Two important new signals — or rather, one signal and one group of signals — became available for military users worldwide last week. Satelles made an exciting announcement of what amounts to a new dimension in satnav: a whole new constellation in low-Earth orbit, bringing global coverage and most critically, a signal strength hitherto unknown to GNSS users. The satellite time and location (STL) has primary application in the timing realm, which is vital in many applications.
Higher in the sky, Europe’s GNSS satellites constituting the Galileo system officially began offering their services, and the multiple frequencies available here mean robustness, greater availability in obstructed environments, and — some say, though this is controversial — greater positioning accuracy, largely through more precise timing onboard.
Meanwhile, GPS World seeks a new defense editor for this column, and adopting the concept of “promoting from within,” now turns to its readership for interested parties to volunteer.
A New SatNav That’s Not GNSS
A strategic alliance announced on Dec. 15 between companies Orolia and Satelles includes will provide positioning, navigation and timing (PNT) solutions provided by the Iridium satellite constellation, independent of GPS/GNSS signals. The companies intend to provide PNT solutions to military, defense, government and commercial customers worldwide. Their new satellite timing and location (STL) service can supply much-needed robustness to GPS-dependent operations.
Orolia, the parent of GNSS-active companies Spectracomm, McMurdo, and Spectratime, has extensive experience in the defense realm. The company says it is #1 worldwide in the manufacture of military beacons outside the U.S. with a 60% market share, and #2 within the U.S., and that it is the first-ranked provider of Medium-altitude Earth Orbit Search and Rescue system (MEOSAR) worldwide. In partnership with Satelles, it will provide the STL service independent from traditional GPS and other GNSS satellite signals. STL is reported to be less susceptible to vulnerabilities such as spoofing, interference and jamming that are associated with GPS/GNSS — and the stronger signal penetrates buildings where GPS/GNSS cannot reach.
Iridium satellite, courtesy Iridium.
Based on the low-Earth orbit (LEO) Iridium satellite constellation, STL signals are up to 1,000 times stronger than GPS/GNSS; this signal strength, due in part to the constellation’s closer proximity to users, helps to prevent jamming and enables signal reach into buildings and other difficult locations. STL’s additional cryptographic security also enhances performance, productivity and security.
Projected key applications and use cases include energy/utility grids, enterprise data networks including financial systems, maritime/aviation navigation, fleet/asset tracking management, search and rescue and data center management.
“The timing signal is very accurate and close enough to GPS for most timing applications, although the positioning accuracy is lower than what GPS users are used to,” said Orolia CTO Jean-Yves Courtois. “It is an augmentation for timing primarily, and secondarily for positioning.”
“In terms of timing accuracy, it provides on the order of tenths of microseconds in accuracy, and this covers a lot of timing applications, very familiar to us and to our customers. This is an ideal timing backup or augmentation of GPS. As number 2 worldwide in high-precision timing, we know this market and its applications very well.”
“In positioning it’s closer to fifty meters or more. Much better for fixed objects than for mobile objects. The more mobile, the faster the vehicle, then the lower the positioning accuracy. It’s not directly usable for GPS applications that require a few meters accuracy, but it can be associated with inertial navigation for much better results.”
“The signal is encrypted, so you have to subscribe to a service to receive a key, allowing access to the signal. Applications are developing based on equipment that will be STL-enabled. For the user it will be transparent. The user will have a different antenna.”
“We are also active in tracking and emergency location devices, where this is also of interest. It has some authentication capability, to guarantee that the person who accesses the signal is in the location that he pretends to be.”
Galileo, live at last!
Also on Dec. 15, the European Commission issued the Galileo Initial Services Declaration. The Declaration of Initial Services means that the Galileo satellites and ground infrastructure are now operationally ready. These signals will be highly accurate but not available all the time, since the constellation is not yet complete and users cannot always count on four satellites being visible at one time at all points on the Earth.
Galileo has a significant role to play in military operations. It adds multiple frequencies to the GNSS palette, important for resistance to jamming. It adds satellites, and will add more in the new future, very important for signal availability. And its Public Regulated Service (PRS) is specifically designed with special features for security, defense and military operations.
I attended a GNSS Symposium recently in Australia where an academic expert repeated the oft-made assertion that Galileo is the only GNSS that is civil-designed and civil-controlled. At which point an industry expert leaned over, grabbed the microphone and growled “Yeah, right.”
No matter how you look at it, Galileo add important benefits to GPS for the suitably equipped warfighter.
This Newsletter Enters a New Era
Beginning in January 2017, this Defense PNT newsletter will combine with our GeoIntelligence Insider e-newsletter to offer broad coverage of both hardware and software matters, driven by GPS/GNSS, and enhancing the capabilities of security, defense, military and other government forces. Readers of both newsletters will receive the new combined edition as a matter of course.
Many readers will know of the recent passing of Don Jewell, the longtime editor of Defense PNT. We must soldier on, and GPS World hereby extends an invitation to readers of this newsletter — many of whom, we know, are military experts in your own right — who may wish to volunteer to fill Don’s position. Please write to [email protected] to request details, and please provide a brief outline of your background and experience.
Pursuant to a recent announcement of new PNT solutions independent of GPS/GNSS signals, provided via the Iridium constellation, GPS World talked with Jean-Yves Courtois, CEO of Orolia. Orolia has partnered with Satelles to bring new PNT products and services to the global market, with a focus on military, and defense, government and commercial customers worldwide.
Jean-Yves Courtois, CEO of Orolia.
“We are a manufacturer and integrator of timing equipment,” Courtois said. Orolia is the parent company of GPS/GNSS product and service providers Spectracom, McMurdo and Spectratime. “This new STL service is not fully commercialized yet, but it’s operational and it can be tested. Receivers are available and can be integrated into our equipment.
“The timing signal is very accurate and close enough to GPS for most timing applications, although the positioning accuracy is lower than what GPS users are used to. It is an augmentation for timing primarily, and secondarily for positioning.
“In terms of timing accuracy, it provides on the order of tenths of microseconds in accuracy, and this covers a lot of timing applications, very familiar to us and to our customers. This is an ideal timing backup or augmentation of GPS. As number 2 worldwide in high-precision timing, we know this market and its applications very well.”
The STL signal strength is much greater than GNSS because the LEO satellites are much closer. (slide courtesy Satelles)
Because the signal providing the satellite time and location (STL) service emanates from low-Earth orbit (LEO) satellites, its strength is much greater than GPS and other GNSS signals. Among its key characteristics: it gets good reception inside buildings and beneath other obstructions.
“The STL signal works very well,” Courtois continued. “We were surprised. Satelles is very conservative in their statements, and we got better results than they promised in our tests. They under-promised and over-delivered. It penetrates buildings well, it has unique features and it performs at a high level. So we decided to invest in it. All our engineers are excited about it!
“In positioning it’s closer to fifty meters or more. Much better for fixed objects than for mobile objects. The more mobile, the faster the vehicle, then the lower the positioning accuracy. It’s not directly usable for GPS applications that require a few meters accuracy, but it can be associated with inertial navigation for much better results.
“The signal is encrypted, so you have to subscribe to a service to receive a key, allowing access to the signal.
“Applications are developing based on equipment that will be STL-enabled. For the user it will be transparent. The user will have a different antenna.
“We are also active in tracking and emergency location devices, where this is also of interest. It has some authentication capability, to guarantee that the person who accesses the signal is in the location that he pretends to be.”
“For customers to be able to use this service, there is some integration work to be done, some dedicated STL receivers to integrate into our current hardware set up, and software modifications. Our engineers are ready, we are all ready to work with government and defense organizations and other new clients.”
“Our basic interest is to add some robustness to our equipment for our current customers, and then of course to develop new customers worldwide.”
“Now that we can rely on the powerful Ariane 5, we can anticipate the quicker completion of Galileo deployment, permitting the system to enter full operation,” said Paul Verhoef, ESA’s Director for the Galileo Programme and Navigation-related Activities, following the successful launch Nov. 17 of four satellites at once.
Verhoef made the following further remarks to GPS World regarding Galileo’s future. The full text of his article will appear in the December issue.
Paul Verhoef, ESA Director Satellite Navigation, at the Kourou launch site to witness Thursday’s liftoff.
“The European Union is set to declare Galileo operational for initial services at the end of this year, bringing the system to the point where it can start serving users.
