GPS Vulnerable Says DOT The U.S. Department of Transportation (DOT) released the results of a study assessing the vulnerability of the national transportation infrastructure that relies on the Global Positioning System (GPS). The study notes that GPS is susceptible to unintentional disruption from such causes as atmospheric effects, signal blockage from buildings, and interference from communications equipment, as well as to potential deliberate disruption. It contains a number of recommendations to address the possibility of disruption and ensure the safety of the national transportation infrastructure. The report was mandated by a Presidential Decision Directive and prepared by the DOT Volpe National Transportation Systems Center. "This report provides a roadmap for addressing possible vulnerabilities in GPS so that we can continue maintaining the highest standards of transportation safety," said U.S. Transportation Secretary Norman Y. Mineta. "The Department of Transportation takes this report's findings very seriously, and we will be working to ensure that GPS will fulfill its potential as a key element of the nation's transportation infrastructure." Secretary Mineta charged the administrators of each DOT operating administration to thoroughly review this report and consider the adequacy of backup systems for each area of operation in which GPS is being used for critical transportation applications. The administrators are to report their findings back to the Secretary within 60 days.

IN THIS ISSUE CGSIC Report ION GPS 2001 2001 Kepler Award Winner: Dr. Elizabeth Cannon Departments: From the ION President: The ION Remains Strong Congressional Fellow Report: An Unusual Two Months Portney’s Corner: Lady Be Good From the ION Historian: The Shape of the Earth 2 GNSS Around the Globe: News in Brief, Section News, Launches, and more Calendar

DOT, in consultation with the Department of Defense (DOD), sponsored the study to assure the continued safe operation of the U.S. transportation system. All modes of transportation are increasingly reliant on GPS and, according to the study, GPS is susceptible to various forms of interference. This study identified transportation operations that employ GPS, methods for GPS disruption, possible impacts to transportation safety, and approaches to ensure service reliability. Among the report's recommendations:

• Create awareness among the aviation, maritime and surface user communities of the vulnerability of GPS and the need to reduce degradation or loss of the GPS signal.
• Implement systems to monitor, report and locate unintentional interference to GPS.
• Assess the applicability of military GPS anti-jamming technology and work with DOD and industry to make appropriate technologies available for civilian uses.
• Identify appropriate backup systems, integrity warning, or operational procedures for each safety-critical application.
• Encourage the development of low-cost systems as backups to GPS.
• Continue the ongoing GPS modernization program involving higher GPS broadcast power and the eventual availability of three civil frequencies.

In addition to the review of backup systems, the findings will initially be used by DOT's operating administrations to strengthen safety-critical areas that have an impact on aviation, maritime, railroads, and intelligent transportation systems. DOT will work with DOD to take appropriate steps to address GPS vulnerability in order to assure safe, secure transportation.

The DOT held a public meeting in early October to solicit views on the study. An additional public meeting will be scheduled by January to present the department's response to the study's recommendations.

The report, Vulnerability Assessment of the Transportation Infrastructure Relying on the Global Positioning System, may be obtained through the Coast Guard Navigation Center Web site at http://www.navcen.uscg.gov/.

GNSS Market Discussed

Reprinted from the Sept. 12 ION GPS 2001 Show Daily, as written by Scottie Barnes, Advanstar Communications

The marketplace for GPS and other Global Navigation Satellite System (GNSS) technologies, products, services, and applications highlighted a panel discussion at the opening session of The Institute of Navigation Satellite Division's 14th International Technical Meeting titled "GNSS Market Projections and Trends." The panel took place against the backdrop of stuttering economies worldwide and significant mergers and acquisitions within the GPS manufacturing and services community. Panel members included Mike Swiek, executive director of the U.S. GPS Industry Council; Professor Vidal Ashkenazi, CEO of Nottingham Scientific Ltd.; Lyn Dutton, business development manager, Thales UK (formerly Thomson-CSF); and John Shewfelt, with SiRF Technology. Dutton and Shewfelt were replacing Alain Bories, corporate vice president for space systems, the Thales Group, and Dr. Jackson Hu, CEO of SiRF Technology, both of whom had to cancel at the last minute due to the emergency closing of all U.S. airports. Glen Gibbons, editor of GPS World, introduced and moderated the discussion.

Despite the event's GPS-centric name, conference organizers couched the plenary panel and numerous technical sessions in GNSS terminology so as to embrace not only GPS and Russia's Glonass systems but also the proposed European satellite navigation system, Galileo. Gibbons introduced the subject by describing the difficulty of finding reliable and comparable GNSS market research, due to differences in study terms of reference and a "top-down" approach to the subject. He framed the issue of trends and projections in terms of "old" and "new" sectors within contemporary economies, illustrating their varying fortunes in terms of the performance of public stock markets.

For the GNSS marketplace, Gibbons said, "old economy" segments include such things as surveying, civil engineering, construction, air/land/sea transportation, mapping & geographic information systems, especially in natural resources, extractive industries, and utilities. "New economy" segments included are those associated with the dot.com community, built around Internet products and services, mobile computing, wireless communications, and portable devices.

Swiek continued the line of inquiry by raising the fundamental question of whether there is a GPS market in and of itself, or whether GPS plays a critical role in many other markets, and hence becomes difficult to measure as a distinct category of products and services. He reflected on some of the amazing and amusing applications that have emerged for GNSS, and underlined the need for coordination and cooperation with other technologies and markets such as wireless communications.

