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First responders see real-time data a top benefit of using drones

Photo: ResponDrone

Photo: ResponDrone

Emergency response providers participating in a Design Thinking workshop organized by the ResponDrone Project have indicated that they would like to use drones to gather and distribute crucial information and provide communication networks in disaster areas.

Preliminary results from the workshop, held in Thessaloniki, Greece, in November, indicate that first responders view the constant provision of real-time information in crisis situations as one of the most valuable benefits arising from using drones in disaster management missions.

The results of the Design Thinking workshop will be presented and discussed with the ResponDrone consortium at the project’s General Assembly, which will take place on Dec. 10–12 in Paris.

ResponDrone is an international project co-funded by the EU and the Korean government, which aims to develop an integrated solution for first responders to easily operate a fleet of drones for multiple synchronized missions to enhance their situation assessment capacity and their own protection.

The workshop, attended by representatives from first-responder organizations and industry partners of the ResponDrone consortium, took place to assess the best possible system requirements.

The aim of the ResponDrone project is to develop and evaluate a situation awareness system for first responders in emergency situations. The system will provide crucial information and communication services to all relevant stakeholders in a disaster situation.

First responders said they would like the ResponDrone system to:

  • provide reliable and validated real-time information
  • be flexible and open to information from already existing data sources
  • be able to visualize different information layers in a customizable manner
  • be fast and easy to deploy
  • be able to provide near future predictions regarding the development of the disaster situation.

Workshop participants included regional and national authorities in charge of first response, state agencies responsible for carrying out on the ground first response actions, rescue services and fire departments from Greece, France, Armenia, The Netherlands, Latvia, Bulgaria and Israel.

According to the first responders, a disaster can initially be described as a black box, which needs to be opened. Gathering relevant and reliable information from the disaster area and combining it with already available data, as well as rapid distribution of information to all relevant stakeholders, are the top priorities in disaster management.

The deployment of drones as a means of enabling the afore-mentioned capabilities seems to be a promising approach. It is crucial that the data gathered by drones is presented to the right people as soon as possible, preferably in real time.

“The workshop clearly showed the urgent need for the constant provision of real time information,” said ResponDrone project coordinator Max Friedrich from the German Aerospace Center (DLR).

“First responders wish to receive real-time data on current occurrences in the disaster area, on the position and status of potential victims and the first response units deployed in field, as well as the status and current location of available resources.”

Friedrich added that the ResponDrone system would be designed to provide highly accurate real-time information. The flexible system would gather information from various data sources and should be designed for fast and easy deployment.

ResponDrone has already begun developing an integrated solution for first responders to easily operate a fleet of drones with multiple synchronized missions to enhance their situation assessment capacity and their own protection. This system of systems will simplify and accelerate situation assessment and sharing, decision making and operations management, while requiring only a small crew to operate it.

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Septentrio PPK gets a boost with BaseFinder function

Septentrio Post-Processing Kinematic (PPK) software has been upgraded with multi-GNSS and BaseFinder functionality. BaseFinder improves project efficiency by automatically finding the most suitable reference station data needed for centimeter-level accuracy.

Septentrio has released a key upgrade for its GPS post-processing kinematic (PPK) software. Both GeoTagZ and PP-SDK now feature BaseFinder, a tool that speeds up survey workflow by automatically finding reference data needed for augmenting GNSS logs with sub-centimeter accuracy.

BaseFinder accesses an online database of reference networks and extracts the most suitable corrections available. BaseFinder is available via an app or an API and can be incorporated into any existing software.

Septentrio has two decades of experience delivering reliable and robust RTK and PPK sub-centimeter positioning to industrial applications. PPK is often used for ground surveys with aerial drones, allowing high precision georeferencing without the need for a real-time base station link or ground control points (GCPs).

GPS Post-Processing SDK architecture provides high-accuracy positioning without the need for a real-time correction stream. (Image: Septentrio)

GPS post-processing SDK architecture provides high-accuracy positioning without the need for a real-time correction stream. (Image: Septentrio)

“Surveying without a base station will allow users to reduce costs and set-up time. With this PPK upgrade we are improving the end-user experience as well as developer experience,” commented Danilo Sabbatini, Product Manager at Septentrio.

The new release of this GNSS post-processing software also includes two additional GNSS constellations: European Galileo and Chinese BeiDou. Having access to all the signals from all GNSS constellations improves reference network compatibility. It also improves positioning availability in difficult environments. This is particularly important when working in areas of low satellite visibility such as near tall structures or under foliage.

When doing photogrammetry with a drone, GNSS data is often recorded and then post-processed together with base station data to achieve sub-centimeter positioning accuracy. This base station data can be obtained either with proprietary base stations or by using base station data from a public reference network (see diagram below). Septentrio receivers are designed to bring accurate and reliable positioning to photogrammetry, aerial inspection, marine survey as well as mobile mapping.

