Category: GNSS

Research Roundup: Navigation in urban environments

Image: Moncherie/E+/Getty Images

Of the hundreds of papers researchers presented this year at the Institute of Navigation’s annual ION GNSS+ conference, which took place virtually Sept. 21–25, the following three focused on navigation in urban environments. Papers are available at www.ion.org/publications/browse.cfm.

Low-Cost Single-Frequency PPP System

Featuring multi-constellation global availability, fast convergence and continuous navigation solutions, Instant PPP (IP3) was developed as an ideal precise positioning solution for mass-market applications in urban environments. The low-cost single-frequency PPP system demonstrates 50-cm accuracy in open-sky and suburban environments, and is further enhanced to support precise positioning in urban environments. The IP3 library is uniquely designed and enhanced. For instance, the instant receiver velocity based on the Doppler observations and the coordinate changes calculated from the carrier-phase differences between two consecutive epochs are integrated for the one-step prediction of the receiver positions in the Kalman filter.

Meanwhile, the weight of carrier phase, pseudorange and Doppler observations are smartly tuned as a function of signal-to-noise ratio (SNR) respectively. Additionally, quality control adapts to different scenarios, such as open-sky or urban environments. The receiver clock drifts for different constellations are specifically modelled in the velocity estimation to increase the degrees of freedom, which further enhances the solution availability in these extreme challenging situations.

To evaluate the IP3 library in urban environments, real-time vehicle-based field tests were carried out with an IP3 evaluation kit in Calgary, Canada. Results indicate the IP3 library can provide 50-cm accuracy in suburban areas with 100% solution availability. In an urban environment with numerous high buildings, the positioning root-mean-square error (RMS) of IP3 degrades to meter level while the solution availability remains 100%. IP3 can provide precise positioning solutions with low-cost GNSS receivers even in urban environments.

Citation. Hongzhou Yang, Fei Liu and Yang Gao, Profound Positioning Inc., Canada, “Precise Positioning into Urban Environments: A Low-Cost Single-Frequency PPP System.”

A Sub-Meter Real-time Positioning Service for Smartphones

A real-time positioning service for smartphones that meets a target threshold of 50 centimeters in urban environments is evaluated. The evaluation is possible through the Flamingo service, an API library for smartphone developers that enables higher accuracies than standard Google location services. The API is offered in a format that simply replaces Android location, streamlining its integration into new and existing applications that require better positioning. The service provides reference station infrastructure and correctional data products through a modified version of traditional NTRIP services. Duty cycling, low-quality clocks and high RF interference are common in a smartphone, so pre-filtering algorithms have been designed and calibrated to reject and de-weight poor measurements.

Based on proximity to a local base station, the service decides whether to use RTK or PPP-like processing. Performance is assessed on positioning accuracy, reliability and availability. Different operational environments are tested, such as pedestrian navigation in a congested area, and cycling scenarios. These are chosen to closely correspond to various applications. Rather than proving ideal test conditions and post-processing to optimize performance, the study focuses on realistic, real-time processing inside a smartphone.

Results are collected through a simple logging app that uses the Flamingo API. A target is set for 50 cm or better accuracies, where current smartphone positioning is within only a few meters. This enables mass-market location services to be applied in new markets such as augmented reality, lower accuracy surveying, GIS asset collection, and navigation assistance applications.

Citation. Joshua Critchley-Marrows, William Roberts, Malgorzata Siutkowska, Maria Ivanovici, NSL, UK; Valentin Barreau, Soufian Ayachi, Laurent Arzel, Telespazio, France, “A Sub-Meter Real-Time Positioning Service for Smartphones.”

The Path to Robust Municipal PNT

This research identifies where municipal governments fit in the positioning, navigation and timing (PNT) ecosphere, their awareness of PNT-related issues, whether and how they are approaching these issues, and actions they can take to improve their services to citizens and travelers. Lessons from other areas are applied, such as the resource typing construct used in FEMA’s National Incident Management System, to develop best practices for city PNT activity. This work will guide cities in addressing this important area and assist policy makers in efforts to involve cities in the development and implementation of PNT processes.

Citation. Steven Polunsky, Alabama Transportation Policy Research Center, University of Alabama, “The Path to Robust Municipal PNT.”

October 5, 2020
Prominent companies describe GNSS solutions

In a special advertiser-sponsored section of our October issue, we spoke with prominent GNSS companies about their current solutions for today’s industry challenges.

Q&A with CAST Navigation

Answered by Lou Pelosi, vice president

Lou Pelosi, vice president

Q: What is your most proven GNSS solution?