Following on with the discussion, Ashkenazi pointed out that, over the past 25 years, GPS has moved from a purely military satellite navigation system to "an indispensable positioning and timing tool," for hundreds of civilian scientific, engineering, navigation, and positioning applications. He said GPS is now poised to play a leading role in the emerging "info-mobility" society, by combining its location and timing information with mobile communications and information technology. The new emerging services will range widely, from emergency 911 and network synchronization, to M-commerce and mass-market location-based services (LBS).

"In this context, the addition of the Galileo system, which will be fully interoperable with GPS, will provide GNSS not only with an enhanced capability, but also help meet the tight requirements of certifiable safety-critical applications," Ashkenazi said. Recent estimates of potential users in both the specialist and professional markets, as well as in the much larger mass markets, justify the European investment in a second global satellite navigation system, which must be both compatible and interoperable with GPS, and yet independent of it, he continued.

Dutton, the other European panelist, also dwelled on the prospects for Galileo. Noting Thales' existing presence in the GPS marketplace through its acquisitions of Magellan, DSNP, Racal, and Wilcox GPS-related businesses, Dutton said, "Our largest future challenge is Galileo. We consider Galileo as a huge opportunity for industry to develop new applications and new services, because it will enhance performance and availability through the use of both constellations, GPS and Galileo - and hopefully Glonass if our Russian colleagues succeed in refurbishing the constellation." Dutton estimated that, in Europe alone, Galileo will boost the GNSS market to more than $60 billion between 2010 and 2020.

"Galileo will be a success if we, users, equipment manufacturers, and service providers are in the loop from the beginning, in order to have proper specifications and constraints taken into account in the design," Dutton said. He added that Galileo should be market-focused, user driven, and managed by organizations with proven track records and technological expertise.

In remarks prepared in advance, Dr. Jackson Hu described his company's focus on GPS technology and market development for high-volume consumer and commercial applications. "SiRF has a vision that one day GPS can be incorporated in every mobile device to bring us convenience, safety and security and to facilitate information access based on our locations," Hu said.

In the past five years, Hu said, the industry has made tremendous progress in reducing power consumption, cost structure, and the form factor for GPS receivers, thanks largely to the advances in silicon process technologies. However, silicon alone cannot solve all the problems, he continued. For example, location determination in obstructed environments for location-based services and E911 emergency response require the development of high-sensitivity receiving software. High-volume markets such as wireless handsets also require a new business model to address the stringent cost objectives, he noted, as well as new approaches in addressing product development, quality, and customer support.

From the ION President: The ION Remains Strong Ronald R. Hatch

Sept. 11 was a day of national tragedy. We are praying for those who suffered the loss of loved ones and for those who suffered severe financial loss. Yet there are things to be thankful for even in events like these. It is encouraging to see how many are ready to step in and help in any way they can. It is encouraging also to see the outpouring of patriotism and signs of spiritual renewal. America remains strong.

The grounding of all aircraft on the openning of ION GPS 2001 left many without any means of attending the conference. Others made Herculean efforts to be there. Thank you. Those who arrived early to set up exhibits or to attend tutorials or the CGSIC meeting were, in effect, stranded in Salt Lake. This was one of the primary reasons we decided the conference should proceed as planned.

In spite of it all, it was a good conference. There were some 1,100 participants and exhibitors who attended. Most of the scheduled papers were presented - sometimes by an associate author who had not planned on making the presentation. Many of the remaining slots were filled by others who volunteered to present material on short notice. Larry Hothem, the general chair, and Gerard Lachapelle, the program chair, together with the track chairs, did an outstanding job of revising and adjusting the presentation schedule in real time. Thanks also to the ION staff, who preformed beyond the normal call of duty. The ION remains strong.

Dr. Elizabeth Cannon was the recipient of this year's Kepler award. Congratulations Dr. Cannon. Dr. Clark Cohen was selected as the ION's new Congressional Fellow. He has completed the AAAS Fellow orientation program and now serves on the staff or Sen. Carl Levin of Michigan. Congratulations Dr. Cohen.

The deadline is nearing (Dec. 14) to submit nominations for the 2002 ION Fellows and for the ION Annual Awards (Feb. 20). Please take the time to submit nominations for those you feel are worthy of these awards.

Finally, plan on attending the ION National Technical Meeting, which will be held in San Diego, Jan. 28Ð30. It should be a strong program and a chance to meet with some of those you missed at the Satellite Division meeting.

Regards,

Annual Award Nominations Requested   Members are encouraged to submit nominations for one or more of the following annual awards given by the ION for excellence in navigation. Superior Achievement Award—for individuals making outstanding contributions to the advancement of navigation. Captain P.V.H. Weems Award—for continuing contributions to the art and science of navigation. Norman P. Hays Award—for outstanding encouragement, inspiration and support leading to the advancement of navigation. Thomas L. Thurlow Award—for outstanding contributions to the science of navigation. Tycho Brahe Award—for outstanding achievement in space navigation. Early Achievement Award—for an individual early in his or her career who has made an outstanding achievement in the art and science of navigation. Official nomination forms, along with brochures on the background and purpose of each award, are available from the ION National Office by phone, 703-683-7101, or at www.ion.org. Nominations must be received by February 20, 2002. The awards and accompanying engraved bronze plaques will be presented at the ION’s 58th Annual Meeting, June 23–26, 2002, in Albuquerque, New Mexico. The ION urges you to participate in the nomination process so that a representative group of deserving individuals from the navigation community will receive appropriate recognition. In addition to the above awards, the winner of the Samuel M. Burka Award - for outstanding achievement in the preparation of papers advancing navigation and space guidance — chosen by the editorial panel of the ION’s journal, NAVIGATION, will be honored.

