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B: Applications

Active GNSS Networks and the Benefits of Combined GPS + Galileo Positioning
December 1, 2007

Active GNSS Networks and the Benefits of Combined GPS + Galileo Positioning

Without question GPS has revolutionized precise positioning since its advent about 20 years ago. Real-time methods to quickly fix carrier phase integer ambiguities — the key to precision — have been developed and are often referred to as RTK (“real-time kinematic”) techniques.

Without question GPS has revolutionized precise positioning since its advent about 20 years ago. Real-time methods to quickly fix carrier phase integer ambiguities — the key to precision — have been developed and are often referred to as RTK (“real-time kinematic”) techniques.

RTK is an advanced manifestation of the principle of differential positioning, a method that requires at least one reference station with known coordinates to simultaneously track GNSS satellite signals. Carrier phase measurements are used in addition to pseudoranges due to their superior accuracy.

Nevertheless, ambiguity resolution is only possible as long as the user (the “roving receiver”) is located in the vicinity of this reference station — let us say, within a radius of approximately 10 kilometers. Within this short range the benefits of the often-employed “double differences” technique can be effectively exploited: Differences of observations between a primary and a secondary satellite are formed on both the rover and the reference site and these two quantities are then subtracted, yielding a derived measurement between both sites that is free of satellite and receiver clock offsets or errors.

Fortunately, the atmospheric errors are spatially correlated and can be reduced in the double difference measurements to a reasonable extent. Thus, it is relatively easy to fix ambiguities of short baselines, whereas it becomes increasingly difficult to do so over longer baselines due to decorrelation of the atmospheric delays.

As a result of this decorrelation, the service area of conventional RTK systems allowing for quick ambiguity fixing covers about 300 square kilometers. To provide service in an area the size of the contiguous United States (9,800,000 square kilometers) would require more than 30,000 reference stations. Even for a country as small as Germany (357,000 square kilometers) more than 1,100 reference sites would still be needed to provide complete coverage — an enormous challenge in terms of infrastructure installation, operations, and maintenance costs.

The solution for this problem: Use multiple reference stations to derive atmospheric corrections. Because the coordinates of these fixed stations can be determined precisely — or can be treated as tight constraints — the atmospheric (ionospheric and tropospheric) effects on GNSS signal propagation can be derived from the correlated data.

These station-, baseline-, or satellite-specific corrections can be interpolated at the rover site. Hence, atmospheric errors can be significantly reduced and GNSS reference networks can substantially increase the distance between stations while still providing the accuracy level on conventional RTK systems.

The reference networks that provide such correction data are often called “active GNSS networks,” referring to their continuous operation. Most of them offer both real-time and post-processing services.

By adding to the number of satellite signals available to these networks, users on the road/in the field can improve their performance by allowing optimization of satellite geometry (the selection of a subset of available signals that reduces the dilution of precision (DOP) factor), use of multiple frequencies for carrier phase integer ambiguity resolution, and for achieving so-called “overdetermined solutions.” With multiple GNSS systems under development in addition to GPS that are increasingly compatible or even interoperable, this prospective approach is becoming ever more attractive.

This article outlines the added value from combined GPS+Galileo data processing — rather than GPS-only data processing — in the framework of active GNSS network positioning. In particular, we will look at how such an approach can improve performance in the presence of traveling ionospheric disturbances that produce marked increases or decreases of signal propagation delays.

(For the rest of this story, please download the complete article using the link above.)

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By
John W. Betz

John W. Betz

John W. Betz developed the binary offset carrier modulation and participated in the design of modernized signals including GPS M code and L1C. He contributed to aspects of receiver processing for modernized signals and a range of systems engineering activities in support of GPS modernization.

He has participated in bilateral discussions between the United States and the European Community, Japan, Russia, and other nations, and helped improve compatibility and interoperability of current and future GNSSs.

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By Inside GNSS
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Zupt Portable Inertial Nav Unit
November 26, 2007

Zupt Portable Inertial Nav Unit

Zupt offers B-PINS, a high-precision surveying system incorporating inertial sensors and optional RTK GPS/INS integration. Designed to provide positioning and navigation in GPS-denied areas, such as in dense vegetation or in urban canyons, B-PINS includes data fusion software, a handheld data collector (Recon PDA), Li Ion batteries, and a rugged backpack. Applications include land seismic surveys, military or tactical GPS operations, and emergency or disaster response. Zupt, LLC, Houston, Texas.

