Författare: admin

GNSS researchers presented hundreds of papers at the 2023 Institute of Navigation (ION) GNSS+ conference, which took place Sept. 11-15, 2023, in Denver, Colorado, and virtually. The following four papers focused on the use of precise-point positioning for various applications. The papers are available here.

Smartphone Positioning Resiliency

Ultra-low-cost GNSS receivers used in smartphones have several drawbacks that include insufficient observations and poor signal reception quality compared to higher-cost receivers. The authors of this article proposed that using native sensors and precise-point positioning (PPP) augmentation can offer resilient smartphone positioning.

During their research, the authors deployed only inertial measurement unit (IMU) and GNSS sensors native to existing smartphones. They were able to achieve a standalone solution using PPP and IMU integration that performed better than standard techniques.

In vehicle experiments with unobstructed sky, the sensor integration algorithm achieved 1.6 m horizontal RMS. This reduced 80% of horizontal errors in GNSS-challenged environments through a tightly coupled GNSS-PPP solution that has not appeared in any other publications according to the authors.

To address resilient smartphone positioning, the authors stated that sensor fusion is also being explored by using smartphone sensors, including IMUs, cameras, and other fusion techniques.

Yang, Yi, Vana, and Bisnath, “Resilient Smartphone Positioning Using Native Sensors and PPP Augmentation.”

---

Multi-GNSS PPP and MEMS IMU Integration for Navigation in Urban Environments

This paper addressed the issue of accurate, precise and continuous navigation in obstructed environments for vehicles. To provide a low-cost lane-level navigation solution for automotive applications, the authors proposed an integrated solution featuring low-cost GNSS PPP and MEMS-based IMUs.

During the authors’ research, they introduced a low-cost, triple-frequency GNSS, a MEMS-based IMU and a patch antenna to achieve decimeter-level accuracy in suburban and urban environments. Low-cost hardware and software were used to bridge GNSS gaps in urban environments to provide a continuous, accurate, and reliable position solution that is novel and has not been previously published, according to the authors.

The low-cost navigation system demonstrated an accuracy of less than a decimeter in the presence of a sufficient number of satellites. During half a minute of introduced GNSS signal loss, the overall RMS of the algorithm was 10% to 40% better than dual-frequency PPP with IMU as the satellite availability was reduced.

The results obtained during partial GNSS availability indicated a step forward in the low-cost navigation area for applications such as low-cost autonomous vehicles, intelligent transportation systems, and more that demand a decimeter level of accuracy.

Vana and Bisnath, “Low-Cost, Triple-Frequency, Multi-GNSS PPP and MEMS IMU Integration for Continuous Navigation in Simulated Urban Environments.”

---

Message Authentication for PPP/PPP-RTK Data

This paper analyzed candidate schemes for PPP/PPP-real-time kinematic (RTK) data authentication. As current PPP/PPP-RTK services are not authenticated, the motivations behind the authors’ research were the new availability of GNSS authentication services such as the Galileo Open Service Navigation Message Authentication (OSNMA), new PPP/PPP-RTK services such as QZSS Centimeter Level Augmentation Service (CLAS) and Galileo High Accuracy Service (HAS), and more.

In this paper, asymmetric schemes were proposed based on existing standards and compatibility with GNSS messages. Post-quantum cryptographic signatures were also reviewed and discussed. Two of the schemes were selected for analysis: digital signature based on ECDSA, and delayed disclosure based on a hybrid scheme using the TESLA protocol.

Each of the schemes was described in detail for both Galileo HAS and QZSS CLAS. The performance of the schemes in terms of time to receive the corrections message and the increase in the age of the data was analyzed. The analysis was complemented by a review of the CPU consumption at receiver level.

Fernandez-Hernandez, Hirokawa, Rijmen, and Aikawa, “PPP/PPP-RTK Message Authentication.”

