NDGPS Heads Toward the Budget Chop Block

August 30, 2006  - By

Nationwide Differential GPS (NDGPS) heads toward the budget chop block. Its 2007 allocation has been scaled back to zero.  As in aught, nought, zot.

NDGPS, also referred to as the Coast Guard differential system, made its first NDGPS broadcast in the early-to-mid-90s. After years of industry talk about real-time DGPS, NDGPS was the first, mostly reliable source of real-time corrections that was free of charge (via your tax dollars).

Support from the mapping and non-aviation navigation markets pushed the government (the Department of Transportation took the lead) to continue the build-out of the NDGPS network. Each year, more sites were added, and NDGPS became a solid resource for folks wanting a free source of DGPS corrections that delivered meter-level accuracy. They just had to buy the hardware (beacon receiver and antenna) to use it. Today, more than ten years later, there are more than 80 broadcasting sites — and more planned — spread out over the continental United States, Alaska, and Hawaii, providing free DGPS coverage used by hundreds if not thousands of users on a daily basis.

A successful program?

Up to and including FY 2006, Congress and the President allocated a substantial annual budget for NDGPS improvements, operations, and maintenance. For example, the FY 2006 budget came to approximately $10 million — half of what was originally requested. Almost $100 million more is needed to complete the network build-out. After that, about $9.2 million is needed annually to operate and maintain the system.

However, unlike years past, this years budget (FY2007) for NDGPS improvements, operations and maintenance is………………….$0 (zero). The rumor mill says that since there’s no money to operate and maintain, some sites may actually be shut down. That’s not the case according to the Department of Transportation, however.

“The FY06 budget provides approximately $10 million for the NDGPS program.  These funds will be used to operate and maintain the existing NDGPS system through October 1, 2007”, says Steven Kulm, Director, Office of Pubic Affairs for the DOT’s Federal Railroad Administration.

So that means no money for new sites that were planned for FY 20007, and no money for developing new technologies such as High Accuracy (HA)-NDGPS.

Wow, what went wrong?

The problem facing NDGPS today, in my opinion, is the lack of a “killer app.” In other words it’s a neat tool and serves hundreds (if not thousands) of people on a daily basis, but if it disappeared tomorrow, life would go on. Therefore, when it comes to cutting the budget during tight times, programs like NDGPS are prime targets.

Now, I’m guessing the DOT may say that PTC (Positive Train Control) may be the killer app for NDGPS because it reportedly will save the railroad industry “billions” each year. That may be so, but if it was that easy to sell, then no one would be hacking away at the relatively puny NDGPS budget.

Putting the pressure on NDGPS is the Federal Aviation Administration’s (FAA) Wide Area Augmentation Service (WAAS) program. Like NDGPS, WAAS is a free government service providing corrections to improve accuracy and reliability of GPS positioning. The FAA began developing WAAS in the mid-90s and it was declared operational in July 2003.

WAAS has two things going for it that NDGPS doesn’t.

• A killer app. The future of aviation navigation is based squarely on GPS, and WAAS is an integral part of that program. The FAA is banking so heavily on GPS and has so many initiatives based on GPS, that there is no way it can back its way out of the program…and it shouldn’t. There are so many valuable uses for GPS in aviation that it boggles the mind. Some applications are focused on efficiency (e.g. better traffic control and throughput) and others are safety-of-life driven (e.g. situational awareness such as ADS-B). Because of this, the FY 2007 budget for WAAS is close to $100 million.

• WAAS is easy to use for non-aviation folks like us. It’s a no-brainer and it comes standard on every GPS receiver you purchase today. Whereas NDGPS requires the use of additional hardware (a 300khz receiver) and a separate antenna, no additional hardware or software is required to use WAAS. Using WAAS is virtually automatic. NDGPS receivers will never reach that level of simplicity. Good quality NDGPS antennas, by their nature, are bulky and I have serious doubts that any company will attempt to design an NDGPS receiver-on-a-chip (some have tried and failed), especially at this late stage of the game. With those two strikes, consumer GPS units will never incorporate NDGPS technology. And thus NDGPS will never achieve mass-market status like WAAS already has.


The foothold that NDGPS-supporters are hanging onto is the issue of the correction availability. Whereas WAAS is satellite-based and is dependent on line-of-sight between the user and the broadcast satellite, NDGPS broadcasts corrections on the 283-325khz band and does not require line-of-site between the user and the transmitter. It can even be received inside some buildings. However, signal propagation is interrupted by rough terrain and in metro areas, and ambient radio interference can interrupt the signal too. Although it’s not a true national service, there are certainly areas where the NDGPS can be received and WAAS can’t. The reverse can be stated also.


The NDGPS vs. WAAS debate in the surveying/mapping community has been a lively one this past year. This is due largely to major GPS manufacturers introducing professional mapping GPS receivers that use WAAS to achieve meter-level accuracy. Although NDGPS has the capability of being more accurate than WAAS, meter-level accuracy seems to be good enough for most mapping applications given the additional expense and equipment overhead required to use NDGPS. Think about it: Garmin discontinued their NDGPS receiver product line and now every GPS product they sell is WAAS-enabled.


Clearly, from a funding perspective WAAS has won the battle for now and has NDGPS back on its heels. The next twelve months (or less) will determine the direction of the NDGPS program.

“At this time, the U.S. Department of Transportation is deliberating how to administer the program in the future.  We anticipate the Administration’s proposed FY08 budget (to be released in early 2007) will provide guidance on what the future of NDGPS will be,” says Kulm.

The challenge for NDGPS-supporters in the next few months is to not let the purse-string holders forget about NDGPS and its niche applications. If it’s business-as-usual in FY 2007 and the purse-string holders don’t feel the pain, what are the odds they’ll throw money at NDGPS in FY 2008?

— Eric Gakstatter

This article is tagged with , and posted in Opinions, Survey

About the Author:

Eric Gakstatter has been involved in the GPS/GNSS industry for more than 20 years. For 10 years, he held several product management positions in the GPS/GNSS industry, managing the development of several medium- and high-precision GNSS products along with associated data-collection and post-processing software. Since 2000, he's been a power user of GPS/GNSS technology as well as consulted with capital management companies; federal, state and local government agencies; and private companies on the application and/or development of GPS technology. Since 2006, he's been a contributor to GPS World magazine, serving as editor of the monthly Survey Scene newsletter until 2015, and as editor of Geospatial Solutions monthly newsletter for GPS World's sister site Geospatial Solutions, which focuses on GIS and geospatial technologies.

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