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By Glen Gibbons
Trimble Snares USCG DGPS Contract; NDGPS Imperiled

Trimble Snares USCG DGPS Contract; NDGPS Imperiled

Even as the fate of the inland portions of the Nationwide Differential GPS (NDGPS) reference network hangs in the balance, the U.S. Coast Guard (USCG) has awarded a contract to Trimble for up to 400 high-accuracy GPS reference receivers.

The Trimble NetRS reference receivers will be installed over the next three years as part of the coast guard’s modernization of the Maritime DGPS Service, which is not part of the NDGPS elements that being considered for termination.

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By Glen Gibbons
Congress Pares GPS III Funds, Slams Air Force Space Acquisition Efforts (updated 11/28/07)
November 25, 2007

Congress Pares GPS III Funds, Slams Air Force Space Acquisition Efforts (updated 11/28/07)

The GPS III modernization program came up short in the 2008 fiscal year (FY08) Department of Defense (DoD) appropriations bill signed into law by President Bush on November 13.

In passing H.R. 3222, Congress reduced the president’s request by $100 million to $487.23 million for the budgetary year ending next October 1.

Military GPS M-code user equipment (MUE) did better, however: gaining $63.2 million on Capitol Hill, over and above the $93.27 proposed in the administration’s budget, for a total of $156.47 million.

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By Glen Gibbons
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COMPASS
October 31, 2007

COMPASS

As of late October 2007, China’s Compass (Beidou 2) Navigation Satellite System (CNSS) has manifested little change since the launch of its first medium Earth orbit (MEO) satellite in April 2007. Four geostationary satellites from the prototype Beidou system had previously been launched, the first on October 31, 2000.

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By Glen Gibbons
Changdon Kee

Changdon Kee

Changdon Kee is a professor and associate head of the School of Mechanical and Aerospace Engineering at Seoul National University. He developed the basic concept and presented the first experimental test results of wide area differential GPS in the early 1990s.

Kee has published widely on GNSS, pseudolites, space mechanics and UAV Automatic navigation and control and holds more than 15 domestic and international patents for his work on GNSS.

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By Inside GNSS
U.S. Department of Commerce Proposes Update to Office Overseeing GPS and Related PNT Activities
October 27, 2007

U.S. Department of Commerce Proposes Update to Office Overseeing GPS and Related PNT Activities

The Department of Commerce has proposed legislation to boost the U.S. government’s space commerce activities. Specifically, the bill would reauthorize the Office of Space Commercialization (OSC), restore the office’s original name — Office of Space Commerce — and focus the office’s responsibilities to enable a robust and responsive U.S. commercial space industry.

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By Glen Gibbons
PatInLab5.jpg
October 21, 2007

Pat Fenton: GNSS from the Outside In

Patrick Fenton’s career as the guiding mind behind the design of six generations of breakthrough GNSS receiver technologies began the moment he realized his hobby — computer programming — might end the need for surveyors to spend long evenings reducing and verifying the data they collected each day.

Patrick Fenton’s career as the guiding mind behind the design of six generations of breakthrough GNSS receiver technologies began the moment he realized his hobby — computer programming — might end the need for surveyors to spend long evenings reducing and verifying the data they collected each day.

It was the summer of 1981. Fresh out of the University of Calgary’s survey engineering program, Fenton was enjoying a taste of what he’d envisioned would be a “professional outdoor career” as a rookie land surveyor for ShellTech Surveys, a now defunct division of Shell Canada.

“We would spend all day turning the angles and measuring for a road project,” he said. “Then, evenings we would spend hours reducing the data and making sure it was all correct. I was able to hop on the computer and get that done for the crew very quickly.”

Fenton’s inspired effort ended his work outdoors. “They told me to stay in the office and develop the software,” he recalled. “From then on I worked on processing the data and developing equipment that would make their jobs easier.”

When the oil crunch hit, ShellTech was sold in January 1982 and became Nortech Surveys Ltd. Fenton worked on a number of high-tech survey systems for the oil exploration industry, including INS, microwave ranging, and GPS. He became software manager of a Nortech subsidiary, Norstar Instruments.

