfer program. This program loads Map Assist Client, maps to the PFCBS data directory on the hard drive of the data logger, checks for closed data files, and transfers any closed files to the ftp server.

Having the station installed in Central Dispatch provides access to a very robust and stable operating environment. The file server which hosts the transfer program is the same machine that hosts the county's E-911 dispatch system, so it is very stable and reliable. The whole system is in an environmentally controlled room and is powered by a large un-interruptable power supply.

A concern in the installation of the system was the antenna's vulnerability to lightning strikes since the area in which the Security Center is located boasts one of the highest lightning strike counts in the valley. The grounding and lightning arrestor system in place on the telecommunications tower provides a high degree of protection. However, in addition to this system, we decided to install a static dissipator system and an antenna cable surge suppressor.

The static dissipator system was purchased from: Lightning Master Corporation 1920 Sherwood Street Clearwater, FL 34625 800-749-6800 Part Number TN-61

The surge suppressor was purchased from: PolyPhaser Corporation 2225 Park Place PO Box 9000 Minden, NV 89423 800-325-7170 Part Number IS-MR50LNZ+15

All of the hardware installation and computer programming associated with this station was performed by Utah County employees. The antenna was installed by Mike Christensen of the Telecommunications Division and positioned by the Surveying Division, under the direction of Gary Ratcliffe. The CBS hardware and associated software was installed by Donald Nay. The program that transfers data from the CBS to the ftp site was written by Diane Butler of the Information Systems Department. The web pages are created and maintained by Donald Nay. The Web Basic script that does the redirection from the web page to the ftp data directory was created by Neil Peterson, the IS Department Director. The station is operated by Donald Nay.

This CBS equipment was purchased through a cooperative agreement between Utah County, Brigham Young University, and Mountainland Association of Governments. The CBS is operated and maintained Utah County.


Utah County Government, Brigham Young University (BYU), and Mountainland Association of Governments (MAoG) hereby disclaims all warranties relating to the GPS base station information contained on this Internet site whether express or implied, including without limitation any implied warranties related to data integrity, fitness for a particular purpose, or functionality. Utah County, BYU, and MAoG will not be liable for any special, incidental, consequential, indirect or similar damages due to the use or misuse of this Internet site and the information contained hereon, even if Utah County, BYU, and/or MAoG have been advised of the possibility of such damages. The person or entity using this Internet site and the information contained on it bears all risk as to the use and application of this information.

Contact Information

Contact : Don Nay

Utah County Public Works Department
Donald C. Nay, Associate Director
2855 South State Street
Provo, Utah 84606