The Purpose of The ION The Institute of Navigation, founded in 1945, is a non-profit professional society dedicated to the advancement of the art and science of navigation. It serves a diverse community including those interested in air, space, marine, land navigation and position determination. Although basically a national organization, its membership is worldwide, and it is affiliated with the International Association of the Institutes of Navigation. 2000-01 National Executive Committee President: Mr. Ron Hatch Executive Vice President: Dr. Rudy Kalafus Treasurer: Mr. Larry Hothem Eastern Region Vice President: Ms. Sally Frodge Central Region Vice President: Maj. John Raquet Western Region Vice President: Dr. A.J. Van Dierendonck Immediate Past President: Ms. Karen Van Dyke How to Reach The ION Telephone: 703-683-7101 Facsimile: 703-683-7105 Web site: http://www.ion.org E-mail: membership@ion.org ION National Office Staff Director of Operations: Lisa Beaty Technical Director: Carl Andren Office Manager: Jennifer Murphy-Smith Assistant to the Technical Director: Miriam Lewis Meeting Services/Author Liaison: Connie Mayes Member Services/Registrar: Wendy Hickman Graphic Design/Editor: Paula Danko Information Manager: Rick Buongiovanni

From the ION Congressional Fellow: The War Room Phil Ward

I find myself in awe of the extreme events taking place around me in the past two months. This is a time of great tragedy and trial for our country, but also a time of renewed national strength and unification. I was running later than usual for work on Tuesday because of the Oklahoma Bankers Reception Nancy and I attended the night before. Besides, we were in the middle of mark-up on the Defense Authorization Bill and my part of that activity was already done.

Watching in Disbelief
As did millions of Americans, I watched and listened as the attacks on the World Trade Center unfolded. I was thinking that Sen. Inhofe would want to know what was going on, so I had better get as many facts as I could before I left. I dashed out the door heading for the office. Shortly after I entered the building, but before I actually reached the War Room, I was told that we had been instructed to vacate the building and return home. The Pentagon had been hit at 9:43 a.m. by another hijacked commercial jet. I could see the smoke and hear the sirens.

I walked to the Union Station Metro with two other staff members from Sen. Inhofe's office. On the Metro, I was struck by the contrast with the normal impersonal atmosphere on the train. Everyone was freely sharing the news (and rumors) that each had heard. When I changed trains at Gallery Place, the terminal was packed because most of the federal buildings had dismissed their staff, but people were far more courteous and controlled than usual.

I was back at work the next day. The change in the political atmosphere on the Hill was immediate and positive. It has been magnificent to see how well Congress can operate if there is a force greater than partisan interests to unify it!

The Anthrax Factor
As we all know, on Oct. 15, an envelope containing anthrax was sent to Sen. Daschle and opened by a staffer in the Hart Senate Office Building. As the science fellow, I was asked that day to attend a 5:30 p.m. briefing by the Capitol security and medical staff. After the briefing, I returned to my office and sent a detailed report to our chief of staff, Glenn Powell, and our office administrator, Kim Powell. The following morning, Kim asked me to send it to all of the staff, including the Oklahoma staff.

The Association of Old Crows and GPS
In the meantime, I have been working with a fellow Institute of Navigation member and good friend, Dr. Terry McGurn, to get an audience with Rep. Joe Pitts (R-Penn.), chair of the Electronic Warfare (EW) Caucus in the House. Terry prepared an excellent white paper on the growing jamming threat to military use of GPS and the need for more Navwar funding to measure, locate and mitigate this threat. Terry convinced the Old Crows Association (the EW professional organization) to include GPS jamming countermeasures under its interest umbrella. Now we are setting our sights on convincing Congressman Pitts to do the same in his caucus. We have had two productive meetings with Pitts' Military Legislative Assistant (MLA), Ken Miller, who agreed that his member would be interested in this subject. A meeting scheduled for Oct. 17 was cancelled when all the congressional offices were closed to test for anthrax contamination. Our office was closed for five days from, Oct. 18-22.

War Briefings
We brief Sen. Inhofe regularly on the war. I have attended meetings with Aaron Amin, the D.C. representative of the Afghanistan Northern Alliance (the closest thing to an Ambassador from friendly forces in Afghanistan), and with Daoud Yaqub, executive director of the Afghanistan America Foundation, who works in the office of former King Zahir Shah. I prepared a letter signed by the Sen. Inhofe on behalf of Dr. Ahmed Nuristani to the Immigration and Naturalization Service to expedite the renewal of his U.S. Refugee Travel Document. Dr. Nuristani is an Afghan refugee residing in the United States who is with King Zahir Shah to reconstruct a broad-based representative government to succeed the Taliban.

Appreciated for a Job Well Done
On Oct. 25, the SASC hearing was to receive testimony on the role of the Department of Defense in homeland security. Witnesses included Secretary of the Army and Interim Executive Agent for Homeland Security Thomas White; Gen. Peter Pace, USMC, Vice Chairman of the Joint Chiefs of Staff; Gen. William F. Kernan, USA, Commander in Chief, U.S. Joint Forces Command; and Gen. Ralph Eberhart, USAF, Commander in Chief U.S. Space Command/North American Aerospace Defense Command. After USAF Maj. Dave Teal, the military congressional fellow, and I had finished briefing the senator before the hearing started, we stood up to escort the senator to the hearing room. Sen. Inhofe beat us to his office door and opened it for us. I stood frozen for a few eternal seconds looking first at the open doorway and second at the senator. Dave said instinctively, "Go ahead, Phil." As I walked through I said, "I'm not used to having a senator open the door for me!" Sen. Inhofe put his arm around me, gave me a big hug and laughed.