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uAvionix announces FAA qualification of ADS-B transmitter


Photo: uAvionix

uAvionix has announced U.S. Federal Aviation Administration (FAA) approval of the Vehicle Tracking Unit (VTU-20) Automatic Dependent Surveillance – Broadcast (ADS-B) transmitter for airport surface management.

uAvionix is a designer and manufacturer of communications, navigation and surveillance (CNS) equipment for unmanned and manned aircraft.

Adhering to the performance and design assurance specifications of FAA-E-3032, the externally mounted VTU-20 ensures integration and interoperability with Airport Surface Detection Equipment, Model X (ASDE-X), Airport Surface Surveillance Capability (ASSC) and ADS-B receiver surveillance solutions for airport
surface control and situational awareness.

The VTU-20 can be permanently or magnetically mounted to all airside vehicles, including utility, emergency, snow-removal and maintenance equipment. Each vehicle is clearly and uniquely identified, providing an essential addition to any surface movement guidance and control system.

The VTU-20 implements FAA-approved Squitter Transmission Maps to automatically enable transmission on airport movement areas and disable transmission in low-risk areas or outside airport airside operations.

“Ground vehicle incursions into critical safety and movement areas is on the rise. With this achievement, uAvionix continues to promote safety and common situational awareness not only in the airspace but also on the airport surface,” states Christian Ramsey, uAvionix president.

This recent uAvionix achievement will be made available through an exclusive relationship with L3Harris Technologies, Inc., a leader in surveillance and air traffic management known for the Symphony product line of airport operations and environmental compliance solutions — to promote and sell the VTU-20 in the United States.

For sales inquiries or questions, contact L3Harris Symphony VTU-20 sales at, or uAvionix at

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Editorial Advisory Board PNT Q&A: Policy on jamming

What is or would be the best policy response from Congress and/or executive branch agencies to the growing threats to GPS from jamming and interference?

Brad Parkinson

Brad Parkinson

“Homeland Security has declared GPS to be an essential system to virtually all of our infrastructure. It is time to install a national system to identify and shut down interference. As part of that, all cell phones should periodically report interference to that national system and allow law enforcement to pinpoint and eliminate offenders.”
Bradford W. Parkinson
Stanford Center for Position, Navigation and Time

Allison Brown

Allison Brown

“On Dec. 5, 2018, the president signed into law the National GPS Timing Resilience and Security Act tasking the Secretary of Transportation with establishing a backup timing system for GPS within two years. To date, only limited technology demonstrations have been performed. Congress needs to fund the Department of Transportation to rapidly acquire and deploy a back-up timing capability, using available commercial solutions, to assure resilience within the Air Traffic Control system and other critical infrastructure to GPS jamming or spoofing.”
Alison Brown
NAVSYS Corporation

Members of the EAB

Tony Agresta

Miguel Amor
Hexagon Positioning Intelligence

Thibault Bonnevie
SBG Systems

Alison Brown
NAVSYS Corporation

Ismael Colomina

Clem Driscoll
C.J. Driscoll & Associates

John Fischer

Ellen Hall
Spirent Federal Systems

Jules McNeff
Overlook Systems Technologies, Inc.

Terry Moore
University of Nottingham

Bradford W. Parkinson
Stanford Center for Position, Navigation and Time

Jean-Marie Sleewaegen

Michael Swiek
GPS Alliance

Julian Thomas
Racelogic Ltd.

Greg Turetzky

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CBS News goes inside GPS

Screenshot: CBS

Screenshot: CBS News

On CBS’ Sunday Morning show Dec. 1, correspondent David Pogue was invited into the Air Force’s GPS Master Control Station at Schriever Air Force Base in Colorado Springs, Colorado, to show viewers what GPS is all about.

Pogue discussed the GPS program with Brigadier General DeAnna Burt, who oversees the program as the director of operations at Air Force Space Command at Peterson Air Force Base in Colorado Springs.

He also discussed GPS vulnerabilities with Dana Goward, president of the Resilient PNT Foundation and contributor to GPS World magazine.

Pogue also visited Lockheed Martin’s satellite assembly facility, where the new generation of GPS III satellites is being built.

Watch the video here.

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Universities compete in new autonomous race

By Kevin Dennehy
GPS World Contributor

University teams will go head-to-head in a two-year autonomous race car competition to test new software and other self-driving technologies at Indianapolis Motor Speedway.

The competition, called the Indy Autonomous Challenge, culminates in a high-speed autonomous vehicle race, scheduled for Oct. 23, 2021, on the speedway’s famed 2.5-mile oval track that is home to the annual Indianapolis 500.