---

Creating Consistent RVIM By Estimating Receiver Biases

Ionospheric augmentation is one of the most important dependences of PPP-RTK. Due to the dispersive features of the ionosphere, the ionospheric information is usually coupled with satellite- and receiver-related biases. This could result in inconsistent ionospheric corrections if a different number of reference stations are involved in the calculation.

In this paper, the authors aimed to introduce a consistent regional vertical ionospheric model (RVIM) by estimating receiver biases. First, they presented the inconsistent ionospheric corrections under sparse networks. Then the RVIM was compared with the International GNSS Service (IGS) final global ionospheric map (GIM) product, and the average of differences between them is 1.13 TECU.

The slant ionospheric corrections were then employed as a reference to evaluate both RVIM and GIM. The RMS values were 1.48 and 2.23 TECU for the RVIM and GIM. Finally, the authors applied the RVIM into PPP-RTK.

The results showed that the PPP-RTK with RVIM constraints improved horizontal errors, vertical errors, and convergence time by 43.45%, 29.3%, and 22.6% under the 68% confidence level, compared with conventional PPP-AR.

Lyu, Xiang, Tang, Pei, Yu, and Truong, “A Consistent Regional Vertical Ionospheric Model and Application in PPP-RTK Under Sparse Networks.”

Trimble and Sabanto have partnered to integrate Trimble’s BX992 dual antenna with Trimble CenterPoint RTX into Sabanto’s autonomous solutions.

Farming requires a high level of uptime and reliability to avoid service disruption. By using Trimble’s BX992 GNSS receiver and satellite-delivered Trimble CenterPoint RTX corrections service, Sabanto’s autonomous solutions can now receive centimeter-level L-Band corrections across the globe. The integration aims to provide users with precise positioning, which can result in greater productivity, minimize downtime and alleviate workforce shortages through autonomous vehicles.

In addition to RTX corrections, Trimble will offer correction stream-switching enabling farmers to automatically switch from IP to satellite seamlessly, to offer the best signal in a variety of environments.

savvy navvy has partnered with ProtectedSeas to bring ProtectedSeas Navigator data to boaters through the savvy navvy app.

After eight years of research and development, boaters and watersport users worldwide can now have access to comprehensive data and resources of ocean regulatory information, including marine protection areas, through the savvy navvy app.

ProtectedSeas Navigator provides boaters with 22,000 marine protected and managed areas in more than 220 countries. These areas include speed-limit zones to protect marine mammals, fisheries management areas and more.

ProtectedSeas compiles marine protection information into the Navigator database of marine protected areas (MPAs). It collects both large and small amounts of data and created the first public digital maps for more than 2,400 areas.

savvy navvy – often referred to as ‘Google Maps for boats’ – is an award-winning boat navigation app. It integrates multiple sustainable data sources from different conservation agencies and bodies.

Since launching its first global view of marine life protections, ProtectedSeas has been complimented by several industry-renowned leaders and bodies, including the U.S. National Oceanic and Atmospheric Administration (NOAA), Dr. Sylvia Earle, American marine biologist and oceanographer, and Gavin Newsom, governor of California.

Some ProtectedSeas data is already available in the savvy navvy app, with more to follow soon. Click here to learn more about the sustainable data or to download the app.

On December 5, in Houston, Texas, at a gala event to celebrate the 50^th anniversary of GPS hosted by the Resilient Navigation and Timing Foundation, Matteo Luccio, Editor-in-Chief of GPS World, interviewed Brad Parkinson. Here are two excerpts from the interview:

 How does GPS today differ from the design that came out of the Lonely Halls meeting 50 years ago this past September?

Well, I’m very proud of what happened because, to my knowledge, there is no fundamental difference. Basically, that fundamental design has held up. … As a matter of fact, I still have one of the old Trimble handhelds, it’s called an EnsignGPS. It was one of those little devices that got shipped to the Iraq War. The other day, I pulled it out, batteries were kind of crummy, I got those squared away and went out, sure enough and navigated. I probably hadn’t pulled it out in at least 20 years. The point of the story is that evidently it still works.

What do you consider the most significant impact of GPS on society?

