Global Navigation Satellite Systems Engineering, Policy, and Design
The Federal Communications Commission ignored a technical standard defining radio-frequency interference. The five commissioners licensed powerful terrestrial broadcast next to the satellite band, exposing national defense and critical infrastructure to harm.
Order-of-magnitude advances in inertial technology seem to take place roughly every 20 years, and the industry is poised at such a point now. New developments in photonic technology make high-performance inertial measurement accessible at lower size, weight and power. Many applications from driverless cars to UAVs can now take advantage of positioning that can independently bridge GPS outages from 2 minutes up to 10 minutes.
By Inside GNSS
Britain’s own satellite navigation system, envisioned to fill the country’s Galileo void created by Brexit, may never see the light of day. Government officials don’t want to spend tax revenues to meet projected increasing costs.
By Inside GNSS
A new mobile app, Galileo Green Lane, facilitates the free movement of freight, reduces waiting times at European Union borders, and prioritizes essential goods during pandemic response. The app uses Galileo positioning services to address the needs of border control authorities and truck drivers, with two intuitive user interfaces. The app was developed by the European GNSS Agency (GSA) in collaboration with the European Commission.
By Inside GNSS
The MEMS-based inertial measurement unit (IMU) represents the single biggest positioning and navigation advance of the last 20 years. That assertion is made during the first of three panels in the webinar “Inertial Technology for Robotics, UAVs and other Applications,” freely available on May 6. The 1.5 hour presentation examines how this breakthrough plays in the fields of autonomy, high dynamics and challenging environments, including on the frontiers of space.
Three experts takes a close-up look at contemporary and emerging inertial sensor technologies and applications, from the laboratory to the factory to the field. Register here to attend. The webinar is sponsored by Sensonor.
MEMS (micro-electromechanical sensors) make possible a miniaturization of size, weight, power requirements and cost never thought achievable before. When MEMS inertial navigation pairs with GPS for navigation, the key factor is the error budget of each sensor and how that plays into the accuracy of the solution. Attendees will learn how the new inertial sensors’ reduced error budgets translate into higher system performance.
The presentation begins with the current state of the inertial art, delivered by a recognized expert. The second speaker describes a high-accuracy tactical-grade inertial measurement unit (IMU) with increased accelerometer performance to support demanding guidance and navigation applications.
This knowledge is taken to the field to examine the IMU’s role in successful satellite launch missions during the third panel. The attitude determination and control system (ADCS) rises to the challenge of an extremely demanding environments and set of requirements. A satellite moving at a speed of 7,500 meters/second over ground requires precise maneuvering, stabilization and point in order to obtain imagery at 1-meter resolution.
Questions from the audience are actively encouraged and will be addressed by the three speakers in the final portion of the webinar.
Webinar speakers:
Ralph Hopkins is a Distinguished Member of the Technical Staff and Group Leader in the Positioning Navigation and Timing (PNT) Division at Draper, a leading research & development organization. He is responsible for the design and development of inertial instruments and sensors. Ralph has served as Technical Director of advanced inertial instrument development programs including strategic, navigation and tactical grade gyroscopes and accelerometers. He holds an ME in Engineering Mechanics from Columbia University, and an MS in Engineering Management from The Gordon Institute of Tufts University.
Reidar Holm is a Product Development Manager at Sensonor, a producer and developer of high-precision, light-weight gyros and IMUs. He works MEMS R&D and design, ASIC design, low-stress package design, system design, assembly and calibration, and high-volume production for automotive, MEMS pressure sensors, accelerometers, gyros and IMUs. He has a Degree in Electrical Engineering and Electronics from University of Manchester Institute for Science and Technology (UK) in 1982.
Ryan Robinson is the Lead Guidance, Navigation and Control Engineer at LeoStella, a small satellite design and manufacturing company, He is responsible for the design, development, test, and delivery of ADCS subsystems on LeoStella satellites. He received a Ph.D. in Aerospace Engineering from the University of Maryland, College Park. Technical areas of interest include attitude determination and control systems design, sensing and actuation, nonlinear dynamics, and autonomy.
Register here for the free webinar, “Inertial Technology for Robotics, UAVs and other Applications.” The webinar will also be available for subsequent download, for those registrants unable to attend at the appointed time.
By Inside GNSS
In its order allowing Ligado Networks to use satellite frequencies for on-the-ground wireless, the Federal Communications Commission set conditions on the firm’s operations, but only at the very tail end. Those conditions are there to help protect GPS receivers from interference — interference the FCC acknowledges as being quite possible.
By Dee Ann Divis
“Ligado’s planned usage will likely harm military capabilities, particularly for the U.S. Space Force, and have major impact on the national economy,” two ranking Senators and a Representative wrote. The timing could not be worse, they said to allow what “is fundamentally a bad deal for America’s national and economic security.”
By Dee Ann Divis
The U.S. Air Force 2nd Space Operations Squadron has put the last operational GPS IIA satellite, SVN 34, into disposal cycle for April 13 to 20. This is effectively end of life, or space hospice if you will, for a satellite that has outlived its 7.5 year design span by 19 years.
The rite of passage brings to a close a 26.5-year era in which the IIA generation carried the gold standard of positioning 20,200 km (12,550 miles) above the Earth, circling the globe twice a day.