A: CAST Navigation does not supply GNSS receivers (GNSS solutions), rather we manufacturer GNSS simulators which are used to test GNSS receivers. CAST has had the most success with our GNSS/INS simulator. It provides an Embedded GPS Inertial (EGI) navigator with coincident GPS and inertial data. The EGI “thinks” it is moving while it remains stationary.

With our GNSS/INS simulator, the operational flight program of the EGI can be tested. During development of a platform’s navigation system, the CAST simulator is used to recreate the identical test conditions as the EGI’s software is modified. Once the platform’s navigation system is finalized, the output of the EGI is used to drive other systems, such as flight control or radar.

The GNSS/INS simulator can also include Controlled Radiation Pattern Antenna (CRPA) test features. If the EGI being used by the platform has an anti-jam antenna, the simulator can also test that feature.

The CAST GNSS/INS simulator has proven to be a key piece of equipment in system integration laboratories as new aircraft are developed.

Photo: CAST Navigation

Q: What are the solution’s key specs?

A: A key element of our GNSS/INS simulator is the inertial model contained in the simulator. It is a whole value inertial model rather than an error model. In its normal state, it reacts in the same manner as the actual inertial of the EGI. It also had degraded modes that are used to simulate hardware failures. When analyzed by the EGI manufacturers, its noise characteristics are almost identical to fielded navigation systems.

Q: What are the solution’s key features and benefits?

A: The most obvious benefit of using a CAST GNSS/INS simulator is cost savings. Even with the cost of lab equipment and personnel, there is still a savings over flight testing. A key feature of using a simulator for testing is its repeatability. Every time you rerun a test; the conditions are the same. In the real world, the satellites change constantly. Being able to accept real-time trajectory data is another key feature of CAST simulators. Instead of using our internal point mass model for scenario generation, an actual flight profile can be sent to the simulator from an external computer.

CAST has also been authorized by the GPS Directorate to provide classified functions to authorized users. Available options include Y-code, SAASM and M-code MNSA.

castnav.com

[email protected]

Q&A with Kolmostar

Answered by Lucy Fan, VP of Sales and Marketing

Lucy Fan, VP of Sales and Marketing

Q: What is your most proven GNSS solution?

A: Kolmostar specializes in ultra-low-power, instant cold-boot GNSS positioning solutions for internet of things (IoT) applications, mobile devices and beyond.

Q: What are the solution’s key specs?

A: Our advanced GNSS positioning module JEDI-200 is specially designed for location-based IoT applications such as asset tracking, fleet management, pet/livestock tracking, smart wearables and share economy. It is also optimized for integration with LPWAN (low power wide area network) technologies such as LoRaWAN®/NB-IoT/LTE-M to provide the ultimate ultra-low-power profile for IoT applications. There are two outstanding advantages of JEDI-200: ultra-low-power and instant cold-boot. With 25 mW power consumption and the revolutionary 1-second TTFF (time to first fix), JEDI-200 is able to reduce the energy consumption to get one position fix by up to 120x compared to traditional GNSS modules on the market.

Q: What are the solution’s key features and benefits?

Photo: Kolmostar

A: GNSS/GPS sensors are one of the most power-consuming sensors in IoT or mobile devices. Battery life will be significantly shortened when GNSS/GPS sensors are turned on. Hence, many IoT and mobile devices either do not include GNSS/GPS sensors or have to equip themselves with very large batteries, incurring much inconvenience and cost. Kolmostar’s ultra-low-power and instant cold-boot JEDI-200 module is specially designed to solve this long-standing industry pain point.

With its ultra-low-power feature, JEDI-200 is able to reduce the energy consumption to get one position fix by up to 120x when compared to traditional GNSS modules. IoT devices with very limited-sized batteries are now able to have GNSS positioning ability while still maintaining a battery life up to 10+ years. Another key feature of JEDI-200 is instant cold boot. Unlike traditional GNSS modules’ 30-second TTFF in cold boot, JEDI-200 can achieve an instant 1-second TTFF, providing a better and more seamless customer experience when short latency/response time is particularly desired in certain applications. In addition, JEDI-200 is optimized for LPWAN technologies such as LoRaWAN®/NB-IoT/LTE-M, further reducing both the cost and the power consumption of devices’ wireless communication, which is another big challenge most IoT and mobile devices previously faced.

kolmostar.com

[email protected]

Q&A with Racelogic

Julian Thomas, founder & managing director, Racelogic

Answered by Julian Thomas, Managing Director

Q: What is your most proven GNSS solution?

A: The LabSat 3 Wideband GNSS simulator offers multi-constellation and multi-frequency capabilities for reliable, repeatable and consistent testing. Its one-touch Record and Replay provides an efficient way to test and develop GNSS receivers without the cost, inconvenience and limitations of live-sky signals. Combining LabSat with the custom simulation software SatGen enables the creation of GNSS RF I&Q or IF data files based on a bespoke scenario, allowing for almost any kind of test at a set time, date and location.

