Welcome to the City of Madison, Wisconsin
GPS Community Base Station

The information provided here is subject to change without notice.

JUNE 12 to 14, 2007 - Correction data was not being logged or sent to our web server from 6:00 AM June 12th to 9:00 AM June 14th due to a configuration problem with the computer at the base station.
JUNE 12, 2007 - The base station was down from 6:45 AM to 9:15 AM due to a power failure.
JUNE 11, 2007 - Users can now view a list of DAT, RINEX and Ephemeris files and download individual files.
MAY 03, 2007 - The software that controls our base station was upgraded to Trimble's GPSBase (version 2.500) on April 20, 2007. The new software no longer creates SSF or ALMANAC files. The correction data is still being created and stored on this web server in DAT and RINEX format. We have provided revised instructions for users of PathFinder Office (see below). Correction data is still being broadcast in CMR+ and RTCM + RTK (version 2.2) formats.

If you have any questions, please contact -
Dave Davis (608)266-4097 or Eric Pederson (608)266-4056.

NOTE: THE REFERENCE POSITION FOR THIS GPS BASE STATION WAS CHANGED ON SEPTEMBER 06, 2005 AT 8:10 AM. THE NEW REFERENCE POSITION HAS BEEN DETERMINED USING GEOID03. PLEASE CONTACT YOUR GPS VENDOR TO DETERMINE WHAT, IF ANYTHING, YOU WILL NEED TO DO TO RECONFIGURE YOUR GPS RECEIVER TO USE THE NEW REFERENCE POSITION.

Click to see the current reference position

The City of Madison has implemented a GPS Community Base Station that provides real-time broadcast of correction data and correction data files for download over the internet. The base station is located at the City of Madison Traffic Engineering Field Operations Center on Sayle Street on the near south side of Madison.

Correction data files are available in the following formats and time slices:
Hourly files Daily files Time used in the correction files is based on UTC. Hourly files are generally available 5 minutes past the top of each hour. Daily files are generally available 5 minutes past midnight UTC (GMT). The hourly correction files are retained for 30 days and the daily correction files are retained for 180 days. After those time periods, the files are deleted from the web server. The files are not archived.
Check the current UTC time.
DAT DAT
RINEX and
Ephemeris		 RINEX and
Ephemeris

The correction data is currently being broadcast at 460.425 MHz in CMR+ and RTCM + RTK (version 2.2) formats, at 9,600 baud, from the City's communications tower at Larkin Park on the west side of Madison. The correction data is broadcast using a Trimble TrimMark 3 radio feeding a 100 watt booster amplifier. The effective signal strength from the transmitting antenna is somewhat less than 100 watts.

The City of Madison has established 10 high-order control points located throughout the city. These points are in the process of being "Blue Booked" by the NGS. The City has received tentative positions for these control points. Click here to view the latest information about these control points.

Users of Trimble's PathFinder Office can view PDF files containing instructions for using the correction data files from this base station for post-processing:
Click here to view a PDF file (104 KB) with instructions; or
Click here to view a PDF file (518 KB) with instructions and screen shots from the PathFinder Office Differential Correction Wizard.

These GPS correction files are provided as is, with no warranty, either expressed or implied. It is your responsibility to use these files properly. The City of Madison assumes no liability for the accuracy, or subsequent use, of these files. By downloading files you agree to these terms and conditions.

Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement or recommendation by the City of Madison.

General base station position information
Additional information regarding the establishment and verification of the base station position
Base station status announcements
GPS Control Points