Tag: First Fix

First Fix: Arrivals and Departures

Matteo Luccio

As we begin 2023, GNSS development continues apace, as described in this issue’s annual “Directions” section by representatives of Galileo, GLONASS, and BeiDou. We plan to publish a similar update on the GPS program soon.

Galileo’s user base now stands at more than 3.5 billion, and the services it provides continue to improve and expand. Beginning early this year, free precise point positioning (PPP) corrections for Galileo and GPS (single- and multi-frequency) will improve real-time user position by up to 10 times. While the discontinuation of Soyuz launch services from the Kourou Space Centre in French Guiana, due to the Russia-Ukraine conflict, delayed the two Galileo launches that had been planned for last year, 2022 was a key year for the development of Galileo Second Generation (G2G) satellites. They will provide, among other innovations, a reconfigurable fully digital navigation payload, point-to-point connection between satellites, and advanced jamming and spoofing protection mechanisms.

On Nov. 29, 2022, Russia launched the 51st Glonass-M satellite, about 20 years after launching the first one. Currently, 13 of these satellites are operating beyond their guaranteed lifetime, with an average orbit lifetime of more than 10 years. Starting this year, the constellation will be renewed by Glonass-K and Glonass-K2 satellites, which provide CDMA signals to users.

Currently, 45 BDS satellites are operational in orbits, including 15 BDS-2 satellites and 30 BDS-3 satellites. The constellation says that it has reached a continuity of 99.996% and an availability of 99%, with a global positioning accuracy better than 1.5 meters horizontally and 2.5 meters vertically (95% confidence).

Tracy Cozzens, who has been a pillar of this magazine for 17 years, is retiring this month. We will miss her journalistic acumen, dedication to clarity and style, attention to detail, and wealth of institutional knowledge. We wish her a well-deserved retirement. At the same time, we welcome aboard Maddie Saines, our new managing editor, who is near the beginning of her career.

I am pleased to announce that Rob VanBrunt has joined GPS World’s Editorial Advisory Board. In mid-December, the board of directors of Spirent Federal Systems, a provider of PNT test solutions for the U.S. government and contractors, appointed him as the company’s president/CEO-designate, a role he will assume when the onboarding process is complete.

VanBrunt began his career at Spirent Communications in 1990 as product developer and manager, and then held posts of increasing responsibilities, moving to director and vice president roles focused on management, strategy and mergers and acquisitions. Most recently, he was executive vice president in the Office of Business Excellence. VanBrunt has a B.S. in electrical and electronics engineering from Rutgers University.

Spirent Communications is a global provider of automated test and assurance solutions for networks, cybersecurity and positioning. In July 2001, the company formed Spirent Federal Systems as a wholly owned subsidiary and U.S. proxy company. Spirent Federal markets and sells Spirent Communications’ products in North America. It also provides value-added features and ongoing customer support.

On Jan. 1, I lost my beloved mother, Maristella “Mimi” Luccio. She was 87.

Matteo Luccio | Editor-in-Chief
[email protected]

January 20, 2023
GNSS constellations create four strong winds

Matteo Luccio

First, there was one. In July 1995, the U.S. Air Force declared the Global Positioning System had met all the requirements for full operational capability (FOC). Soon thereafter, there were two. In December of that same year, Russia’s Globalnaya Navigazionnaya Sputnikovaya Sistema (Global Navigation Satellite System, or GLONASS), also achieved FOC. For a quarter century, that was it.

Then, last year, the number doubled, as both the European Union’s Galileo and China’s BeiDou Navigation Satellite System (BDS, named after the Big Dipper asterism, which is known in Chinese as Beidou) achieved FOC.

The Indian Regional Navigation Satellite System (IRNSS, aka Navigation Indian Constellation, or NavIC, which means “sailor” or “navigator” in Hindi) and Japan’s Quasi-Zenith Satellite System (QZSS, also known as Michibiki) are not global yet, but plan to become so. Currently, NavIC is an autonomous regional satellite navigation system, and NavIC-based trackers are compulsory on commercial vehicles in India. QZSS currently complements GPS to improve coverage in East Asia and Oceania, but Japan plans to have an operational constellation of seven satellites for autonomous capability by 2023. The Korea Positioning System (KPS) plans to join the party by 2035.