Q: What are the solution’s key specs?

A: With three channels, a bandwidth of up to 56 MHz and 6-bit sampling (3-bit I and 3-bit Q), LabSat 3 Wideband can handle almost any combination of constellations and signals that exists today, with plenty of spare capacity for future planned signals.

Q: What are the solution’s key features and benefits?

A: LabSat 3 Wideband is small and affordable, making it an ideal solution for companies to provide their employees with a suitable method of testing their GNSS devices whilst working from home. In addition to its compact size, an internal battery delivers up to two hours of run time to record scenarios in even the most challenging field environments.

Photo: Labsat

It is incredibly user friendly with one touch record and replay and an HTML interface that makes setup simple and problem-free. A range of additional signals can also be recorded and synchronized to the GNSS input: dual-CAN, RS232 and digital inputs are simultaneously captured, increasing the level of playback realism and allowing for a wider range of testing.
The latest version of SatGen can be used to create a single scenario containing all the upper and lower L-band signals for GPS, Galileo, GLONASS, BeiDou and NavIC, and takes advantage of the LabSat 3 Wideband’s ability to read RF data at up to 95 MB/s. Creating an artificial scenario using SatGen allows for precise control of the data content, creating a standardized file for repeatable testing and carrying out true comparisons between receivers.

The versatility of the LabSat 3 Wideband makes it a familiar sight on the desks and benches of technology companies around the world. From GNSS device and application testing to receiver sensitivity and end-of-production-line testing, LabSat 3 Wideband is a perfect testing partner.

labsat.co.uk

[email protected]

Q&A with Trimble

Q: What is Trimble OEM GNSS’ most proven GNSS solution?

A: The Trimble BX992 is the flagship product from the Trimble OEM GNSS portfolio, proven in multiple environments and applications. Powered by the BD992-INS receiver module, this rugged yet compact enclosure allows original equipment manufacturers and system integrators to rapidly integrate precise position and orientation data to guidance, control and autonomous applications. Continuous data sets collected from test sites and real-world applications around the world have been used to create a powerful engine that performs in the most challenging of GNSS environments.

The Trimble BX992. (Photo: Trimble)

Q: What are the solution’s key specs?

A: The Trimble BX992 delivers low-latency 100-Hz centimeter-level positions with tight integration of IMU sensor data and GNSS observations in the RTK/RTX engine. The rugged IP67 enclosure supports multi-frequency tracking from GPS, Galileo, GLONASS, BeiDou, QZSS and NavIC constellations. The dual-antenna inputs allow rapid and robust alignment of onboard gyro sensors. With Trimble RTX correction services, the BX992 delivers reliable, high-accuracy positioning without a local base station or cell modem.

Q: What are the solution’s key features and benefits?

A: The BX992 is a full-featured solution with an onboard spectrum analyzer, a critical tool for developers to identify interference from unwanted signals, thus allowing products to be released to the market within specification and on schedule.

trimble.com/Precision-GNSS

[email protected]

October 5, 2020
ESA studies lay path to navigating the moon

Illustration of side-lobe signals from GPS satellites. (Image: ESA)

Two European Space Agency studies found that the signal from navigation satellites orbiting Earth could be used to navigate the moon’s surface.

News from the European Space Agency (ESA)

To pinpoint a location accurately, a receiver — in smartphones or on a spacecraft — needs to collect and combine signals from at least four navigation satellites. The receiver determines its distance from each of the satellites by measuring the time that it takes for the signal to travel from the satellite to the receiver.

Navigation satellites aim their antennas directly at Earth. Satellites orbiting above the navigation (GPS in this image, but Europe’s own navigation system is Galileo) constellation could only hope to detect signals from Earth’s far side. Now spacecraft can make use of signals emitted sideways from navigation antennas, within what is known as “side lobes.” Just like a torch, they shine energy to the side as well as directly forward.

Navigation satellites orbit 22,000 kilometers above Earth’s surface. As they point in the direction of Earth, any spacecraft between them and Earth are served well by their signal. But around 10 years ago, engineers started demonstrating that spacecraft outside the orbit of navigation satellites could also navigate in space using “spill over” signal from the satellites.

Then in 2012, two discovery and preparation studies explored a seemingly radical question: could this spillover signal even be used to navigate our way around the moon, and if so, what kind of receiver would we need to build to be able to use these signals?

The studies found that the signal from navigation satellites orbiting Earth could be used to navigate the moon’s surface. But with the signal being so weak, they found that a new type of receiver would need to be built, and at the time there was no clear application for this.

