Tag: GNSS

With new space program, UK continues march to more holistic PNT

Photo: U.K. government

News from the British government appears to be a part of the United Kingdom’s diversification away from primary reliance on GNSS for positioning, navigation and timing (PNT) services, and toward a more diverse set of sources.

The nation has previously undertaken establishment of a National Timing Centre for distribution of time from suites of atomic clocks and has long transmitted an eLoran timing signal from a government facility in Anthorn.

Thursday’s press release, titled “Government to explore new ways of delivering ‘sat nav’ for the U.K.,” reinforces the government’s commitment to space-based PNT, but not necessarily from GNSS.

OneWeb satellites

The announcement follows significant criticism in Parliament of the nation’s purchase of a 45% share of the bankrupt communications satellite company OneWeb, with the India’s Bharti Holdings having the majority stake. OneWeb had 74 of its planned 648 satellites in orbit when it declared insolvency. With new ownership and financing in place, it plans to resume operations and launch another 36 satellites in December.

Prime Minister Boris Johnson’s motivation for making the investment was to offset Britain’s post-Brexit exclusion from Europe’s Galileo system. The idea was that OneWeb assets in low earth orbit (LEO) could provide a global British PNT capability.

This concept faced political and technical opposition from the start. Many technologists in the U.K. and elsewhere doubted that the constellation could be easily adapted to provide sufficiently accurate PNT services. The doubts were so serious that the senior career civil servant responsible for signing the agreement to invest in OneWeb took the very unusual step of refusing to do so without written direction from the political appointee she worked for.

Before the OneWeb investment, the U.K. government had been studying establish of its own GNSS like America’s GPS and Europe’s Galileo. Sources say the required investment was much higher than the nation wanted to make and would provide little added capability beyond that available from extant systems.

According to Thursday’s press release, the UK GNSS effort was exploratory and will end this month. It will be “reset” as the Space-Based Positioning Navigation and Timing Programme (SBPP). This project “will explore new and alternative ways that could be used to deliver vital satellite navigation services to the United Kingdom which are critical for the functioning of transport systems, energy networks, mobile communications and national security and defence, whilst boosting the British space industry and developing the U.K.’s own capabilities in these services.”

While the press release is short on detail, it does mention satellites at low earth orbit and that “a wider range of options” will be examined. This could suggest redoubling efforts on getting PNT from OneWeb, and/or investing in regional PNT satellites.

Galileo again?

The press release also says SBPP will “consider collaboration with international allies to share satellite navigation services, costs and technology.” This may signal reengagement with Europe on involvement with Galileo.

Some observers have said that Brexit did not have to automatically mean that the U.K. was excluded from the Galileo project. European Union membership is not required for participation in the European Space Agency which is responsible for Galileo. Switzerland and Norway, for example, are not EU members, but are members of ESA and sit on its governing board.

The U.K. government has been very concerned with PNT and GNSS vulnerability since at last 2012 when large solar flares became part of its National Risk Register. In 2017 a London Economics Report found that a five-day GNSS disruption would cost the nation more than $1.3B per day.

This most recent announcement indicates that Britain is still intent on going its own way and diversifying PNT sources, while still acknowledging the ongoing importance of GNSS and keeping its options open with allies.

Dana Goward is president of the Resilient Navigation and Timing Foundation. He is the proprietor at Maritime Governance LLC. In August 2013, he retired from the federal Senior Executive Service, having served as the maritime navigation authority for the United States. As director of Marine Transportation Systems for the U.S. Coast Guard, he led 12 different navigation-related business lines budgeted at more than $1.3 billion per year. He has represented the U.S. at IMO, IALA, the UN anti-piracy working group and other international forums. A licensed helicopter and fixed-wing pilot, he has also served as a navigator at sea and is a retired Coast Guard Captain.

September 25, 2020
Transiting to GPS and beyond

Terry Moore, professor emeritus, University of Nottingham

The end of July was quite a momentous occasion for me as I accepted the offer of voluntary redundancy from the University of Nottingham after almost 35 years of employment. If I then add the six years I spent at Nottingham as an undergraduate and then as a postgraduate student, that totals almost 41 years of my life spent at the university.

I guess it is not surprising that recently I have spent some time reflecting on those years and the changes that have occurred in positioning and navigation throughout that long period. My first degree was in civil engineering, although I did specialize in land surveying in the final year.

Professor Ashkenazi. My first contact with satellite navigation was early in 1981, when Professor Vidal Ashkenazi, later my mentor and good friend, brought a JMR-1 Transit Doppler NAVSAT receiver into our second-year surveying lectures. That gentle repetitive beep as the receiver tracked the Transit satellites had me hooked for life. I don’t think I realized then that navigation and positioning would be the focus of my working life, but I was fascinated by the technology and prospects, and it really was one of those life-changing moments.