Who’s next? Will it be another country or a private company? Given that the state-sponsored systems are free to end users, I don’t see what the business model would be for a private GNSS constellation, unless it were to piggyback on one built mainly for another purpose.

Surveyors who have begun to routinely use three or more constellations are over the moon. One, quoted in this month’s cover story, recalls that “the use of GPS for construction staking was an extremely risky proposition” because its residuals exceeded most construction tolerances. Using multiple GNSS constellations, however, has increased confidence in the accuracy of results to the point that some construction companies are relying on GNSS receivers for staking. Additionally, multi-constellation receivers can now increasingly be used under tree canopies and against structures, whether natural or built.

Whatever their mix of military, political and commercial motivations for building, deploying and operating their own GNSS constellations in addition to the original two, the European Union, China, India, Japan, Korea and whichever entity may follow are greatly improving satellite-based positioning, navigation and timing (PNT) for all users everywhere — by increasing accuracy, shortening the time to first fix, and making GNSS more impervious to jamming and spoofing.

In 1978, the year that the U.S. Department of Defense launched the first NAVSTAR GPS satellite (“NAVSTAR” was later dropped from the system’s name), Neil Young sang “Four Strong Winds” (originally written by Ian Tyson and performed by him with his wife Sylvia as the Canadian folk-duo Ian and Sylvia).

Now, GNSS has “four strong winds,” two lighter ones and several more breezes to follow. As a sailor and a navigator, I welcome them heartily. As this magazine’s editor-in-chief, I don’t mind that, like Jeep, Kleenex, Popsicle and Xerox, GPS probably will stick in popular culture as a generic term for global satellite navigation systems way past its accurate description of what is in the box.

Matteo Luccio | Editor-in-Chief
[email protected]

October 1, 2021
Building a planetary navigation system

Matteo Luccio

Soon, global navigation will no longer suffice. Humanity is preparing to return to the Moon after more than half a century. U.S., European, Chinese, Indian, Japanese and Russian governments and companies want a slice of the “eighth continent.”

NASA’s Artemis program, which aims to put astronauts on the Moon’s south pole in 2024, will explore more of the lunar surface than ever before. Robots and humans will search for, and potentially extract, resources such as water, which also can be converted into other usable resources, including oxygen and fuel.

Astronauts searching for spots where robotic spacecraft have pointed to the ice on the lunar map and for equipment sent on ahead of them will need precise navigation guidance. So will astronauts and ground controllers operating the Gateway outpost in Moon orbit and the Orion spacecraft. This will require extending the reach of our Earth-centric positioning, navigation and timing (PNT) systems to cover our planet’s nearest neighbor.

A permanent and reliable source of PNT on the Moon will reduce the amount of gear each mission will have to develop and carry, making more funding and rocket-lift capabilities available for scientific equipment. It also will free bandwidth on NASA’s communications networks, which have historically provided navigation services near the Moon.

NASA and the European Space Agency (ESA) are laying the foundations for this navigation system. Their efforts include the development of a special receiver able to pick up GPS signals that, already very weak on Earth, are extremely so on the Moon; NASA’s LunaNet communications and navigation architecture; ESA’s public-private Pathfinder satellite navigation and communication mission, due to launch into lunar orbit by the end of 2023; and ESA’s Moonlight initiative, which will establish lunar communication and navigation services.

Studies already have proven that it is possible to navigate between Earth and the Moon, as well as on the latter’s surface, using the side lobes of the signals from GNSS satellites. In 2023, the Lunar GNSS Receiver Experiment (LuGRE), developed in partnership with the Italian Space Agency, will demonstrate and refine this capability on the Moon’s Mare Crisium basin. NASA will use data gathered from LuGRE to refine operational lunar GNSS systems for future missions.

Besides the low signal power, other challenges to using GNSS satellites for Moon navigation include geometry, with all the signals coming from a relatively small portion of the sky; the fact that in polar regions the Earth would be low on the horizon and therefore GNSS signals could easily be blocked by hills or crater rims; and the complete occultation of the signals when moving beyond the side of the Moon always facing Earth. Meeting this last challenge will require at least a couple of Moon-orbiting satellites. (Artificial satellites orbiting our planet’s natural satellite as a supplement to the artificial satellites orbiting our planet…)

The Moon will be our steppingstone to Mars. I bet it will not be long before the Institute of Navigation establishes a Planetary Navigation division!