Well, the most significant impact is also probably the most perilous: kids today just take it for granted. They know where they are.

Watch the full interview below. 

Space Systems Command (SSC) and SpaceX are preparing to launch the U.S. Space Force (USSF)-52 mission into orbit. The Falcon Heavy mission is set to launch on Dec. 10, 2023, from the historic Launch Complex (LC)-39A at NASA’s John F. Kennedy Space Center in Florida.

USSF-52 is the seventh mission of the X-37B Orbital Test Vehicle, an experimental program with technologies designed to provide the U.S. Space Force with a reliable, reusable, unmanned space test platform.

This launch adds to a notable year. The last NSSL Falcon Heavy launched in early January; that mission, USSF-67, was followed by a Falcon 9 launching a GPS satellite 61 hours later, both from the Eastern Range and using the same Space Systems Command crew. The Assured Access to Space team worked alongside SpaceX to complete both launches.

In preparation for a challenging and busy launch schedule, the U.S. Space Force is placing greater importance on being agile and resilient. The ability to conduct launch operations at a faster pace will be particularly crucial for successfully deploying multiple constellations, the Space Force said.

Furuno Electric Co. has released its dual-band GNSS receiver chip, eRideOPUS 9, which can achieve 50cm position accuracy without correction data.

The product is designed to provide absolute position information and can be used as a reference for lane identification, which is essential for services such as autonomous driving. It also serves as a reference for determining the final self-position through cameras, lidar and HD maps.

By using Furuno’s Extended Carrier Aiding technology, the product can achieve high-precision positioning, which eliminates the need for RTK reference stations, correction data usage and correction data reception components.

The eRideOPUS 9 supports all navigation satellite systems currently in operation, including GPS, GLONASS, Galileo, BeiDou, QZSS and NavIC. It can also receive L1 and L5 signals. The L5 band signals are transmitted at a chipping rate 10 times higher than L1 signals, which reduces the effects of multipath. The L5 signals also improve positioning accuracy in environments where radio waves are reflected or diffracted by structures, such as in urban areas.

A dual-band GNSS module incorporating eRideOPUS 9 is being jointly developed with Alps Alpine Co. and is scheduled for future release as the UMSZ6 series.

When Boston Light — an 89 ft-high, white lighthouse on Little Brewster Island in Boston’s outer harbor — opened in September 1716, it was the first one in the Thirteen Colonies. Sally Snowman, who has been its keeper for most of the past two decades, is the last official lighthouse keeper in the United States. Contemplating the horrible trips across the Atlantic on merchants’ galleons, when many gale-tossed passengers despaired of ever setting foot on land again, she recently commented: “Imagine what they felt when they spotted the light.” See Dorothy Wickenden’s article “Last Watch” in the November 6, issue of my favorite magazine, The New Yorker. Of the roughly 850 lighthouses currently in the United States, Wickenden reported, only about half serve as active aids to navigation and the U.S. Coast Guard has automated all of them. “The rest,” Wickenden wrote, “have been made obsolete by GPS.” Yet, she pointed out, even hardheaded ship captains and pilots say that “lighthouses still have a place.”

When Snowman retires at the end of this month, it will mark the end of an era that lasted more than three centuries. This month also marks the 50th anniversary of the approval of Navstar GPS (as it was originally called) by the Defense Systems Acquisition Review Council (DSARC) of the U.S. Department of Defense. Three months earlier, at the meeting now remembered as Lonely Halls (see my editorial in the September issue), Brad Parkinson and his team had made the key decisions about the system’s architecture, including the number of satellites, their orbits, and what kinds of signals to use.

In this month’s issue, we revisit how, after initial opposition, the U.S. armed forces adopted GPS; how the civilian/commercial GPS (now GNSS) industry was born; and how surveyors reacted to this disruptive new technology.

