Fish Radio

GPS signal retained, for now

February 16, 2016

Differential GPS  Credit:

Differential GPS

This is Fish Radio. I’m Laine Welch – Plans to pull the plug on a popular GPS signal are put on hold. More after this —

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Plans to pull the plug on a GPS signal still counted on by many mariners have been put on hold, thanks to an outpouring of comments from sea goers, mostly from Alaska.  Claiming declining usage across the country, the federal government planned to shut down 62 Differential Global Positioning Systems, or DGPS last month 15, leaving 22 sites available to users in coastal areas.  Alaska has 15 DGPS sites; six were scheduled to close.

The DGPS came on line in 1999 to supplement satellite-based GPS. The augmented signal provided better accuracy using land-based reference stations to transmit correction messages over radio frequencies. Many believe it has outlived its usefulness.
What we’ve discovered is that the technology for GPS satellites and receivers has increased so much, the need to have so many signals really isn’t there anymore. A Federal Aviation Administration study in 2014 showed that GPS without the Differential antenna signal achieved accuracy of position of less than one meter, in most cases.

Petty Officer John Gallagher serves aboard the USCG Cutter Spar based in Kodiak.

Others argue that’s fine for open seas, but operating in harbors, fjords and other tight spots prevent a line of sight. Most of the nearly 170 comments to the Dept. of  Transportation argued in favor of keeping the back up system.

Wayne Carnes, for example, is captain of the Fairweather which travels at 36kts while carrying 250 passengers and 40 vehicles.  He said the  DGPS signal is needed  in the narrow waterways of Southeast Alaska, and that it is especially important during times of bad weather when standard piloting methods and RADAR become limited.

A Coast Guard memo this week said that, “all lights remain on” for DGPS sites in Kodiak, Cold Bay, Kenai, Potato Point, Gustavus, Biorka Island, Level Island and Annette Island. One site – Cape Hinchinbrook was lost due to an equipment failure. Given the range of comments received,  the Coast Guard said DGPS will get closer review.

Fish Radio is also brought to you by Ocean Beauty Seafoods – who salutes and says thanks to the men and women fishing across Alaska for their hard work and dedication. ( In Kodiak, I’m Laine Welch.