August 1, 2021
First Fix: Let’s start a conversation

Matteo Luccio

Last year, GPS World marked its 30th anniversary. That is a testimony to this magazine’s continued relevance, its commitment to its marketing partners, and its unmatched audited audience of 54,000 GNSS/PNT buyers, integrators and specifiers.

Taking on my new role on GPS World’s edit team was a homecoming of sorts because I began my current career a little more than 20 years ago as this magazine’s managing editor. I look forward to an ongoing conversation with many of you in the GNSS/PNT community — scientists, engineers, civil servants, uniformed service members, company executives and product managers. You may get an email message from me, and I will always welcome yours, at the e-mail address below.

“I look forward to an ongoing conversation with many of you in the GNSS/PNT community.”

Let me tell you a little about three passions that led me to this job.

Navigation has been one of my passions since I was a kid. When I was five years old, I lost track of my mother as she entered a store in Berkeley, California, and I kept walking down the street. It happened again when I was seven and had insisted on walking home alone from school in Milan, Italy. I was determined never to get lost again. So, when I was 11 and my family moved to Pisa, I was the only kid I knew who walked around — from school to sabre-fencing practice, to piano lessons, to my bus stop — studying a map and a compass. When I was 13, in shop class, I built a crude optical-range finder, based on trigonometry. Next, came the topo maps I used for hiking the hills and mountains of Tuscany. A few years later, as a graduate student at MIT, I began to sail around the Boston Harbor islands and off the coast of Maine. I learned to navigate using nautical charts, sextants, radio direction-finders, sonar, radar, Loran-C and, finally, GPS receivers.

Magazine journalism has been another one of my passions, since I co-founded a public policy magazine, Oregon’s Future, 25 years ago and became its editor. That was the first of seven editorial positions with magazines I have had over the past quarter century. Finally, my passion for public policy led me to degrees in political science and to my previous career as a research analyst — first for an independent research institute, then for state and local government. It gave me a solid grounding in public policy, statistical analysis and querying large databases.
So, this navigation enthusiast, policy wonk and experienced writer and editor is now in position to report on and advocate for the continuing growth and development of GNSS. I will also showcase new products and projects, and present facts and opinions from across the GNSS/PNT community.

This month’s cover story on autonomous vehicles is a perfect example. It confirms the central role of GNSS in one of the most significant technological advances we can expect to see in the coming decade — having vast implications for our society and environment — with facts and opinions from four industry leaders.

Matteo Luccio | Editor-in-Chief
[email protected]

June 1, 2021
First Fix: Two PNTs are better than one

With a very good PNT device already installed for flying the aircraft, why not just tap into that one for the payload, right? This might not be a good idea, for several reasons.

By John Fischer
Vice president, Advanced R&D, Orolia

John Fischer. (Photo: Orolia)

The navigation device in a UAV is very important, precisely because there is no pilot. It must navigate autonomously. It must also be optimally suited for the airframe, either fixed or rotary wing, providing the accuracy and reliability for all modes of flight, from takeoff to landing. A lot of engineering goes into the design and certification of each UAV’s navigation system to qualify it for flight.

UAVs can have multiple missions with interchangeable payloads: cameras for observation and inspection; communication equipment for relaying links or supplying emergency cellular base stations; or sensing equipment such as radar, lidar, spectrometers, etc. These payloads also need positioning, navigation and timing (PNT) sources for their missions, for example, to accurately geo-timestamp the collected data.

With a very good PNT device already installed for flying the aircraft, why not just tap into that one for the payload, right? Actually, this might not be a good idea, for several reasons.

Recertification. Modifying the navigation device, which is part of the flight control system, risks having to re-certify the aircraft for flight safety. Though a UAV has less severe restrictions on safety than a manned aircraft, it can still cause property damage or even injury and loss of life if it crashes in a populated area. The Federal Aviation Administration has numerous standards — DO-178 for software, DO-254 for hardware, DO-160 for testing — to ensure avionics are designed and tested for safe operation. Every modification, regardless of how small, must follow these standards and may require expensive re-certification of the aircraft’s airworthiness.