The competition was inspired by the 2005 Defense Advanced Research Projects Agency (DARPA) Grand Challenge, which pitted university teams against each other and spurred commercial development of autonomous vehicles.

“The idea for the Indy Autonomous Challenge originated with DARPA’s winning team captain, [Stanford University’s] Sebastian Thrun. Sebastian joined us at the 2018 Indy 500, where he reflected on the inspiration and excitement that came from participating in the DARPA challenge, and how a high-speed automated vehicle race at the Indianapolis Motor Speedway had the potential to be on par with that experience with today’s teams,” said Matt Peak, Energy Systems Network director of mobility.

Like the DARPA competition, the Indy Autonomous Challenge focuses on university participation. “I can’t speak for DARPA, but our focus on universities is deliberate,” Peak said. “It was advised by not only Thrun, but other original DARPA competitors such as [Aurora CEO] Chris Urmson, all of whom commented on how participation by universities — their students, faculty, departments, alumni — was a key to DARPA’s success.”

The Indianapolis Motor Speedway will be the site of the race. (Photo: IMS)

The Indianapolis Motor Speedway will be the site of the race. (Photo: IMS)

The autonomous racing software developed through the competition could assist in developing commercial self-driving vehicles and enhance existing advanced driver-assistance systems (ADAS). Some of the cornerstone technologies include GNSS and digital maps, which provide the accurate location for fully autonomous vehicles.

As was the case with the original DARPA challenge, spurring new innovations and socially beneficial products and services is a goal of the competition, Peak said. “In our case, we see inspiring teams’ creation of software that can solve for edge cases — those problems or situations that occur only at an extreme operating parameter, such as avoiding unanticipated obstacles at high speeds while maintaining vehicular control,” he said. “This applies not only for highly automated vehicles, but also for vehicles equipped with ADAS that aim to help human drivers avoid obstacles altogether. The notion is, if our university innovators can enable cars to outmaneuver others at 200 mph, they certainly can help enable you to avoid that piece of lumber that fell off the pickup in front of you on the 65-mph highway.”

Peak said that a perfect place to demonstrate these technologies is the famous speedway, which for 100 years has tested automotive technology in a demanding environment. “Tackling automation at 200 mph in a race car is a bit more alluring than with a 20-mph people mover,” he said.

In addition to ESN and Indianapolis Motor Speedway, other challenge partners include race-car manufacturer Dallara Automobili and the Clemson University International Center for Automotive Research (CU-ICAR).

$1.45 Million in Prize Money

During the final race at the speedway, teams will compete for $1 million as the first-place prize. Second- and third-place finishers receive $250,000 and $50,000, respectively.

The five-round competition starts with the submission of a white paper to demonstrate vehicle automation with a video of an existing vehicle or participation in Purdue University’s self-driving go-kart competition at the speedway.

During the initial rounds, teams will use sponsor ANSYS’ driving simulator to develop autonomous vehicle software. ANSYS, which will provide $150,000 in prizes to top finishers of a third-round race, will co-host a hackathon to let teams work with the simulator, the company said. The fourth round allows teams to test their vehicles at the speedway in advance of the final race.

So far, five universities have registered:

  • Korea Advanced Institute of Science & Technology (KAIST)
  • Texas A&M Transportation Institute (TTI)
  • University of Florida
  • University of Illinois
  • University of Virginia.

Not Everyone Has Championed Autonomous Vehicles…

The new competition is commencing during a time when media reports show that the once-hot autonomous vehicle industry has vocal critics. Recently, Apple pioneer Steve Wozniak, who once headed a GPS-based fleet company called Wheels of Zeus, said he didn’t expect to see a fully autonomous vehicle operating on the streets in his lifetime.
In addition, a few automakers have reined in autonomous vehicle development or have scaled back their technology expectations in recent months.

“Not at all surprising. The traditional OEMs were never going to be disrupters that put driverless mobility-as-a-service cars out there. It isn’t their business model, and it won’t be,” said Alain Kornhauser, Princeton University professor and transportation program director, who was head of the university’s team during the DARPA Challenge, in his Smart Driving Cars weekly newsletter. “Self-driving, I dare say Level 2, is and has always been their sweet spot — it sells cars. Now watch these same companies throw monkey wrenches into those driverless mobility machines to protect their conventional business model.”

Peak says the recent negative press on autonomous vehicles is what happens when any new technology is rolled out. “For any new technology, such as automation, we’re going to see euphoric coverage (automation will solve all of our problems) and pessimistic coverage (automation will never arrive and, if it does, it will make things worse),” he said. “It’s a cycle, it swings back and forth, and we happen to be touching upon the latter, pessimistic end of that cycle.”