To answer the first question, I asked Gaylord Green, who was on Parkinson’s team and later led the GPS Joint Program Office, to write his recollections on the subject. I also interviewed Marty Faga, whose long and distinguished career included four years as both Director, National Reconnaissance Office and Assistant Secretary for Space, U.S. Air Force. Faga passed away on October 19. To answer the second question, I turned to Charlie Trimble, who in 1978 co-founded the company named after him and was its CEO until 1998. To answer the third question, I chose Dave Zilkoski, who earned a master’s degree in geodetic science in 1979, the year after the first GPS satellite was deployed, while working for the National Geodetic Survey, of which he was later the director for about three years. Many readers of this magazine also know Zilkoski as the regular contributor to one of our four digital newsletters, Survey Scene.

This issue’s cover story also focuses, in part, on the 50th anniversary of GPS, as seen by three large players in the aerospace industry: Spirent, BAE Systems, and Northrop Grumman.

Matteo Luccio | Editor-in-Chief
mluccio@northcoastmedia.net

As part of our celebration of the 50th anniversary of the Global Positioning System, three long-time players in the industry share their “GPS origin story,” recent breakthroughs, and their view on the next 50 years of positioning, navigation and timing (PNT). All three began their involvement with GPS between the late 1970s and the late 1980s, before the system was completed. All three are continuously making GPS more resilient and resistant to jamming and spoofing or augmenting it with layered multi-orbit architectures of complementary PNT.

Read the origin stories, recent breakthroughs, and more insights from the following companies:

BAE Systems: Pioneering military GPS technology

Northrop Grumman: Integrating and developing GPS technology

Spirent: From testing GPS to assuring PNT

What is BAE Systems’ GPS origin story?

BAE Systems has more than 45 years of military GPS experience. In fact, the first ever GPS signal reception on Earth happened at one of our offices in Cedar Rapids, Iowa, on July 19, 1977, when one of our legacy companies received the signal. Since that historic day, BAE Systems’ engineers have introduced more than 50 GPS products, including GPS anti-jam and precision landing systems.

As a pioneer in military GPS technology, BAE Systems has delivered nearly two million GPS devices on more than 280 platforms around the world. We design and produce advanced GPS technology compatible with the next generation M-code signal, improving security and anti-jamming capabilities for critical defense applications.

Can you share any recent innovations from BAE Systems?

BAE Systems innovates a full portfolio of M-code-compatible military GPS solutions to meet warfighters’ needs. Our Strategic Anti-jam Beamforming Receiver — M-code (SABR-M) is the most capable integrated anti-jam (AJ) electronics GPS receiver and the first integrated AJ M-code receiver available for weapons systems. It delivers assured, global position, velocity, altitude and timing, as well as strong protection against GPS signal jamming and spoofing — critical capabilities for unmanned aerial vehicles (UAVs), precision-guided munitions (PGMs), and missiles in threat environments.

This past June, at the Joint Navigation Conference in San Diego, BAE Systems unveiled NavGuide, a next-generation Assured Positioning, Navigation and Timing (A-PNT) device featuring M-code GPS technology. It is our response to strong defense market demand for a cost-effective, high performance handheld GPS upgrade. NavGuide provides an intuitive user interface and integrates easily into platforms currently using BAE Systems’ Defense Advanced GPS Receiver (DAGR).

How is your company preparing for the next 50 years of PNT with GPS and beyond?

BAE Systems is making advancements in our critical navigation capabilities for the warfighter through the Military GPS User Equipment (MGUE) Increment 2 program. We are developing a Next-Generation Application Specific Integrated Circuit (NG ASIC) for our small form factor Miniature Serial Interface (MSI) receiver. This will enhance our full portfolio of ground, airborne and weapons M-code assured GPS receivers beyond 2030.

We have invested an enormous amount of time and energy into our facilities and simulator capabilities, especially in our state-of-the-art simulators powered by Spirent Federal signal generation and RF wavefront technology. We want to be prepared to meet the technical demands of an ever-changing threat environment, and we need to be certain our receivers are prepared for the fight the first time, every time. We put our receivers through the paces by running them through thousands of trials on our Spirent simulators to validate and verify our performance under the most demanding scenarios.