Eight years later, ESA invested in the development of such a receiver, and is exploring whether it could be demonstrated on the Lunar Pathfinder mission. ESA is collaborating with Surrey Satellite Technology Ltd. and Goonhilly Earth Station on this mission, which will provide exciting new opportunities for science and technology demonstration. In particular, it will help lay the groundwork for providing navigation services around the moon, currently studied through two ESA NAVISP activities and culminating in the Moonlight initiative.

“We have now accurate simulation results that show that navigation signals may be used at moon orbit and provide good performances,” said Dr. Javier Ventura-Traveset, head of the Galileo Science Office and in charge of coordinating all GNSS moon activities for ESA’s Navigation Directorate. “And with an innovative receiver in Lunar Pathfinder, we could have the first ever experimental evidence of this.

Artist’s impression of the Lunar Pathfinder mission. (Image: SSTL)

“Furthermore, we are also studying how existing navigation constellations may be complemented by additional moon-orbiting satellites, providing additional ranging signals for an optimal navigation service including moon landing and moon surface operations. This is being done as part of the ESA NAVISP program and through the ESA Moonlight initiative.”

“The discovery and preparation studies have been eye-openers and they are currently being followed up by a NAVISP activity aiming to develop the highly sensitive spaceborne navigation receiver planned to fly on board Lunar Pathfinder,” said ESA Radio Navigation Engineer Pietro Giordano. “This technology will enable improved performances and much more cost-effective ways to navigate and operate missions to and around the moon.”

October 2, 2020
Webinar to highlight GPS program updates, SMC space enterprise architecture

GPS World, in conjunction with Spirent Federal Systems, will be hosting a webinar on Oct. 8 that will cover GPS program updates, as well as the program’s role in the Space and Missile Systems Center’s (SMC) space enterprise architecture.

The event will also discuss the effects of COVID-19 and any future plans for the GPS program.

Event speakers will include Col. Ryan Colburn, director of SMC’s Spectrum Warfare Division; Shawn Ryan, BAE Systems Navigation & Sensor Systems director of business development for SMC; Mike Shepherd, associate director of business development at Collins Aerospace Mission Systems; and Christopher Hogstrom, engineer at Spirent Federal Systems.

Col. Ryan Colburn leads a team charged with designing and integrating the United States Space Force’s current and future integrated satellite communications and position navigation and timing enterprise architectures. He works with military, commercial, allied and government partners to ensure SMC is able to design, acquire, integrate and field the space systems needed to support today’s warfighters.

Shawn Ryan provides local leadership for all SMC and Los Angeles Industrial NSS efforts and engagement. NSS, headquartered in Cedar Rapids, Iowa, develops, designs and manufactures the most advanced GPS receivers and anti-jam GPS antenna electronics for military applications.

Mike Shepherd leads integrated business development for A-PNT, FVL, TITAN and JADC2. Previously, he was the senior manager of the ground U.S. military GPS receiver business and managed major accounts for all branches of the U.S. military users of GPS and A-PNT systems.

Christopher Hogstrom joined Spirent Federal in 2020. He currently supports various engineering efforts as well as customer trainings and product demos. He has worked extensively with adaptive beamforming and its applications in GPS anti-jam technologies. Hogstrom received his Bachelor and Master of Science in Electrical engineering from Brigham Young University.

Register for the event here.

October 2, 2020
From racecars to boundless opportunities

Julian Thomas, founder & managing director, Racelogic

When I started Racelogic nearly 30 years ago, I could not have foreseen how intrinsically embedded GPS would become in my life. I started out with the goal of supplying electronic control systems to the motorsport world. From traction control systems to paddle shifters for automatic cars, our technology rapidly built a reputation for quality and accuracy. It was this pursuit of accuracy that led me to GPS.

GPS can be used for a wide variety of applications, but still not many people realize just how accurate it is for measuring the speed of a moving object. It was whilst looking for a solution to measure ground speed to use as a reference for a traction control system for a 4-wheel drive rally car that we came across an Ashtech 20-Hz GPS engine and were amazed to find out just how accurate the speed output was. This was a turning point in Racelogic’s history, which led to the development of one of our best-known products, the Velocity Box (VBOX), which is used to measure speed, distance and acceleration of vehicles for use in the test and development of new cars.

It is undoubtedly an exciting time for GNSS. New signals and constellations are delivering a huge improvement in performance, which has spurred the release of new, lower cost, game-changing products into the marketplace. With cm-level position now becoming affordable for almost any application, it will be fascinating to follow how this changes the face of the positioning market, and see what innovations and novel applications will appear.