I feel very much appreciated by him. The senator used most of my questions during the hearing. You know you did well when your member uses your questions.

From the ION Congressional Fellow: An Introductory Report Clark Cohen

For better or for worse, there may not soon be a more eventful time to move to Washington, D.C., where a new definition of "business as usual" has cropped up. Sept. 11 struck halfway through our two-week fellowship orientation. One slight interruption to my placement process occurred when, a few minutes before, I unknowingly (twice) walked through what had just become the "anthrax hot zone" of the Hart Senate Office Building. So now I have the distinct privilege of joining the ranks of those lucky senators and staff now on the CDC 60-day regimen of government-issue antibiotics.

I am pleased to report that I have accepted an offer with the office of Sen. Carl Levin (D-Mich.) and have spent about two weeks on the job so far as of this writing (Nov. 12, 2001)Ñacquiring my sea legs on some current issues in the automotive industry. Sen. Levin is chairman of the Armed Services Committee and the Permanent Subcommittee on Investigations (Governmental Affairs Committee). He also serves on the Small Business and Select Intelligence Committees. I look forward to a challenging and exciting time ahead, and I appreciate the sponsorship of the ION for making this fellowship possible.

CGSIC Report

Reprinted in part from the Sept. 14, issue of the ION GPS 2001 Show Daily, as written by Scottie Barnes, Advanstar Communications.

One of the activities that brought several hundred people to Salt Lake City ahead of the air traffic shutdown was the regular meeting of the Civil GPS Service Interface Committee (CGSIC), which met Sept. 9-11.

The group, coordinated by the U.S. Department of Transportation's (DoT's) office for transportation policy and the U.S. Coast Guard's Navigation Center, offered a forum for airing a wide range of progress reports and issues.

Among these are plans to separate the biannual Federal Radionavigation Plan (FRP) into two activities and documents: An FRP that would update U.S. radionavigation policies every two years and a Federal Radionavigation Systems report on available services that would probably take place less often, according to DoT staff member Heywood Shirer. The matter of whether to phase out Loran-C is still being evaluated, Shirer said, as is the schedule for phasing out ground-based landing systems that had been expected to be rendered unnecessary by GPS.

WAAS Update
Mitch Narins of the Federal Aviation Administration's Navigation Integrated Product Team reported on his agency's revised expectation for initial operational capability of the GPS Wide Area Augmentation System (WAAS) in December 2003. That new target date for a system original planned for completion in 1997 is based in part on a report and recommendations earlier this year from a WAAS Independent Review Board (IRB).

WAAS will comprise a ground- and space-based infrastructure including reference and integrity monitoring stations and geostationary satellites that will provide improved accuracy (through differential corrections), additional ranging signals, and integrity reports alerting users to "unhealthy" satellite signals. The current system design calls for one "bent-pipe" signal generated on the ground and rebroadcast from the satellite and four satellites with full navigation signal packages.

Narins also said that phase out of ground aids for aircraft approach and landings is now expected to begin in 2010, noting that a ground presence of navigation aids would always exist. Indeed, the concept of GPS as a "sole-means" navigation system that would require aircraft to carry only a single nav system has disappeared from the FAA and FRP vocabulary, replaced by GPS as a "primary" navigation system.

A State Department report on international activities revealed that the United States and the European Union (EU) appear to still be talking past - rather than to - each other on matters of cooperation on global navigation satellite operations. Agency staff member Nate Johnson noted that the EU response in May to a draft agreement proposed by the United States last year had "omitted many key provisions" of the U.S. proposal. Johnson declined to provide any details of either the U.S. or EU positions, but past reports have indicated a U.S. focus on general policy matters while European interest lies in discussing more technical details of achieving compatibility and interoperability between GPS and the proposed Galileo system. The European Council of Transport Ministers is expected to give a go-ahead in December for the development and validation phase of Galileo.

A panel session reviewed the July 28, 2001 incident involving a failed clock in GPS satellite PRN 22, which produced large positioning errors in many GPS receivers before the U.S. Air Force's GPS operators set the satellite as unhealthy (eliminating its use by user equipment) about two hours later. Within minutes of the failure, WAAS testbed monitoring stations had noted the erroneous satellite transmissions, followed by U.S. Coast Guard monitoring station staff, who contacted the GPS Master Control Station (MCS) at Shriever Air Force base. Because PRN 22 was at a low-elevation angle to the MCS, USAF personnel were not able to confirm the reported failure for some time before deciding to take the satellite off-line.

Another panel discussion explored the potential interference to GPS and other radio system by possible unlicensed use of ultrawideband technology.

CGSIC Timing Update
In the CGSIC Timing Subcommittee meeting, Ken Senior from the U.S. Naval Observatory reported on an investigation into use of the International GPS Service (IGS) network of continuous GPS monitoring stations to produce a global, high-accuracy, time-scale reference that might augment or replace the timing source for GPS. The States and Localities Subcommittee heard about plans by the U.S. Coast Guard to demonstrate a high-accuracy differential capability providing centimeter real-time positioning in the Nationwide Differential Global Positioning System (NDGPS) coverage area. The service would provide pseudorange and carrier phase corrections in a compact format broadcast every second. A one-year test of the system using NDGPS sites in Maryland and Pennsylvania is scheduled to begin in November.