“At the time, there wasn’t a suitable GNSS instrument on the market that met the needs of Nortech; so, the management decided that we had the talent to jump into the survey instrument business,” Fenton said. “We did create a very nice product; however, we lacked knowledge in high quality manufacturing. Each one we built was a little bit different.”

A Better Mouse Trap

NovAtel, then a giant in Canada’s cell phone industry, acquired the NorStar division in 1989.

“The combination of skills at NovAtel was exactly what was needed for our GPS products, that is RF, software and production engineers, DSP chip designers, and marketing experience,” Fenton said. “At NovAtel, we completely redesigned the receiver from the antenna down.”

At about the same time, Fenton hit upon an insight that led to an industry first: true sub-meter pseudorange positioning capability.

“I realized that the signal processing design and tracking loops within the GNSS receivers of that day were optimized for maximal signal power to signal processing complexity ratio,” he explained. “They were not optimized for range or carrier phase tracking accuracy — the elements driving position accuracy. It was during this period that I came up with the Narrow Correlator concept.”

His invention, commercialized into the GPS1001 receiver in 1991, was five times more precise than the previous technology. It received the Better Mouse Trap Award that year from the Institute of Navigation (ION).

Today Fenton is vice-president and chief technology officer (CTO) for NovAtel, which has become a leading provider of GPS and augmentation components and subsystems designed for rapid integration into an endless variety of high precision, commercial applications.

At the tender age of 49, he holds 15 patents and has authored more than 20 technical articles for the ION. So significant are his contributions to the evolution of GNSS that his peers have recognized him with the ION Satellite Division’s highest honor: the Johannes Kepler Award.

Fenton is also known for projects that have significantly improved receiver capability to allow reliable positioning and precise navigation even in obstructed environments where GPS alone doesn’t work. Marine, mining, precision agriculture, and surveying and mapping are among the applications benefiting from such advancements.

On the Fast Track

For example, he has spent several years leading a small team that is integrating inertial measurement units with NovAtel’s GNSS receivers. The results of their success using digital terrain modeling (DTM) techniques to improve precise position output availability are showcased during telecasts of NASCAR and IndyCar races.

“Our challenge was to provide Sportvision a continuous stream of time-tagged position and velocity measurements from each race car,” Fenton said. “Sportvision uses this information to annotate the TV camera image stream with details such as the driver’s name, speed, and lap time while the race is underway.”

Sounds simple enough. But NASCAR tracks presented formidable challenges for radio frequency coverage, the lifeblood of GNSS technology.

“In addition to lots of steep bleachers there are cat walks around and over the track,” Fenton explained. “Probably the worst obstacle was the steel mesh catch fence that completely surrounds and overhangs the track. When the cars are up against the wall, more than half the sky is blocked by the catch fence.”

No sky, no satellite coverage. Not only that, but the tracks are very short. Laps can take as little as 15 seconds. “When a car is halfway around the track, it has blocked the other half of the sky. In this case, as a result, we could never lock in a satellite for more than 10 seconds.”

Using a DTM of the NASCAR track, Fenton’s team was able to constrain a car’s position. “This algorithm acted like an additional satellite and improved the availability substantially,” he explained. “But it wasn’t until we added integrated IMUs [inertial measurements units] that we were able to deliver 100 percent position and velocity availability.”

Fenton’s hallmark is a knack for finding and integrating technologies that drive powerful new applications. During the mid-1990s, as he rose from chief engineer to director of research and development, he was instrumental in NovAtel’s acquisition and commercialization of the MEDLL (Multipath Estimation Delay Lock Loop) technology, licensed from Delft University. WAAS, the U.S. Federal Aviation Administration’s Wide Area Augmentation System, and the European Geostationary Navigation Overlay Service (EGNOS) use it.

This powerful combination of scientific chops and market acumen earned Fenton a vice presidency in 1997 and the additional title of CTO in 2003. He was appointed to NovAtel’s board of directors in 2005.

The company’s latest generation OEMV series of GNSS receivers, released last year, illustrates the exponential changes in core technology that occur between versions. NovAtel’s “system on a chip” now has more than four million gates, almost eight times as many as its predecessor.