Taking a moderate and realistic position about the technology is what the Indy Autonomous Challenge is striving to do, Peak said. “Automated vehicle technologies have a role to play, both in helping humans drive better, and eventually in enabling new markets, such as first/last mile transit solutions. The technologies are light years ahead of where they were a decade ago, and low-level automated technologies are already making a difference and saving lives in today’s vehicles,” he said. “We have a bit of a ways to go before the full potential of automation will be realized, and the Indy Autonomous Challenge will help us address the concerns brought about by the media and others to reach this end goal much sooner than we otherwise would.”

For more, go to

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US falling behind protecting GPS/GNSS, civilian users

No One Is in Charge


Dana Goward

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

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

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

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

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

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

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

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

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

Most significantly, no one is in charge.

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

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

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

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

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

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

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

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How NGS can implement a time-dependent geopotential datum

The National Geodetic Survey (NGS) has published a technical report that describes options for how NGS can implement a time-dependent geopotential datum and thus a time-dependent geoid model. My last column described the latest version of NGS’ VERTCON model. As mentioned in the column, NGS is developing these models and tools to support the implementation of the North American-Pacific Geopotential Datum of 2022 (NAPGD2022). NAPGD2022 is going to be a time-dependent geopotential datum. In other words, the reference geopotential will change over time and therefore the geoid height value will change over time. NAPGD2022 was described in detail in NGS’ publication “Blueprint for 2022, Part 2: Geopotential Coordinates,” and my December 2017 column. Blueprint for 2022, Part 2 states that a gridded geoid model GEOID2022 will be created and it will contain two components: (1) the first component will be time independent, denoted as the Static Geoid model of 2022 (SGEOID2022) and (2) the second component will be a time-dependent geoid undulation model, encompassing permanent geoid changes greater than or equal to 1 millimeter per year, denoted as Dynamic Geoid model of 2022 (DGEOID2022). NGS will publish a GEOID2022 value that will be based on both SGEOID2022 and DGEOID2022. As stated in the document, GEOID2022 will be the official zero-height surface for orthometric heights within NAPGD2022, and thus within the NSRS. The box titled “Excerpt from Blueprint for 2022, Part 2, Figure 10-2” is a diagram that describes the process of creating the regional high resolution gridded GEOID2022 model. I have highlighted the GEOID2022 model and its two components, SGEOID2022 and DGEOID2022.

Excerpt from Blueprint for 2022, Part 2, Figure 10-2

Image: National Geodetic Survey

Image: National Geodetic Survey

First, it’s important to note the role of the geoid in estimating GNSS-derived orthometric heights. As described in a previous column, GNSS-derived Orthometric Heights are computed using the following formula: orthometric height (H) = ellipsoid height (h) minus geoid height (N). See the box titled “NAPGD2022 GNSS-Derived Orthometric Height.”

NAPGD2022 GNSS-Derived Orthometric Height

Source: Slide 9 from Gillins and Fancher presentation titled ‘Leveling after 2022’ presented at the 2017 Geospatial Summit

Source: Slide 9 from Gillins and Fancher presentation titled “Leveling after 2022” presented at the 2017 Geospatial Summit

So, what does it take to compute a time-dependent geoid model and what is NGS’ plan to accomplish this project The technical report titled “ A Preliminary Investigation of the NGS’s Geoid Monitoring Service (GeMS)” describes options for how NGS can implement a time-dependent geopotential datum and thus a time-dependent geoid model (See box titled “NGS Publishes Report on GeMS”). The report contains too much information for a single column. This column will highlight some of the sections of the report. The document does contain a lot of technical information and I would encourage everyone to download the document.

NGS Publishes Report on GeMS

Screenshot: National Geodetic Survey

Screenshot: National Geodetic Survey

The technical report describes the current state of knowledge and outlines next steps required to define a time-dependent geopotential datum for the Nation. NGS created a project called “The Geoid Monitoring Service,” or simply GeMS, to accomplish their long-term goal of establishing a time-dependent geopotential model.

The report addressed the following five topics:

(1) a foundational introduction to the various types of geophysical phenomena that are causing both size and shape change to the geoid,
(2) geodetic observing techniques that are presently available to monitor geoid change,
(3) an objective evaluation of NGS’s current ability to incorporate these techniques into a long-term monitoring service like GeMS,
(4) known barriers to accomplishing such a project, and
(5) potential observing techniques that might become available in the next 10-20 years, but are not currently mature enough for operational use.

The document presents a roadmap of options for how NGS could realize a time-dependent
geopotential datum, and how NGS can support the dynamic datum into the future with independent validation surveys and datasets.