“November’s launch has been years in the making, employing a specially customized variant of Europe’s heavy-lift workhorse rocket called the Ariane 5 ES (Evolution Storable) Galileo. It has more powerful lower stages and a reignitable upper stage, first used in 2008 to supply the low-Earth orbiting International Space Station.
“Two further Ariane 5 SE Galileo flights are planned to follow, one each for the remaining orbital planes.
Ariane 5 ES on liftoff from Kourou, French Guiana
“This new launcher design, adapted beginning in 2012 for Galileo, carried a lower mass payload — four fully-fuelled 738-kg Galileo satellites plus their supporting dispenser — but hauled it to the much higher altitude of medium-Earth orbit, 23,522 km. This precisely targeted orbit actually lies 300 km above the Galileo constellation’s final working altitude, leaving Ariane’s upper stage in a stable graveyard orbit, while the quartet of satellites maneuver themselves down to their final height.
“The four-satellite dispenser, the interface between the satellites and its launcher, is a wholly new design by Airbus Defence and Space. Its first role is to hold the satellites safely in position during their orbital flight and then to gently release them in separate directions. Its structure has been specially tuned to prevent harmful oscillations being triggered by the vibration and noise of launch. Its design was validated using complex finite -element-modeling software, followed by practical testing of the dispenser together with dummy satellites.
Launcher. “Ariane’s interstage Vehicle Equipment Bay, hosting the rocket’s avionic brain, underwent a redesign to reduce mass. Engineers also had to take into account this Ariane ES version’s flight time, much longer than any of its predecessors, more than four hours in all. This involved a reworking of the launcher’s electronics and thermal subsystems, to ensure it maintains an optimal operational environment throughout a ballistic coast phase of more than three hours, between two firings of its EPS storable propellant upper stage.
Ground Control. “This launch marked the first time that ESA carried out launch and early operations (LEOP) for four satellites simultaneously. Usually, simply shepherding a spacecraft through the first critical days in orbit is a demanding enough task. A combined team from ESA and France’s CNES space agency based in Toulouse will make contact, establish control, and then see the four satellites through their initial critical activities. Within the combined team, each position is paired with a counterpart from the other agency to provide three mixed shifts around the clock for these first crucial days. This same team has conducted all Galileo early operations to date alternately from Toulouse or ESA’s ESOC control center in Germany.
“The work starts with an initial check of on-board health and attitude, progressing to ensure each satellite’s pair of 1 x 5-meter solar wings are deployed and tracking the Sun, and then to point their antennas back towards Earth. Next comes a series of thruster firings to set the satellites onto a drift course into their final orbit, at which point they can be handed over to the Galileo Control Centre in Oberpfaffenhofen, Germany, for routine operations, and to ESA’s Redu Centre in Belgium to commence a few months of detailed payload testing.
Galileo at Your Service
“Around the same time as this key launch, GSAT-210 and GSAT-211, the two previous satellites launched in May of this year, will have completed their in-orbit testing, allowing them to be formally certified as operational members of the constellation. The four new satellites should follow them into operational status by mid-2017. However, the Galileo system will reach initial operational status without these latest six satellites. The European Commission on behalf of the European Union expects to declare the system operational and ready to offer initial services before the end of this year.
“This will mark a major milestone in the programme, awaited by many citizens in Europe and around the globe. Everyone with a Galileo-enabled receiver will be able to benefit from improved positioning, supplementing the already operational GPS constellation. ESA and the European GNSS Agency (GSA) have been working with European manufacturers of mass-market satnav chips and receivers to ensure that their products are Galileo-ready, offering detailed laboratory testing to close the loop between Galileo and industry.
Transition. “In parallel to the declaration of initial services, there will also be an institutional change, as the GSA takes up its role overseeing the exploitation of Galileo. At the start of 2017, the formal handover of Galileo infrastructure will be initiated, targeted to conclude by the middle of the year. This mission includes not only the Galileo satellites in space but also the far-flung ground stations located on every continent, essential to the continued high-performance operations of the Galileo system. It also includes the two European Galileo control centers, with the signals overseen from Fucino in Italy and the platforms monitored from Oberpfaffenhofen, plus the communication infrastructure connecting them all together.
Upgrade. “2017 will see the upgrade of various elements of the Galileo Ground Segment to reinforce its robustness, including updated releases to the Galileo Control Segment overseeing the satellites and the Galileo Mission Segment, overseeing the navigation signals. A new release of elements of the Galileo Security Facility, for security monitoring of the system, as well as the secure Public Regulated Service, will be deployed at the two Galileo Security Monitoring Centres. The Galileo Ground Segment will gain a sixth tracking telemetry and control facility, for monitoring the satellite platforms in Papeete, Tahiti, and additional processing chains for increased redundancy will be deployed across the Uplink Stations in Kourou, Reunion and Noumea used to update the navigation message information. Similar redundant chains will be finalized for all 15 current Galileo Sensor Stations, which perform continuous collection of Galileo signals to identify the tiniest clock error or satellite drift.”
Not with Purple Haze, but with signal interference — although, come to think of it, the two may be not unalike, phenomenologically.
The October reader’s poll asked “Have you directly experienced any of the following? Check all that apply.
GPS/GNSS jamming.
GPS/GNSS spoofing.
Unintentional RF interference.
RF interference from unknown source; unknown whether intentional or not.
None of the above.
Other, please specify.
The answers rather stunned me in their magnitude. To be sure, respondents were self-selected and thus not totally representative of the electorate (you) out there. People who have undergone jamming or spoofing would be much more likely to step forward and say “Yeah, here,” than those who had not would be to fill out an online form, however brief, simply to say “Nah, not me.”
At any rate, the answers came back:
Jamming: 70 percent (70 percent!)
Spoofing: 25 percent
Unintentional RF interference: 55 percent
Unknown RF interference: 65 percent
None of the above: 5 percent
Among the “other” answers we received were these:
I’ve participated in official test activities; Incidents caused by GPS booster (low-cost repeater); We regularly see our vehicle tracking systems jammed or providing incorrect positions believed to be via organised theft using sophisticated jammers; Every time I drive past Newark, NJ on I-95; Badly installed GPS antennas, RF interference from old GPS antennas.
Scanning the affiliations of those answering, the names of organizations actively involved in monitoring or countering jamming and spoofing rise to the top. Still, to get such overwhelming response — only one in 20 was not experienced in this realm — suggests time and energy invested in protections and countermeasures should be doubled, quadrupled or more. Disasters of many kinds loom.
Speaking of disasters, and of our fondness for placing our finger on the pulse of the GNSS/PNT community, we held a mock presidential plebiscite at ION GNSS+ in September. “Who will be the best GPS president?” That is, who would be the best president for GPS, in terms of funding and support? The answers: Clinton 60 percent, Trump 34 percent. The real results may already be known by the time you read this. And, to paraphrase Gerald Ford (something I never thought I’d find myself doing), our long national nightmare may be over.
Soldier-borne sensors, leader-follower cargo-hauling technology and tiny, handheld unmanned aircraft are in the forefront of new technologies planned for U.S. warfighters, according to Maj. Gen. Robert M. “Bo” Dyess. The deputy director of the U.S. Army Capability Integration Center told AUVSI’s Unmanned Systems Defense keynote audience that developing tools and systems demanded by soldiers is key. He cited a recent demonstration exercise, in which soldiers responded enthusiastically to small, backpackable UAS that would let them see over the next hill or fence.
The Army is also developing autonomous ground systems including an unmanned combat vehicle, fully autonomous convoy operations and swarming unmanned aircraft. Autonomous weapons are seen as key in combatting both relatively low-tech guerilla and militia groups as well as high-tech “near-peer” combatants from organized industrial powers. A contested electromagnetic spectrum is emerging as a critical battlefield in the contemporary and future warscape, Dyess said. Cyberspace, racked by fundamental threats of spoofing, jamming and hacking, becomes the new killing ground.
Shad Reese, Tactical Warfare Systems, Unmanned Vehicles coordinator for the Office of the Undersecretary of Defense, said DoD is elaborating a new unmanned systems roadmap, which should be published in the first quarter of 2017. The roadmap will cover the period 2016-2041.
