“GPS has proven to be a boon to all the users”

I am particularly proud of the ION’s work with students. This is largely done through the Sections. Most of our Sections have a Student Activities Committee. For example, my own Section in Washington DC has a program of activities with a number of local high schools, in which Section members assist various science teachers develop field projects to engage students in using positioning, navigation, and timing related technologies. The ION loans equipment and reference materials, and Section members serve as mentors with the teachers conducting and assessing field work. Favorite projects are surveying the school’s athletic field with GPS and other equipment, and analyzing findings.

Other Sections, including Dayton Ohio and Rocky Mountain (Colorado Springs Colorado area), Alberta Canada, and Southern California, have programs to award undergraduate and graduate scholarships. Once awarded, although there are no strings attached, Section members frequently offer to mentor students in the study activities or onward research.

The ION Satellite Division has also created a number of lesson plans on positioning, navigation, and timing suitable for the junior high school (12- 14 year old) level. These are available on the ION’s website (www.ion.org).

The Dayton Section, supported by the ION’s Satellite Division and several local sponsors, also runs the annual Autonomous Lawnmower Competition. The course is challenging—a fixed plot of grass, with obstacles (in known and unknown locations), an upper time limit for completion, a maximum speed limit, and a required technical presentation on (among other things) system affordability. Once started, the lawnmower must work complete the course autonomously, without manual or remote intervention. There are penalties for “cutting outside the lines,” for failing to mow areas, for hitting obstacles, and for taking an optional restart. This year, I had the pleasure of watching five university teams compete, and the competition was heated. Ohio University’s team won. However, I was most inspired when I talked with the students from all the teams—they had been particularly innovative in their integration of technologies, from simple deadreckoning computing (based on compass and wheel revolution counters) to integration of carrier phase differential GPS with optical sensors and inertial measurement units.

You had been involved in the Maritime Differential GPS service for the US. Would you like to elaborate on this?

In my last tour of duty as an active duty officer of the United States Coast

Guard, I was the Commanding Officer of the Navigation Center. When I arrived there in 1996, the Maritime Differential GPS (DGPS) had just achieved initial operational capability (IOC). It was largely installed and operating, but it had not yet been certified, and it was experiencing a few equipment problems and maintenance difficulties. There were standards in place for service operations and receiver performance, and we had a number of users. Over the next several years, the Navigation Center helped focus a Coast Guard wide effort to update equipment, standardize the sites, and certify coverage and system performance to mandated standards. In March 1999, the Secretary of Transportation and Commandant of the Coast Guard, in a ceremony at the Navigation Center,

declared the Maritime DGPS fully operationally capable (FOC)–in other words ready for full use by mariners.

By the time of FOC for the US DGPS network, virtually all maritime nations of the world had installed their own similar service, operating to the same standards in their own critical ports and waterways. This made it possible for mariners to travel anywhere in the world, using GPS when in open water and taking advantage of the improved accuracy and integrity of the DGPS when entering virtually any port.

What about nationwide DGPS expansion programme?

The Nationwide DGPS (or NDGPS) expansion began with a test station in the Pacific Northwest, which began operating in 1997. The test station filled a gap in maritime coverage in the upper reaches of the Columbia River and also provided coverage for terrestrial user tests, dominantly railroad users. As a result of the tests, the Department of Transportation made a decision to move forward with the NDGPS. The Federal Railroad Administration sponsored the system, with additional sponsorship by the Federal Highway Administration, and the Coast Guard agreed to develop, operate, and maintain the service as reimbursed by the other agencies. The NDGPS would be operated to the same standards as, and in concert with, the maritime DGPS service.

Most of the NDGPS sites were developed economically using decommissioned United States Air Force GWEN stations. These sites were nearly perfect for broadcast of the DGPS correction signals, and the site infrastructure was ruggedly built. It was relatively simple to add reference station and integrity monitor receivers, and then modify the signal generators to update a GWEN site to NDGPS operations. The first few NDGPS sites were also declared operational in the March 1999 FOC ceremony for the maritime service.

DGPS and NDGPS are specified as 10-meter accuracy systems, but in reality most users experience closer to meter level accuracies. There is a new variant, called High Accuracy NDGPS, or HA-NDGPS. Employing long range carrier phase corrections, it appears possible to upgrade the installed DGPS and NDGPS infrastructure for decimeter level accuracies nationwide. I am hopeful to see these developments occur.

What is your focus area of the work in Institute of Defence Analysis?

I retired from active military service with the Coast Guard in June 1999, and about two weeks later I began a second career with the Institute for Defense Analyses (IDA). It is hard for me to believe that I have been with IDA for more than 7 years. At IDA, I am a member of the GPS Independent Review Team. I also participate in or lead various reviews and assessments of position-navigationtime (PNT) and other technologies for the Department of Defense and on occasion for other Federal agencies.

What trends you see in the field of navigation in terms of technological innovations?

Very clearly GPS/GNSS has put navigation literally “on the map” for many users worldwide. The major trends I see include: increases in efficiency and safety in traditional maritime and aviation navigation applications; new applications in automobiles and personal navigation; increased demands for global position and time information to support new, non-navigation but navigation-related, applications; miniaturization of user equipment; and new integrations of user equipment.