The Satellite Division Perseveres

A Truly Determined Group

In the midst of the grief that surrounded the tragedy of Sept. 11, the Satellite Division vowed to carry on; and considering the circumstances, the ION GPS meeting was remarkably successful.

By the afternoon of Sept. 11, the meeting's organizers calculated that a minimum of 500 people had already arrived in Salt Lake City for the Navtech tutorials, CGSIC meeting, related government meetings, exhibit set-up, and to recover from the jet lag.

Furthermore, the ION's members are a resilient and determined bunch. Many took extreme measures to arrive at ION GPS 2001 to showcase their wares, present their papers, and participate in the world's largest GNSS event. The ION received numerous calls from authors stranded in airports all around the world, informing us that as soon as the airlines took to the skies, they would be there! Grounded participants took to the streets, some driving in excess of 15 hours to arrive in Salt Lake City. Alison Brown, Charles Fay, and other NAVSYS team members drove straight through the night from Colorado Springs. Another group arrived by car caravan from Silicon Valley.

Because of the dogged determination of the conference chairs, speakers, and participants, the first day of the technical program remained 80 percent intact. Of course program adjustments were made each day to accommodate late arriving speakers. Volunteers rallied to present additional technical presentations. (It is amazing how many technical papers travel on laptops!) Papers that were not presented due to the curtailment of air travel will be included in the meeting's proceedings together with the papers that were presented but were not part of the scheduled technical program.

Despite the challenges, six full parallel tracks were presented on Wednesday and Thursday, and five on Friday. Eighty-eight of the originally scheduled ninety-six exhibiting companies were also represented.

By the end of the conference, 1,098 people had arrived. While this was approximately 50 percent of the prior year's attendance and only 45 percent of the 2,400 people we expected to attend, the number of people who arrived amidst many obstacles is truly remarkable. The Institute thanks you for your perseverance and looks forward to setting a new attendance record at ION GPS 2002, Sept. 24-27 in Portland, Oregon!

For more details about ION GPS 2001, read the conference newsletter, the Show Daily, available on ION's Web site at www.ion.org.

Kepler Award Winner

2001 Recipient: Dr. M. Elizabeth Cannon

For Sustained and Significant Contributions to the Development of Satellite Navigation

This year's Kepler award winner, Dr. Elizabeth Cannon, earned her B.S. in mathematics and computer science from Acadia University in 1982 and in 1984 went on to earn a B.S in surveying engineering from the University of Calgary in 1984. After graduating, Dr. Cannon took a job at Nortech Surveys and became responsible for the development of precise static differential GPS methodology and softwareÑbreaking ground in a field that was relatively new at the time. She earned her M.S. in surveying engineering in 1987 and was the first winner of the ION student paper competition at ION GPS 1988.

From 1988-1991, Dr. Cannon conducted extensive research in GPS/INS integration for precise airborne positioning and semi-kinematic differential GPS positioning techniques, earning her Ph.D. in surveying engineering and becoming a recognized leader in both areas. She remained at the University of Calgary as an assistant professor, rising to full professor within a few years.

During the past 10 years, Dr. Cannon has been a leader in many GPS-related research areas, including attitude determination using GPS, multipath parameter estimation, precision farming based on GPS and GIS, precise positioning using GPS carrier-phase integer ambiguity resolution, multiple reference station RTK positioning, precision aircraft-to-aircraft positioning, receiver performance characterization under high dynamics, and GPS augmentation with other sensors.

She has raised approximately $4 million dollars to support her research programs, published 64 journal articles and over 100 conference papers. She has developed five different GPS-related software products that have been licensed to over 140 organizations in 18 countries and she has lectured extensively in Europe and North America.

From 1996-1997, Dr. Cannon served as president of the U.S. Institute of Navigation. She was a member of the editorial board of both the Journal of Geodesy and GPS Solutions, a trustee of the Alberta Heritage Foundation for Science and Engineering Research and served on the boards of other professional societies. She has received numerous different awards, including 8 best-paper awards at ION GPS conferences, Canada's Top Forty Under Forty award, many awards recognizing her outstanding teaching abilities and other awards for her work. She is also a fellow of the Canadian Academy of Engineering.

Dr. Cannon is actively engaged in the community, giving hundreds of presentations on GPS to students and teachers, as well as to community, professional, and government groups. She has presented her GPS research on Parliament Hill in Ottawa to members of parliament, senators, and government personnel. She holds the NSERC/Petro-Canada chair for Women in Science and Engineering, which is aimed at increasing the representation of women in science and engineering.

ION GPS 2001 Best Presentation Awards

A tradition at the GPS meeting is to recognize the best paper prepresentation given in each session. Recipients are selected by the session's co-chairs. The criteria used to evaluate each presentation is as follows: 70 percent: relevance, timeliness and originality of technical work/information; 20 percent: quality of visual aids (legibility, relevance to topic, etc.); and 10 percent, quality of presentaion delivery (enthusiasm, enjoyment as a speaker, etc.)

A list of recipients of this year's Best Presentation Awards can be found on the ION Website at http://www.ion.org/meetings/past/gps2001bpa.cfm.

