DH9212 CORS reference, Petaluma, CA - U.S. Benchmarks on Waymarking.com

The National Geodetic Survey (NGS), an office of NOAA's National Ocean Service, coordinates two networks of continuously operating reference stations (CORS): the National CORS network and the Cooperative CORS network. Each CORS site provides Global Positioning System (GPS) carrier phase and code range measurements in support of 3-dimensional positioning activities throughout the United States and its territories (map).

Surveyors, GIS/LIS professionals, engineers, scientists, and others can apply CORS data to position points at which GPS data have been collected. The CORS system enables positioning accuracies that approach a few centimeters relative to the National Spatial Reference System, both horizontally and vertically.

This particular CORS site uses a U.S. Coast Guard DGPS reference station mast for its data. Coast Guard reference stations always have 2 reference antennas; one reference station recieverused to calculate DGPS correction data, and a second "integrity monitor" receiver used for error checking and to reduce multipath errors. The two antennas are located 1 meter apart, but each one is surveyed independantly and receives it's own PID.

The actual reference mark is the L1 phase element inside the antenna, and is covered with a weather cone so you can not see the physical marker.

This PID has been archived but the antenna mount remains. In the photo, DH9212 is the smaller antenna on the left and is normally connected to the reference station reciever; DH9211 is the larger antenna on the right and connects to the integrity monitor.

1. A closeup photo of the mark taken by you is required.
2. A 'distant' photo including the mark in the view is highly recommended. Include the compass direction you faced when you took the picture.