Return to City Home

Community Base Station
Reference Station Files

 Site Details:
 Datum: WGS-84 Elevation Mask: 0 Trimble NetRS GPS receiver
 NGS Calculated Position
 NGS Coordinates
Logging Interval: 5 s
 City of Modesto
Coordinate System
Rollover period: 1 hour
Antenna ht: 0.000 m

Data collected with Trimble NetRS GPS receiver and Trimble Reference Station software


 Data Files:

DAT SSF(old) Rinex Almanac(old)

Note that the data files indexes are extremely large and may require several minutes to display over slow connections. 


 File Naming:

The directory structure is RefData.YY/Month.XXX/Day.DD where YY is that last two digits of the year, XXX is an abbreviation for the month and DD is the day of the month.

Each file is named using a format.  Where YY is the last 2 digits of the year, MM is the month, DD is the day of the month and HH is the start time of the data file in Pacific Time (24-hour format).

The file directory structure and the file naming format and time will change to the NGS standard at some future date.


 Data Storage:

Data Files are normally available online for 30 days, after which they will be deleted. Data is archived prior to deletion and is therefore recoverable. Users are encouraged to download data as soon as practicable. Archived data may be obtained by e-mail or through regular mail by contacting Curt Chappell at the e-mail address below.



If you have any comments please Email them to the Reference station administrator at


 Antenna Information:


View from the east
(click to enlarge)

View from the north-west
(click to enlarge)

View from the south-east
(click to enlarge)

NGS (National Geodetic Survey) Cooperative CORS (continuously operating reference station)

CMOD Site Information Form
Go to
Go to