Portney's Corner: Lady Be Good Courtesy of Litton Guidance and Control

The Lady Be Good (LBG), a WWII B-24 bomber of the USAAF 376th Bomber Group, is about to experience its first and last combat mission - a daylight bombing raid of Naples harbor. The delayed takeoff and insufficient winds force the LBG to arrive at the target area after sunset. The LBG returns homeward in the dark, chased by a stronger tailwind than predicted and cloud layers below interfering with pilotage. Relying solely on dead reckoning (DR), Lt. Hays, navigator, does not realize that the LBG already crossed the Mediterranean and passed over its home base at Soluch, Libya. Lt. Hatton, pilot, makes an emergency request (breaking radio silence) for an inbound bearing from Benina Tower's high frequency direction finding (HF/DF) equipment serving Benghazi 30 miles north of Soluch. The equipment could only detect a bearing and its reciprocal and not its sense. The tower reports that the LBG is on an inbound magnetic bearing of 330°. This reciprocal bearing, accepted by the LBG, will etch this event in aviation history and reinforce the belief by Hays and Hatton that they are still over the Mediterranean. This meant that the LBG's inbound bearing of 330° from Benina Tower could just as well have been an outbound bearing of 150° from Benina Tower. The LBG continued on its perilous journey. The crew bailed out as the LBG began to lose engines from fuel starvation. How could the navigator resolve this ambiguity of the radial bearing (at the expense of extending the break in silence) and prevent this tragedy (Figure 1)?

Crew members of the Lady Be Good: 1st Lt. William J. Hatton, pilot; 2nd Lt. Robert F. Toner, copilot; 2nd Lt. Dp Hays, navigator; 2nd Lt. John S. Woravka, bombardier; Tech. Sgt. Harold J. Ripslinger, flight engineer; Tech. Sgt. Robert E. LaMotte, radio operator; Staff Sgt. Guy E. Shelly, gunner/ assistant flight engineer; Staff Sgt. Vernon L. Moore, gunner/ assistant radio operator; Staff Sgt. Samuel R. Adams, gunner. Navigation was achieved by dead reckoning (using elapsed time and distance between fixes to determine speed and with known heading and deduced winds projecting position), pilotage (using visible landmarks), radio and celestial. Celestial was used solely for ferrying to the theater. Limited outward visibility in the B-24 hampered dead reckoning and pilotage. Navigators were trained in 15-to-20 weeks at that time.

The navigator would know Benina Tower was:

A. South if the LBG turned right and the reported bearing lines increased in value
B. North if the LBG orbited clockwise and the reported bearing lines would initially decrease in value
C. North if the LBG turned left and the reported bearing lines decreased in value
D. North if the LBG orbited counterclockwise and the reported bearing lines would initially increase in value

Figure 2 shows the Benina Tower HF/DF radial pattern and illustrates how the ambiguity of the bearing is resolved.

If the LBG were north of Benina Tower based on its DR position and 330° inbound bearing given by Benina Tower, it could turn right and note that the reported bearings decreased in value thus resolving the ambiguity and showing that the B-24 was actually north of the Benina Tower. However, the opposite would be true since the LBG was south of Benina Tower and such a maneuver would result in increasing reported bearings.

The LBG was flying on a magnetic heading of approximately 150°. When Benina Tower provided the LBG with an inbound magnetic bearing of 330°, the B-24 was already south of the tower. The navigator was lost (we shall find) and simply accepted the reported inbound bearing believing that the B-24 was still north of Benina Tower. Since the bearing line had two possible values 180° apart, the navigator had to judge which side of the radio direction finding (RDF) station he was on (inbound or outbound) based on his DR position. The erroneous interpretation of the reported bearing is often referred to as obtaining the reciprocal direction from the backside of the station since 150° (330° - 180°) was valid for the outbound bearing from Benina Tower and would place the Lady Be Good south of Benina Tower. Tragically the Lady Be Good continued on for 1 hour and 48 minutes before the crew bailed out at 2 a.m., 5 April 1943. The LBG crashed 25 nmi south of the bailout point. The LBG was the only aircraft that failed to return from the bombing mission - lost on its first combat mission.

Fifteen years later in 1958 during an aerial survey, the Lady Be Good became an archeological find when a British oil exploration team spotted its crash site 351 nmi southeast of Soluch Air Base. This led to follow-up investigations by American teams that pieced together the saga of the Lady Be Good which was believed to have fallen into the Mediterranean. The reconstruction of the events of the mission also revealed that the LBG was heard over Soluch Air Base shortly before midnight 4 April 1943. The investigation revealed that the crew of the LBG made an extraordinary and valiant effort to survive under impossible odds. The essential instruments for navigation on the crashed LBG: magnetic compass, automatic direction finder (ADF) and long range radios were all found to be functional after more than fifteen years.

Postscript
The navigator's log recovered at the crash site of the Lady Be Good is now part of an exhibit at the Air Museum at Wright Patterson Air Force Base, Ohio. The exhibit reveals that the navigator failed to make any entries on the inbound leg indicating that he was lost.

From the ION Historian The Shape of the Earth: Part 2

In Part I, we observed that by the beginning of the 16th century, most of literate mankind recognized that the shape of the earth was close to spherical. The journeys of Columbus and Magellan and the transition from the Dark Ages to the Renaissance, opened up a new era which saw the world's greatest minds applied to the refinement of the knowledge of the shape of the earth.