Fenton, who grew up in Canada’s capitol (Ottawa) has retained his zest for the outdoors including a passion for photography. He met his wife Tanis through her brother, a skiing buddy. They have three children; two in college and one in high school, and the entire family takes full advantage of Alberta’s rich recreational opportunities.

But even in the remotest glacier field, Fenton never completely loses touch with GNSS. Each winter he and a group of friends rent a backcountry hut and helicopter in for a week of alpine skiing. “Four times in our lives we’ve been up in a whiteout,” Fenton said. “We were able to navigate back to the hut with GPS.”

Fenton’s coordinates:
N51 06’ 59” W114 02’ 18”

COMPASS POINTS

Engineering Specialties
System conceptualization, GNSS receiver design and signal processing, multipath mitigation techniques, and firmware development.

His Compass Points
• Home and family: wife Tanis and three children, household activities, weekend trips, summer vacations, extended family, and friends
• Career: applied technology, mentoring, teamwork, business relationships, learning, and change
• Hobbies: photography, and outdoor activities

Favorite Equation
This formula is a derivative of the Central Limits Theorem. It’s a simple formula but I use it all the time to estimate expected signal-to-noise ratio levels at the output of hardware correlators at various stages of designing GNSS receivers.

GNSS “Aha” Moment
In the summer of 1985, I started developing position processing software from data Nortech had collected from their various survey operations. I realized that I could make a significant contribution.

First Significant GNSS Achievement
I came up with the Narrow Correlator concept. This technique made for a five-fold improvement in pseudo range accuracy, leading the way to reliable sub-meter positions.

GNSS Mentor
Probably the single person that I’ve learned the most from in GNSS over the years is Dr. A.J. Van Dierendonck. He was the chief scientist with Stanford Telecommunications Inc. where we were sourcing GPS receiver channels for the first GPS product I was involved with in 1986. He has been a technical consultant with us, periodically, for nearly 20 years.

GNSS Event that Most Signifies That GNSS had “Arrived”
I think the first Gulf war with all the publicity and TV images of the smart weapons provided a huge boost to the popularity and awareness of GNSS. Before that time, I always had to explain what GPS was. After that time, everyone seemed to have a good appreciation for what GNSS was.

Influences of Engineering on His Daily Non-Work Life
My engineering mind is always churning. For example, over the last couple of years my wife and I built an energy-efficient house. I was heavily involved with all the engineering aspects of that; producing all the CAD construction drawings, design of all the mechanical systems including the in-floor geo-thermal heating system, and the networks for phone and internet connectivity to all the rooms.

Popular Notions about GNSS That Most Annoy
The notion that GNSS will work deep indoors, under ground, or under water – perhaps for oil exploration at the bottom of a drill tip or for diving. If you can’t pick up FM radio, then most likely your GPS won’t work.

Favorite Non-GNSS Activities
Winter: skiing, snowboarding, alpine touring
Spring/Summer/Fall: cycling, canoeing, camping, sailing, fly fishing
All seasons: photography

What’s Next
There are several possibilities. The first would be multi-constellation, multi-frequency GNSS. This is where a single receiver tracks multiple satellite constellations (GPS, Galileo, GLONASS, etc.) and provides a blended robust position solution. The second may come from time of arrival (TOA) positioning of cellular phone tower signals. The density of cell phone towers is continuing to increase. At a certain point, the use of TOA processing of cell signals will rival consumer GPS for the large urban and indoor markets.

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By
The Two Worlds of Philip Mattos

The Two Worlds of Philip Mattos

Aside from messing about in boats on the estuary near his holiday house in Rock, a village in Cornwall, few activities delight Philip Mattos quite so much as solving the constellation of challenges involved in creating Galileo-ready receivers targeted to reach European consumers within two years.

Aside from messing about in boats on the estuary near his holiday house in Rock, a village in Cornwall, few activities delight Philip Mattos quite so much as solving the constellation of challenges involved in creating Galileo-ready receivers targeted to reach European consumers within two years.

Mattos is the chief engineer for GPS and navigation at STMicroelectronics R&D Ltd. in Bristol, the largest city in southwest England. Located near the mouth of the River Avon, Bristol’s economy centers on the aerospace industry and information technology. The area’s dependence on navigation traces back to its emergence as a major port city in the 12th century.