The report discusses the available geoid monitoring techniques that NGS has to support modeling the changes in the geoid. There are three existing NGS program areas and associated technical expertise that could be utilized in an operational GeMS: (1) NGS’s Gravity Program, (2) the NOAA CORS Network, and (3) GPS/geodetic leveling campaigns. It is noted that individuals these techniques cannot provide 100% of what GeMS requires but combining various programs would be sufficient. The report does a great job of describing these three program areas. The box titled “Summary of Geoid Monitoring Techniques within NGS’ Current Expertise” is table 3 from the Technical Report. The table list the affordability and accuracy attributes for each of the program areas. NGS’ Gravity Program provides high quality gravity data to internal and external stakeholders. The program provides gravity data required for NGS’s geoid modeling.

Summary of Geoid Monitoring Techniques within NGS’ Current Expertise

Source: National Geodetic Survey

Source: National Geodetic Survey

The report provides a good overview of the expertise and instrumentation of NGS’ Gravity Program. The table titled “Summary of NGS’ Terrestrial Gravity Instruments” is a compilation of information on historical methods and instrumentation from the technical report.

Summary of NGS’ Terrestrial Gravity Instruments

The document highlights something about the United States gravity data that most users don’t think about. That is, gravity values are referenced to a gravity network just like NGS’ published orthometric heights are referenced to the NAVD 88. In the mid-1950s, a coordinated effort was initiated by the International Association of Geodesy (IAG) to make gravimeter ties throughout collaborating parts of the world to support establishment of an International gravity datum.

It incorporated intercontinental, north-south, calibration lines and long-distance ties established by airplane. The majority of USA relative gravimeter work was done from 1965 – 1967, resulting in the network shown in the box titled “International Gravity Station Net of 1971 (IGSN71) in CONUS.” The report states that the calculations were completed by Urho A. Uotila of The Ohio State University around 1970. The gravity network was constrained by a network of ballistic absolute gravimeters. Five of the eight absolute gravimeter sites were in CONUS. It was a world-wide, simultaneous adjustment and published as The International Gravity Standardization Net 1971 (I.G.S.N. 71). As of December 2019, the IGSN71 remains the official international gravity datum. Many of these stations have been destroyed over the decades, in particular those at passenger airport terminals.

International Gravity Station Net of 1971 (IGSN71) in CONUS

(Source: Figure 14 from

Figure 14: IGSN71 Gravity Stations. (Source: National Geodetic Survey)

Figure 14: IGSN71 Gravity Stations. (Source: National Geodetic Survey)

In the mid-1970s, NGS was involved in two major readjustment projects, replacement of NAD27 with NAD 83 and the replacement of NGVD 29 with NAVD 88. At the same time, the NGS gravity group were evaluating the gravity data in NGS database and the gravity stations involved in the IGSN71. During the period 1975 and 1979, NGS and NGA (formally DMA) performed relative gravity surveys around CONUS to evaluate the stations. A report by Robert Moose titled “The National Geodetic Survey Gravity Network” published by NGS in 1986 documents the results of the surveys. This network is denoted as the National Geodetic Survey Gravity Network (NGSGN) and depicted in the box titled “National Geodetic Survey Gravity Network (NGSGN) in CONUS.” The NGSGN was constrained by 8 absolute gravimeter stations and consisted of 232 stations. Differences between NGSGN values and IGSN71 values were computed to evaluate or detect change in gravity values. The box titled “Gravity Differences between NGSGN and IGSN71 Common Stations” depict these differences. The report states “In summary, the gravity differences between NGSGN and IGSN are generally small and many of the larger differences may be due to vertical motion.

National Geodetic Survey Gravity Network (NGSGN) in CONUS

(Source: Figure 15 from

Figure 15: NGSGN Stations. Destroyed stations known as of July 2019. (Source: National Geodetic Survey)

Figure 15: NGSGN Stations. Destroyed stations known as of July 2019. (Source: National Geodetic Survey)

Gravity Differences between NGSGN and IGSN71 Common Stations

(Source: Figure 16 from

Figure 16: Difference between NGSGN and IGSN71 AG values [mgal] (Source: National Geodetic Survey)

Figure 16: Difference between NGSGN and IGSN71 AG values [mgal] (Source: National Geodetic Survey)

The basic rule of thumb for estimating land movement using gravity changes is: 1 meter of change equals 0.3086 mgals (1 cm of change equals 0.003086 mgals). It should be noted that a positive difference in gravity in the figure indicated apparent subsidence. As stated by the 1986 report by Moose, the large difference in Houston-Galveston region is most likely due to subsidence. A report documenting the apparent movement in the Houston-Galveston region was published by NGS in 1980. The boxes titled “ Estimate of Subsidence in Houston-Galveston Area During 1963-78 Epoch” and “Estimate of Subsidence in Houston-Galveston Area During 1973-78 Epoch” provide estimates of the movement in the region that include the same epoch of the two gravity networks. These two plots agree with the summary statement in the 1986 report.