1984: Texas Instruments TI-4100. (Photo: NOAA National Geodetic Survey)

My Ph.D. continued in surveying and geodesy, and the focus was on the precise orbit determination of the LAGEOS geodetic satellite using Satellite Laser Ranging measurements. The goal was to investigate the determination of Earth Rotation Parameters (the Polar Motion and diurnal spin of the Earth) as part of an international collaboration known as Project MERIT.

Using Transit. I remember taking a Magnavox MX 1502 Transit receiver down to a conference at Herstmonceux Castle, and over the weekend I set up the instrument in my parent’s back garden in Sheffield, much to their amazement.

2020: Garmin Fenix6 smartwatch. (Photo: Garmin)

I did not start working on GPS until 1985, through my post-doc research position, sponsored by British Petroleum. This was investigating the first uses of GPS within the oil-and-gas sector for precise offshore positioning on platforms and survey vessels. The early GPS receivers we used were the Texas Instruments TI-4100 receivers, of which we borrowed five for the first long survey campaign to measure precise heights down the East Coast of England and Scotland. What a “pleasure” they were to use. I remember manually typing in the elements of the almanac for the receiver to acquire one satellite at a time.

Soon after we bought our first two Wild-Magnavox WM-101 receivers, which looked to be masquerading as Samsonite luggage. And now here I sit typing this article with GNSS receivers in the Garmin watch on my wrist and the Samsung phone beside me on the desk.

Last weekend, I was walking in the Lake District of England with my wife and daughter, and I did a quick count of our GNSS receivers. We had eight GNSS receivers (in watches, phones and handheld receivers) between the three of us, and of course there were others in our cars and the cycling GNSS receivers all nearby. How things have changed and how could we have imagined such as staggering growth in the ubiquity of GPS, and now GNSS, over those past 35 years.

September 23, 2020
The evolution of GPS satellites and their use today

1960: ARPA launched Transit, the first satellite in what would become the world’s first GPS. (Photo: U.S. Army/DARPA)

Sixty-three years ago, on Friday, Oct. 4, 1957, the Space Age began — most everyone alive today is a progeny. The Soviet Union sent a shiny, metal, beach-ball-sized sphere into orbit. Sputnik beeped every second for 21 days before going silent. Its beeps were heard ’round the world. Using the Doppler effect, a listener could tell whether the tiny satellite was moving toward or away from them. Scientists pinpointed the satellite’s exact location by observing it in a single pass, and realized the reverse could also be true. A terrestrial observer’s unknown location could be derived from the known orbit of a single satellite. That idea turned into the first satellite navigation system.

In 1964, the Navy Navigation Satellite System (NNSS) became operational. The highly classified system called Transit was built to support the Polaris ballistic missile submarine fleet. It operated on a small constellation of less than five polar orbiting satellites. With so few satellites in orbit, it could take more than an hour to get a positional fix. Twenty-meter accuracy could be attained by using specially encrypted signals, but these were restricted to submarines. All other users of Transit could only achieve accuracy within 200 meters.

Accuracy was a challenge. The problem was solved the same way John Harrison’s chronometer solved it 300 years earlier, threading together the past and present. More accurate location required more precisely measuring time (see geospatial-solutions.com/from-the-great-pyramids-to-gis-gps/). The problem was solved by two Timation satellites launched in 1967 and 1969 to broadcast a time reference signal. Essentially, the Timation satellites were space-based chronometers.

Timation improved location accuracy, even though it took hours to achieve sub-meter precision. It proved a success, and as a result, in 1967, Transit became available for non-military users, such as surveyors. In fact, everyone today who has ever worked with a reference system is familiar with WGS 84, which was originally based on “Doppler surveying receivers” called georeceivers, referring to measurements from the Transit system. Transit was also known as NavSat as it became more broadly adopted for civilian purposes such as commercial shipping.

In 1973 the Department of Defense sought to combine the success of Transit (NNSS) and Timation into one satellite system, which evolved into the NavStar-Global Positioning System. The first launches began in 1978 and reached a full constellation of 24 GPS satellites in 1993. Since that time, Russia, Europe, China, India and Japan have all created their own constellations. All of those systems combined with GPS make up the global navigation satellite system (GNSS), which totals more than 120 satellites.

Recognizing GPS’s sustained success and positive global impact, in February 2019 the Queen Elizabeth Award for Engineering went to four of the primary developers of the GPS program for their contribution to the world. These four gentlemen are Engineering Stars. On Feb. 12 of this year, President Trump signed an Executive Order further acknowledging the value of position, navigation and timing (PNT) as the invisible infrastructure of modern society. And, on July 1, Capt. “Sully” Sullenberger addressed the Space-Based PNT Advisory Board, stating how GPS has become a universal part of every facet of our lives including financial transactions, transportation, agriculture, rescue operations, surveying and construction.