What was Northrop Grumman’s GPS Origin Story?

Northrop Grumman’s involvement with GPS has its origins during the mid-1980s, when we became an early adopter. We applied our prior decades of technical expertise in defense and commercial navigation solutions to recognize the significance of GPS as an emerging technology to optimize our inertial navigation products. The first GPS receiver was integrated with the LN-33, our main product for military aircraft, in 1987.

Around the same time, our engineers began to develop an indigenous civil GPS receiver to complement our inertial navigator for use in commercial airliners. This resulted in the certification and fielding of the LTN-2001 product, an eight channel C/A Code GPS receiver. This receiver, in concert with our Autonomous Integrity Monitored Extrapolation (AIME) algorithm, provided our customers a first-ever sole means navigation system using GPS/inertial for non-precision approach.

By the early 1990s, advancements in the semiconductor industry facilitated the reduction of the GPS receiver from a 1,000 cu in stand-alone box to a roughly 6-in by 6-in circuit card. This critical milestone allowed GPS to be embedded into an inertial navigation system (INS) without a significant increase in its size or power consumption and thereby the ubiquitous Embedded GPS INS (EGI) was born. Our first inertial navigation system with embedded military GPS capability was the LN-100G in 1991. This standard form factor was produced across the industry with installations on virtually all the front-line tactical aircraft and rotorcraft for the U.S. Department of Defense (DOD) and many of our allies.

Can you share a breakthrough?

Inspired by accomplishments in the survey community, our team conducted early location accuracy experiments to demonstrate a few decimeters of accuracy between our Woodland Hills, California, location and a facility in San Jose, California, about 500 km away. Leveraging this experience and the same signal processing, our teams became a broader solution provider for adjacent mission applications including precise formation flying for in-flight automated refueling, precision approach and landing, and decimeter-level positioning for the intelligence, surveillance and reconnaissance (ISR) community.

In parallel with these developments, Northrop Grumman, in partnership with the Defense Advanced Research Projects Agency (DARPA), improved the resilience of embedded GPS receivers with a more intimate coupling of INS and GPS. The DARPA GPS Guidance Package (GGP) program demonstrated a Navigation Grade Fiber Optic Gyro (FOG), greatly improved GPS tracking performance under extreme vehicle dynamics, and the ability to track at lower signal-to-noise levels. Our success on this program reinforced our reputation as a GPS integration leader and led to the introduction of Northrop Grumman’s current LN-251 product line, which is broadly used in tactical military aircraft.

In the early 2000s, Northrop Grumman initiated research into the feasibility of a Global Navigation Satellite System (GNSS) software-defined radio and started development of what we now call SERGEANT (Software Enabled Reconfigurable GNSS Embedded Architecture for Navigation and Timing). The company used Spirent signal simulators to evaluate proper GPS M-code tracking over a wide range of test cases in a controlled laboratory environment. Together with the Air Force Research Laboratory (AFRL), Northrop Grumman demonstrated advanced receiver capabilities using SERGEANT starting in 2010. In 2018, AFRL used SERGEANT for the first real-time flight demonstration of a GPS M-code SDR.

How is your company preparing for the next 50 years of PNT with GPS and beyond?

Northrop Grumman foresees the world of GNSS being dramatically influenced by the emergence of alternative radio navigation sources as augmentations to traditional GNSS constellations to provide additional robustness and resilience. Our PNT SDR technology is a foundational tool to integrate these emerging radio navigation signals quickly and accelerate deployment to our customers.

Northrop Grumman has led medium-Earth orbit (MEO) and low-Earth orbit (LEO) PNT technology studies through the DARPA Blackjack proliferated LEO (pLEO) program, starting in 2017. Northrop Grumman’s SERGEANT SDR transceiver is currently being integrated for use in emerging pLEO constellations. We anticipate that these capabilities, as well as emerging cooperative radio navigation signals, will become a critical part of the next 50 years of PNT with GPS.