In the latter half of the 17th century it was observed that pendulum clocks require adjustment of their pendulum lengths when the clocks are moved from one latitude to another. Sir Isaac Newton (1687) showed that variations in gravity indicated by the pendulum observations made at different latitudes can be explained by allowing for the equatorial bulge produced by the earth's rotation. He deduced that the earth has the shape of an oblate spheroid, with a radius about 17 miles greater at the equator than at the poles. He estimated flattening of the earth of 1/230. Flattening is the ratio of the difference between the major (equatorial) and minor (polar) axes of an ellipse to the major axis.

In 1693, the Dutch mathematician, astronomer, and physicist, Huygens, developed the principle that the sea surface everywhere is perpendicular to the plumb line. Using accounts of pendulum experiments at different locations, he deduced a ratio of polar to equatorial axes of 577/578 and obtained an equation approximating the earth's surface. He calculated that the centrifugal force at the equator is 1/289 that of the mass attraction, and therefore that the plumb line at Paris deviates about 6 arc minutes from the direction in a nonrotationg earth.

An arc of meridian was first measured by Picard in France in 1669. The Italian Cassini, who became the director of the Paris Observatory, where he was the first to observe Saturn's 4 moons, discovered the gap in the ring system of Saturn, and developed the theory of Cassinian curves, also made measurements of meridian arcs in 1712. On the basis of these measurements, Cassini and his son, concluded that the shape of the earth is a prolate spheroid (Figure above), not the oblate spheroid previously deduced by Newton and Huygens. This resulted in an international controversy that stimulated the Paris Academy to undertake an expedition to resolve the issue of whether the earth's shape was an oblate or prolate spheroid. The fact that the determination of the earth's ellipticity was a challenging issue during this time can be appreciated by noting that if the earth is represented by a globe with an equatorial diameter of 12 inches, the polar diameter would be about 11.96 inches, or only 0.04 inches less.

The Paris Academy Expedition
In 1735, Pierre de Maupertius, who earlier introduced Newton's theory of gravitation to France, showed that the axes of an earth ellipsoid of revolution can be calculated from lengths of a degree of latitude obtained by meridian-arc measurements. Based on this formulation, the Paris Academy sent an expedition to Peru in 1735 to measure a length of arc at a low latitude, and shortly thereafter sent another expedition to Lapland to make similar measurements at a high latitude. These expeditions, under the direction of DeMaupertius and with renowned geodesists as Bouguer and Clairaut as participants, demonstrated conclusively that the Newton-Huygens deductions were correct. Clairaut had been conducting studies on the theory of fluid equilibrium and in 1743 derived the relation between the variation of gravity from equator to poles, and the flattening of the ellipsoid. He observed that the advantage of determining the flattening from the gravitational field, as opposed from direct meridian arc measurements, is that the best mean value for the earth is obtained.

 

Estimating The Earth's Flattening Many renowned mathematicians made theoretical contribution to the knowledge of the shape of the earth. Euler (1736), the most prolific writer in mathematics, developed the theory of rotation of solid bodies, including ellipsoids or revolution and triaxial ellipsoids. MacLaurin (1742) investigated attractions on ellipsoids of revolution, giving exact values of the attractions at the poles and equator. D'Alembert investigated the problem of equilibrium of a fluid on a nearly spherical ellipsoid, obtaining formulas for the attraction at any point on the ellipsoid. Laplace, beginning in 1776, introduced the theory of gravitational potential and his book Theorie du Movement et de la Figure Elliptique des Planets (1784) was a major contribution to the theory of attraction of ellipsoids at both internal and external points. Legendre (1785) developed the gravitational potential in the form of a spherical harmonic expansion and he showed that forces can be expressed as the gradient of this potential. He also calculated the flattening of the earth, obtaining a value of 1/318. Numerous scientists have estimated the earth's flattening ( see Table) since Newton's first approximation. Bessel in 1841 and Clarke in 1866 provided ellipsoids that were used extensively in navigation. Helmert (1901) using astro-geodetic measurements determined a value that is almost identical to that now accepted, albeit with sparse data. Hayford (1909) obtained a flattening of 1/297 which was officially adopted by the International Geodetic Association in 1924 and was used until improved flattenings were determined from analysis of the orbital paths of artificial satellites.

Gravitational equipotential pertubations about the reference ellipsoid, referred to as geoidal undulations, further define the shape of the earth and were studied by Stokes (1849) using observed gravity anomalies. These investigations led to the famous Stokes' theorem, which enables calculation of the geoid from worldwide gravity anomaly measurements. Numerous geodesists, notably Hayford and Bowie (1912), Heiskanen (1924, 1938), Vening Meinesz (1929, 1941), and Uotila (1960) have subsequently used Stokes' theorem with available gravity anomaly measurements to compute the shape of the geoid. It has only been in the last three decades, with the dissemination of worldwide at-sea gravity anomaly measurements and the development of precise satellite altimeters to directly measure sea surface height, that the shape of the earth has been refined down to geoidal undulation wavelengths of about 60 nautical miles with a precision of less than 0.1 meter. (See, for example, May, M.B., "The G Connection: Gravity and GPS," GPS World, September 1996, for further information on satellite utilization in the determination of the shape of the earth).

One last lesson in history and mankind: there appear to be no concepts, no matter how apparently incontrovertible, that are universally accepted. Witness the existence of the International Flat Earth Society (See Figure), Box 2533, Lancaster, CA 93534.