And while these facts about his home provide a nice bit of context, nothing really explains Mattos’s genius for GNSS. His prolific contributions, which touch hundreds of millions of people around the globe, seem all the more remarkable considering that the 1948 tractor he keeps for mowing his field represents the peak of technologies associated with his rural English childhood.

“Engineering clearly has formed me over the years,” he says with relish. “If something appears broken, take it apart and fix it!”

Since 2004, Mattos has focused on developing a new chip for a project funded by GR-POSTER, the acronym for the Galileo-Ready POSitioning TERminal Consortium. It’s the next big step toward the launch of Europe’s independent satellite navigation system, and Mattos has been breaking trail in this direction for nearly 30 years.

An Early Start in GPS

A Cambridge graduate, Mattos earned bachelor’s and master’s degrees in electronic engineering. His career began at British Telecom Research Labs, the equivalent to Bell Labs in the U.S. “They sponsored me through additional master’s degrees in telecoms and computer science from Essex; so, I was with them for about nine years,” he says. “At the end of my career there I was specializing in the architecture of the actual processor in microcomputers.”

When the British government set up the semiconductor industry in 1979, Mattos was recruited by INMOS (now STMicroelectronics) to help build the transputer, the United Kingdom’s first 32-bit micro. That’s when he happened across a feature in an electronics magazine that inspired him to develop a demonstration application using LORAN. “But there was a hold on the market.” he says. “Nobody wanted LORAN because GPS was ‘just around the corner.’ Of course, it stayed ‘just around the corner’ for about seven more years.”

So Mattos moved on to doing a GPS demonstrator, helped by a year’s posting to Colorado Springs in the United States. Back then, Mattos worked as “a team of one.” His presentations at conferences in Dallas and London led to partnerships with Inmarsat, Bristol University, and Columbus Positioning that supported taking a software-only demo to full-fledged prototypes integrating radio frequency, software, and hardware. The resulting handheld GPS was launched at the Royal Institute of Navigation conference in 1989 and the London Boat Show in 1990.

On to Galileo

When the sum of these efforts produced a dedicated chip for GPS in 1996, the way was opened for mass-market products and, in turn, increased resources for research. Four years ago, Mattos did the blue-sky thinking for the Galileo-ready chips now being perfected at five STMicroelectronics sites in Europe and India. At the moment, he divides his time mainly between England and Italy.

“In Italy, they work deep in silicon, doing detailed design and verification to check that the silicon we’re about to create is exactly what the people who designed the silicon asked for, and what I asked for when creating the specifications,” Mattos says. “The cost of manufacturing the chip is a huge investment. Our company does it from end to end, from initial design to final test.”

In addition to earning a Ph.D. from Bristol University for his work on GPS, Mattos holds nine patents: eight in the area of GNSS and one in telecommunications. His latest invention, patented earlier this year, provides extended use of broadcast ephemeris. Last year, he received a patent for new methods of processing multi-signal GNSS services, which applies to Galileo and GPS III signals.

His major innovations also include development of the HPGPS in the Teseo and Cartesio basebands as well as a new RF chip, applications which arose from his 2001 patent on accelerated acquisition of GPS signals and his 2003 patents on GPS code acquisition and GPS radio clock generation. Earlier, he obtained patents for microprocessor control of a packet-switched data exchange (1976) and the GPS radio design that led to the STB5600 RF IC (1996).

Asked to name a few milestones in his career, Mattos offered this list:

• Producing the prototype GPS/satcom for Inmarsat in 1990
• Developing the first fully integrated baseband with just 3 chips (compared to 14 in the 1990 model) in partnership with Panasonic, in 1995
• Creating a complete system in two chips, with the baseband having integrated memory and the RF portion being a single chip based on his doctoral work at Bristol University, in 1998
• Widespread acceptance of Vespucci in the automotive market, which changed from the ST20 processor to the ARM7 with embedded Flash memory, in 2001
• The success of Palinuro, with the RF front end on the same chip as the digital baseband, making a one-chip solution from antenna to PVT output, in 2003

The Future in GNSS

Currently, he’s involved in partnerships with Galileo Joint Undertaking in the GR-POSTER Project; ST teams in Bristol, Milan, Naples, and Catania; and lead customers (whose names are not public) on the following projects:

• A high performance 16-channel GPS plus RF chip for Teseo by the end of the year
• A high performance 32-channel GPS, with full PDA/PND functionality, for Cartesio (by early 2007)
• Cartesio’s extended version, with Galileo, for 2008

Mattos also makes time to consult on the next generation of GNSS chips including one-chip GPS (radio frequency plus digital) and high sensitivity GPS for indoor applications.