Nineteen Block IIA satellites, slightly improved versions of the Block II series (the first full scale operational GPS satellites), were launched from November 26, 1990 until November 6, 1997. The satellites were built by Boeing, formerly Rockwell Corporation. They broadcast the L1 C/A signal for civil users and the L1/L2 P(Y) signals for military users.
SVN-34, the last of its generation, was removed from service October 9, 2019 but kept on as part of the constellation as a decommissioned, on-orbit spare until April 13.
In the disposal process, “We push the satellite vehicle to a higher, less congested, ‘disposal orbit’ to eliminate the probability of collision with other active satellites,” said Capt. Angela Tomasek, 2SOPS GPS mission engineering and analysis flight commander. “[Then,] the vehicle is put into a safe configuration by depleting the leftover fuel and battery life and shutting off the satellite vehicle transmitters so no one else can access the satellite in the future.”
“As we continue to manage the influx of GPS III and maintaining other vehicles in a residual status, we have to be cognizant of effective risk management,” Tomasek continued. “As SVN-34 continued to age, we had to manage its aging components and likelihood of having a critical malfunction. We are at a stage where we are confident in the robustness of the overall GPS constellation to remove the last remaining IIA vehicle.”
Once SVN-34 arrives in its final orbit, 2 SOPS will hand over full tracking responsibility to the 18th Space Control Squadron at Vandenberg AFB, California, where it will be treated and catalogued like every other space object, on April 20.
“This disposal marks the end of an era in GPS history,” said Lt. Col. Stephen Toth, 2nd SOPS commander. “There are senior leaders and long-time contractors [who] launched and operated the IIA satellites at the beginning of their careers [who] are now here to see it end. It is an opportunity to reflect on the legacy and heritage of 2 SOPS and GPS to see how far we have come.”
By Inside GNSS
Thirteen agencies responsible for much if not most of the nation’s military, civil, security and economic activity say Ligado Networks’ plan to use satellite frequencies for 5G communications would interfere with GPS users in general and DOD use in particular.
By Dee Ann Divis
Experts at the NATO Communications and Information (NCI) Agency have developed a software-based tool that can estimate the area where an interfering signal would degrade or deny GNSS signals, and assess the scale of the interfering signal and its potential impact on operations. Principally of interest are jamming or spoofing attacks on GPS or Galileo, of course.
The Radar Electromagnetic and Communication Coverage Tool (REACT), was sponsored by the NATO Navigation and Identification Programme of Work. It serves as a proof-of-concept of how analytical tools could support the execution of operations. The tool is also available to NATO Nations free of charge. For now, the software is only used for trial and experimentation.
To use the software, operators input information on the particular jammers – their locations and technical characteristics — and the software produces a map of the area where the interfering signals would degrade or deny GNSS receivers. This can be displayed on the NATO Core Geographical Information System (GIS) map.
The next phase of the project focuses on ensuring the software can work on NATO classified networks, which would make it more available to operational commands to test and ensure such support measures are properly integrated into NATO operations.
The software and its estimations were demonstrated to operators during exercise Trident Jupiter 2019, part 1, to collect their feedback. The exercise gathered 3,000 military and civilian personnel as participants, evaluators and observers. Thirty NATO member and partner nations participated in nine different exercise locations across Europe.
“Ten consecutive twelve-hour working days and a relentless, ever-increasing, battle-rhythm tempo came to an end as Exercise Trident Jupiter 2019-1 (TRJU19-1) reached completion on Thursday, Nov. 14, 2019,” the agency stated.
TRJU19 was the largest and most complex exercise planned and executed by the Alliance’s Joint Warfare Centre to date. TRJU19-2 took place in March 2020.
“NATO’s adversaries have the ability to degrade or deny GPS-enabled capabilities,” said Jean-Philippe Saulay, a NATO Navigation and Identification Officer. “NATO must take appropriate measures to ensure Allied forces can operate in a degraded or denied environment.”
“NATO must maintain superiority in the electromagnetic environment, including but not limited to, positioning, navigation and timing services,” said Dr Enrico Casini, Communications and Navigation Engineer at the NCI Agency. “Situational awareness of navigation systems in a contested electromagnetic environment contributes to that superiority. NATO is enhancing its knowledge of electronic warfare technology,” Dr Casini said. “The electromagnetic environment has become even more contested in recent years. One aspect of that is interference with GNSS systems.”
Photos courtesy NATO Communications and Information Agency.
By Inside GNSS
Knowledge gained in close study of post-processed GNSS/INS data from very high-dynamic aerial maneuvers can improve position monitoring in machine control, precision agriculture and other industrial applications.
A new methodology targets sub-meter GNSS accuracies in the consumer realm for applications such as augmented reality and visually impaired navigation. Recent Android RTK smartphone services in a real-time environment achieve accuracies below 50 cm. Can these be matched with PPP?
By Joshua Critchley-Marrows, et al.
An assisted GPS direct positioning estimation (DPE) technique for urban environment copes with a full spectrum of direct-line-of-sight and non-line-of-sight or multipath conditions. A new approach using signal visibility and specular reflection predictions within the DPE shows the potential to reduce positioning error from approximately 30 to 10 meters.