The GPS satellites are our own constellation and each of them should be named in honor of a scientist or engineer who helped conceive and develop the Transit, Timation and GPS programs; even though the earlier systems no longer exist, their legacy should long be remembered.

From those Cold War origins of a chirping beach ball traveling through space 63 years ago, now more than 2,600 satellites enhance our terrestrial lives providing better communication, location and understanding. We are all children of the stars, albeit stars of our own making.

September 16, 2020
The expanded role of positioning through advancements in GNSS

Auto Mining: A driverless Cat 793F CMD truck leaves an iron ore pit. (Photo: Caterpillar)

Individuals who use GNSS today may not know the significant advancements that have been accomplished over the past 30 years to obtain accurate GNSS-derived coordinates, especially GNSS-derived orthometric heights.

Thirty years ago, there were two limiting factors for estimating GNSS-derived heights — estimation of accurate ellipsoid heights in a timely manner and the availability of an accurate geoid model. The geoid model was only good to the decimeter level, between two stations relatively close together. A significant improvement of the measurement of the Earth’s gravity field (such as from the GRACE mission) and digital elevation data (from the Space Shuttle Radar Topography Mission) facilitated the creation of more accurate geoid models. Geoid models went from decimeter values to centimeter, and then sub-centimeter values between closely spaced marks.

A new national network

During the past three decades, the U.S. National Geodetic Survey (NGS) has developed a national network of Continuously Operating Reference Stations (CORS). These CORS, along with the states’ real-time networks (RTNs), have provided the ability to compute accurate GNSS-derived coordinates in an efficient and effective manner. The modeling of antenna phase patterns was a critical development for combining different types of antennas.

Today’s GNSS processing software is basically a “hands-off black-box” system. But 30 years ago, the analyst had to identify cycle slips and ensure that all unknown cycle ambiguities of the carrier-phase data (integers) were determined correctly. It was a time-consuming task, and analysts needed to understand the data. So many things can go wrong when someone relies on an answer from a black box. That said, federal agencies such as NGS and GNSS software companies have produced hands-off software that provides statistics and warning messages, as well as guidelines for ensuring results are consistent and accurate.

The advancements in estimating GNSS-derived coordinates (including orthometric heights) have changed the way many industries do business. Farmers use it to drive their tractors and combines, mining companies control driverless vehicles, construction companies use automated machine guidance to build roads, and, of course, it has improved how individuals navigate from one location to the next.

Hands-off farming and mining

Thirty years ago, few farmers thought they would be able to sit in their cab and let their combine harvester drive itself. Geodesist, surveyors, and engineers had a vision of using GNSS to automate the use of farming and construction equipment, which became a reality.

What will it be like in another 30 years? Will it be routine for individuals to program their car for a destination, and then sit back and read a book?

Positioning with GNSS will be critical for the safety factor of driverless vehicles and the use of drones for delivery. Geodesists, surveyors and engineers, once again, need to lead the way to meet the positioning requirements of the future.

September 14, 2020
Defense small-vehicle navigation system designed for export

Photo: Etion Create

A new military vehicle navigation system designed and developed by South Africa-based Etion Create is ready for the local and export markets.

Designed for harsh environments and battlefield conditions, the CheetahNAV provides outstanding situational awareness, according to Etion Create. The crew of a light military vehicle can count on highly accurate position information, irrespective of whether they are denied satellite navigation. This is achieved through an advanced inertial measurement system (IMS), comprising several aids, including a gyro-compensated compass and an advanced Kalman filter-based algorithm.

A brochure on CheetahNAV is available here.

“We are confident that the system provides dead-reckoning horizontal position accuracy of 0.2% of distance travelled in a GNSS denied situation,” said Jan Hurter, senior product manager. “This translates, by way of example, to accuracy of just 200 metres over a distance of 100 kilometers.”

The CheetahNAV can integrate with any number of different inertial navigation systems (INS) and can be aligned with any of the satellite navigation constellations. Combined with GNSS and compass information, the system enables dead-reckoning and accurate positioning of the vehicle in tactical situations. The tactical grade integral inertial measurement unit (IMU) ensures jamming-free operation.

Some of the guidance cues the system provides to the crew during tactical maneuvers include the vehicle’s current position, true heading and desired heading towards the next waypoint, current speed and desired speed to reach the next waypoint or destination on time, and the next waypoint or destination. It also shows the pitch and roll attitude of the vehicle and the track it has travelled.

This data is displayed on a sunlight-readable touch-screen enabled moving map display unit measuring 11.6-inch diagonal, in 16:9 TFT format, with a 1920×1080 resolution. Etion Create is also offering a slave unit for the vehicle driver, as the main display might be positioned elsewhere in a space constrained vehicle. This slave unit, measuring 3.5-inch diagonal TFT, displays information that is specifically required by the driver.

Significant benefits of the CheetahNAV system include ruggedness for extreme battlefield conditions and 28V or 12V DC operation in line with military standards. Moreover, it boasts a high operational reliability.