In the Coast Guard, I served as navigator aboard a Coast Guard Cutter early in my career, and even earlier, as a cadet at the Coast Guard Academy, I sailed aboard a 44-foot sailboat in several ocean races. I was then part of an elite group of mariners and aviators who could call themselves “navigators.” In those days, we used sextants, compass, fathometer, charts, and even though we had some radionavigation systems, such as radiobeacons and Loran-A, navigation was a tough-to-master, learned skill, which required constant practice to remain proficient. Later in my Coast Guard career, I was a circuit and system engineer working on the more modern Loran-C system, upgrading transmitter and receiver systems to improve performance and automate or remotely control operations. Still, the art and science of navigation remained the domain of the skilled professional.

Today those professionals have a new tool, more accurate than ever before, and more universally available—GPS. With the Wide Area Augmentation System (WAAS) and other spacebased augmentations, DGPS/NDGPS, new signals of GPS modernization, and companion elements of GNSS (Galileo, GLONASS, et al), not only do the navigation professionals have access to these services but so also everyone else. More and more people, with limited or no “navigation” training, are using the position and time information from this robust GNSS. For example, road maps have not quite disappeared from auto club shelves, but increasing numbers of drivers are relying on factory installed or after market GPS-based navigation systems.

So, with all that as background, what’s next? Users demand new services, market forces generate innovations to meet those user needs and expectations. Sometimes users are disappointed with their new GPSbased

services, for example when their automobile navigation system stops working in an urban canyon, tunnel, or parking garage. Some smart innovator then integrates the GPS unit with maps, odometer, and differential wheel counters to enable higher accuracy dead reckoning through the interruption in signal reception. I look for this type of integration within user equipment to continue.

Would you like to highlight some of the emerging application areas?

When people ask me this question, I like to turn it back on them … but with a bit of a hint. That is, how do you think having access to a globally consistent, precise and accurate, position and time grid will help you? Will, for example, having upto- the-minute traffic information, keyed to your current position and planned route, be helpful? Or, how about having your cell phone call ahead to your home to reset the furnace or air conditioner and make other preparations for your comfortable arrival?

On a more serious note, highways are getting more crowded, as are all modes of transportation. At the same time, there is a continuing demand to move goods and people faster and more directly from point to point, and while also improving the level of safety. Intelligent transportation system (ITS) technologies will help increase automation to improve efficiency in transportation, and I believe if done right, improve safety.

Any specific issue you would like to raise?

You have seen my comment above about the student activities of the ION.

When one of my sons graduated from high school (longer ago than I care to remember), I remember the graduation speaker’s theme—“if you can dream it, in your lifetime you will have the chance to achieve it.” That one line particularly resonated with me.

I knew then that some technologies I worked on enabled some dreams to become reality for my generation. I would like to see that same opportunity for future generations. To that end, I hope to see the ION and other professional organizations continue to have active student programs—to get young students interested in technology and what it can do to improve the quality of life … and to stimulate some of them to further their formal technology education to become the innovators of the future.

What is your perception about the Galileo initiative?

I believe that GPS provided a breakthrough capability—ubiquitous position and time information—that has led to major productivity and quality of life gains. Galileo will add robustness to the overall GNSS services, in that it will provide more satellites and thus improved geometry when users have a limited view of the sky. The key is that the services be interoperable, such that the sum is greater than the total of the parts.

Some the countries like India don’t want to depend on US GPS. Please comment.

It has been Presidential policy since the 1980s that GPS be provided free of direct user charges for peaceful global use. There is even a law enacted

by Congress to that effect. You are aware of the US-EU agreement on GPS and Galileo which also supports such a policy. In a democracy such as ours, I figure that is about as good a guarantee as one can get. Additionally, there are two formal user groups, those “professional navigators,” which help assure consistent global quality in GPS and all GNSS services. That is, the International Maritime Organization (IMO) and the International Civil Aviation Organization (ICAO) set rigorous standards for the operation and use of GPS/GNSS in maritime and aviation safety applications worldwide.

Those are the facts. But let me add a few thoughts. It is not an inexpensive venture to develop, deploy, operate, maintain, and sustain a GNSS constellation of satellites. Yet it is clear from the widespread acceptance of GPS that it has proven a boon to all who would use it. GPS is not alone in providing GNSS services. GLONASS remains in operation, and Galileo has launched its first test satellite. Thus, there are definite indications that GNSS will become more robust. In that light, your question might be considered in benefit vs. cost terms—can countries afford not to take advantage of those services offered by others?

Finally, it is clear that through their own DGPS or WAAS-like spacebased augmentation services, each country has the capability to establish the ultimate accuracy and assure the integrity of GPS and other GNSS for their own users. And, if a local or regional backup service were desired, there are several legacy radionavigation systems, such as Loran-C and modernized variants (e.g., “Enhanced Loran”), as well as mode-specific systems (e.g., VOR/DME), that would provide a measure of independence within critical infrastructures.

Jim Doherty retired from the U.S. Coast Guard at the rank of Captain in 1999; his last duty assignment was Commanding Officer of the Navigation Center. Under his leadership, the Maritime Differential GPS service achieved full operational capability,the Nationwide DGPS expansion was initiated, and the first phase of Loran recapitalization was begun. He also served as Deputy Chair of the Department of Transportation’s Civil GPS Service Interface Committee.

Jim is currently a Senior Analyst at the Institute for Defense Analyses, Science & Technology Division. Among his responsibilities, he serves on GPS Independent Review Team and the WAAS Independent Assessment Team. He has served on the Council of the Institute of Navigation and in various elected national offices of the ION since 1999. He was Chair of the Washington DC ION Section from 2000 until 2005. In June 2005, he became the Institute’s President, a position he will hold until January 2007.