ALBERTA SECTION
On Sept. 27, the Alberta Section heard a presentation by Chris Carver and Cameron Baird on CSI WirelessÑNow and Beyond CSI Wireless is a Calgary-based leading international designer, manufacturer and marketer of DGPS and wireless technology products. The presentation focused on two of the technology sector's fastest-growing industriesÑwireless and GPSÑand on how CSI Wireless has been integrating them to create new products and pursue new markets

DAYTON SECTION
The Dayton Section restarted its monthly luncheon series in September following a summer break. Two luncheons have been held so far in the series with speakers discussing the use of GPS for ejection seat testing, and the history of navigation. In November, the section will tour the Avionics Engineering Center at Ohio University for its monthly meeting. In September, the Dayton Section got approval to serve as one of two test sites for a new Navigation Apprenticeship program. The program will award a $2,500 college scholarship to a high school junior or senior interested in studying in a navigation-related field. In addition, the recipient will participate in an approximately three-week long apprenticeship at a local navigation company. The first apprenticeship will be award in spring 2002. More information will be available soon on the Dayton Section portion of the ION Web site.

ROCKY MOUNTAIN SECTION
On Oct. 20, the Rocky Mountain Section (RMS) supported the Boy Scout Jamboree on the Air (JOTA), held in Calhan, Colorado. The JOTA is a scouting jamboree focused upon the use of radio. It included a high-altitude balloon launch, carrying GPS, which broadcasts its position back to base. At the JOTA, the RMS gave a computer presentation to a number of scout groups explaining how GPS works, its capabilities and limitations, and many applications where it is used. RMS also hosted a field exercise where the boys could practice using GPS receivers. Other RMS-ION displays included pictures, a satellite model, a computer animation of the GPS constellation, and a computer-mapping program periodically updating the location of the balloon.

SOUTHERN CALIFORNIA SECTION
Fifty-five members attended the Oct. 18 section meeting at The Aerospace Corporation in El Segundo to hear Dr. A.J. Van Dierendonck discuss the new GPS civil signals and Galileo developments. His presentation is available for download in PowerPoint format at www.ion.org/sections/socaloctober.ppt (approx. 1.1 MB). These new civil signals will greatly benefit the diverse civil community. The new receivers using the new signals will perform significantly better. After summarizing the characteristics of the new signals, Dr. Van Dierendonck detailed the benefits of them to a representative set of civil applications. He also covered some of the current problems for civil GPS receivers in adverse environments, and described how these signals alleviate those problems.

WASHINGTON SECTION

On Oct. 30, the Washington, D.C. Section held its fall meeting at the NASA Goddard Space Flight Center. The event included hors d'oeuvres, a short business meeting, and a tour of various control centers and clean rooms at the center, including the observation deck of the Hubble Space Telescope clean room, TRMM satellite control center, NASCOM (Space Station/ Shuttle) and communications control center. Exhibits of the GPS technology being developed at NASA Goddard were on display during the social hour.

RTCA Corner

Special Committee-159 Global Positioning System Report

Special Committee 159 met Aug. 30, 2001 at RTCA and approved these documents: a revision to DO-229B, Wide Area Augmentation System (WAAS) MOPS; a revision to DO-246A, Local Area Augmentation System (LAAS) Interface Control Document (ICD); and a revision to DO-253, LAAS MOPS. These documents will be presented to the PMC for review/ approval at their November meeting.

Next Meeting: Dec. 10-14, 2001
Chair: Larry Chesto, Consultant
Vice Chair: George Ligler, PMEI
Program Director: Harold Moses, RTCA, Inc.

Working Group-1, 3rd Civil Frequency, reported that the GPS Joint Program Office has published the L5ICD (ICD-GPS-705). Several action items from the L5 Interface Control Working Group meeting, held in July, were discussed and resolved. The International Telecommunication Union recommendations being developed on sharing between radionavigation satellite service and the Distance Measuring Equipment/ Tactical Air Navigation in the band 1164-1215 MHZ were reviewed.

Working Group-2, GPS/WAAS, resolved all issues and approved the revised DO-229B. The WAAS status information presented to the committee is available on the FAA Web site. Data on the signal Ôblip" due to a software upgrade on a master station (and satellite 22) was not yet available.

Working Group-2A, GPS/GLONASS, continues to monitor GLONASS activity to determine if DO-229 should be updated to include GLONASS. No new information was presented.

Working Group-2C, GPS/Inertial, resolved the comments received on the Appendix R to DO-229.

Working Group-4, GPS/WAAS, approved the revisions to DO-246A and DO-253. With the completion of both the LAAS ICD and MOPS revisions, WG-4 will work on revision of the LAAS MASPS.

Working Group-5, Airport Surface Navigation and Surveillance, continues to monitor airport surface requirements.

Working Group-6, GPS/Interference, is finalizing drafts of the L5 interference report and an update of DO-235. A preliminary draft, Assessment of Radio Frequency Interference, (RFI) Relevant to the GPS L5 Frequency, was reviewed. WG-6 plans to distribute the revised DO-235 for plenary approval in December. The L5 report is scheduled for presentation at the April meeting. The working group received briefings on Bluetooth/ 802.11b On Board Emitter RFI, GPS Intra-system Interference and an update on the results of the Ultra Wide Band RFI tests conducted on the LAAS Verification Receiver.

RTCA, Inc. is a private, not-for-profit corporation that develops consensus-based recommendations regarding communications, navigation, surveillance and air traffic management system issues. RTCA functions as a federal advisory committee. Its recommendations are used by the Federal Aviation Administration as the basis for policy, program and regulatory decisions, and by the private sector as the basis for development, investment and other business decisions.