“It is important to note that Etion Create, as original design manufacturer, is focusing the CheetahNAV on the export market, including the possibility of technology transfer for indigenous manufacturing,” said Hurter. “Besides we offer a multi-language option, which is certainly a key advantage in multinational operations that are almost the norm nowadays.”

The CheetahNAV is non-ITAR controlled, which is the preference of most land forces around the world today to meet their battlefield management requirements.

Having utilized the building blocks of previously developed military off-the-shelf technologies, Etion Create considers the system to be at a high TRL (technology readiness level), and thus available for the export market.

Previously called Parsec, Etion Create is a South African original design manufacturer (ODM) with a long-standing international reach and a professional portfolio of technology offerings and experience across a wide range of business sectors, including defence and aerospace, information security, and mining and industrial sectors.

September 11, 2020
30 years of GNSS and the surveyor

Photo: Ed Koziarski for GPS World

Depending on your age, 30 years represents a varying opinion of time. For some, it may seem like forever; for others, it may be a blink of an eye. In respect to technology, it can represent a complete change in the way we do things.

When we turned the calendar page to January 1990, our world had yet to experience the internet, the Hubble telescope had not been deployed to share its fantastic views, and The Simpsons television series was preparing to become the cartoon juggernaut it remains today.

Yes, lots has changed since 1990, and surveying is no exception.

Most professions look back through their history and see various periods where discoveries and inventions revolutionized how the work was completed.

For surveyors, the past 30 years have contained more advancements than all other years combined, with the greatest achievement being the global navigation satellite system (GNSS). With the United States leading the way with its Global Positioning System and the civilian ability to use this measuring system, modern surveying was forever changed.

Solar and lunar observations replaced

Before the implementation of a satellite navigation system, true global navigation was only computed using solar and lunar readings under specific conditions. GPS provided a new frontier for surveyors to establish positions without having to perform traversing from known points or collecting solar/lunar observations.

As the constellation grew, it became easier to use GPS to gain initialization for accurate and redundant position determination. As processor speeds and data storage capability increased, real-time kinematic (RTK) observations became the norm for surveyors everywhere.

The Russian satellite constellation, GLONASS, began operating fully in the late 1990s, and is now included to create today’s GNSS. More satellites provide more coverage, which in turn means more data collection potential.

Many nations and regions are building their own constellations to augment the current GNSS lineup, and also to safeguard the ability to obtain geographic locations when other systems are not available.

Bathymetric surveys made easy

GNSS capability and integration revolutionized several aspects of surveying, including a new and more reliable way of performing bathymetric surveys over large bodies of water. Computerized depth sounders were programmed to coincide readings with GNSS data collection to provide a more accurate and precise method of hydrographic surveying.

The past decade has continued the reliance on GNSS technology with many more devices and applications — not just for the surveyor, but for the public as well. While surveyors are using GNSS receivers on unmanned vehicles such as UAVs and boats, satellite navigation has infiltrated into many of our everyday routines. Cellphones, fitness trackers and our automobiles use this technology to guide us to our destinations.

Surveyors have used the GNSS revolution to create a digital world for better data collection, asset management and increased efficiency. Much has changed in 30 years for the surveyor and the world around us, so we should not be surprised about what technology will bring us next.

September 11, 2020
Random recollections of GPS/GNSS

2000: An Allstar OEM receiver. (Photo: NovAtel)

GPS had been around for about five years before first launch in February 1978 and Full Operational Capability (FOC) was eventually declared in April 1995. It takes time to develop, field and prove something as complex as the world’s first satellite navigation system. But we’re now well into a third generation of the venerable GPS, with GLONASS, Galileo, BeiDou and IRNSS/NavIC and QZSS around the world and in geographic locales. So, putting aside Transit or anything else, this would make GPS about 47 years old — heading into middle age.

Therefore, it would seem that Glen Gibbons waited until “this GPS thingy” looked like it might actually work — circa 1990 — to launch GPS World, since the magazine is now 30 years old and is also into its third-generation of editor-custodians! Alan Cameron bravely carried the flag after Glen and nurtured the magazine for a good number of years and brought me into the fold as a contributor. We shared ION GNSS conventions and GPS World Leadership dinners and he was able to cajole monthly articles out of me for many years. Now Marty Whitford has his hand firmly on the tiller as publisher, with Tracy Cozzens as senior editor.

So what went down during these decades of technological advancement and for many of the people in the satnav industry? It would be impossible to answer within my word-limit, so I’ll take on an extremely small subset and recount a few things I can still remember.

µGPS. I got into GPS around 1990 in an OEM board-level product spin-off program from a certified GPS airborne receiver at CMC in Montreal — we initally called that L1 receiver µGPS because then it was a small GPS board. Later it became known as the AllStar receiver. We found pretty neat applications for the early ’90s — golf-course systems, vehicle tracking, airport vehicle tracking, the start of vehicle nav systems and such.