Delivering solutions to these emerging applications will require agility and flexibility to integrate GPS with sector-specific technology. If this can be combined with solutions that overcome some of the limitations of GPS, then the opportunities are boundless. I for one am excited to see where the next 30 years takes us.

October 2, 2020
GPS III launch aborted with 2 seconds to spare

UPDATE (Oct. 5): Elon Musk, SpaceX founder and CEO, said a Falcon 9 launch was halted Friday night due to an “unexpected pressure rise in the turbomachinery gas generator,” referring to a part in the rocket’s Merlin engines, reports SpaceflightNow.

SpaceX has not yet set a new launch date. Another planned launch, for a Starlink satellite, was also aborted.

UPDATE (Oct. 3): Only two seconds before launch, SpaceX aborted the scheduled launch of the fourth GPS III satellite on Oct. 2. SpaceX has not yet announced a new launch window, or stated the reason for the cancellation.

We will need to make a lot of improvements to have a chance of completing 48 launches next year!

— Elon Musk (@elonmusk) October 3, 2020

One Twitter user responded with video of the launch up to the moment it was cancelled.

that’s okay… I caught the moments leading up to the scrub haha🥺♥️🚀 pic.twitter.com/105N9K8Z38

— jordan🚀 (@AstroJordy) October 3, 2020

(Oct. 1) The U.S. Space Force’s newest GPS III satellite, Space Vehicle 04 (GPS III SV04), rolled out to Cape Canaveral’s Space Launch Complex 40 on Sept. 27. Originally scheduled for launch Sept. 30, then Oct. 1, the satellite is now slated to launch 9:43 p.m. EDT on Oct. 2 (01:43 a.m. UTC on Oct. 3).

The launch was delayed because of a “traffic jam” at the launchpad. According to Spaceflight Now, SpaceX initially rescheduled the GPS launch for Wednesday night after a Delta 4 launch was delayed to Tuesday. After the Delta 4-Heavy’s scrub Tuesday, SpaceX announced the GPS launch would be pushed back to Friday, when there is a 15-minute launch window available opening at 9:43 p.m. EDT (0143 GMT Saturday, Oct. 3).

The Lockheed Martin-built GPS III SV04 is scheduled to launch aboard a SpaceX Falcon 9 rocket — the third National Security Space Launch (NSSL) mission on a Falcon 9 rocket, the second U.S. Space Force (USSF) first-stage booster recovery, and the sixth USSF launch on Sept. 30. The 15-minute launch window opens at 9:51 p.m. EDT. A live feed will begin 20 minutes before the launch and conclude approximately 45 minutes afterward. A simulcast of the broadcast can be viewed at www.spacex.com.

“The GPS III program office in partnership with our contract teammates continue to push the envelope on the capabilities they deliver to users, both civil and military around the globe. Our latest GPS III satellites’ nearly 70 percent digital payload provides the U. S. Space Force with greater operational flexibility and cutting edge capabilities while continuing to support legacy users,” said Cordell DeLaPena, Air Force program executive officer for SMC’s Space Production Corps.

GPS III SV04 will be launched to augment the current GPS constellation comprised of 31 operational spacecraft. GPS satellites operate in Medium Earth Orbit (MEO) at an altitude of approximately 20,200 km (12,550 miles) in six orbital planes. Each satellite circles the earth twice per day. GPS is the premier space-based provider of positioning, navigation, and timing services for more than four billion users worldwide. This latest generation of GPS satellite boasts a 15-year design life — 25 percent longer than the previous generation of GPS satellites on orbit.

GPS III brings new capabilities to users such as the new L1C civilian signal, which opens the window for future interoperability with international satellite navigation systems.

“Our GPS III team is excited to be here once again. Less than 3 months ago, we successfully launched GPS III SV03. Since then, the team has successfully delivered the satellite to its final orbit, performed on-orbit testing and delivered the satellite to operations, while executing a mature satellite production line. I can’t be more proud of everyone involved in this mission,” said Col. Edward Byrne, Medium Earth Orbit Space Systems Division chief. “The launch of GPS III SV04 will continue to modernize our GPS constellation by increasing our capabilities with advanced features for both our civil and military users across the world.”

A Falcon 9 with GPS III SV 04 encapsulated inside the payload fairing the stands vertical on the pad at Cape Canaveral’s Space Launch Complex 40 in preparation for launch. (Photo: USAF/SpaceX)

October 1, 2020
COVID-19 contact tracing discussed in CGSIC meeting

News from NAVCEN

The 60th meeting of the U.S. Civil GPS Service Interface Committee was held Sept. 21-22, utilizing a virtual meeting platform. This was an opportunity for anyone in the world with access to a computer to attend these public meetings of the U.S. Civil GPS Program.

