This month’s column is an irresistible departure from sensible, autonomous UAVs and artificial intelligence (AI) news. We’re taking a small leap into who knows where.

How many of GPS World’s readers have interest in sci-fi, or at least are somewhat interested in the weird and wonderful stuff that shows up on some TV “reality” shows? Or maybe have a passing interest in the U.S. Navy’s Unidentified Aerial Phenomena Task Force, the U.S. Congress’s interest in unidentified flying objects (UFOs) and now the Airborne Object Identification and Management Synchronization Group (AOIMSG) of the Department of Defense (DOD)?

Yes, this a short meandering around what we now apparently call unidentified aerial phenomena (UAP), but mostly because one of those reality shows made use of UAVs in an effort to find out how or why UAPs may be concentrated in a particular location. That’s a location in northeastern Utah where Robert Bigelow may have previously spent millions of dollars of the Pentagon’s money conducting a study on UFOs. You may have heard of Bigelow Aerospace and their efforts to build inflatable orbital space stations. Bigelow was apparently intent on finding a logical answer to the UFO phenomenon and may have been involved for a while in the gathering of UFO sighting data on behalf of the Federal Aviation Administration (FAA).

The UFO/UAP flame has apparently been carried since around 2020 by a “scientific team” that puts out a regular TV program called “The Secret of Skinwalker Ranch,” which is broadcast on the History channel. There is a side of this program that also tries to deal with apparent paranormal “giant-red-eyed-wolf” activity at this location, but for today’s story, we are focusing on slightly more plausible, significant scientific efforts to identify UAP phenomena, not the less likely investigation of worm-holes at a site on the ranch (there goes all credibility, but please keep reading).

The cast of this show includes lead investigator, actor/scientist, Dr. Travis Taylor, who has two doctorates and three master’s degrees in engineering, physics and astronomy. He’s been involved with and has authored several articles in scientific journals, as well as nonfiction books and novels, appeared in TV presentations and worked for NASA and DOD on various programs.

The instruments of choice for this effort include forward-looking infra-red (FLIR), hand-held and UAV-mounted thermal and HD video cameras, wide-band frequency synthesizers and monitors, lidar scanners, and a data acquisition and display system that collects and analyzes all of the outputs of these systems, and GPS data. So, somewhat serious tech.

There are two areas on the ranch where UAP activity has been observed and has even been apparently stimulated by launching short-range rockets: a triangular intersection of three pathways or roads — referred to not surprisingly as the “Triangle” — and a field some distance off to the east, both at the foot of a mesa or flat-topped, raised area of land. As a side investigation, there were earlier efforts to determine what might lay buried inside the mesa, via video poked inside small caves, and then a horizontal drilling rig that apparently turned up exotic material similar to heat-shield re-entry coatings on spacecraft. This may be another diversion from the true search for UAPs, but then again maybe not.

Finally, some UAV involvement — a UAV aerial survey of the whole 512 acres of the Skinwalker site was carried out collecting data over a seven day period by VCTO Labs in Washington state with GPS RTK, acquiring the necessary 1 cm accuracy for a 3D model created by PIX4Dmatic processing.

About 32,000 images were captured and the resulting 3D model is now used as the geolocation truth model for the site. Nevertheless, surveying efforts over the last three years may have been hampered by the loss of three UAVs, thought to be due to some form of electromagnetic interference that brought them down.

When the team focused on the Triangle, there seemed to be one “anomaly” of some description at the center of the area at about 2,500 ft. So, to stimulate the anomaly or to create some sort of reaction, high density lasers were located at the corners and focused at about 2,500 ft. With these beams highlighting the suspect area, a large rocket was fired straight up toward the focus point. After a launchpad explosion that destroyed the first rocket, another was hustled into position, and launched successfully. At about 1,000 ft, the rocket was diverted some 30° off to the side, with no apparent high-level winds or other apparent influence, perhaps from some sort of guidance error.

As a follow-up and to gain more insight into another anomaly found flying a hand-held lidar in a helicopter at 300 ft above the triangle, it was decided to bring in a UAV lightshow by Sky Elements Drone Shows — an outfit based in Fort Worth, Texas, associated with SPH Engineering in Riga, Latvia. They run a heap of UAV shows in the United States and ran a recent 600-UAV show for the coronation in the United Kingdom and claim to have worked in 75 countries around the world. The object of the UAV show at Skinwalker was to see whether any “anomalies” would affect UAV guidance, and obviously many lighted UAVs in formation at altitude would make for good TV. The show uses a GPS RTK set-up, and the drones are guided by u-blox M8P GPS/GLONASS GNSS receivers.