Reese said that a key aspect of the new roadmap is swarming technology, although at present there is little work underway in industry to support this. “Everyone and their mom is talking about swarming, but if you step back and look at what’s going on in industry, there are no real players in industry working on swarming.” Some work is underway in academia, but “we would like to have commercially available swarming technology.”
The Army’s squad mission support transport robot (SMET).
Army’s Ground Robots
The Army has put a robotic vehicle, the squad mission support transport robot (SMET), designed to carry heavy loads for troops, into an accelerated acquisition program. SMET is a 1,000-lb. tracked or wheeled platform carrying rucksacks, water or ammunition. A SMET version was recently tested in Afghanistan.
An Army spokesperson said the SMET has also been chosen as a pilot program a new way to do acquisitions that could shave time off development and fielding of new technologies, with industry involved from the start in specifications and requirements.
Swarms
Hordes of flying, thinking armed robots that autonomously coordinate amongst themselves, altering attack strategies in mid-mission and pushing through to strike targets kamikaze-style, are also seen as critical to future combat. The Air Force Research Laboratory calls the tactical weapons “distributed collaborative systems.”
Three drones work together to beam back information about an enemy’s location, and blocks their radar signals. (Image: DARPA)
The Air Force seeks to put “that next level of decision making and capability on the platform. Not only can it maintain itself, but it can work other parts of the team, whether those be airmen, or whether those be other machines to perform a mission task.”
Swarming micro-drones can be “really fast, really resistant. They can fly through heavy winds and be kicked out the back of a fighter jet moving at Mach 0.9, like they did during an operational exercise in Alaska last year, or they can be thrown into the air by a soldier in the middle of the Iraqi desert.”
“Swarming is a way to gain the effect of greater intelligence without each individual unit needing to be intelligent,” added one strategist. Last year Gen. Ellen Pawlikowski, commander of the Air Force Material Command, called swarming drones “very much a game-changing reality for our Air Force in the future.”
One consultant added that a human operator may not be able to compete with a fully autonomous system that identifies, analyzes and geolocates a target, especially in such a scenario where the swarm is moving rapidly. “The power and the sheer speed of execution would give them a huge advantage over their adversaries.”
Kristen Kearns, autonomy portfolio lead at AFRL, said that a major challenge with any autonomous system is verifying and validating that the decisions it is making are correct. Trust, or “verification and validation,” becomes paramount with artificial intelligence, Kearns added. “How do we assure safe and effective operations when we put decision making in the platforms?”
Steve Walker, deputy director of DARPA, said his agency has been working on developing battle management systems with a blend of manned and unmanned vehicles. “You have humans and unmanned systems and you need data fused together quickly and things are happening fast and you don’t want to overload the human with all that information. … You want to give him or her exactly what he needs to make a decision and have all these distributed effects work together,” he said.
One official noted the presence of many YouTube videos demonstrating robots flying, sailing or moving in formation. “It’s a good illustration of how so much of the advancement in this space is happening outside the defense world.”
Two workshops convened in recent weeks in the U.S. and Canadian capitals, respectively, sought to bring into focus looming threats to the nations’ positioning, navigation and timing capabilities and critical infrastructures. Some of the threats are pervasive — jamming and spoofing — and formed the general topic of the Canadian workshop. Some threats are specific — powerful terrestrial transmitters overwhelming GPS/GNSS receivers — and occasioned the U.S. gathering.
Canada. In a first for Canada, the October 21 GNSS Vulnerabilities Innovation Policy (VIP) Workshop brought together 19 federal government departments as well as provincial and municipal agencies and private sector companies. U.S. State Dept. and Homeland Security gave presentations, as did the European Space Agency, Bell Canada, NovAtel and Spirent Communications.
Integrity challenge for automotive positioning, presented by NovAtel
The workshop was sponsored by the the Federal Global Navigation Satellite Systems Coordination Board (FGCB), a government board with representations from various government departments and agencies. The GNSS Coordination Office (which organized the workshop) is hosted at Canada’s Ministry of Innovation, Science and Economic Development and sponsored by the FGCB members.
Presentations covered such topics as Demonstration of the Geolocation of GPS Jammers, GNSS & the Telecom Sector, Detecting and Protecting Against GPS Cyberthreats, and Safety Critical, High Precision, GNSS Positioning for Autonomous Vehicles.
United States. The U.S. Department of Transportation (DOT) hosted its fifth workshop on the GPS Adjacent-Band Compatibility Assessment effort on October 14. This lengthy, thorny and occasionally acrimonious process started out benignly enough in 2010 with the statement, “Demand for commercial spectrum to support broadband wireless communications has led the government to consider repurposing various radio frequencies, including the satellite communications bands next to GPS.”
The workshop discussed the results from testing of various categories of GPS/GNSS receivers including aviation (non-certified), cellular, general location/navigation, high precision and networks, timing, and space-based receivers. The workshop also included a discussion on the development of use-case scenarios for these categories — which is where the going got heavy and differences of opinion truly emerged.
The furor stems from a renewed effort by Ligado, formerly known as LightSquared and now re-emergent from a 2-year bankruptcy process, to convert relatively inexpensive satellite-to-earth spectrum into very valuable terrestrial spectrum. The company stands to gain billions of dollars and secured rights from the process.
Members of the DoT team presented the first results from the GPS Adjacent-Band Compatibility (ABC) Assessment, an effort to determine the power limits by frequency, or interference tolerance masks (ITM), needed to protect both existing and future GPS receivers. Test results indicated a need to limit interfering signals at different levels depending on the type of receiver being used. 80 receivers in six categories were tested: cellular, general location/navigation, general aviation, timing, high precision and space receivers. Certified and military receivers are undergoing separate tests.
The tests of current receivers took place April 25–29 at White Sands Missile Range, New Mexico, using a 100 x 70 x 40 anechoic chamber. The signals used in the test included GPS L1 C/A-code, GPS L1 P-code, GPS L1C, GPS L1 M-code, GPS L2 P-code, SBAS L1, GLONASS L1 C, GLONASS L1 P, BeiDou B1I and Galileo E1 B/C. Tests were conducted within 100 megahertz on either side of the GPS L1 center frequency of 1575.42 using a 10-megahertz LTE signal and a narrow bandwidth 1-megahertz bandpass white noise signal.
The tests were conducted for GPS and GNSS receivers processing signals in the 1559–1610 MHz Radionavigation Satellite Service (RNSS) frequency band, as well as receivers that process Mobile Satellite Service (MSS) signals in the 1525–1559 MHz band to receive differential GNSS corrections.
The tests determined the power levels at which each device experienced a one-decibel degradation in the carrier-to-noise density ratio (CNR) at a particular frequency. The DoT team graphed results for each device. The recommended power limits were the lowest in frequencies closest to the GPS bands.
The receivers most affected by the test transmissions were identified as high-precision receivers. They experienced interference at power levels as low as –90 to –95dBm at around 1550 MHz and –90 dBm at roughly 1610 MHz.
The strictest limit for both the general aviation, general navigation/location, and timing receivers was a little below –80 dBm at about 1550 MHz, while space-based receivers were equally sensitive on both sides of the RNSS band with the toughest limit being about –85 dBm.
FAA. The Federal Aviation Administration (FAA) has authority to set power and out-of-band emissions limits to meet aviation safety standards, and it had been thought that these limits might address interference with other types of receivers as well. But the test results showed that “protecting the FAA-certified mask does not necessarily protect the rest of the receiver categories,” according to Hadi Wassaf, technical lead for GPS interference analysis at DoT’s Volpe Center.
Use Cases. Ligado has proposed that position error as experienced by the user is a better guide to interference levels than degradation in the carrier-to-noise density ratio. The GPS community generally opposes this approach. The next step is the development of use cases. According to the test plan, use cases define the regions of operations for a receiver, and they identify applications that “that are vital to economic, public safety, scientific, and/or national security needs and any other factors supporting why this particular receiver model is important to be tested (e.g., quantity in use, economic impact, etc.).”
In the exercise, the Thales Watchkeeper looks seaward, spotting passing ships and feeding data to headquarters vessel MV Northern River in the Irish Sea. (Photo: Royal Navy)
Unmanned Warrior 2016, the largest exercise for marine unmanned vehicles, is underway in the North Atlantic, off the coast of Scotland. The U.K. Navy hosts the event, and the U.S. Navy’s Office of Naval Research is a key participant.