Estimate of Subsidence in Houston-Galveston Area During 1963-78 Epoch

(Source: Figure 7 from

NOTE: 30 cm approximately equals to 1 foot (Source: National Geodetic Survey)

NOTE: 30 cm approximately equals to 1 foot (Source: National Geodetic Survey)

Estimate of Subsidence in Houston-Galveston Area During 1973-78 Epoch

(Source: Figure 8 from

NOTE: 30 cm approximately equals to 1 foot (Source: National Geodetic Survey)

NOTE: 30 cm approximately equals to 1 foot (Source: National Geodetic Survey)

What does all this mean to the geoid? Accurate and current gravity data are critical to the development of an accurate geoid model that includes estimating changes in the geoid model over time.

The technical report on NGS’ Geoid Monitoring Service (GeMS) ( describes geodetic and geophysical techniques that are currently known to NGS and show promise for GeMS (see the box titled “Summary of Known Geoid Monitoring Techniques that are currently outside of NGS’s Expertise). It should be noted that all of these techniques rely on a non-NGS entity to create a product (such as a model or dataset) that NGS can utilize in their products and services. This is nothing new, NGS leverages partnerships for other products such as the GOCO05S satellite gravity model produced by an ESA consortium led by the Technical University of Munich. This model is used by the NGS geoid team in static geoid modeling.

Summary of Known Geoid Monitoring Techniques that are currently outside of NGS’s Expertise

(Source: Table 7 from Technical Report NOS NGS 69)

(Source: Table 7 from Technical Report NOS NGS 69)

Continuation of Summary of Known Geoid Monitoring Techniques that are currently outside of NGS’s Expertise

(Source: Table 7 from Technical Report NOS NGS 69)

(Source: Table 7 from Technical Report NOS NGS 69)

As apparent by all of the types of data required to monitor the geoid, NGS has a challenging task to establish a Geoid Monitoring Service. Why is it important to invest resources to monitor the geoid? Analyzes of temporal satellite gravity missions provide changes in gravity values that can be use to create changes in the geoid. The GRACE (Gravity and Climate Experiment) satellite mission was designed to provide the temporal gravity field variations throughout its mission (duration 2002 – 2017). There are analysis centers that produce models using the GRACE data – University of Texas at Austin Center for Space Research (UTCSR), NASA Jet Propulsion Laboratory (JPLEM), and GFZ German Research Center for Geosciences (GFZOP). Release 6 denoted as RL06 is the most current GRACE data from these groups. The data can be used to illustrate the magnitudes and resolutions that GRACE models provide to the seculargeoid rates for CONUS and Alaska. The boxes titled “GRACE Trend over CONUS from UTCSR RL06” and “GRACE Trend over Alaska from UTCSR RL06” are plots from Technical Report NOS NGS 69 that show these secular geoid trends from UTCSR-RL06. The plots indicate very small changes in the geoid but they are significant if the goal is to monitor the geoid model to the mm/year level.

GRACE Trend over CONUS from UTCSR RL06

Figure 27: GRACE Trend over CONUS from UTCSR RL06 Model [mm/yr] (Source: Figure 27 from Technical Report NOS NGS 69)

Figure 27: GRACE Trend over CONUS from UTCSR RL06 Model [mm/yr] (Source: Figure 27 from Technical Report NOS NGS 69)

GRACE Trend over Alaska from UTCSR RL06

Figure 28: GRACE Trend over Alaska from UTCSR RL06 GRACE Model [mm/yr] (Source: Figure 28 from Technical Report NOS NGS 69)

Figure 28: GRACE Trend over Alaska from UTCSR RL06 GRACE Model [mm/yr] (Source: Figure 28 from Technical Report NOS NGS 69)

Another product available from various processing centers are surface mass concentrations (mascons) as observed by the GRACE satellites. Once again, these mascons can be used to generate a secular geoid rate. The boxes titled “Geoid rate over CONUS based on the GSFC mascon model” and “Geoid rate over Alaska from GSFC mascon model” are plots from Technical Report NOS NGS 69 that provide the secular geoid rate based on the NASA GSFC mascon model. Once again, the plots indicate very small changes in the geoid but there is a systematic change to the geoid based on the analysis of the data from the GRACE mission.