For readers who were unable to attend, a synopsis of the meeting is provided below. The full agenda and presentations are available for download from the GPS.gov website.

The meeting of the CGSIC is an annual event, free and open to the public, conducted to provide updates from U.S. GPS program officials and ensure effective information exchange between the U.S. government and civil GPS users. The two-day meeting is hosted by the U.S. Department of Transportation (DOT) and the Coast Guard Navigation Center (NAVCEN). DOT serves as the civil lead for GPS and chairs the CGSIC in this capacity. NAVCEN is assigned duties as Deputy Chair and Executive Secretariat for the CGSIC.

Subcommittees of the CGSIC for Timing, International Information, and Surveying-Mapping-Geosciences held meetings on Sept. 21, and a summary of these meetings was presented during the CGSIC plenary session conducted on September 22nd.

Major General John E. Shaw, Combined Force Space Component Commander, U.S. Space Command, and Commander, Space Operations Command, U.S. Space Force, provided the keynote for this year’s plenary session. This address was followed by comments from Colonel Curtis Hernandez, Director of National Security Space Policy on the National Space Council and briefings from a variety of other government agencies.

This year’s meeting was replete with briefings from all over the world including an explanation in the International Information Subcommittee of COVID-19 Tracking in South Korea from the Deputy Director of the Korea Ministry of the Interior and Safety.

Everett Hinkley from the U.S. National Forest Service spoke in the Surveying, Mapping and Geosciences Subcommittee showing how the National Remote Sensing Program supports a variety of business areas of the Forest Service including how they are tracking the spread of the Mountain Pine Beetle infestation in our nation’s forests.

The Timing Subcommittee provided an engaging presentation on the current and future plans of the National Institute of Standards and Technology’s new Network Time Services.

Presentations during the plenary session focused on the operational status of the GPS constellation and ground control system modernization, U.S. Space-Based PNT policy, GPS augmentation systems, U.S. engagement with other international GNSS providers, PNT resiliency efforts, as well as a variety of topics related to the status and progress of ongoing GPS programs in the U.S. government.

If you have suggestions for topics to include in upcoming CGSIC meetings, would like to present a topic, or if you found information from past meetings useful and would like to hear more, please contact us via our Navigation Center “contact us” form. Please be sure to select “Civil GPS Service Interface Committee (CGSIC)” from the pull-down menu.

From a GPS operational perspective, civilian non-aviation users can submit GPS-related inquiries or report signal interference or degradation to the U.S. Coast Guard Navigation Center online or to the 24-hour watch desk at 703-313-5900.

Civil aviation users within the United States should contact the Federal Aviation Administration for GPS user support. The GPS Operations Center at Schriever Air Force Base, Colorado, is the Department of Defense lead for operational issues and questions from military users of GPS.

Rick Hamilton
CGSIC Executive Secretariat
GPS Information Analysis Team Lead
U.S. Coast Guard Navigation Center

October 1, 2020
Four decades of leadership

Miguel Amor, chief marketing officer, Hexagon’s Autonomy & Positioning Division

GPS World celebrates its 30th anniversary, and together we’ve seen huge leaps of innovation over the years. Reflecting on these developments, I wanted to share some of the contributions Hexagon | NovAtel made to support the evolution of the GNSS industry.

We began in 1978 in Alberta, Canada, in the telecommunications industry. In the 1990s, we shifted our focus to satellite receivers, choosing to forge ahead in GPS/GNSS technology. This decision would see NovAtel become one of the world’s leading manufacturers of high-precision GNSS components and systems developing multiple new patents and innovative solutions.

Our engineers have seen first-hand the growth of GPS and other satellite positioning systems worldwide, GNSS adoption across industries from aerospace to agriculture, and the present-day developments of precise positioning in autonomous applications. A rising tide raises all boats, and we helped foster the evolution of the industry through our goals of assured autonomy and positioning.

GAJT-710ML anti-jam antenna. (Photo: Hexagon)

Assured positioning means a reliable and robust solution you can trust. Technologies we’ve contributed to the broader industry include our GPS Anti-Jam Technology (GAJT) protecting users’ positioning, time and navigation, and SPAN technology, which expertly combines GNSS and inertial navigation systems (INS) measurements for seamless motion observations and a robust positioning solution. The capabilities of these technologies have been major contributors to the evolution of the GNSS industry.

Hexagon acquired NovAtel in 2007, and we’ve continued to grow and develop exciting new opportunities around the world where GNSS can grow, strengthen and improve applications in agriculture, automotive, defense, marine and many other industries. Our mission of assured autonomy and positioning encourages us to continue providing assured positioning in the most demanding environments and begin bringing autonomy to these markets.