The exercise will test many teamed technologies, including ONR’s lidar package for SeaHunter unmanned aerial vehicle. Researchers will evaluate the ability of different systems to communicate and operate as a unified force.
“These systems can help protect our Sailors and Marines from some of the Navy’s dull, dirty and dangerous missions, like mine countermeasures . . . Additionally, these systems can increase our capabilities at a more affordable cost of the conventional systems we currently employ,” said Chief of Naval Research Rear Adm. Mat Winter. “Autonomy will enable our naval forces to stay longer, see farther, understand more, decide faster, do more, adapt more quickly and when necessary be more lethal.”
Mine-hunting robots will be deployed on a test range set up by U.K defense contractor QinetiQ in one set of exercises, to compare their performance with those of crewed U.K. Navy minehunters. Remotely piloted submarines are already routinely employed in manned mine-hunting, but the exercise seeks to find if matters can be taken a stage further.
Unmanned vehicles are supplied by Thales, Seebyte and BAEwill participate.
Unmanned Warrior is part of Joint Warrior, a twice-yearly NATO naval exercise. Nearly 6,000 personnel, more than 30 warships and 70 aircraft will participate in joint maneuvers off Scotland during the drill.
With great sadness we report that Don Jewell passed away unexpectedly on October 12. For more than nine years Don wrote the Defense PNT monthly e-newsletter column for GPS World, after a distinguished career in the U.S. Air Force, retiring as Deputy Chief Scientist for Air Force Space Command with the rank of Lieutenant Colonel. A service of remembrance and celebration of his life was held on October 20 in Colorado Springs, Colorado.
The December issue of GPS World magazine will carry a fuller remembrance and appreciation of Don Jewell, and it will subsequently appear online. Readers and friends may send memories and appreciations of Don to be included in an online tribute page, to [email protected].
Contributions in his memory may be made to Christ the King Lutheran Church, where he was recently elected president, or to the Amyloidosis Foundation.
Geonumerics reported a mapping benchmark achieved in June 2016: operation of a tandem aerial-terrestrial system conceived for simultaneous geodata acquisition in corridor mapping missions.
The mapKITE system tests were carried out at the BCN Drone Center on 2,500 hectares of segregated airspace outside Barcelona. A 2-kilometer rural road served as a testing corridor and was operated successfully around ten times. The testing site was prepared with several ground control points for quality checking.
Kinematic ground control point enables tandem ground-air mapping via sensor orientation and calibration.
Tethering the UAS to the terrestrial vehicle. By means of a real-time navigation system, the terrestrial vehicle generates the basic source information for generating waypoints to be followed by the aerial platform. Schematically, for every terrestrial position, a geometrical shift is applied to keep a particular relative air-ground geometry. A “follow-me” scheme keeps the UAV coordinated as the vehicle moves; the tether is set to maintain a constant relative speed. Additionally, the ground vehicle is observed in most of the aerial images.
Top, left and right: mapKITE aerial images from the corridor flown at the BCN Drone Center (June, 2016); bottom: 3D model extracted from aerial images only.
Linking the two with an optical target. An optical coded target on the roof of the ground vehicle is automatically identified and measured in the aerial images in a fast and robust manner. Its goal is twofold: firstly, it enables a complementary guidance scheme based on target-tracking, adding robustness to the virtual tether. Secondly, the image measurement of the optical target together with the high-quality trajectory of the ground vehicle introduces a kinematic ground control for a posteriori sensor orientation and calibration.
By performing photogrametric pointing-and-scaling measurements of the optical target, and linking these with the precise terrestrial vehicle trajectory by means of image synchronization in a common time reference, mapKITE introduces an analogy to the conventional ground control points (GCPs) ready-to-use kinematic ground control points (KGCPs) for every image.
Equipment used in the first mapKITE campaign
Fundamental mission parameters
Aerial camera
Sony NEX-5 (c=20mm)
Gruond Sampling Distance
2,4 cm
GNSS receiver (UA)
Javad TRE-3
Flying altitude
100 m
TV navigation system
Applanix POS-LV420
Forward image overlap
80%
TMM system
Optech Lynx
Image footprint
120 m across-track
More information can be found in the following material:
• download the PDF mapKITE brochure with more information about the test campaign.
• The video of the mapKITE test campaign explains the system and the performance test.
GeoNumerics is a research and development company specializing in geomatics and accurate navigation, located in Catalonia, Spain. The company licenses software and provides R&D services focused on applications of unmanned aircraft, Galileo satellite navigation and inertial navigation in remote sensing and mapping.
Point cloud obtained with the terrestrial mobile mapping system.
MapKITE is currently being developed by an international consortium within the frame of the project “mapKITE: EGNOS-GPS/GALILEO-based high-resolution terrestrial-aerial sensing system“. The project is funded by the European Commission (EC) through the European Union (EU) “Horizon 2020 Programme for Research and Innovation,” supervised by the GSA on behalf of the EC, and coordinated by GeoNumerics. The mapKITE consortium includes ten organizations from five European countries and Brazil.
The plenary talk by John O’Keefe at ION GNSS+ stimulated a lot of neuron firing inside this old noggin. For a synopsis of “The Positioning System of the Brain,” see this column by Managing Editor Tracy Cozzens. I had the difficult task of following this brilliant scientist to the podium and introducing ION’s track chairs for previews of the conference’s technical content. Here’s how I attempted to stitch together the two parts of the evening program.
Dr. O’Keefe’s talk called two things powerfully to my mind. The first is us, here, now. In the Oregon Convention Center, where we have gathered four times before. How do we remember its hallways, spaces, electronic stairways? What will direct us to technical sessions over the next three days? Our neural system enables us to orient within an environment, to navigate from one place to another and to remember spatial information. I’ve always struggled to understand aspects and workings of memory. Now to find that place is a key driver, that’s powerful.
The second thing it called to mind is a book I read forty years ago, that has lingered with me since. In Cheyenne Autumn, Mari Sandoz evokes the Native American precursive sense of place. Both past and future exist simultaneously in the present. When the nomadic tribe on their annual migration cycle rode to their summer hunting grounds or through their autumn passages, the events in their past that took place in those areas became very much alive in their awareness. And the figures from their history spoke to them and rode with them through the sandhills, ravines and river crossings of Nebraska and Wyoming.
In their tragic 1878 outbreak for freedom, the Cheyenne eluded the technological might of the U.S. Army sent to intercept them. They did so through their multisensory connection, through memory, to place and direction. Though ultimately defeated, they left us a legacy, an awareness, a state of mind to nurture: understanding memory — with place. And understanding place — with memory.
These columns have focused on procedures and routines for establishing GNSS-derived orthometric heights. There are many ways to analyze and investigate GNSS data and adjustment results. I have provided some basic concepts that I believe are important for users to understand.
The selection of constraints is a very important part of establishing accurate and consistent NAVD 88 GNSS-derived orthometric heights. All of the analysis and recommendations have been based on using the National Geodetic Survey‘s latest scientific geoid model.
I recommend first performing the analysis using the scientific geoid model because the hybrid geoid model has been warped to be consistent with the published NAVD 88 values. However, as mentioned in Part 7 (June 2016), in practice, GNSS-derived orthometric heights are incorporated into the NAVD 88 using the latest hybrid geoid model GEOID12B. This column will focus on the NGS “GPS on BMS (GPSBM)” dataset that was used to create the hybrid geoid model.
As mentioned in Part 3 (October 2015), the hybrid geoid model is designed to fit the published NAVD 88 leveling-derived orthometric heights. Saying that, the GPSBM dataset can be used to identify potential issues in the NAVD 88 published orthometric heights. GNSS users should be familiar with this dataset and how it can be used in their analysis. This column will provide tools and routines that can be used to identify potential issues in NAVD 88 heights and/or NAD83 (2011) published ellipsoid heights.
Each of the below regions uses variants of the NAD 83 reference frame and a local vertical datum. Several versions of NAD 83 exist conforming to significant plates: Pacific, Mariana, and North America. Likewise, each region has its own vertical datum. It is not possible to level across water, so islands will have selected a tide gauge to serve as the local datum point and all leveling is tied to that site. The only exception to this is Hawaii. No tide gauge was selected in the Hawaiian Islands and no vertical datum has been established as of yet. Hence, GEOID12B in Hawaii transforms between NAD 83 (PA11) and the same geopotential (geoid) surface as the USGG2012 model ( W0 = 62636856.00 m**2/s**2).