When the European Union and the European Space Agency launch their 30 Galileo satellites about two years from now, Mattos expects the most noticeable difference for navigation users will be the availability of service in urban canyons. Some indoor areas will be more accessible as well, though not those made of dense materials like concrete or metal.

“Galileo’s biggest benefit is that it can be combined with GPS and be compatible,” Mattos says. “If you’re down in an urban canyon, there will be enough satellites in the sky that your navigation system will continue to work. We need four or five satellites to operate properly and we don’t get that today in urban canyons. With GPS and Galileo together, we will.”

Mattos’s coordinates:
51° 32.450 N 2° 34.600 W

COMPASS POINTS

Engineering Specialties
“From 1990 to 1995 I was a team of one, so I needed to do everything – design engineering, system integration, software, hardware, signal processing, RFIC, and so on. Once the system was proven, more people were allocated and areas delegated. Now I specialize in architecture, system level design, advanced signals and DSP, tending to move away from GPS and towards Galileo. As a system specialist I advise the silicon experts, both RF and baseband, but leave the detail design to them.”

His Compass Points
• A childhood in the country, “before any of the technological stuff”
• Going to Cambridge
• Buying his first house “way out in the country looking out at the marshes and the river, which reinforced my existing love of the country, love of the water, and dislike of cities.”

Favorite Equation
The great circle distance between two points on the earth.

D = r x arrcos {sin φ1 sin φ2 + cos φ1 cos φ2 cos Δλ}

GNSS “Aha” Moment
I was demonstrating my software-based LORAN system, when a sales manager who was also a yachtie said, ‘This is pointless. LORAN will be replaced by GPS in a year or two.’ It’s 18 years later and the world is still having that debate!”

First Significant GNSS Achievement
In 1987 he worked in the same building as now, for his current employer (at that time, called INMOS) making the transputer, a then-revolutionary 32-bit microprocessor. “Having been advised that LORAN would be replaced by GPS, I did a demo of a software GPS, with one processor emulating the satellite, and a second processor performing all the DSP correlation, and demodulation in software to acquire and track the signal. The goal was to demonstrate the very high computing performance of the transputer processor: software GPS in 1987!”

Why he fell in love with GNSS
“My interests were boats, electronics, computers, and radio. How else to combine them all and play on company time? The challenge was to do something that covered so many technical areas, from antennas, low noise amplifiers, radio frequencies, digital signal processing, baseband, software, and map-matching, to dead-reckoning equipment, and have ownership of the entire design. This entire system was demonstrated in 1992, when a color map meant placing a six-inch CRT (cathode ray tube) display in a car. I have the TV to this day.”

GNSS Event that Most Signifies that GNSS has “Arrived”
Shipping the company’s Palinuro single-chip GPS. “Connect active antenna, power, and RS232 comm port to a PC/PDA and you have a GPS.”

Popular Notions about GNSS that Most Annoy
First, that the $2,000 box in the car is a GPS. “The GPS is the $15 module inside the box that delivers PVT.” Second most annoying, that the satellites track the user. “They have no idea you exist.”

Dream Device
An all-bands radio, initially a receiver but also a transmitter that listens to all the channels for all the aircraft, all the boats, and all the ships. It would display the active ones on screen and record activity so that one needn’t be present to monitor it. “You can get this information now, just not all in one place. It’s not what they call rocket science, because all the elements have been done. It’s a matter of bringing it all together. Such a device would let me feel a part of things when I’m at the office, working in the garden, or engaged in the ongoing refurbishment of our holiday house.”

What’s Next
Galileo in consumer vehicles throughout Europe.