Geoid rate over CONUS based on the GSFC mascon model

Figure 32 From Technical Report NOS NGS 69: Geoid rate over CONUS based on the GSFC mascon model [mm/yr] (Source: Figure 32 From Technical Report NOS NGS 69)

Figure 32 From Technical Report NOS NGS 69: Geoid rate over CONUS based on the GSFC mascon model [mm/yr] (Source: Figure 32 From Technical Report NOS NGS 69)

Geoid rate over Alaska from GSFC mascon model

Figure 33 From Technical Report NOS NGS 69: Geoid rate over Alaska from GSFC mascon model [mm/yr] (Source: Figure 33 From Technical Report NOS NGS 69)

Figure 33 From Technical Report NOS NGS 69: Geoid rate over Alaska from GSFC mascon model [mm/yr] (Source: Figure 33 From Technical Report NOS NGS 69)

The report stated that when considering monitoring the geoid, the greatest change to the geoid from glacial isostatic adjustment (GIA) processes is centered in northern Canada, but there is “still a significant geoid height trend in the Northern Plains, Great Lakes, and Northeast regions of CONUS.” It was noted that if GIA processes are not considered, a 1 cm error in the geoid undulation would occur within 18 years. NADGPD2022 orthometric heights are going to be established using a NATRF2022 ellipsoid height and a GEOID2022 geoid height. This is why the geoid needs a time-dependent component.

This column highlighted NGS new Geoid Monitoring Service (GeMS); and, that NGS’ will be publishing a gridded geoid model GEOID2022 that will contain two components: (1) the first component will be time independent, denoted as the Static Geoid model of 2022 (SGEOID2022) and (2) the second component will be a time-dependent geoid undulation model, denoted as Dynamic Geoid model of 2022 (DGEOID2022). NGS will publish a GEOID2022 value that will be based on both SGEOID2022 and DGEOID2022. The column provided examples of how GRACE data can be used to illustrate the magnitudes of secular geoid rates for CONUS and Alaska.

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Trimble acquisitions increase VRS network in Canada, New Zealand

Photo: Trimble

Photo: Trimble

Trimble has acquired Cansel Survey Equipment’s Can-Net and AllTerra New Zealand’s iBase networks. The acquisitions significantly increase the global footprint of Trimble-owned Virtual Reference Station (VRS) networks by adding key geographies in North America and New Zealand.

Subscription-based VRS correction services are now accessible to more customers around the world who rely on high-accuracy corrections to increase productivity and reduce operational costs. The correction services are designed for professionals in agriculture, geospatial and construction as well as emerging high-accuracy applications, such as on-road positioning for passenger vehicles. Financial terms were not disclosed.

The Can-Net and iBase acquisitions add over 1.1 million square kilometers (over 425,000 square miles) to Trimble’s correction services coverage that has grown robustly over the past eight years, contributing to Trimble’s shift toward software, services and subscription business emphasis.

Can-Net Network. The Can-Net network comprises multiple VRS networks and single-base solutions offering GNSS corrections across Canada. The acquisition provides Trimble with the largest VRS footprint in Canada, covering more than one million square kilometers (386,000 square miles).

Subscribers primarily work in the agriculture, survey and construction industries. In addition, the Can-Net network enables Trimble corrections technology to be used by automotive stakeholders deploying ADAS systems along the Trans-Canadian Highway.

iBase Network. The iBase network expands Trimble’s VRS footprint across both the north and south islands of New Zealand, totaling more than 100,000 square kilometers (39,000 square miles).

“The high-accuracy precision provided by VRS technology is a powerful tool in driving operational and financial efficiency for industries that require easy access to positioning services,” said Patricia Boothe, vice president of Trimble’s Advanced Positioning Division. “We are aggressively expanding the accessibility of VRS corrections around the globe. Our vision is to make high-accuracy positioning available to the broadest base of commercial users worldwide for applications in agriculture, construction, automotive, autonomy and others where precise positioning is a critical part of the solution. Trimble will continue to invest in technology and infrastructure to push the boundaries of performance and accessibility for our portfolio of services.”

Trimble networks are supported by a global network operations team made up of GNSS system engineers, geodesy experts and IT professionals. The team monitors the networks 24/7 from operation centers located on three continents, ensuring consistent and reliable service uptime and performance integrity.

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GPS pioneers honored with Queen’s award at Buckingham Palace

On Dec. 3, four U.S. engineers were awarded the 2019 Queen Elizabeth Prize for Engineering  during a ceremony at Buckingham Palace for their work creating the first truly global, satellite-based positioning system, GPS.

The QEPrize is the world’s most prestigious engineering accolade, a £1 million prize that celebrates the global benefit of engineering innovation on humanity. The honorees were announced in February.

His Royal Highness The Prince of Wales presented the trophy to Dr. Bradford Parkinson, Hugo Fruehauf, Richard Schwartz and Anna Marie Spilker, who accepted the award on behalf of her late husband, Professor James Spilker, Jr. Learn more about Spilker from his wife’s account.