Items that are listed in the below table include the final GPSBM files for each region as both Excel spreadsheets and text files as well as thumbnail images linked to larger images showing the distribution of the GPSBM’s. Alaska and the island regions are more consistent, so not many points were dropped and each is provided in its own spreadsheet/text file and identified with the appropriate ellipsoidal reference frame and level datum (see below).
The most significant work occurred in the COnterminous United States (CONUS). For CONUS, there were 24,782 points with 911 rejected leaving 23,961. These were supplemented from the OPUS-database with 737 points of which 238 were rejected leaving 499. There were also 579 points in Canada with 5 rejected leaving 574. In Mexico, there 744 of which 497 were clipped since they were too far south and another 70 were rejected leaving 177. This brings a total of 26,932 points of which 1,721 were rejected or clipped and 25,211 retained for modeling GEOID12B. The data in Canada and Mexico provide continuity up to and across the U.S. borders but do not make the GEOID12B model valid in those countries.
Points were rejected either because the State Advisor recommended it be dropped (e.g., known subsidence region), the residual ellipsoid height errors (from the NA2011 project) indicated a point was too noisy in comparison to other points in a state/region, the orthometric height was suspect, or the residual errors during geoid modeling were too high. The corresponding error flags are ‘S’, ‘h’, ‘H’, and ‘N’ as seen on the spreadsheet and text files. These points then represent the control data that were used to define the transformation between NAD 83 and NAVD 88 for CONUS.
The control data were much simpler in other regions due to the lack of quantity (more than two orders of magnitude less). Data in these regions follows a similar pattern where some data are rejected based on the codes given above for CONUS. The columns on the right side give the respective datums realized by GEOID12B for each region.
Table 1 is an excerpt of the excel spreadsheet for the GPSBM dataset and provides a sample of the contents. The headings of the columns are fairly self-explanatory. What’s important here is that the excel spreadsheet provides the name, latitude, longitude, NGS’ PID, the ellipsoid height and orthometric height of the stations used in making GEOID12B.
Table 1
Excerpt of the Excel spreadsheet for GPS on benchmarks (GPSBM) used to make GEOID12B.
The “GPS On Bench Marks (GPSBM) Used To Make GEOID12B” write up states that 1,721 stations were rejected and were not used in developing the hybrid geoid model. It also states that for the conterminous United States (CONUS), there were 24,782 stations with 911 rejected leaving 23,961. This column is going to focus on CONUS but the analysis can be performed everywhere.
As the write up states, stations were rejected for four different reasons:
Code h – The residual ellipsoid height errors from the NAD 83 (2011) project indicated that the point was too noisy,
Code H – The orthometric height was suspect,
Code N – The residual errors during geoid modeling were too high.
These rejected stations were not used to make the hybrid geoid model but since the hybrid geoid model is distorted to fit the NAVD 88, these rejected stations as well as stations nearby the rejected stations should be re-evaluated using the latest scientific geoid model, e.g. xGeoid16b.
So, what should the user do with the GPSBM table? I recommend that users perform the following steps when analyzing the stations in the GPSBM table.
Step 1: Compare the modeled GEOID12B (N12B) value to the computed GPS/Leveling (h minus H) value using the following formula: Published N12B from the NGS data sheet minus (ellipsoid height from the GPSBM table minus orthometric height from the GPSBM table). We discussed this procedure a year ago in Part 3 (October 2015). It should be noted that the orthometric height in the GPSBM table may be different than the published NAVD 88 height on the NGS data sheet if the station has been readjusted since the GPSBM table was created.
Step 2: Repeat the procedure in Step 1 using the latest NGS experimental geoid model, e.g. xGeoid16b. At this time, NGS only provides the experimental geoid models referenced to IGS08 so the user will have to use NGS’ xGeoid16 web tool to obtain the station’s IGS08 ellipsoid height and xGeoid16b value. The input to the tool is the station’s NAD 83 (2011) coordinates (latitude, Longitude, and ellipsoid height). [An example of using the xGeoid16 web tool is provided in the box titled “Example of Using NGS xGeoid16 Web Tool.”] As discussed in Part 3 (October 2015), the user will have to remove a bias and trend based on the differences in the region.
The user could also transform xGeoid16b/IGS08 geoid values to xGeoid16b/NAD 83 (2011) geoid values using their own tools, and then remove a bias and trend based on the differences. Michael Dennis, a PhD candidate at Oregon State University, created an ArcGIS raster of the xGeoid16b model, where his model has been referenced to NAD 83 (Michael L. Dennis, RLS, PE, MS Civil Eng., Geodetic Analysis, LLC, 55 Creek Rock Road, Sedona, AZ 86351). He removed a trend using the GPS/Leveling data set as input; therefore, this raster file is a form of a hybrid geoid model distorted only to remove the tilt assumed to be in the NAVD 88. I will refer to this model as Geoid16B_NAD83 to avoid confusion with NGS’ xGeoid16b model.
*Orthometric height difference between xGEOID16B to model shown
Step 3: Use the station’s data sheet to identify how the station’s orthometric height was determined; for example, was it rigorously adjusted into the NAVD 88 (published height attribute – Adjusted). We discussed the attributes of the NGS data sheet in Part 5 (February 2016). A summary of the attributes from the NGS data sheet DSDATA.TXT file is provided in the box titled “Extracted from NGS’ DSDATA.TXT.” I have highlighted the most common attributes of the stations involved in making GEOID12B.
Extracted from NGS’ DSDATA.TXT
***************************************************************************
* dsdata.txt *
***************************************************************************
There are various Vertical Control sources, as specified below:ADJUSTED = Direct Digital Output from Least Squares Adjustment of Precise Leveling.
(Rounded to 3 decimal places.)ADJ UNCH = Manually Entered (and NOT verified) Output of Least Squares Adjustment of Precise Leveling.
(Rounded to 3 decimal places.)
POSTED = Pre-1991 Precise Leveling Adjusted to the NAVD 88 Network After Completion of the NAVD 88 General Adjustment of 1991.
(Rounded to 3 decimal places.)
READJUST = Precise Leveling Readjusted as Required by Crustal Motion or Other Cause.
(Rounded to 2 decimal places.)
N HEIGHT = Computed from Precise Leveling Connected at Only One Published Bench Mark.
(Rounded to 2 decimal places.)
RESET = Reset Computation of Precise Leveling.
(Rounded to 2 decimal places.)
COMPUTED = Computed from Precise Leveling Using Non-rigorous Adjustment Technique.
(Rounded to 2 decimal places.)
GPSCONLV = Leveled Orthometric Height tied to GPS HT_MOD Orthometric Height.
(Rounded to 2 decimal places.)
LEVELING = Precise Leveling Performed by Horizontal Field Party.
(Rounded to 2 decimal places.)
H LEVEL = Level between control points not connected to bench mark.
(Rounded to 1 decimal places.)
GPS OBS = Computed from GPS Observations.
(Rounded to 1 decimal places.)
VERT ANG = Computed from Vertical Angle Observations.
(Rounded to 1 decimal place; If No Check, to 0 decimal places.)
SCALED = Scaled from a Topographic Map.
(Rounded to 0 decimal places.)
U HEIGHT = Unvalidated height from precise leveling connected at only one NSRS point.
(Rounded to 2 decimal places.)
VERTCON = The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height.
(Rounded to 0 decimal places.)
Step 4: Use the station’s NGS data sheet to determine the adjustment date of the station’s published NAVD 88 orthometric height. We discussed this in Part 7 (June 2016). As mentioned in Part 7, if the station has a different adjustment date than other stations nearby, there could be inconsistencies due to adjustment distribution corrections and/or movement.