So, with a rocket launched and the 1.6 GHz signal detected — it may have also been rebroadcast — the Sky Elements UAVs were powered up, lit up, lifted off and flown to altitude above the Triangle. All seemed well with all 200 lighted UAVs hovering in the night sky until a couple of UAVs “disconnected” — presumably from the 5 GHz Wi-Fi control channel, which has a secondary 915 MHz back-up. Then pandemonium erupted as the whole UAV display collapsed from the middle section, and the UAVs returned to the ground. To be sure, the 200 lighted UAVs were spun up again, flown up to altitude, and after a few minutes, the drop-out happened again as the fleet of UAVs returned to the ground.

The UAV show was moved to the notorious East Field and everything was repeated. However, other than what looked like a timing error as one UAV left early and was joined at altitude by the rest of the two hundred UAVs, no anomalies disturbed the formation.

The Skinwalker research team had instrumented the four corner UAVs of the display with a separate GPS receiver (and radio link?), so that their recorded position data could be used for subsequent analysis. Therefore, when the team huddled round the replay of the Triangle show in their control room, they had access to the UAVs’ location data from all the UAVs and the GPS location information from the four corners. Unfortunately (for our purposes) or fortunately (for the team), as the video/data analysis ran, a UAP was noticed flying over the proceedings. The image was clear enough for Travis Taylor to come up with a drawing of it, similar to a foreshortened dumb-bell.

Other than noting that the GPS altitude data for the UAVs that landed had been recorded as negative, or below the surface of the ground, the drone show analysis was put aside for extensive review of the UAP video — after all, the whole effort is prioritized to stimulate and analyze UAP anomalies, right?

So, what could we make of all this? Certainly, for me, the presence of the 1.6 GHz signal seems to be an indication that the UAVs’ GPS receivers and the GPS RTK reference receiver may have been jammed at L1. However, for the UAVs to return to their ground location, they may be programmed to do so when GPS guidance is lost.

So, why didn’t they behave the same at the East Field? Perhaps the jamming signal was localized at or near the Triangle? So, the next step would be to determine where this 1.6 GHZ signal originates. If it is re-broadcast by the team it might be a good idea not to do so. The u-blox M8P receiver includes GLONASS, but it doesn’t sound like there was associated RTK for GLONASS, so when GPS RTK was lost, GLONASS positioning alone may not have been able to meet the requirements of formation flight. So, the UAVs probably default to return-to-base logic, even though they may dead-recon back to the ground?

I asked my friends in Latvia whether they could confirm this layman’s hypothesis, but they needed the logs stored on the UAVs from those shows, and they were not apparently downloaded. It seems like there might be an opportunity for a re-run with post-show access to the individual UAV logs.

What about the analysis of the apparent UAP? Now, I must go watch more Skinwalker Ranch shows.

ComNav Technology has launched the A200 dual antenna heading receiver. It is designed for precision agriculture, machine control, fleet management, robots and other applications.

As a solution capable of real-time kinematic (RTK) heading, the A200 is equipped with a K823 GNSS module, which is a dual-antenna, dual-frequency and full-constellation OEM board that includes an inertial measurement unit (IMU) module. The A200 can track all existing and planned satellite systems, including GPS, BSD, GLONASS, Galileo, QZSS and SBAS, providing RTK-level position and precise heading to users. It also features 1,226 channels.

The A200’s third generation IMU delivers fast initialization and ensures the output of heading during temporary GNSS signal loss. The built-in data link has low power consumption and a long working range. It can also be upgraded to a super-long-range data link module.

The A200 now is available through ComNav Technology authorized local distributors or ComNav Technology directly.

Position Partners has announced the availability of Quantum-Systems’ Trinity Pro remotely piloted aircraft system for the Australian and New Zealand market.

The Trinity Pro is a UAV designed to adapt to changing demands, provide additional connectivity, and accelerate decision-making. The UAV features Quantum-Skynode autopilot, which uses a Linux mission computer. This provides additional onboard computing power, increased internal storage, versatility, and interoperability.

Included in the Trinity Pro system is Quantum-Systems’ proprietary operations software, QBase 3D, and a portfolio of industry workflow and software integrations. The Trinity Pro’s capabilities include planning functions for missions requiring take-off and landing at different locations, allowing for efficient and safe long corridor flights and beyond visual line of sight operations.

The platform also incorporates advanced self-diagnostics to ensure safe operation.

The Trinity Pro now includes an enhanced terrain-following system, which improves safety during operations. The UAV also features automatic wind simulation for crash avoidance in bad weather and a linear approach for landing.

