Global Navigation Satellite Systems Engineering, Policy, and Design
An April 9 webinar will field all comers — professional users across a range of industries — with questions about PNT issues involved in drone surveying and mapping: best methodologies and practices, how to extract maximum cost efficiency, which systems are suited to which types and scale of jobs, and much more.
By Inside GNSS
A new API for GNSS simulators enables greater accuracy, integrity and control for growing sensor-fusion testing needs. Spirent Communications’ SimHIL, an integrated hardware-in-the-loop (HIL) testing software API for Spirent GNSS simulators, brings high-fidelity GNSS signal simulation with low latency to automotive industry HIL testbeds.
By Inside GNSS
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.
The European Union’s eCall emergency response system automatically calls emergency services in the event of a serious road accident, transmitting location information from a GNSS receiver (GPS and/or Galileo) installed in the car to local emergency agencies.
By Inside GNSS
A new series of disciplined oven controlled crystal oscillators (OCXOs) incorporates an internal GNSS receiver with a 1PPS output, compatible with an external GPS, GLONASS, BeiDou or Galileo source. The IQCM-112 series from IQD is housed in a 14-pin 60mm square package.
By Inside GNSS
Hundreds, thousands of tiny satellites no bigger than a breadbox orbit the Earth, gathering a staggering amount of data and relaying petabytes of communication. These nanosatellites, commonly called cubesats, serve a variety of research and, increasingly, commercial roles. They work for science, exploration, technology development, education, telecommunications and other operations.
They are built to a standard dimension of 10 cm x 10 cm x 10 cm, or small multiples thereof. Typical weight is less than 1.33 kg (3 lbs) per U, or Unit, which equals on 10 cm cube.
Among other launch opportunities, the National Aeronautics and Space Administration’s (NASA’s) CubeSat Launch initiative (CSLI) can give a ride up to small satellites as auxiliary payloads on planned rocket missions.
To meet performance requirements, commercial cubesats must often report from a precisely known location. Faulty positioning can produce inaccurate data that will adversely affect commercial operations on Earth. Cubesats typically carry a commercial GPS L1 receiver to determine their orbit, as altitude and orbit determination and control form key parameters.
Cubesats often fly in formation and wil then use a GPS/GNSS receiver to co-ordinate and synchronize among themselves. Finally, they use GNSS for onboard synchronization of operations and for precise timestamping of Earth observation data
Though small is size, cubesats can carry a large price tag, up to hundreds of thousands of dollars per project. Pre-launch testing for quality assurance is critical, particular of the satellites’ PNT capabilities. Earth-bound testing cannot replicate the conditions of low-Earth orbit, where the satellites will be moving at several kilometers per second, and need to maintain awareness of the also moving GNSS satellites above them in mid-Earth orbit. Thus the key role of GNSS simulation in this burgeoning industry.
The content of this article is largely drawn from a blog post by Talini Pinto Jayawardena, a space science technologist with Spirent Communications, and also a research manager at the University of Bath. To read her full blog, which contains a detailed description of key performance criteria to test with a simulator, visit here.
Extensive discussion of Doppler shift handling, precise orbit determination, antenna performance, time synchronization, special events, onboard interference handling, and the impact of environmental test (vibration and thermal vacuum) is presented.
By Inside GNSS
GPS got a twofer on March 27 with major advances for the ground segment and the space segment. The Contingency Operations (COps) program, an upgrade necessary to the Operational Control System for it to command and control the new GPS III satellites, was approved. And the second GPS III satellite to orbit was approved, a stage that should shortly be followed by it becoming available to military and civilian users.
Both steps occurred upon receiving the U.S. Space Force’s Operational Acceptance approval.
COps has operated on a trial basis since last October, supporting the developmental testing of the GPS III ground and space capabilities. The trial period culminated in a fully mission capable rating from the Air Force Operational Test and Evaluation Center’s Operational Utility Evaluation.
GPS SV02 launched on Aug. 22, 2019, and upon completing its test, COps took control of it, bringing it into the III fold along with its earlier sibling, GPS III SV01. Administering COps and in direct control of both satellites is the 2nd Space Operations Squadron at Schreiver Air Force Base, Colorado.
“Of all the programs that will be delivered this year, there are few that carry with it as significant an impact to the warfighter and civilian users as [COps] will. This is truly a remarkable leap forward for the GPS enterprise and the capability it provides, and I couldn’t be more proud of the team that came together to make it happen,” said Lt. Col. Stephen Toth, 2nd Space Operations Squadron commander.