At NovAtel in Calgary in the early ’90s, we watched things develop through L1/L2 dual frequency, began RTK market applications in survey, geographic information systems (GIS), agriculture, mining and all multitudes of attempts to get new companies off the ground.

2013: NovAtel’s WAAS G-II reference receiver. (Photo: NovAtel)

WAAS. Eventually the U.S. Wide-Area Augmentation System (WAAS) program came and swallowed us up through three different prime contractors. Once that Federal Aviation Administration program was running well, we were into programs in Europe, Japan, India and China, and that led into Galileo ground reference receivers. The software qualification work we did on Galileo positioned us to take on mil-spec receiver work, and even anti-jam products.

Then CMC bought NovAtel, and we also joined with CMC to develop a certified airborne receiver. In 2003, NovAtel bought the AllStar OEM product line from CMC — funny how things work out! The joint certified receiver program eventually resulted in a new generation of high-accuracy airborne sensors. We again changed hands in 2007 when Hexagon bought us, and then NovAtel began working closely with Hexagon subsidiary Leica on survey applications. Many new and interesting developments are still going on there.

Nowadays, my interests lie with assisted GNSS and with Rx Networks in Vancouver, which I support and advise. Assisted GNSS comes in many forms, has many avenues in the marketplace, and presents its own unique challenges.

As GPS has evolved into GNSS and into so many, many applications, companies have come and gone but the core of people who drive the industry has grown and acquired new and specialized skills, developing ever more capable technology and products. Even after 47 years of the industry and 30 years of GPS World, we aren’t anywhere close to done.

September 9, 2020
The value of point clouds is unlimited

By Jacob Amacker
Oxford Technical Solutions

What is a point cloud?

A point cloud is fundamentally a simple construct. It is a collection of points in 3D space, each point being given a coordinate in Cartesian convention. The points can also be given other properties, often these will be indicative of how they were obtained.

Examples might include the time at which they were “seen” by the surveying device that collected the data. The intensity or error in position that the point has might also be included.

Often point clouds will have around 100 million points after conducting a survey. Photography can also be overlaid on point clouds using photogrammetry techniques to essentially build 3D photography.

Image: OxTS

INS survey: point clouds

The principal method of collecting point-cloud data is by using lidar. Lidar technology is akin to radar: light is sent out from the device and bounces back off of objects. The difference is that radio uses large wavelength radio waves and lidar uses small wavelength lasers for high precision.

The time for light to return to the device is used with the speed of light to calculate the distance away. Typically, a lidar device will contain lasers with a fixed vertical angle, but which spin around in the horizontal plane. Internally, the device knows at what angle the laser is pointing vertically and its azimuth angle. This gives the device the position of the point on the object in 3D spherical coordinates.

The lasers inside produce thousands of points per second. Intensity, mentioned above, refers to the intensity of the reflected beam and indicates the reflectivity of the object.

What is a georeferenced point cloud?

Lidar requires navigation data to conduct a survey. We combine the navigation data with the lidar data to create georeferenced point clouds. Lidar devices know where points are in relation to each other, but they need to be told where they are in the world to be able to build a point cloud while moving the lidar.

The navigation data often comes from an inertial navigation system (INS). An INS is a sophisticated combiner of inertial measurement unit (IMU) and GNSS data to get the best navigation data — so a device knows where it is in the world and how it is moving.

The coordinates from the INS are added vectorially to the point coordinates of the lidar to get the final coordinates that would be used in the point cloud. This allows a user to put their lidar device on a vehicle like a van or an unmanned aerial vehicle (UAV) with an INS, to survey large areas efficiently instead of doing multiple static surveys and stitching them together.

Photo: OxTS

What are point clouds used for?

There are a wide range of applications for which point clouds can be used. They are increasingly used in real time for robots and autonomous driving computers to understand their environment and navigate through it. The data in a point clouds is convenient for recognizing and identifying surfaces and objects; for example, other cars, road signs and lane markings.

OxTS has been a global leader in inertial and GNSS technologies since 1998. OxTS is fundamentally involved in helping car manufacturers get the navigation data they require to go with lidar data in autonomous vehicle development, and in point clouds creation for use in surveying.

Distances and volumes are easy to calculate using point-cloud analysis software, and intensity can help identify different materials.

Another feature that lidar offers is multi-returns. This allows a laser pulse (which has a finite cross-section) to bounce back off of multiple surfaces to give multiple points from the same pulse. This is particularly useful for seeing windows and also seeing through them, and also for a myriad of other uses such as seeing the top of a treeline and the ground when flying over with a UAV.

It can also be used to see snow depth. The lidar can see the top layer of snow and also gets another strong return from the ground beneath.