The Trinity Pro is equipped with a downfacing lidar scanner that provides highly accurate ground avoidance and landing control. It is protected against dust and water damage and features increased wind limits of up to 14 m/s in cruise mode and 11 m/s during hover.

AUVSI XPONENTIAL 2023 has officially concluded. GPS World had the opportunity to visit several booths during the conference and attend a variety of educational sessions while in the heart of beautiful, downtown Denver.

See below for some takeaways from XPONENTIAL.

While I’m likely preaching to the choir here, GNSS cannot work unless we have an accurate description of the orbits of the satellites and the behavior of their atomic clocks. The accuracy with which this information is provided to a receiver or data processing software is the most important component of the error budget of GNSS positioning, navigation and timing and constitutes most of what is known as the signal-in-space (SIS) range error.

Each GNSS satellite broadcasts a description of its orbit or ephemeris along with the offset of its active clock from the system’s time standard in a navigation message decoded and used by the receiver. These data are predictions of the orbit and clock offset as computed by the system’s ground control segment and uploaded to each satellite. A recent assessment by U.S. Space Systems Command of the GPS SIS error averaged across all active satellites for a one-week period was about 50 centimeters, root-mean-square. While this is entirely adequate for many GNSS uses, it falls short of the required accuracy for high-demanding applications such as surveying, geodesy, atmospheric sensing, reference frame studies and tectonic monitoring. Which is why various organizations both private and public compute very accurate orbits and clocks and provide these to users. These computations, using data from global receiver networks, are very exacting and model the tiniest effects on the (primarily) carrier-phase measurements these receivers provide.

These effects include the offset in the electrical phase centers of a GNSS satellite’s transmitting antenna from the satellite’s center of mass and how that varies with the direction of the signal from the satellite to a receiver on Earth. Furthermore, this behavior must be calibrated and modeled for each radio frequency that the satellite transmits. Another effect that must be accounted for are the perturbations caused by non-perfect yaw-steering of a satellite’s solar panels. These panels continuously track the Sun but they have difficulty keeping up at orbit noon and midnight. Accurate models of the actual yaw angle are very important for high-precision GNSS orbits. As if these model requirements were not enough, the effect of solar radiation pressure on satellite orbits must also be modeled. While they don’t have (rest) mass, photons have energy and this can be imparted to satellites when they impinge on them. While a single photon has a negligible effect, the billions upon billions of photons making up sunlight do have a noticeable effect on a GNSS satellite’s motion and must be accounted for by orbit models.

One organization producing precise orbits for GNSS satellites – arguably the most precise in the world – is the International GNSS Service (IGS), a voluntary federation of more than 200 agencies, universities and research institutions across the globe. Several of these organizations each produce precise orbits, which they submit to the IGS to establish orbit products. One of these organizations is the Navigation Support Office (NSO) at the European Space Agency’s European Space Operations Centre. In this quarter’s Innovation column, a team of NSO engineers discusses how they have improved the orbit modeling of the GPS III satellites by around a factor of two with estimated orbit errors of about 2 centimeters or less. Wizardry? Not really – just rocket science.

Read the full “Innovation” column: New type on the block: Generating high-precision orbits for GPS III satellites.

Read Richard Langley’s introduction column, Innovation Insights: Antennas and photons and orbits, oh my!

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To produce GNSS satellite orbit ephemerides and clock data with high precision and for all constellations, the Navigation Support Office of the European Space Agency’s European Space Operations Centre (ESA/ESOC) continually strives to keep up and improve its precise orbit determination (POD) strategies. As a result of these longstanding efforts, satellite dynamics modeling and GNSS measurement procedures have progressed significantly over the last few years, especially those developed for the European Galileo satellites. Because the accuracy of ESA/ESOC’s GNSS orbits has reached such a high level (about 1 to 3 centimeters), introducing a completely new type of GNSS satellite into the processing is not as easy as it used to be. New spacecraft models – the first and foremost being a model for a satellite’s response to solar radiation pressure (SRP) – are needed for the “newcomer” so that the quality of the overall multi-GNSS solution does not suffer. Just as important are spacecraft system parameters, or metadata, such as the location of the satellite antenna’s electrical phase center and the satellite attitude law.

In this article, we show the efforts we have made at ESA to bring the quality of our orbit estimates for the GPS Block III satellites up to par with those for Galileo and the earlier GPS satellite blocks. We report on the results from on-ground and in-flight determinations of the Block III transmit antenna phase center characteristics up to 17 degrees from the antenna boresight direction. Moreover, we take advantage of the non-zero horizontal offsets of the transmit antenna from the spacecraft’s yaw axis to estimate the satellite yaw angle during Earth eclipse season and present a simple analytical formula for its calculation. Finally, we describe the development and validation of improved radiation force models for the Block III satellites.