Step 1 was demonstrated in Part 3 (October 2015) so we don’t need to describe the process in this column. Comparing published GEOID12B values with computed values is the first step; the difference is an indication of how well the data fit the model and can be useful for identifying large outliers. It can be helpful in prioritizing where additional observation should be obtained when there are limited resources. Provided below is an example of where to obtain the information for comparing the modeled GEOID12B (N12B) value to the computed GPS/Leveling (h minus H) value using the following formula: Published N12B from the NGS data sheet minus (ellipsoid height from the GPSBM table minus orthometric height from the GPSBM table). The user can obtain the GEOID12B value from the NGS data sheet [see box titled “Excerpt from NGS Data Sheet For Station L 275 (HW2088)”]; for this example, the GEOID12B value for station L 275 is -30.813 m. Table 2 is an excerpt from the GPSBM file that contains the ellipsoid height (599.253 m) and the orthometric height (630.016 m) for station L 275. It should be noted that the ellipsoid and orthometric heights in the GPSBM table are given in millimeters. The first row of table 3 provides the results of the computation: [-30814 mm – (599253 mm – 630016m m) = 51 mm], or 5.1 cm.
Table 2
Excerpt of the Excel spreadsheet for GPS on benchmarks (GPSBM) used to make GEOID12B – Stations on plots in this column.
Excerpt from NGS Data Sheet For Station L 275 (HW2088)
PROGRAM = datasheet95, VERSION = 8.9.1
1 National Geodetic Survey, Retrieval Date = OCTOBER 1, 2016
HW2088 ***********************************************************************
HW2088 CBN – This is a Cooperative Base Network Control Station.
HW2088 DESIGNATION – L 275
HW2088 PID – HW2088
HW2088 STATE/COUNTY- WV/RANDOLPH
HW2088 COUNTRY – US
HW2088 USGS QUAD – MILL CREEK (1995)
HW2088
HW2088 *CURRENT SURVEY CONTROL
HW2088 ______________________________________________________________________
HW2088* NAD 83(2011) POSITION- 38 43 54.95105(N) 079 58 19.75931(W) ADJUSTED
HW2088* NAD 83(2011) ELLIP HT- 599.253 (meters) (06/27/12) ADJUSTED
HW2088* NAD 83(2011) EPOCH – 2010.00
HW2088* NAVD 88 ORTHO HEIGHT – 630.016 (meters) 2066.98 (feet) ADJUSTED
HW2088 ______________________________________________________________________
HW2088 NAD 83(2011) X – 867,581.099 (meters) COMP
HW2088 NAD 83(2011) Y – -4,906,352.726 (meters) COMP
HW2088 NAD 83(2011) Z – 3,969,521.039 (meters) COMP
HW2088 LAPLACE CORR – 0.13 (seconds) DEFLEC12B
HW2088 GEOID HEIGHT – -30.814 (meters) GEOID12B
HW2088 DYNAMIC HEIGHT – 629.553 (meters) 2065.46 (feet) COMP
HW2088 MODELED GRAVITY – 979,873.5 (mgal) NAVD 88
HW2088
HW2088 VERT ORDER – FIRST CLASS II
HW2088
HW2088 Network accuracy estimates per FGDC Geospatial Positioning Accuracy
HW2088 Standards:
HW2088 FGDC (95% conf, cm) Standard deviation (cm) CorrNE
HW2088 Horiz Ellip SD_N SD_E SD_h (unitless)
HW2088 ——————————————————————-
HW2088 NETWORK 1.00 1.94 0.45 0.36 0.99 -0.05669181
Table 3 contains the comparisons between modeled geoid values and their computed geoid values for five station pairs that have large relative differences. Looking at table 3 one can see that there are several large relative differences between the published GEOID12B model and computed geoid model (see column titled “N12B minus (h-H)” in table 3). This doesn’t mean that the model is incorrect, it only means that there were large relative differences that the model had to account for. As previously mentioned, GEOID12B was created to be consistent with the NAVD 88.
Since the experimental geoid model xGeoid16b_NAD is not distorted to conform to the NAVD 88 everywhere, it should provide better information for identifying outliers and determining which stations appear to be inconsistent with its neighbors.
Figure 1 – All GPS on BMS Residuals Using Geoid16b_NAD model (note: rejections by geoid team have been removed).
Table 3
Table of selected stations involving large relative differences depicted in plots in this column.
(Results are provided for GEOID12B and Geoid16B_NAD Models*) *Michael Dennis, a Ph.D. candidate at Oregon State University, created the xGEOID16B ArcGIS raster, where the model has been referenced to NAD 83 with a trend and bias added to account for the apparent tilt in the NAVD 88. This model is denoted as Geoid16B_NAD (N16b) in this column.
Figure 1 is a plot of all of the GPSBM residuals using the Geoid16B_NAD83 model. This plot indicates that there are a lot of large residuals. First, let’s define what I’m calling residuals. The residuals on my plots are the differences between the modeled geoid height value and the computed geoid height value using the ellipsoid height (h) and orthometric height (H) from the GPSBM data set; that is, residual = modeled gravity value – (h minus H). The largest negative residual is -37.3 cm and the largest positive residual is 33.8 cm.
Figure 2 – Positive GPS on BMS Residuals Using Geoid16b_NAD model (note: rejections by geoid team have been removed).
Figure 2 is a plot of the positive GPS on BMS residuals using Geoid16b_NAD geoid model. There are 5957 residuals greater than 5 cm (not including the stations rejected by the NGS geoid team). As you can see, it appears that most of the positive residuals are on the eastern half of the United States.
Figure 3 – Negative GPS on BMS Residuals Using Geoid16b_NAD model (note: rejections by geoid team have been removed).
Figure 3 is a plot of the negative GPS on BMS residuals using Geoid16b_NAD geoid model. There are 4113 residuals less than -5 cm (not including the stations rejected by the NGS geoid team). As you can see from the plot, the negative residuals appear to be more evenly distributed across the United States than the positive residuals. It does, however, appear that there are more negative residuals greater than -5 cm along the Gulf Coast, Atlantic Coast, and the Great Lakes than there are positive residuals greater than 5 cm. In addition, there appears to be a lot of negative residuals in the northeastern United States.
Figure 4 – GPS on BMS Residuals Using Geoid16b_NAD model in North Carolina and South Carolina (note: rejections by geoid team have been removed).
Figure 4 is a plot of the GPS on BMS residuals using the Geoid16b_NAD geoid model in the North Carolina and South Carolina border region. What’s interesting about this plot is that South Carolina doesn’t seem to have many negative residuals where North Carolina has both negative and positive residuals. We will look at this in more detail later in this column.
Figure 5 – GPS on BMS Residuals Using Geoid16b_NAD model in Washington and Oregon Region (note: rejections by geoid team have been removed).
Figure 5 is a plot of the GPS on BMS residuals using Geoid16b_NAD model in the Washington and Oregon Region. This graphic shows some large grouping of negative and positive residuals, especially along the Pacific Coast in Northwestern Washington State.
Now, let’s look at some large relative differences in residuals between stations that are spatially close together. Figure 6 is a plot of large relative differences between groups of GPS on BMS residuals (using Geoid16b_NAD model) at the North Carolina/South Carolina border. In figure 6, two stations (FA1337 and FA1560) are about 20 km apart and the difference in residuals is -18.6 cm (-12.4 cm minus 6.2 cm). This is a large difference for only 20 km. What is even more significant is that the group of stations near FA1337 are all negative residuals (around -10 cm) and the group of stations near FA1560 are all positive residuals (around 6 cm), this could be an indication of a large distribution correction due to the NAVD 88 design. We discussed the distribution correction in Part 7 (June 2016). These stations definitely needs to be investigated.
The next step in my process is to look at the NGS data sheets for these stations to determine how the stations were adjusted.
Step 3: Look at the station’s data sheet to identify how the station’s orthometric height was determined; for example, was it rigorously adjusted into the NAVD 88 (published height attribute is “Adjusted”) or was it determined by precise leveling performed by horizontal field party (published height attribute is “Leveling”).
The data sheet for station FA1337 states that the NAVD 88 attribute code is “GPS OBS.” [See box titled “Excerpt from NGS Data Sheet for PID FA1337.”] The data sheet for FA1560 states that the NAVD 88 attribute code is “Adjusted.” The orthometric height on the GPSBM file is different than the current published NAVD 88 orthometric height for station FA1337 (See table 3). This station’s leveling-derived orthometric height was superseded by a GNSS-derived orthometric height. Saying that, the GPSBM file only uses leveling-derived orthometric heights; therefore, stations that have been superseded by GNSS surveys are still included in the GPSBM file but their original published leveling-derived height is used for the analysis. Table 3 provides the orthometric height for FA1337 that was used in making GEOID12B. As previously mentioned, stations may be rejected by the geoid team based on the criteria outlined in the beginning of this column. Saying that, neither of the two stations were rejected by the NGS geoid team. This implies that the stations were consistent with their neighbors as far as the geoid model was concerned. Figure 6 confirms that all the stations around FA1337 and FA1560 are consistent with each other based on the Geoid16b_NAD geoid model. The fact that the two groups differ by 18 6 cm needs to be investigated.