Galileo-Ready POSitioning TERminal
(GR-POSTER) Project: www.st.com/stonline/galileo

By
Karen Van Dyke: Re-Engineering the Airways

Karen Van Dyke: Re-Engineering the Airways

Karen Van Dyke at Glacier Bay National Park near Juneau, Alaska

Karen Van Dyke probably isn’t someone you’d expect to see driving around Virginia with one hand piloting the steering wheel and the other gripping a map. But for Van Dyke, an electrical engineer who wryly describes herself as “geographically challenged,” the maps piled on her passenger seat remain a lifeline even though two years have passed since she moved from her native Boston to Washington D.C.

“It’s my GPS secret,” she admits. “When I get lost, I tell my husband that’s why I work in this field.”

Karen Van Dyke probably isn’t someone you’d expect to see driving around Virginia with one hand piloting the steering wheel and the other gripping a map. But for Van Dyke, an electrical engineer who wryly describes herself as “geographically challenged,” the maps piled on her passenger seat remain a lifeline even though two years have passed since she moved from her native Boston to Washington D.C.

“It’s my GPS secret,” she admits. “When I get lost, I tell my husband that’s why I work in this field.”

Why doesn’t one of the profession’s leading innovators have GPS in her car? The answer reveals just how recently GPS has come into its own. “When I bought my car in 2001, adding a navigation system wasn’t an option,” she explains. “I’d gladly have paid extra for it.”

Since then, GPS has vaulted the divide between geek speak and consumer chic. “Legislation has brought it into our cell phones. The world’s banks rely on it to time stamp their transactions,” says Van Dyke. “Eventually, coordinates will be part of every product and process in our lives – but first GPS must be improved and integrated with other technologies in order to achieve accurate positioning, navigation, and timing (PNT) information anytime and anywhere.”

That challenge keeps Van Dyke on her toes in her work for the U.S. Department of Transportation (DOT). Her specialty: incorporating GPS into the transportation infrastructure for various applications.

Little did she know, when she accepted a summer research job following her graduation from the University of Lowell in 1988, that she was sealing her professional fate. Her professor, Dr. James Rome, was doing a project for the John A. Volpe Transportation Systems Center looking at whether a new system, GPS, might reduce aircraft separation on the North Atlantic routes by providing position information where there was no radar coverage.

“That summer gave me an opportunity to learn about GPS, which I found to be a fascinating technology with tremendous future applications,” Van Dyke says. By summer’s end, she was hired by Volpe, part of the DOT Research and Innovative Technology Administration (RITA).

She says her engineering mentor, Frank Tung, modeled a well-rounded approach toward the profession. Tung was director of aviation programs when she joined Volpe and has since retired. “He always emphasized enjoying what you work on and ensuring that your work contributed to making a positive difference for the organization and transportation community,” she says.

For Van Dyke, one of the most enjoyable aspects of her work is its global nature.

“Many countries have approached the Volpe Center for assistance with development of similar satellite outage reporting systems for air navigation – especially third world countries that do not have the sophisticated ground-based infrastructure that the U.S. has,” she says. “The cost-effective and innovative benefits that GNSS technology can provide to them are tremendous.”

Van Dyke is a Fellow and past president of the Institute of Navigation (ION) whose many publications include collaborating on the first and second editions of the book, Understanding GPS: Principles and Applications. She has received the Meritorious Achievement Award (Silver Medal) from the Secretary of Transportation, the Superior Achievement Award (Bronze Medal) from the Research and Special Programs Administrator, and the ION Early Achievement Award.

She has helped spearhead many innovations – including these personal favorites:

GPS RAIM Outage Reporting Systems

Van Dyke led the Volpe Center team that designed, developed, and implemented GPS RAIM satellite outage reporting systems for both the U.S. Air Force and the FAA. These receiver autonomous integrity monitoring systems brief GPS availability to pilots during pre-flight planning to support use of TSO C129a receivers.

“Subsequently, similar work was performed for Australian, German, and Chilean aviation authorities on the implementation of systems for use by pilots and air traffic control in those countries,” she says.

Prior to commissioning the GPS Wide Area Augmentation System (WAAS) in 2003, she led a team that supported the FAA in development of the WAAS prediction model and integration into the air traffic control system to supply Notice to Airmen (NOTAM) information for all phases of flight, including precision approaches.