Bradford Parkinson — often regarded as the “father of GPS” — led the development, design, and testing of the system. Hugo Fruehauf developed a highly accurate, miniaturized atomic clock, a foundational component of the system. Richard Schwartz engineered a satellite hardened to resist intense radiation in space, with a lifespan three times greater than expected. Professor James Spilker, Jr, was the main designer of the GPS civil signal and, with his team at Stanford Telecommunications, built the receiver that processed the first GPS satellite signals.

Lord Browne, chairman of the Queen Elizabeth Prize for Engineering Foundation, highlighted the critical role of collaboration in engineering, and in groundbreaking innovations such as GPS: “Our laureates’ success was the result of inter-disciplinary collaboration, a drive for excellence, and an ability to turn the fruits of scientific discovery into practical solutions. That is what engineers do,” he said.

Today, an estimated four billion people around the world use GPS. At just $2 per receiver, GPS provides an accessible service and a powerful tool that people can integrate with their applications. Simple smartphone apps can track disease outbreaks, self-driving tractors can optimize crop harvests, and sports teams can improve team performance. New applications for GPS continue to revolutionize entire industries, and its annual economic value has been estimated to be $80 billion for the USA alone.

GPS combines a constellation of at least 24 orbiting satellites with ground stations and receiving devices. Each satellite broadcasts a radio signal containing its location and the time from an extremely accurate onboard atomic clock. GPS receivers need signals from at least four satellites to determine their position; they measure the time delay in each signal to calculate the distance to each satellite, then use that information to pinpoint the receiver’s location on earth.

This year’s QEPrize trophy was designed by 17-year-old Jack Jiang from Hong Kong. Jack’s elegant trophy design won the 2019 Create the Trophy competition, an international competition that invites those aged between 14-24 around the world to submit innovative trophy designs for the world’s leading engineers. The 2019 competition saw a record number of entries, with submissions stemming from over 50 countries worldwide.

From left: Lord John Browne, Richard Schwartz, HRH The Prince of Wales, Bradford Parkinson, Hugo Fruehauf, Anna Marie Spilker at the Queen Elizabeth Prize for Engineering ceremony at Buckingham Palace, December 3, 2019. (Photo: Jason Aldean)

From left: Lord John Browne, Richard Schwartz, HRH The Prince of Wales, Bradford Parkinson, Hugo Fruehauf, Anna Marie Spilker at the Queen Elizabeth Prize for Engineering ceremony at Buckingham Palace, December 3, 2019. (Photo: Jason Aldean)

Lord Browne of Madingley, Chairman of the Queen Elizabeth Prize for Engineering Foundation, said, “This year’s laureates have demonstrated that engineering makes things happen. With the first global, satellite-based positioning system, they created an engineered system which provides free, immediate and accurate information about position and time, anywhere around the globe.

“The world now depends on GPS completely and without exception. The high-frequency trading systems, telecommunications and electricity grids of today are all built around GPS. And we will rely on it for the drone delivery systems, self-driving cars and climate monitoring solutions of tomorrow.

“In honoring the 2019 prize winners, we hope to inspire the next generation of engineers to continue to push back the frontiers of the possible.”

Bradford Parkinson said: “Today marks a landmark moment in all of our lives—there is no prize for engineering greater than this, it is an honor. This recognition reflects the responsibility incumbent upon those developing technology today to strive to do so for the good of humanity. Day-after-day, we are astounded at the new ways in which people across the world use GPS. It is a ‘System for Humanity’ in each and every sense.”

Hugo Fruehauf said: “The accuracy of modern GPS satellites astounds me. The atomic clocks we built for the satellites were accurate to within billionths of a second, but today’s generation are working a factor of 100 times better than that. They’re a lot like wine, in a sense—they only get better with time. And they have to be accurate; the timing for GPS is used for core systems around the world—vital infrastructure like banking systems, telecommunications networks, and power grids. Today the world relies on those clocks.”

Richard Schwartz said: “One of the best things about GPS is its accessibility. We designed the system to produce a signal that anyone can use, regardless of where they are on the planet. Today, engineers around the world can still access that signal, for free, and use it to build creative solutions to benefit people around them. It took a great deal of collaboration to make the system work, and it’s great to see the next generation collaborating on innovative products now because of that.”

Anna Marie Spilker, on behalf her late husband, Professor James Spilker, Jr, said: “Jim’s mission statement has always been to create, teach, and mentor for world-changing benefits to humanity through his engineering talents. When working on GPS, Jim knew that it could be of profound benefit globally, and he was right; because of their work, Jim and his colleagues have helped billions of people around the world. He was immensely proud of that. He said many times that ‘Engineering technology is the necessary catalyst for progress to world changing benefits to humanity; it’s magic.’”