Excerpt from NGS Data Sheet for PID FA1337
PROGRAM = datasheet95, VERSION = 8.9.1
1 National Geodetic Survey, Retrieval Date = OCTOBER 3, 2016
FA1337 ***********************************************************************
FA1337 HT_MOD – This is a Height Modernization Survey Station.
FA1337 DESIGNATION – RU 36
FA1337 PID – FA1337
FA1337 STATE/COUNTY- NC/RUTHERFORD
FA1337 COUNTRY – US
FA1337 USGS QUAD – FOREST CITY (1993)
FA1337
FA1337 *CURRENT SURVEY CONTROL
FA1337 ______________________________________________________________________
FA1337* NAD 83(2011) POSITION- 35 18 08.14237(N) 081 51 17.93516(W) ADJUSTED
FA1337* NAD 83(2011) ELLIP HT- 249.869 (meters) (06/27/12) ADJUSTED
FA1337* NAD 83(2011) EPOCH – 2010.00
FA1337* NAVD 88 ORTHO HEIGHT – 281.79 (meters) 924.5 (feet) GPS OBS
FA1337 ______________________________________________________________________
Figure 6 – GPS on BMS Residuals: Large Relative Differences Between a Group of Stations at the North Carolina/South Carolina Border (note: rejections by geoid team have been removed)
Figure 7 is a plot of the GPS on BMS residuals using Geoid16b_NAD that depicts a large difference between two stations only 20 km apart near the Maryland/West Virginia border. I will use this station pair to demonstrate the next step in my process.
Step 4 is to use the station’s NGS data sheet to determine the adjustment date the of station’s published NAVD 88 orthometric height.
The NAVD 88 attribute on the NGS data sheet states that both of these stations are coded as “Adjusted” but station JW0639 adjustment date is April 1995 (see box titled “excerpt from NGS Data Sheet for PID JW0639”) and JW1296 adjustment date was in June 1991 (the General Adjustment of NAVD 88). These large relative differences could be due to inconsistencies between adjusted heights due to the adjustment distribution corrections and/or constraints imposed in the April 1995 adjustment. Bench marks near the stations should be observed to determine if the same large relative difference exists, and the 1995 NAVD 88 adjustment project report should be reviewed to determine if a large distribution correction was applied.
Excerpt from NGS Data Sheet for PID JW0639
1 National Geodetic Survey, Retrieval Date = OCTOBER 3, 2016
JW0639 ***********************************************************************
JW0639 CBN – This is a Cooperative Base Network Control Station.
JW0639 DESIGNATION – J 17 RESET
JW0639 PID – JW0639
JW0639 STATE/COUNTY- MD/GARRETT
JW0639 COUNTRY – US
JW0639 USGS QUAD – ACCIDENT (1994)
JW0639
JW0639 *CURRENT SURVEY CONTROL
JW0639 ______________________________________________________________________
JW0639* NAD 83(2011) POSITION- 39 37 53.59739(N) 079 18 57.44776(W) ADJUSTED
JW0639* NAD 83(2011) ELLIP HT- 701.266 (meters) (06/27/12) ADJUSTED
JW0639* NAD 83(2011) EPOCH – 2010.00
JW0639* NAVD 88 ORTHO HEIGHT – 732.713 (meters) 2403.91 (feet) ADJUSTED
JW0639 ______________________________________________________________________
*
*
*
JW0639
JW0639.The orthometric height was determined by differential leveling and
JW0639.adjusted by the NATIONAL GEODETIC SURVEY
JW0639.in April 1995.
JW0639
Figure 7 – GPS on BMS Residuals Using Geoid16b_NAD: Large Relative Difference Between Stations About 20 km Apart Along MD/WV Border (note: rejections by geoid team have been removed).Figure 8 – GPS on BMS Residuals Using Geoid16b_NAD: Large relative Difference Between Stations 15 km Apart in Randolph County, West Virginia (note: rejections by geoid team have been removed).
Figure 8 is a plot of GPS on BMS residuals using Geoid16b_NAD that depicts a large relative difference between stations 15 km apart in Randolph County, West Virginia. This plot involves station HW3677 which has a published NAVD 88 attribute of “Leveling.” (See box titled “Excerpt from NGS Data Sheet for PID HW3677.”) The excerpt from the data sheet has the following statement: “The orthometric height was determined by differential leveling. The vertical network tie was performed by a horz. field party for horz. obs reductions. Reset procedures were used to establish the elevation.”
It would be useful if stations near this station were observed by GNSS surveys to determine what is occurring in this region.
Excerpt from NGS Data Sheet for PID HW3677
1 National Geodetic Survey, Retrieval Date = OCTOBER 2, 2016
HW3677 ***********************************************************************
HW3677 DESIGNATION – GPS 1
HW3677 PID – HW3677
HW3677 STATE/COUNTY- WV/RANDOLPH
HW3677 COUNTRY – US
HW3677 USGS QUAD – MILL CREEK (1995)
HW3677
HW3677 *CURRENT SURVEY CONTROL
HW3677 ______________________________________________________________________
HW3677* NAD 83(2011) POSITION- 38 37 50.21531(N) 079 55 29.64175(W) ADJUSTED
HW3677* NAD 83(2011) ELLIP HT- 1129.355 (meters) (06/27/12) ADJUSTED
HW3677* NAD 83(2011) EPOCH – 2010.00
HW3677* NAVD 88 ORTHO HEIGHT – 1159.91 (meters) 3805.5 (feet) LEVELING
HW3677 ______________________________________________________________________
*
*
*
*
HW3677 HW3677.The orthometric height was determined by differential leveling.
HW3677.The vertical network tie was performed by a horz. field party for horz.
HW3677.obs reductions. Reset procedures were used to establish the elevation.
HW3677
Figure 9 is a GPS on BMS residual plot of large relative stations about 30 km apart in Wasco County, Oregon. This plot has two stations with large differences and both stations have the NAVD 88 attribute of “Adjusted.” Their NGS data sheet states that they were both established in the general adjustment of NAVD 88 in June 1991. In this particular case, the leveling in this region is very old. As described in Part 7 (June 2016), you can retrieve all project identifiers for those projects with observations to or from a station using the station’s PID. The output from the NGS Data Sheet Mark Source Routine for PID RC1228 is shown in the box titled “Output from NGS Data Sheet Mark Source Routine.”
Output from NGS Data Sheet Mark Source Routine
Program: mark_sources Version: 3.0 Date: May 1, 2013RC1228OR/065 J 108
———————————————————-
GPS_OBS
———–
GPS_OBS FORE_POINT in GPS1655
DIR_OBS
———–
DIST_OBS
———–
VERT_OBS
———–
LEV_OBS
———–
LEVEL_OBS
———–
LEVEL_OBS STAND_POINT in L3410
LEVEL_OBS FORE_POINT in L3410***********************************************************
Figure 9 – GPS on BMS Residuals Using Geoid16b_NAD: Large relative stations about 30 km apart in Wasco County, Oregon (note: rejections by geoid team have been removed).
Figure 9 is a GPS on BMS residual plot of large relative stations about 30 km apart in Wasco County, Oregon. This plot has two stations with large differences and both stations have the NAVD 88 attribute of “Adjusted.” Their NGS data sheet states that they were both established in the general adjustment of NAVD 88 in June 1991. In this particular case, the leveling in this region is very old. As described in Part 7 (June 2016), you can retrieve all project identifiers for those projects with observations to or from a station using the station’s PID. The output from the NGS Data Sheet Mark Source Routine for PID RC1228 is shown in the box titled “Output from NGS Data Sheet Mark Source Routine.”