Lockheed Martin built both satellites as well as the COps command and control program. The company is under contract to build up to 32 of the new generation and its follow-on version, carrying new technology and advanced capabilities in payloads made by L3Harris. The military advances aboard these satellites include the new military M-code, and COps is necessary to administer this signal.
19 previously orbited IIR-M and IIF generation GPS satellites can broadcast M-Code, as can GPS III SV01 and SV02. The third M-code enabled GPS III satellite should launch in April of this year. The military is getting very close to full M-code capability, which will occur when 24 orbiting satellites have it. Its operational availability is on track for 2020.
The M-Code Early Use (MCEU) upgrade, delivered earlier this year, is a key part of COps, enabling the system to task, upload and monitor M-Code within the GPS constellation. It also supports testing and fielding of modernized user equipment, prior to the completion of the next-generation ground control system, or OCX.
The M-Code encrypted GPS signal enhances anti-jamming and protection from spoofing, and increases secure access for U.S. and allied military forces.
A key to enabling M-Code is a new software-defined receiver Lockheed Martin developed and is installing at all six Space Force monitoring sites. The M-Code Monitor Station Technology Capability receives and monitors M-Code signals.
Finally, Lockheed Martin als0 delivered the Red Dragon Cybersecurity Suite (RDCSS) Phase III upgrade during the fourth quarter of 2019, dramatically improving Defensive Cyber Operations (DCO) visibility into GPS network traffic. Other add-ons include user behavior analytics to analyze patterns of traffic and network taps to improve data collections.
“GPS is an attractive target for our adversaries, so it was critical we bring our best cybersecurity defenses to the table,” said Stacy Kubicek, Vice President of Mission Solutions Defense and Security.
[Image above: Capt. Adam Moody, 2nd Space Operations Squadron Global Positioning System Operations Support flight commander, and Staff Sgt. Carl Ellinger, 2 SOPS GPS mission chief, review a checklist of procedures for a transfer operation at Schriever Air Force Base, Colorado (U.S. Air Force photo/Dennis Rogers)]
By Inside GNSS
Location intelligence software-maker Esri will provides free access to its ArcGIS platform and learning resources to support college and university students who no longer have access to campus computer labs during the COVID-19 outbreak. Access is through the Learn.ArcGIS.com website.
By Inside GNSS
EMCORE Corporation, a provider of advanced mixed-signal products serving the aerospace, defense and broadband communications markets, received the 2019 Raytheon Integrated Defense Systems (IDS) 5-Star Supplier Excellence Award for performance and partnership.
By Inside GNSS
The U.S. Space Force ordered replacement of the computer hardware in the new GPS ground system due to the due to the sale of IBM’s computer product line to a Chinese company, and the consequent cybersecurity risk posed by the IBM hardware in use.
By Dee Ann Divis
The Second Space Operations Squadron (2SOPS) at Schriever Air Force Base, Colorado officially took control of the second GPS III satellite in orbit on March 23. GPS III SV02 was designed and built by Lockheed Martin, with a payload provided by L3Harris.
A video rendering of a GPS III satellite gives a slightly vertigo-inducing experience of a ballet through space and above the Earth.
A satellite firm now offering ship monitoring and tracking is studying whether it can use its new, formation-flying satellites to pinpoint GPS jammers and potential interference.
Virginia-based HawkEye 360 has had three microsatellites flying in sun-synchronous, polar orbit since early 2019. The Hawk satellites can detect radio frequency transmissions from the Earth’s surface and, by working as a coordinated cluster, independently determine the location of the source. They are currently being used to detect transmissions from the Automatic Identification System (AIS) devices ships are required to carry and independently geolocating the source so the reported and actual location of the ship can be compared and reported. The system can locate a transmitter with an accuracy of 500 meters depending on the signal. That could improve as HawkEye builds out its constellation.
The firm is already committed to putting another five clusters into space by the end of 2021 and HawkEye CEO John Serafini told Inside GNSS, there are plans to launch an additional cluster by mid 2022. Funding is in hand for the additional satellites thanks to a Series B round of financing completed earlier this year. With seven clusters of satellites in orbit the return rate — that is frequency with which a satellite will be flying overhead the same spot on Earth — will jump from about once every five hours to once roughly every 30 minutes, Serafini said.