Performance Requirements. These vary with each mission. The flight control system includes a navigation device that was selected based on the aircraft’s special requirements. These will not necessarily match the needs of the payload. For example, consider pitch, roll, and yaw sensing accuracy. The accuracy required to determine the pointing angle of a camera might not be the same as what is needed for level flight.

Interchangeability. A particular UAV can have multiple payloads for different missions. Conversely, a particular mission payload can be adapted and installed on several different UAVs. Having a second PNT device matched to the payload allows it to stay with the payload as it is moved to different UAVs. This can lower the total cost of ownership and operation, since the extra cost of a second device is small compared to the adaption work and design changes necessary to make a single PNT device be suitable for all situations.

Missing the T in PNT. Typically, the navigation device for flying the aircraft doesn’t have a precise internal oscillator for supplying time and/or frequency — it doesn’t need it. However, most payloads can benefit from the time/frequency component to enhance mission performance. A low phase noise oscillator with low g-sensitivity that is disciplined by the precise time supplied by a GNSS receiver can substantially improve the performance of any payload radar or communication system.

A second device does not impact SWAP or cost significantly — GNSS receivers and inertial navigation systems are no longer large, expensive items. A second PNT device is typically small, weighing less than a kilogram and consuming only a few watts of power. There are also fewer connectors and cable harnesses when a removable payload is not sharing the aircraft’s PNT data, so the weight differential might be zero. PNT devices can share antennas on the aircraft via splitters, so there is no need to place additional antennas.

Technology upgrades. Micro-electromechanical systems (MEMS), inertial sensors, cameras, lidars, radars and other sensors are all evolving at a rapid pace with better technology available with each passing year. Flight control systems evolve at a different pace — mostly because of the flight certification process, but also for lack of a driving need. UAVs navigate just fine with the equipment they have today. A separate payload PNT device allows the system designer to keep pace with evolving technology, choosing the latest and best for the mission without disrupting the navigation system.

Just as “two heads are better than one” for problem solving, having two PNT devices in a UAV is often the better solution.

John Fischer is vice president, Advanced R&D, Orolia, and a member of GPS World’s Editorial Advisory Board.

March 22, 2021
Number of trained US geodesists at crisis level

By David Zilkoski, contributing editor, survey scene

David B. Zilkoski

I attended The Ohio State University (OSU) to obtain my graduate degree in Geodetic Science in 1979. Therefore, I will admit that I am a little biased — once a geodesist, always a geodesist. The basic definition of geodesy is the applied science for determining the size and shape of the Earth, designing and realizing reference frames, and determining where you (and anything else) is on the Earth.

In OSU’s geodesy heyday (1960–1990s), many Americans trained were sent by federal agencies: National Geospatial-Intelligence Agency (NGA), NOAA/National Geodetic Survey (NGS), USGS, Army, Navy and Air Force. During the 1970s, NGS was sending two employees back to school every year. These agencies needed geodesists because they were undertaking major projects such as NGS’ to readjust the U.S. national horizontal (NAD83) and vertical geodetic (NAVD88) networks.

I was one of the employees that NGS sent to OSU to be trained to support the NAD83 and NAVD88.

The advancements in satellites and computers have enabled geodesy to expand into many different disciplines. Geodetic science and technology now underpin many sciences, large areas of engineering (such as driverless vehicles and drones), navigation, precision agriculture, smart cities and location-based services. Geodesy is actually more important than ever.

Today, the environment is different. U.S. federal agencies still need geodesists for developing enhanced and refined geodetic models and tools. However, major U.S. companies, such as Google and FedEx, as well as the automobile industry, precision farming companies and mining companies also need more accurate geodetic models, tools and algorithms. Therefore, these companies also need trained geodesists to perform important research on topics that address their specific geodetic requirements.

Today, OSU’s Geodesy Department is training very few American citizens. As the U.S. moves toward achieving geodetic-grade positioning in real-time in support of new applications such as driverless vehicles and drones, the number of trained geodesists should be increasing, not decreasing [Note: In 1990, there were 92 geodetic science graduate students. In 2019, there were 25; only three were U.S. citizens]. OSU and other universities need to educate and train the next generation of the nation’s scientific workforce of highly skilled research geodetic scientists that will expand industry’s research expertise.