Excerpt from NGS Data Sheet for PID RC1228
PROGRAM = datasheet95, VERSION = 8.9.1
1 National Geodetic Survey, Retrieval Date = OCTOBER 2, 2016
RC1228 ***********************************************************************
RC1228 DESIGNATION – J 108
RC1228 PID – RC1228
RC1228 STATE/COUNTY- OR/WASCO
RC1228 COUNTRY – US
RC1228 USGS QUAD – WAPINITIA (1996)
RC1228
RC1228 *CURRENT SURVEY CONTROL
RC1228 ______________________________________________________________________
RC1228* NAD 83(2011) POSITION- 45 06 49.69715(N) 121 19 19.81396(W) ADJUSTED
RC1228* NAD 83(2011) ELLIP HT- 624.596 (meters) (06/27/12) ADJUSTED
RC1228* NAD 83(2011) EPOCH – 2010.00
RC1228* NAVD 88 ORTHO HEIGHT – 646.140 (meters) 2119.88 (feet) ADJUSTED
RC1228 ______________________________________________________________________
*
*
*
RC1228
RC1228 HISTORY – Date Condition Report By
RC1228 HISTORY – 1934 MONUMENTED CGS
RC1228 HISTORY – 1985 MARK NOT FOUND USPSQD
RC1228 HISTORY – 1985 MARK NOT FOUND USPSQD
RC1228 HISTORY – 20001010 GOOD OR-065
Figure 10 – GPS on BMS Residuals Using Geoid16b_NAD: Large relative Differences between Stations along the Oregon/Washington Border (note: rejections by geoid team have been removed).
Figure 10 is a plot of GPS on BMS residuals using Geoid16b_NAD depicting large relative differences between stations along the Oregon/Washington State border. It is the near Puget Island along the Columbia River. Station SC0330 and SC1086 are only 7 km apart and the relative difference is -20 cm (-11.4 cm minus 8.6 cm). This could be an issue with the NAVD 88 network design because there doesn’t appear to be many river crossing along the river between border stations. The fact that the residuals on the Washington State side are negative and the Oregon State side are positive is an indication that the stations need to be investigated.
Figure 11 – GPS on BMS Residuals Using Geoid16b_NAD: Large Negative Residuals North of Border between Oregon and Washington and Positive (or Small Negative) Residuals South of Border (note: rejections by geoid team have been removed).
The last figure, figure 11, is a plot of the GPS on BMS residuals using Geoid16b_NAD model that depicts large negative residuals north of the border between Oregon and Washington and positive (or small negative) residuals south of the border. This plot shows that the northern side of the river has large negative residuals all the way to the Pacific Coast. Once again, this is an indication that this portion of the NAVD 88 network should be investigated.
This column has focused on analyzing NGS’ GPS on BM data set that is used to make NGS’ hybrid geoid models. It provided procedures that users could employ when analyzing the differences between the modeled geoid values and the computed geoid values using GPS/Leveling data. This GPSBM data set or one similar will be used to make the next hybrid geoid model, as well as provide input to the transformation model between NAVD 88 and the new 2022 Vertical Reference System. All geospatial users should help develop this GPS on BMS data set to help improve the National Spatial Reference System and future hybrid geoid models. This column provided several examples of large relative differences in residuals between neighboring stations. Each example represents stations that should investigated based on different reasons, such as a weak NAVD 88 leveling network design in the region, the station’s published height attribute code implies that the station was not rigorously adjusted into the NAVD 88, and station pairs have different adjustment dates indicating a possible adjustment distribution correction issue or movement.
NGS has a program called “GPS on Bench Mark” to support users that occupy bench marks with GNSS equipment. This web site contains a lot of good information and provides the users with methods to recover, observe, and report information about stations in NGS’ database. The write up from the webpage is given below. I have highlighted a few sentences that the reader may find useful.
Improve the National Spatial Reference System (NSRS):
Recover: Look up the description of an existing bench mark and visit the bench mark of your choice. Observe: Record field notes, take digital photos, and collect GPS observations or coordinates for the bench mark you visit. Report: Use online tools to send the information to NGS.
Where?
Currently there are over 400,000 bench marks across the Conterminous United States (CONUS), Alaska, Hawaii and all U.S. territories. Tidal marks and bench marks are used for determining heights. Use the maps to prioritize which bench marks to observe.
Who can participate?
Anyone with Global Positioning System (GPS) enabled phones, hand held devices or survey-grade GPS receivers can participate. Recommended procedures vary depending on the type of equipment used.
When should I start?
You can collect and share information any time. Join volunteer efforts across the United States in celebration of National Surveyors Week beginning March 20, 2016. Contact the local National Society of Professional Surveyors chapter or your NGS geodetic advisor to learn about projects being planned in your local area.
By providing GPS on benchmarks today you can help NGS improve the next hybrid geoid model, increasing access to NAVD 88, and enabling conversions to the new vertical datum in 2022.
You can also help the local surveying community know about nearby marks by improving scaled horizontal positions and updating the mark condition or description by submitting a mark recovery.
What happens next?
NGS will use your data to update its databases and improve future models and tools. If you still have questions, contact the GPS on BM Team.
In addition to participating in the NGS’ GPS on Bench Mark program, all geospatial users should participate in NGS’ 2017 geospatial summit, which will be held in April in Silver Spring, Maryland.
This summit is an opportunity for all users of the National Spatial Reference System (NSRS) to obtain a better understanding of NGS’ plans to modernize the NSRS. Users will be able to provide feedback directly to NGS leadership. My next column will address NGS plans to replace the North American Vertical Datum of 1988 in 2022.
From a Galileo programme update presented at ION GNSS+ 2016.
Spokespersons from the European Commission, the European Space Agency and the European GNSS Agency (GSA) built a portrait of Galileo at the ION GNNS+ conference of a satellite constellation ready to step upon the world stage. Meanwhile, four new satellites are scheduled to launch aboard a single Ariane rocket on Nov. 17, leading to declaration of initial services by the end of the year.
With 14 satellites in orbit, 12 ordered and four on the launchpad, system operators feel confident in predicting initial operational capability by the end of this year. They already have their eyes set on additional service distinctions driven by emerging new requirement from user communities:
Authentication, for applications requiring trusted position and timing information; a key feature to enable new types of commercial applications such as pay-as-you-drive car insurance, road user charging (highway tolling) and access to mobile content
Key areas identified to drive Galileo evolution included timing for 5G telecoms, digital video broadcasting and autonomous vehicles.
GNSS will increasingly be used not as a sole localization solution but deeply integrated with several positioning networks and sensors to work across an array of contexts, according to the several European experts. However, despite growing alternative solutions, GNSS will remain core as the most cost-effective global positioning technology, especially for outdoor location information and larger scale applications.
Looking at the future, for the majority of mass-market applications, an accuracy of a few meters is sufficient, but key strategic users will need (some already need) better performance that must be satisfied. Galileo evolution has to offer enhanced performance, enabling new and strategic applications, to remain at the center of the positioning and timing market.
Galileo’s evolutionary targets to improve in the future were listed as: a ranging accuracy between 2 and 5 times that to be declared at Galileo FOC (in 2020?); position accuracy down to sub-meter level; timing accuracy increased by two times over Galileo FOC; better support of spoofed users; enhanced authentication (nav message authentication) and anti-replay.
New Operations Center in Spain. The European GNSS Agency (GSA) is gearing up to assume its operational role for Galileo in early 2017. During the summer the GSA formally accepted their Loyola de Palacio facility in Madrid, Spain that houses the European GNSS Service Centre (GSC).
GSA already oversees the operation and service provision for the European Geostationary Navigation Overlay Service (EGNOS) (since 2015) along with managing the security accreditation and general security provision for both programmes.
Since 2013, the core team at GSC has been providing limited services and working as a precursor to GSC v1. Its key work includes supporting the lead-up to Galileo Initial Services provision, along with operating the GSC Helpdesk, disseminating orbital products to the Search and Rescue (SAR) community, supporting GNSS-related research and industrial activity and monitoring user satisfaction. Once operational, GSC v1 will be connected to the Galileo core system, thus enabling the long anticipated Commercial Service. This service is expected to enter operations by mid-2017.
Galileo Hackathon in Berlin. The GSA invites coders, app developers and other interested parties to a two-day event in early November, the Galileo Hackathon. “Be one of the first to use Galileo!” The online invitation seeks those who want to shape the future of Location-Based Services (LBS) and Geo-IoT to become pioneer developers, showcase their skills, connect with the Geo-IoT app-dev community, and win prizes. November 3–4 in Berlin.
