Received Wednesday, August 19, 2015


Per  Federal Register Notice, the Federal government has announced plans to shut down and decommission 62 National Differential GPS (NDGPS) sites on 15 January 2016. This Notice has a comment period that ends 16 November 2015.

The 62 stations listed for shutdown include Appleton, Washington (the very first operational NDGPS site: it was built in support of Positive Train Control), and also Seneca and Klamath Falls, Oregon. All three of these sites are also in the NGS CORS system, and it is possible that NGS could assume ownership of the sites; however, even if this occurs, NGS is not likely to continue the radio broadcast of real-time correctors from the sites. The NDGPS site at Ft. Stevens will remain in operation because it is a maritime site that will continue to be operated by the Coast Guard.

This real time differential service was used by mapping receivers in the early 90's and 2000's in those receivers that either had built-in Coast Guard Beacon receivers or external beacon receivers. This enabled users to receive corrections via ground-based stations resulting in sub-meter accuracy for those receivers that supported that level of accuracy. The advantage of this system is that the low-frequency correction signal would propagate over difficult terrain allowing the user to receive real time corrections where WAAS or other corrections were unavailable. Unfortunately, most manufacturers no longer produce a receiver like this due to the availability of WAAS and VRS correctors today. Most Federal and state agencies no longer use the NDGPS real-time correctors.

Ken Bays, Oregon DOT’s Lead Geodetic Surveyor, would like to see the Appleton, Seneca, and Klamath Falls sites continue as NGS National CORS.  Ken will talk with Giovanni Sella, head of the NGS CORS, about this issue.

Ken encourages interested parties to submit their comments to the US Department of Transportation per detailed instructions listed in the  Federal Register Notice. Those comments are due on or before 16 November 2015. 

Also, Ken is the State of Oregon’s designated representative on the Civil GPS Service Interface Committee, which is chartered to exchange information about GPS with the civil user community, respond to the needs of civil GPS users, and integrate GPS into civil sector applications.  Ken will be attending, through OGUG sponsorship,  the annual CGSIC meeting on 14-15 September 2015.  If you send a copy of the comments you have officially submitted via the official  Federal Register Notice procedures to Ken at  kenneth.bays@odot.state.or.us before 11 September 2015, he will take the comments from Oregon to the September CGSIC meeting.  Note: Do not merely send your comments to Ken without submitting your comments to USDOT via the official process.



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