The shortage of American geodesists poses a significant economic risk for the U.S. Europe and China train many more geodesists than the US. There are very few geodetic science programs in the U.S. today, and education in geodetic proficiencies has been fragmented. The OSU graduate program is one of few surviving geodetic science programs.

Users of geodetic products and services need to support geodetic departments in universities so that U.S. geodesy programs can grow to meet the geospatial demands of the future. The geospatial component of the economy is worth about $500 billion/year. So why are we allowing its foundational discipline to shrink in this country?

July 20, 2020
First Fix: Don’t wait to update GPS

By Paul Crampton, Spirent Federal

Paul Crampton

As we bid farewell to the last GPS-IIA satellite and read of delays to both the launch schedule for GPS III satellites and roll-out of the OCX program, we are mindful of the need to maintain GPS as the “Gold Standard” in GNSS.

Certainly, new signals, enhanced resilience and expanded capabilities are offered by the modernized GPS playbook. Delays relative to both the BeiDou and Galileo constellations could seriously impact the position of GPS on the medals podium — maybe not in the longer term, but certainly in the coming few years.

This may have a secondary impact on the receiver market, shifting focus away from GPS to more capable signals in the near term. Once GPS has caught up, receiver manufacturers may choose to retain the technology that they developed to capitalize on BeiDou and Galileo signals, rather than developing their legacy GPS capabilities.

GPS L2C is currently “pre-operational,” transmitted by slightly more than half the existing mixed-generation satellite fleet and waiting for OCX support. As of Feb. 20, a realistic estimate for operational capability of GPS L2C is now 2023.

GPS L5 is also pre-operational, transmitted by slightly less than half of the GPS satellites and waiting for OCX support. As of Feb. 20, a realistic estimate for GPS L5 is 2027.

The forecast for GPS L1C operational capability is the late 2020s. This is intended to be the signal that offers international interoperability with the current interoperability signals offered by existing BeiDou and Galileo satellites.

Delays to the implementation of GPS L1C may mean that GPS misses the interoperability boat entirely. During the delay, new interoperability capability with even more robust signals could be devised and lofted aboard Galileo, BeiDou and GLONASS satellites. By then, other countries could also develop their own constellations, possibly regional or even global systems.

Potentially, GPS could be left behind as other nations discuss non-GPS internationally interoperable signals on yet-to-be launched satellites. This may have a profound impact on SBAS, too. Differential corrections provided by the Japanese MSAS, Russian SDCM and European EGNOS SBAS systems might evolve to support “beyond L1C” interoperability signals. Aircraft landings at world airports could mandate the use of corrections to these new signals. This might mean that U.S. receiver manufacturers could be frozen out, or will have to incorporate these new interoperable signal standards.

GPS Block III satellites along with OCX offer improved signals, capabilities and resilience, but the satellites need to be flying, OCX needs to be operational and receivers need to be in the hands of the users. Sooner rather than later is a must for Gold-Standard GPS.

Paul Crampton is a senior systems engineer at Spirent Federal Systems with more than 30 years of GPS experience.

June 24, 2020
Maintaining the 1-dB standard

How do we ensure that GPS is protected from harmful interference?

By J. David Grossman, guest columnist

J. David Grossman

Debates in Washington over harmful interference and the coexistence of divergent services are raging. Nowhere are the differences more apparent than when comparing radio navigation services such as GPS to radio communications systems used in wireless communications networks.

How do we ensure that a satellite-based radionavigation service like GPS, which by design operates below the ambient noise floor, is protected from harmful interference? The International Telecommunications Union’s (ITU) definition of harmful interference provides a starting point, by defining harmful interference as a level that “endangers the functioning of a radionavigation service.”

With this foundational definition, the internationally established criterion of a 1-decibel (dB) increase in the noise floor, otherwise known as the 1-dB standard, provides the answer, offering a readily identifiable, objective and predictable metric.

The 1-dB standard uses a 1-dB increase in the noise floor as the distinction between the onset of interference that can be detected by a GPS receiver and harmful interference. (This can be reliably measured by a 1-dB decrease in the carrier-to-noise ratio, C/N₀, reported by the receiver). Thus, the 1-dB standard provides a definitive way to protect GPS receivers from harmful interference. Adherence to this standard helps ensure that systems operating in an adjacent spectrum band do not interfere with GPS.