We start, however, by giving a brief overview of the GPS Block III program.

GPS Block III

The U.S. Space Force GPS Block III (previously referred to as Block IIIA) is a series of 10 satellites being procured by the United States to bring new future capabilities to both military and civil positioning, navigation, and timing (PNT) users across the globe. Designed and manufactured by defense contractor Lockheed Martin (LM), the satellites are reported to deliver three times better accuracy, 500 times greater transmission power, and an eightfold enhancement in anti-jamming functionality over previous GPS satellite blocks. At ESA/ESOC, we are paying particular attention to this new tranche of satellites as they are the first to broadcast L1C, a new common signal interoperable with other GNSS, including Galileo.

At the time of this writing, there are six GPS III space vehicles (SVs) in orbit. The first one – nicknamed “Vespucci,” in honor of Italian explorer Amerigo Vespucci – lifted off atop a SpaceX Falcon 9 rocket from Cape Canaveral Air Force Station, Florida, in December 2018, and entered service on January 13, 2020. An additional four SVs are expected to be launched soon, before moving on to an updated version called GPS IIIF (“F” for Follow On). The first Block IIIF satellite is projected to be available for launch in 2026.

In view of the growing number of GPS III SVs in orbit, and soon to be joined by IIIFs, accurate spacecraft models and metadata information are becoming more and more important in order to maximize PNT accuracy.

Satellite antena phase center parameters

GNSS signal measurements refer to the electrical phase center of the satellite transmitting antenna, which is neither a physical nor a stable point in space. The variation of the phase center location as a function of the direction of the emitted signal on a specific frequency is what we call the phase center variation (PCV). The mean phase center is usually defined as the point for which the phase of the signal shows the smallest (in a “least-squares” sense) PCV.

The point of reference for describing the motion of a satellite, however, is typically the spacecraft center of mass (CoM). The difference between the position of the mean phase center and the CoM is what we typically refer to as the satellite’s antenna phase center offset (PCO). Both PCO and PCV parameters must be precisely known — from either a dedicated on-ground calibration or one performed in flight — so that we can tie our GNSS carrier-phase measurements consistently to the satellites’ CoM.

On-Ground Calibrations. Like for previous GPS vehicles, the Block IIR and Block IIR-M satellites, LM has fully calibrated the GPS III transmit antennas prior to launch at their ground test facilities. Antenna offset parameters for all three carrier signals (L1, L2 and L5) were posted on the U.S. Coast Guard Navigation Center (NAVCEN) website (www.navcen.uscg.gov) shortly after each satellite launch. In December 2021, NAVCEN released the PCOs for SV number (SVN) 78, along with updates to the first four satellites (see Table 1). About ten months later, in October 2022, the antenna pattern for each satellite and signal frequency were published (see Figure 1).

The December 2021 offsets are referred to as predicted values at the end of year one on orbit. They differ from the previous ones by several centimeters in both vertical (Z) and horizontal (X and Y) directions. Particularly surprising are the X- and Y-PCOs, which were initially reported to be close to zero. The differences in the horizontal PCOs have generated uncertainty and debate, especially within the International GNSS Service (IGS) about which values to adopt for the new antenna model release (igs20.atx). Testing of the two different PCO datasets in our software demonstrated that the non-zero values as given in Table 1 are the significantly more accurate ones. We will return to this later in this article.

Combined Ground- and Space-Based Tracking. In this part of this article, we discuss the combination of dual-frequency tracking data from geodetic-quality GPS receivers in low Earth orbit (LEO) with those from a global receiver network on the ground to determine the phase center parameters of the GPS Block III transmit antennas. The LEO-based measurements were taken by the GNSS receivers on board the ocean altimetry satellites Sentinel-6 Michael Freilich and Jason-3. The 1,336-km altitude of both of these missions enables the estimation of the GPS satellite antenna PCVs from 0 up to 17 degrees from boresight while GPS receivers on Earth can only see the satellites up to a maximum angle of 14 degrees. The 14-degree limit is also referred to as the GPS satellites’ edge of Earth (EoE) angle.

The Association for Uncrewed Vehicle Systems International (AUVSI) has named the winners of the sixth annual AUVSI XCELLENCE Awards.

