As per our guidelines (section B.5.) we require that the GPS antenna has to be attached to your mast/monument in such a way that it can be oriented to true north, leveled and returned to the same position in 3-D space if it is replaced or exchanged. Additional details are given in the guidelines available at:
It is acceptable to manufacture your own device. However we strongly encourage you to check with us to ensure that your design is consistent with our guidelines and avoid any rejection of your site due to a non-compliant orienting and leveling adaptor.
Several commercial providers of such devices are listed below. If you know of others we would be very interested to learn about them.We have no preference as to the commercial providers used. Each of the leveling devices listed meet different needs which are user, site, and equipment specific.
They are listed based on approximate cost as of 2006. Please check with the providers for their current prices which may change at any time.
SCIGN Levelling and orienting device (Designed specifically for a choke ring antenna)
John K. McRaney
Southern California Earthquake Center
Zumberge Hall of Science 169
University of Southern California
3651 Trousdale Parkway
Los Angeles, CA 90089-0742
213-740-5842; 213-740-0011 (fax)
e.g. pictures http://pasadena.wr.usgs.gov/scign/group/dome/adaptor.html
small circular leveling device
e.g. pictures http://www.ngs.noaa.gov/CORS/SitePhotos/Required/mdsi/mdsi_ant_monu.jpg
Available from Morse Fabrication & Design 7578 Solley Rd, Glen Burnie, MD 21060
Contact: Brian Callahan 410-437-5534
You will need to specify if you want it mounted on a threaded cap (specify dimension) or a flat base to weld to your mast.
available from Seco
UNAVCO leveling device
e.g. pictures http://www.ngs.noaa.gov/CORS/SitePhotos/Required/nola/nola_ant_monu.jpg
small Circular leveling device
e.g. pictures http://www.ngs.noaa.gov/CORS/SitePhotos/Required/vikh/vikh_ant_monu.jpg
Both the UNAVCO and the small circular leveling devices are available from McRoberts Machine Shop, Boulder, Colorado.
303-776-2397 (Ask for Judy).
For the small circular leveling device you will need to specify if you want it mounted on a threaded cap (specify dimension) or a flat base to weld to your mast.
If you have further questions please email us and in the subject line put the 4-charcter siteId. If this has not yet been assigned, please enter city and state of the site.
Sincerely, CORS Site Selection Team
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Disclaimer - The National Geodetic Survey does not recommend any particular brand of Leveling/Orienting device. We do require that in the event of an antenna replacement that the Antenna Reference Point (ARP) is returned to the same EXACT 3-Dimensional position as the previous antenna's ARP.