At OxTS, we see lidar point clouds being used for driverless-car and work-vehicle development, coastal and forest management, infrastructure monitoring (signs, drains, bridges, road surfaces, railroads, etc.), creating 3D models of cities, pipeline exploration and more.

The final product is a simple file format, for which the possibilities are almost endless — and we see new applications using point clouds all the time.

August 25, 2020
No silver bullet for US PNT: Many sources needed

Many PNT sources from multiple providers needed

“We cannot have GPS signals be a single point of failure for transportation and other critical infrastructure sectors. More safety applications will depend on PNT in the future. Public confidence in these will be critical.

“People will not be comfortable getting into an automated vehicle or with platooning driverless trucks heading down the highway if they think that their invisible hand is not reliable and that their GPS might be spoofed.

“Getting public adoption of other PNT capabilities — space-based, terrestrial, and self-contained — integrated with GPS technology will be critical to the success of any such system.”

— Diana Furchtgott-Roth, Deputy Assistant Secretary for Research and Technology, U.S. Department of Transportation, Nov. 20, 2019, Edinburgh, U.K.

A Single Point of Failure

The Department of Transportation (DOT) is responsible for leading civil positioning, navigation, and timing (PNT) issues for the United States. At the moment, the U.S. GPS provides the vast majority of PNT services in the U.S. and around the world. Yet, like all space-based systems, its signals are weak and very vulnerable to interference.

A recent example of how dangerous that can be in automated transportation systems was revealed recently in an accident report released by the British government. Interference from an unknown source caused a 15.5 kg drone to get away from its operator and crash. Fortunately, no one was hurt. The report cited analysis showing that such a weight could have easily killed someone on the ground.

Even more concerning, GPS signal characteristics are well known and therefore easy to imitate. Thousands of cases of “spoofing” have been documented with government and malicious actors causing receivers to report they are far from their actual location. In the worst cases, this can cause accidents or enable criminal acts.

One result of all of this is the President of the United States issuing an Executive Order encouraging “responsible use” of PNT systems. It also directs steps to encourage development and adoption of alternative systems. This includes a White House-level plan for research and development of non-Global Navigation Satellite System (GNSS) PNT.

In Europe the European Union (EU) has warned that space based PNT alone is insufficient for “…critical applications requiring continuous availability and fail-safe operations.” The EU has also established a monitoring system to detect sources of GNSS interference, and the European Space Agency (ESA) has established an on-going program funding study of both space and terrestrial alternate PNT systems.

Multiple Cooperating Systems

The ultimate solution, though, according to senior government officials, will be development and use of many diverse PNT systems working together to ensure users have what they need when and where they need it.

Image: DOT

The National PNT Architecture, jointly developed by the US departments of Defense and Transportation, envisions a multitude of PNT sources ranging from GNSS provided by national governments, to inertial and clock suites acquired by users as needed.

“Many people are fond of talking about a GPS backup,” said one administration official.

“It’s more appropriate to use the plural ‘backups’ since one system isn’t going to meet everyone’s needs. Even GPS doesn’t meet everyone’s needs which is why we require complementary PNT capabilities.”

The idea that multiple redundancies are required for an essential function as long been a core principle of systems engineering. This is clearly foundational in the National PNT Architecture.

It is also a feature in more recent documents.

One example is the U.S. Department of Defense’s (DoD) PNT strategy publicly released in August of last year. It envisions use of a multitude of systems as a way of “Ensuring a U.S. Military PNT Advantage.”

Image: DOD

It categorizes these in three layers. A global layer of GNSS and other satellites, a regional layer that includes STOIC and eLoran, and a local/autonomous layer populated by inertial, clock, lidar, radar, scene matching and beacon-based systems.

Another project taking the architecture approach is described in detail by the recently completed MarRINav report. Sponsored by the European Space Agency, it analyzed the PNT needs of maritime commerce in the United Kingdom.

The project concluded that a “hybrid approach” using GNSS, eLoran, and the short-range R-mode VDES would be the best and least expensive combination for maritime. It also recommended a local navigation system such as Locata for port cargo operations. The study found that such a combination of systems would also benefit other transportation and infrastructure sectors.

Implementation

Yet identifying solutions is often much easier than making them happen. Especially for national projects with dozens of stakeholders. Stakeholders who may often have competing interests. And there is always the question of “Who pays?”

In the United States both the Congress and the executive branch of the U.S. government are addressing these issues, and in potentially complementary ways.

Congressional Mandates. With GPS as the cornerstone, both the DoD strategy and the National PNT Architecture show the need for one or more complementary systems to “overcome PNT capability gaps, predominantly resulting from the limitations of GPS.”

According to one senior official close to the issue, these systems need to be, “integrated with GPS and each other” and within the U.S. “serve all parts of the country — urban, rural, wilderness — even coastal maritime areas.” The idea being that they will constantly reinforcing GPS services while also serving as a safety net for users when during GPS disruptions.