Reducing Vulnerability

In 2001, she participated in a Volpe Center project that produced sixteen recommendations for reducing the vulnerability of the transportation infrastructure that relies on GPS. The project was done in response to the President’s Commission on Critical Infrastructure Protection.

The team’s study of GPS civilian aviation, maritime, and surface uses assessed the effects of GPS outages and recommended steps to minimize the safety and operational impacts of both short and long term disruptions.

STARWEB

Van Dyke headed the Volpe Center team that developed the prototype traceability requirements tool for the GPS Joint Program Office. That led to the creation of an internal website whose acronym is GPS STARWEB, or GPS Specifications Traceability and Analysis of Requirements. STARWEB uses DOORS software – Dynamic Object Oriented Requirements — for its integrated database that establishes relationships and traceability of requirements within the GPS system.

“This equips the civil GPS community with the information necessary for informed decision making,” she says.

Currently, Van Dyke has several projects going at once. Recently, she has been supporting development of GPS III, evaluating the specifications for the future space and control segment.

She’s also working with the Federal Railroad Administration and Ohio University on the High Performance Nationwide Differential GPS initiative to evaluate whether it can be designed to meet requirements for Positive Train Control and other high accuracy applications.

Another collaboration addresses the potential use of WAAS for maritime applications. She heads a Volpe Center team that is working with Innovative Solutions International (ISI) to develop a GNSS Performance Monitoring System (GPMS) for the Brazil Aviation Authority. This system is responsible for ensuring that satellite-based systems provide a continuous, safe, and reliable signal-in-space (SIS) for navigation users.

And, with all that, she still finds time to volunteer. She has been the air navigation technical representative for the Institute of Navigation (ION) since 1992 and served as ION’s eastern region representative and president (2000-2001).

Lisa Beaty, ION’s director of operations, says “Karen’s international technical reputation precedes her, but many people may not know about her countless hours of volunteer service within the navigation community, including fostering the development of programs for the next generation of navigation professionals.”

Van Dyke’s coordinates:
39° 38.921 N 077° 08.231 W

COMPASS POINTS

 

Engineering Specialties
Identifying positioning, navigation, and timing (PNT) requirements for transportation applications, as well as development and deployment of GPS monitoring and service prediction tools.

 

Favorite Equation
The Keplerian parameters describing orbital motion. Most of the applications we have developed for GPS prediction systems and the analysis begins with modeling the GPS constellation performance based on Keplerian motion, Van Dyke points out.

 

First Significant GNSS Achievement
Back when there wasn’t a full constellation of satellites, Van Dyke was part of the Volpe Center project team that helped develop Receiver Autonomous Integrity Monitoring (RAIM) algorithms to predict the availability of GPS integrity for oceanic through non-precision approach phases of flight. The limitation was availability of service, which then led to development of the augmentation systems.

 

Her Compass Points
Engineer husband Ken Kepchar is, “one of those people who was born with a built-in navigation sensor.” They met at the GPS Joint Program Office at the Los Angeles Air Force Base.

Rather than follow the herd into high tech computer firms when she finished engineering school, Van Dyke’s fascination with early GPS technology led her to take a position with the John A. Volpe Transportation Systems Center.

The University of Lowell (Massachusetts) where she earned her bachelor’s and master’s degrees in electrical engineering (1988 and 1991).

Knew GNSS had Arrived When . . .
“When I first began working on GPS, my friends and family had never heard of it. I would have to explain what the acronym GPS stood for, what the system was, and the various applications of the technology. Over time, my friends and family began telling me about GPS applications they had read about in the paper or seen on the news. Now that the term GPS is commonly used in the media – it has arrived!

Popular Notion about GNSS That Most Annoys
“It is disappointing when I hear someone in the international community say that the U.S. Department of Defense can turn off GPS anytime they want. It is simply not true. The U.S. government has worked very hard to establish national space-based positioning, navigation, and timing (PNT) policy with a coordination office, headed by a civilian, with civil and military representation. The national space-based PNT Executive Committee is co-chaired by the Deputy Secretaries of Transportation and Defense.”

Consumer Engineering Wish List
“My own on-board navigation system with voice is number one on my Christmas list.”

What’s Next
Integration of GPS with other navigation sensor technology and development of a net-centric approach for reliable distribution of PNT information.

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