GPS World has been a key player in covering these technological advancements for the past three decades. Together as an industry, we’ll continue innovating positioning and autonomy, and I’m excited to see how the industry will evolve over the next 30 years.

September 30, 2020
GPS Innovation Alliance refutes 5G claims in regard to Ligado

Image: A-Digit/DigitalVision Vectors/Getty Images

The GPS Innovation Alliance filed an ex parte with the Federal Communications Commission (FCC) regarding its Ligado decision. This follows a letter the alliance sent to FCC Commissioner Michael O’Rielly on July 30 regarding Ligado Networks.

The document covers a number of details regarding the Ligado Networks and the advancement of 5G.

According to the document, former NASA Administrator Daniel Goldin claims that FCC’s approval of the proposal by Ligado Networks to repurpose satellite spectrum in the L-Band for high-power terrestrial use should be upheld because it will help advance American leadership in 5G technologies.

“Winning the race to 5G — against China and other countries — is important, but Ligado’s proposed network is largely irrelevant to 5G,” the GPS Innovation Alliance said in response. “The availability of Ligado’s spectrum for terrestrial use will not contribute to the advancement of 5G but will instead undermine U.S. Global Positioning System receivers and devices that are foundational to wireless technology in general, including 5G.”

In addition, the GPS Innovation Alliance’s stated in its ex party that the use of L-Band spectrum is not critical for 5G services.

Other points mentioned in the document include that Ligado’s spectrum is not internationally harmonized, significantly diminishing its effectiveness as a 5G band, and that Ligado’s proposed network simply will not offer a 5G service. According to the GPS Innovation Alliance, Ligado merely proposes to offer limited internet of things services, primarily delivered over custom private networks to specific geographic areas for limited vehicular and utility operations. Not only is this not a 5G service offering, but similar services are already being provided by wireless service providers, the alliance added.

Read the full document here.

September 29, 2020
SSTL demonstrates new GNSS-R capabilities

The successful demo consolidates concept designs for a proposed land-sensing ESA Scout mission, HydroGNSS

Surrey Satellite Technology Ltd. (SSTL) has successfully demonstrated GNSS reflectometry (GNSS-R) from its 18-kg DoT-1 satellite. SSTL has pioneered the new field of GNSS-R with successful payloads on board TechDemoSat-1 and the CYGNSS constellation, and is continuing to develop the technology and data analysis in pursuit of this new science.

SSTL’s DoT-1 satellite was launched in 2019. (Photo: SSTL)

The GNSS-R payload onboard the DoT-1 satellite is incorporated within a new small-form-factor Core Avionics module integral to all SSTL’s future satellite platforms. This innovation paves the way for any SSTL satellite that can accommodate a nadir pointing antenna to become part of a GNSS-R small-sat constellation.

GNSS reflectometry is an Earth-observation technique that uses GNSS signals as L-band radar sources, allowing the satellite to take measurements of ocean wind speeds, polar ice and hydrological land parameters, at a higher spatial resolution and an order of magnitude lower cost than other methods.

“GNSS-R is a powerful new science that can contribute valuable data to help monitor changes in our global climate, and I am really pleased with the success of our DoT-1 demonstration.,” said Phil Brownnett, managing director of SSTL. “We now have an advanced instrument design and deep expertise in this new field, and I am hopeful that SSTL’s HydroGNSS concept will progress to a full mission to support the global climate-control challenge.”

HydroGNSS mission

The GNSS-R technology demonstration from SSTL’s DoT-1 satellite is also an important stepping stone for a proposed European Space Agency (ESA) Scout Mission Concept called HydroGNSS, which comprises two 40-kg satellites that collect data continually in near-polar orbits, taking hydrological measurements over the whole globe.

The HydroGNSS mission concept makes advanced use of new GNSS reflectometry techniques such as Galileo signals, dual polarization, and coherent signal acquisition to measure four Essential Climate Variables (ECVs) over land: soil moisture, inundation, permafrost freeze/thaw, and biomass. HydroGNSS has been down-selected by ESA for a concept study; the finally selected Scout mission will commence in 2021.

The below animated video illustrates the HydroGNSS mission.

SSTL’s GNSS-R instrument collects and processes measurements into a “delay Doppler map” (DDM) that can be corrected and inverted into Level 2 products such as ocean wind speed, as has already been successfully demonstrated by the SSTL GNSS-R instruments onboard the TechDemoSat-1 and CYGNSS missions.

The plot below shows results from data gathered by the DoT-1 satellite on Aug. 12, and shows simultaneous DDMs from four separate GPS satellites. As this is a forward scattering technique, the stronger signals with redder peaks indicate a calmer ocean with lower wind speeds. Approximately 40 minutes of data were collected from the Pacific to the Antarctic to the Southern Ocean.