The National Timing Resilience and Security Act of 2018 requires DoT to begin filling this layer in the National Architecture by the end of this year. The law, passage of which was overwhelmingly supported by both parties, mandates the department establish a difficult to disrupt, wide area, terrestrial timing system to backup (and complement) GPS timing signals. The system also must be expandable to provide navigation services. Even as a timing service, though, it has the potential to make navigation more reliable. Studies have shown that combining such a timing signal with GPS and other GNSS signals can dramatically decrease users’ vulnerability to jamming and spoofing.

The law also enables the system or systems to be established by leveraging commercial entities and expertise through cooperative agreements, public-private partnerships, and similar arrangements. These tend to be the most expeditious and least costly methods for putting such services in place. As such, they are expected to be very attractive to government program and contracting officials.

On military side, the in-process National Defense Authorization Act for 2021 requires DoD to quickly complete this part of their architecture also. Hinting that the department has failed to respond to combatant commanders “Joint Urgent Operational Needs,” it directs DoD to provide warfighters non-GPS PNT by 2023. It also directs the department to “enable civilian and commercial adoption of [these] technologies and capabilities”.

Presidential Order. The administration’s approach is outlined in a February 2020 presidential Executive Order. The order focuses on commercial entities that contract with the government, critical infrastructure, and research and development.

It calls for, within the next 24 months, agencies to “develop contractual language for inclusion … n the requirements for Federal contracts … with the goal of encouraging the private sector to use additional PNT services and develop new robust and secure PNT services.” The hope is that these new services will be adopted beyond just those companies who routinely serve government needs.

The departments of Energy, Transportation, and Homeland Security are also required to publish plans on how they will engage various critical infrastructure sectors to evaluate the degree of responsible use of PNT by each.

Also, the White House Office of Science and Technology Policy (OSTP) is tasked to “coordinate the development of a national plan… for the R&D and pilot testing of additional, robust, and secure PNT services that are not dependent on global navigation satellite systems (GNSS).” OSTP has already begun this and is seeking input from the public.

Competition and Many Players

Because PNT user needs are so varied and nuanced, most industry observers see growing opportunities for existing and potentially new providers.

“Systems and equipment that improve GNSS services, or that complement and augment GNSS are likely to find ready markets,” said Andrew Bach, a consultant on financial and other PNT issues. “User demands and needs are only going to become more sophisticated as their economic exposure increases.”

Congressional and administration focus on alternative PNT should enhance and multiply such opportunities. So, while there may be no silver bullet for solving national PNT concerns, the need for a robust and resilient architecture of PNT systems will likely mean abundant opportunities for providers.

August 18, 2020
I was expecting a jetpack…

When I was a kid in the 1960s, I was entranced by the vision of the future. Decades later, we’re here, with personal jetpacks nowhere in sight. What gives?

Photo: Photo: ridvan_celik/E+/Getty Images

When I was a kid in the 1960s, I was entranced by the vision of the future offered by science fiction books, movies, television shows and comics. Advances in technology would deliver us so many wonders — flying cars, hoverboards, robot servants. Disneyland was in on it, with an entire section of the park named Tomorrowland and its now-quaint “Carousel of Progress” attraction.

But the coolest thing would be that jetpack. You could slap it on your back and take off into the atmosphere, traveling wherever you wished like a bird. Certainly by the distant year 2020, we would all be jetting around the atmosphere from place to place.

(It didn’t occur to me that would mean strapping an actual jet engine to my body, along with highly flammable jet fuel. Where’s the fun in that?)

Decades later, we’ve all arrived in the “future,” with personal jetpacks nowhere in sight. What gives?

Then again, what I didn’t imagine in our future was a system that could pinpoint my exact location anywhere on the globe, estimate my time of arrival, and tell me about the traffic up ahead.

Back in the 1960s, that was seriously science fiction. Nor did we accurately predict the effect that capability would have on our daily lives. GPS along with internet-capable smartphones have thrust us into the Information Age.

The internet is a promise delivered, in its own way. Having a repository for all of the world’s information was another future concept, but usually envisioned with a giant worldwide computer that eventually turned on its makers.

As for flying cars, we are gradually getting there. Drone technology, supported by GNSS technology for its navigation, has led to unmanned craft and is heading toward vehicles capable of transporting people. We just need to be a little more patient.

In the spirit of looking back and ahead, check out our 30th Anniversary Supplement, which arrived with this issue. In it, experts from across the industry share memories and thoughts, and gaze into their crystal balls to predict the future of GNSS.

August 17, 2020
VectorNav introduces miniature IMU and GNSS/INS product line
Tactical Embedded series of GNSS/IMUs. (Photo: VectorNav)

Embedded navigation company VectorNav Technologies has introduced a new line of inertial products: the VectorNav Tactical Embedded series of GNSS/IMUs.