The awards recognize the accomplishments of companies, organizations and individuals across the uncrewed systems community. The winners were recognized during an awards ceremony at XPONENTIAL 2023 which is being held this week at the Colorado Convention Center in Denver, Colorado. This year’s 50th anniversary event is co-hosted by Messe Düsseldorf North America.

AUVSI’s XCELLENCE Awards honor innovators with a demonstrated commitment to advancing autonomy, leading and promoting safe adoption of uncrewed systems and developing programs that use these technologies to save lives and improve the human condition.

These are the finalists in those categories:

XCELLENCE in Academic Research

First Place: University of Colorado Boulder, 20 Years of UAS Research XCELLENCE
Second Place: Virginia Tech’s Mid-Atlantic Aviation Partnership, Robert Briggs
Third Place: Ocean Alliance, Tagging Whales with Drones

XCELLENCE in Innovation

First Place: Skydio, Skydio Dock, Automated Inspections of Sites with Autonomous, Remote Drone Operations
Second Place: Plus, PlusDrive, An Industry-defining Driver-in, Highly Automated Driving (HAD) Solution
Third Place: Sentera, Eliminating Stitching with the Sentera DGR System

XCELLENCE IN OPERATIONS – Enterprise Application

First Place: JobsOhio and the Ohio Department of Transportation, Propelling AAM in Ohio
Second Place: Advanced Navigation, Cloud Ground Control
Third Place: City of Pendleton, Pendleton UAS Range

XCELLENCE IN TECHNOLOGY

Enabling Components & Peripherals
First Place: infiniDome, infiniDome’s GPSdome2
Second Place: Elsight, Elsight Halo
Third Place: MatrixSpace, MatrixSpace Networked Radar

Hardware & Systems Design
First Place: D-Fend Solutions, EnforceAir
Second Place: Advanced Navigation, Hydrus
Third Place: Connect Tech, Anvil Embedded System with NVIDIA  Jetson AGX Orin

Software Design and Coding
First Place: BlueSpace.ai, Scalable and Explainable AI for Autonomy, powered by 4D Predictive Perception
Second Place: Skydio, Skydio Scout, Situational Awareness for Moving Convoys
Third Place: AlarisPro, Inc., AlarisPro Safety Ecosystem (ASE) – Advancing UAS Reliability Through Shared Data Across UAS Operators and Manufacturers

XCELLENCE in Workforce Development

First Place: Laurel Ridge Community College, Laurels Take Flight
Second Place: DroneUp, with partner, Richard Bland College, Established the First Commercial Drone Workforce Training Program for College Credit
Third Place: Embry-Riddle Aeronautical University Worldwide and Warren College, Better Together: Producing Effective Educational Opportunities for the UAS Workforce

The recipients of the 2023 AUVSI XCELLENCE Humanitarian and Public Safety Awards have established themselves as leaders in the application of uncrewed technology to provide solutions to the world’s most pressing problems. Each awards category recognizes organizations that have made a significant impact using uncrewed systems to serve in humanitarian or public safety efforts. The six organizations will equally divide a $6,000 prize for their  humanitarian and public safety efforts.

This year’s recipients are:

XCELLENCE in Mission

Humanitarian Project/Program
First Place: ArroTech, Dr. Stephen Dunnivant
First Place: MissionGO, Inc., Operation Healing Eagle Feather
First Place: The David McAntony Gibson Foundation (GlobalMedic), GlobalMedic RescUAV Response to La Soufrière Volcano in Saint Vincent and the Grenadines

Public Safety

First Place: DRONERESPONDERS, DRONERESPONDERS Public Safety Alliance
First Place: Texas Department of Public Safety, Texas Department of Public Safety
First Place: United States Forest Service, Testing and Scaling New Technologies for Operations and Safer Mixed Airspace Ops

AUVSI XPONENTIAL is underway in Denver, Colorado, at the Colorado Convention Center. After the second day of touring the XPO Hall, GPS World staff wanted to highlight some key parts of the day.

Safran Landing Systems has signed a contract with Airbus Defense and Space to provide the wheels and brakes system work package for the Eurodrone program, which is designed to outfit France, Germany, Spain and Italy with a highly autonomous medium-altitude reconnaissance UAV.

Safran Landing Systems was selected to design, develop, qualify and produce the work package and to supply the braking control module that will be developed by Safran Electronics and Defense, the company’s partner on this program.

The contract comprises 60 shipsets.

Safran Electronics and Defense has also claimed a contract from Leonardo to develop and supply the high-performance Euroflir 610 electro-optical (optronic) system for the program.

Production of the first prototype will begin in 2024 with a first delivery planned by the end of the decade.