Why use the 1-dB standard instead of other metrics? The 1-dB standard is based upon well-understood GNSS engineering considerations and is associated with quantifiable changes in the overall noise to which GNSS receivers are subject, with equally well-understood effects on receiver operation. (The 1-dB standard enables system designers and spectrum regulators to carefully assess interference from various sources and analyze their net effect on GNSS receivers).

It also has been adopted internationally and has a long and well-established proven history of protecting GPS operations from harmful interference in both international and domestic regulatory proceedings.

So-called “alternatives” to 1 dB, which may be appropriate in the context of radio communications systems, fail to recognize that the accuracy, integrity and reception (availability) of GPS signals used by a receiver can be degraded by interfering noise in ways not immediately apparent to an end user. This means that the effects of degraded service of GPS signals can still be detrimental well before the user loses position accuracy or experiences complete loss of position.

Additionally, C/N₀ is computed at the entry point of a GPS receiver, such that a 1-dB decrease serves as an early warning of interference potentially becoming harmful. Other metrics, computed further downstream, may be indicative of harmful interference already occurring.

GPS has become a fundamental part of our lives and is an integral engine of the U.S. economy, creating new jobs, and unlocking innovation. Maintaining the 1-dB standard ensures that the GPS success story and American innovation will continue for decades to come.

J. David Grossman is executive director of the GPS Innovation Alliance.

February 4, 2020
US falling behind protecting GPS/GNSS, civilian users

No One Is in Charge

Guest column by Dana Goward

Dana Goward

Europe’s scattered monitoring of GNSS signals found almost 500,000 interference events over three years. About 59,000 were clearly intentional. European standards for resilient receivers have been published and acquisition of an interference detection network is underway.

Russia is improving its terrestrial Loran/Chayka PNT system for military use and has promised to make the upgraded service available to civilians.

China has retained its terrestrial Loran PNT system as an augmentation/backup for its BeiDou GNSS. It is also testing PNT satellites in low earth orbit (LEO) to provide more powerful and reliable signals than available from current GNSS.

In contrast to the actions of other countries, little is being done in the United States to protect civilian GPS/GNSS users.

The U.S. Department of Defense (DoD) has been very active protecting its own with GPS M-code signals and receivers. It is exploring use of LEO communications satellites and high-powered, low-frequency ground transmissions, such as Loran, to add to the GPS signals.

Yet DoD claims civilian use of GPS has limited its ability to use it as a military tool. It says it has no intention of sharing any new PNT systems with civilians.

At the same time, the 99% of GPS use in the U.S. that is non-military is arguably more important to the nation’s safety and security. GPS signals are used by every networked technology and every mode of transportation. They are so important that officials at the Department of Homeland Security have called GPS “a single point of failure for critical infrastructure.”

The U.S. military recently updated its PNT strategy, has a designated leader for its PNT efforts, and clearly defines the responsibilities of its various staffs and organizations.

Civil agency responsibilities were last updated in 2004 and are spread across more than a dozen departments, agencies, and staffs.

Most significantly, no one is in charge.

This has meant that over the past 15 years, many of the civil mandates and responsibilities to protect signals and users have gone unfulfilled. As just one example, rather than ramp up to address increases in jamming, the Federal Communications Commission has reduced its enforcement equipment and staff.

Putting someone in charge is key to reversing America’s civil PNT decline and energizing both federal and private stakeholders.

A single, empowered federal leader should be responsible, not for doing everything, but for leading and coordinating federal and other civil efforts. This would be someone to be held accountable, and to hold others accountable — an evangelist for the essentiality of these services, and their advocate at the highest levels of government.

Such a leader should be positioned outside the daily turmoil of the White House and National Security Council. They should be in the civil department with the portfolio that most depends on GPS and other PNT. The one that suffers first when GPS and other PNT are not available — the Department of Transportation (DOT).

DOT is already the federal interface with civil GPS users, and co-chairs the national PNT executive committee with DOD. A few edits to national policy and a few staff reassignments could establish a national PNT leader in DOT and make all the difference.

Regaining U.S. PNT leadership is essential to America’s future security and prosperity. We must take the first step by appointing and empowering a single federal leader to make it happen.

Dana Goward is president of the Resilient Navigation and Timing Foundation.

December 4, 2019