Each satellite cluster flies in formation, a capability enabled by a specially designed propulsion system. Their software-defined radios are able to tune into frequencies ranging from 144 MHz to 15 GHz (approximately VHF to Ku-Band). To be detected from space the signal power on the ground has to be 1 watt or more.
“Generally speaking if the signal is above a watt in power — between 150MHz and 15 GHz — we can detect it and we can geolocate, process and analyze that signal,” Serafini said. Over the first 14 months of operation, Cluster 1 detected 11 million independent geolocations of various signals.
All this capability comes in pretty small packages. The initial three satellites weigh just 15 kg each. Starting with Cluster 2 that will jump to 25 to 28 kg each.
The firm’s originally targeted market leaned toward services for defense, intelligence and security applications. Now HawkEye is assessing offering a new service that would identify the location of GPS jammers.
“GPS jamming is on our product roadmap,” said Serafini and the company hopes to be able to offer the service in approximately six months. “We have to evaluate the opportunity and develop a product.”
It’s entirely plausible that HawkEye’s satellites could locate GPS jammers, according to Logan Scott of LS Consulting, an expert on both navigation and telecommunication signals. Scott said he’d been introduced to the technology a couple of years ago at a presentation and, though he’s not done a link analysis, believes it has potential for such a capability. “If it’s a big jammer. Yeah, I could definitely see something like that — there are some neat things you can do.”
It might also be possible to gain insight into spoofing, albeit indirectly. AIS data already has been used in this way by other organizations. If the AIS location data, for example, indicates that ships are traversing dry land, that strongly suggests spoofing.
Hawkeye might be able to do something similar based on other modes of transportation like trucks and trains. If there is publically available location data being transmitted by a truck or other asset, the satellites are capable of receiving those signals directly, said Serafini. Alternatively the firm could use data from a third party provider. If the reported location and the actual location don’t match that could be the result of spoofing.
“We have not done that yet,” said Serafini, “but we would, and we think there are databases that are commercially available that we could purchase depending on what the asset is that wants to be tracked.”
HawkEye could even map such disruptions over time. This might have been useful in the case of the truck driver whose GPS-jamming personal privacy device disrupted the ground-based augmentation system (GBAS) at the Newark Liberty International Airport in Newark, New Jersey when he drove past. The intermittent disruptions were a puzzle at the time.
The system may also be able to gather enough data to determine if signals in bands near those used by GPS could be interfering with GPS receivers. GPS users have most recently faced this possibility from a proposal by Ligado Networks, which wants to use satellite frequencies neighboring those used by GPS for a terrestrial service. With signal frequency, power and location data from the HawkEye system it could be possible to determine if Ligado signals were interfering with GPS equipment.
One of the challenges in doing that though, said Scott, would be identifying a particular transmitter that might be creating problems — especially if that transmitter is part of a network with other nearby transmitters. This is further complicated by the fact that communication transmitters aim most of their power at the ground.
“I don’t want to say impossible,” said Scott. “I don’t want to shortchange what these guys can do; they’re a very capable group. But at the same time, I’m trying to be cautious in my assessment.”
HawkEye is still engaged in its analysis it is too soon for additional detail about the potential for such a capability.
Scott suggested that HawkEye might be able to create a heat map that shows signals and their power at various geographic locations. “The heat map would be indicative of whether or not, in that area, you could expect to see problems.”
Serafini said they already have such a service.
“One of the products that we offer today is RFMosaic that looks at a specific geographic location and time and frequency range and maps the signals of interest that we see — the spectral energy in that area.”
RFMosaic includes features to help identify changes in RF activity over time and identify potential sources of interference, according to the company’s website.
Art courtesy of Hawkeye 360
By Dee Ann Divis
Since 2015, controlled reception pattern antennas (CRPAs) have come onto the market for civil applications where the need to counter increasing GNSS signal jamming and spoofing has grown exponentially. Highly classified and previously available only to authorized military users, these powerful — and unfamiliar — components expand protection for critical infrastructure. All systems incorporating them should be tested for revamped vulnerabilities. This is how.
A free webinar on Wednesday, March 25 from 1:00 PM – 2:30 PM Eastern Daylight Savings Time addresses the topic “GNSS Vulnerability Testing and the Controlled Reception Pattern Antenna (CRPA).”
By Inside GNSS