DoT-1 sub-satellite track (white) and GPS reflection tracks (yellow) collected during 40 minute data operation. (Image: SSTL)

Four Delay Doppler Maps (DDMs) collected by DoT-1 that show signal reflections from four GPS satellites. (Image: SSTL)

Soil moisture measurements

Data from the SSTL GNSS-R instruments onboard the CYGNSS mission have demonstrated the potential for soil moisture measurement by GNSS reflectometry, and preliminary work shows that GNSS-R also has good sensitivity for freeze/thaw sensing in the active zone of permafrost. Unseasonal changes in the permafrost cycles could potentially release larger quantities of methane, which risks exacerbating global climate change.

GNSS-R can also be used to assess biomass, a measure of forest density which acts as a vital sink for removing carbon dioxide from the atmosphere. In addition to longer term climate observations, soil moisture and inundation measurements from GNSS reflectometry can provide important information for short-term operational purposes, for example, towards Numerical Weather Prediction and flood warnings following rainfall events.

The development of SSTL’s new GNSS-R instrument was funded in part by the European Space Agency.

September 29, 2020
GPS and GNSS: confronting dual-use realities

Jules McNeff, vice president, strategy & programs, Overlook Systems Technologies

I welcome the opportunity to contribute and congratulate GPS World on your 30th anniversary. Over those 30 years, I have watched GPS influence how the world works. Early on, along with its vital contributions to U.S. and allied military operations, there was great optimism that sharing civil GPS technology openly would bring improved safety and efficiency to people around the world. However, that sense of optimism has dimmed as GPS, and the GNSS construct and PNT enterprise that it spawned, confront evolving real-world events.

Several years ago, I wrote a paper positing that in terms of dual-use utility and risks, GPS and related PNT capabilities are analogous to two other technology innovations that have occurred since the Second World War: atomic energy and the internet. The paper considered GPS/PNT in the context of each, reflecting our experiences with those two dual-use extremes.

The paper concluded that, unlike atomic energy, which has been fairly well controlled, GPS/PNT more closely resembles the internet, which has for better or worse been allowed to grow into a global capability virtually without constraint. For GPS/PNT, a fixation on civil, commercial and scientific uses enabled civil authorities uncomfortable with the military side of the dual-use equation to ignore that reality and focus only on “peaceful” civil and scientific endeavors. Unfortunately, the international comity that participants had hoped for, and that appeared for a time to be real, can no longer be assured.

Where the U.S. has been open and transparent regarding a dual-use GPS, others have not. Now, the open sharing of information that has been the hallmark of the civil GNSS community over the years must be viewed seriously and candidly through the clear lens afforded by the overt actions of GNSS providers.

Collective efforts to improve GNSS for peaceful uses ignore the reality that the information shared can equally and dangerously undermine international security. As with the internet, those who have become dependent on precise GPS/PNT services must now reactively create protections and remediations to deal with increasingly real threats from those we had considered colleagues.

So, naivete and optimism must finally yield in the face of hard reality.

September 28, 2020
China’s BeiDou ushers in a ‘golden decade’ for companies

Image: BeiDou program

On Sept. 23, the China BeiDou Application Conference and the Ninth Annual Conference of China Satellite Navigation and Location Services were held in Wuhan, according to a press release from haiwainet (People’s Daily), an official Communist Party newspaper of China.

Attending the conference were 700 experts, officials and entrepreneurs, as well as company representatives from BDStar Navigation, Amap, Allystar, Unistrong and Wuhan Exsun. “Delegates agreed that China’s BDS PNT (positioning, navigation and timing) industry has just started and is ushering in a golden decade of rapid growth,” the press release stated.

Zhou Xianwang, mayor of Wuhan, said that Wuhan, an important city for BDS construction and industrial development in China, is accelerating Beidou industry innovation, application promotion and enterprise development with first-class talents and services, and striving to make Wuhan a new highland for Beidou industry innovation and development.

Yu Xiancheng, president of the GNSS and LBS Association of China, said the Beidou industry in China has reached about $58.8 billion and the industrial ecology has taken shape.

According to the press release, “China’s Beidou is the first-class Beidou and the world’s Beidou as well. The application and space-time services of Beidou technology will become more popular in China and the world, ushering in a golden decade of development.”

BDS basic products have been exported to more than 120 countries and regions, and Beidou-based land ownership confirmation, precision agriculture, digital construction and smart ports, etc. have been successfully applied in ASEAN, South Asia, Eastern Europe, West Asia and Africa.

September 25, 2020