Featuring a tactical-grade inertial measurement unit (IMU) and a multi-band GNSS receivers, the Tactical Embedded delivers milliradian attitude accuracy and centimeter-level positioning capability in a miniature 15-gram package.

VectorNav’s Tactical Embedded line is in a new smaller size, and enables cost reductions for a wide range of autonomous pointing and geo-referencing applications. These include gimballed intelligence, surveillance and reconnaissance (ISR), SATCOM systems, lidar mapping and photogrammetry, among many others.

The Tactical Embedded line supports external SAASM GPS for defense applications in ISR, electronic warfare, munitions and UAV navigation.

“The Tactical Embedded is the culmination of years of development to bring milliradian-level attitude performance and robust positioning into a form factor that represents a disruptive step in inertial navigation capability,” said VectorNav President John Brashear. “Systems integrators worldwide can now embed tactical-grade inertial navigation capabilities into their electronics, unlocking a range of new applications and possibilities.”

Designed and engineered at VectorNav’s AS9100-certified facility in Dallas, Texas, the Tactical Embedded line includes the VN-110E IMU/AHRS, the VN-210E GNSS-aided inertial navigation system (INS), and the VN-310E Dual Antenna GNSS/INS.

Highlights include:
- 0.05-0.1° heading; 0.015° pitch and roll
- 1 m horizontal and 1.5 m vertical position accuracy
- 1 cm RTK positioning accuracy
- < 1°/hr gyro in-run bias; < 10 μg accel in-run bias
- 184 channel, L1/L2/E1/E5b GNSS receiver
- Support for external RTK, PPK and SAASM GPS
- High update rates (800 Hz IMU; 400 Hz Nav)
- Miniature footprint: (< 15 grams; 31 x 31 x 11 mm)
- Low power: < 480 mA @ 3.3 V
The Tactical Embedded line is available for purchase now and ships within two weeks.
August 11, 2020
Case studies reveal survey tech advances
The creed “Neither snow nor rain nor heat” may apply to postal workers, but it also could apply to land surveyors.

Today’s surveyors rely on GNSS as a critical tool to enable completion of their tasks, whether defining a property boundary or mapping mining drill sites.

In the articles that follow, surveyors share their success stories using the latest GNSS receivers, software and correction services, all of which are constantly improving to make their tasks easier — despite the terrain or weather conditions.

How one man triumphs

Adam Plumley is a one-man surveying shop in North Carolina. He also wears another hat as a sales, support and product development consultant to Javad GNSS.

“As a land surveyor, I use the equipment every day,” Plumley said. “Javad’s equipment has made it possible for me to operate solo.”

Photo: Stephen Drake

In the project pictured above, Plumley surveyed a 50-acre farm parcel to separate out the six-acre improved northeast corner. “I located the creek, building and improvements on the property east of the road and ran the lines to the creek on the west side of the road.”

The difficult locations on this 2016 survey were at the creeks. It took Plumley up to a half hour to locate the corners and creek points under the tree canopy.

“It would have taken much longer than it did if I had traversed the boundary conventionally,” he said, “not to mention I would have been much more tired at the end of the day.”

Instead, Plumley used a Javad GNSS Triumph LS and Triumph 2 base/rover system with corrections broadcast over the internet.

“I set up the Triumph 2 base about one mile away in an open yard with great sky view. It took me one day to do the initial recon and locations, and another couple of hours to set the new corners the next day,” he said.

Plumley has since upgraded his base receiver to another Triumph LS and added a J-Link 35-watt external radio to his toolbox.

“One thing this and other challenging surveys have taught me is to be patient. To obtain accurate results that you can be confident in takes time.”

About our cover

Our cover photo this month was taken in June 2019 by surveyor Stephen Drake, near his home on the north coast of California. “These redwood forests and very rugged, remote coastal mountains can really test you,” he said. He was using his Javad Triumph-LS rover with the J-Field built-in surveying software, communicating to a Javad GNSS Triumph-2 base station attached to his house. A Verizon Jetpac mobile hotspot (in the black pack hanging below the Triumph-LS in the photo) picks up signals from his home router; the port-forwarded corrections are configured with Javad software.

Stephen calls this his standard configuration, but finds it very flexible. When he is more than 20 miles from home base, he relies on a Triumph-2 and a radio modem placed near the site. He can also use the California Real Time Network (CRTN) with the Jetpac.

He also relies on Javad’s Hybrid RTK, automated post-processing with Javad’s DPOS, automatically generated raw data and quality reports, and the many built-in indicators in J-Field that provide real-time feedback and “give me assurance on almost every measurement before I walk away from it,” he said.

The efficiency that his equipment provides has made Stephen valuable even to firms that already have in-house surveyors, he said. “I honestly do not think I would be here without Javad. It has been a true potent business partner.”

Read about another one of Stephen’s projects here.

Check out more surveying case studies here.
Feature image: AP Surveying PLLC
July 23, 2020