The European Space Agency (ESA) and Leonardo are embarking on a joint project to explore smart antennas powered by machine learning to block unwanted signals.
Representatives of ESA and Leonardo signed a contract at the Paris Air Show to research and develop machine learning techniques to steer antenna arrays to block out unwanted signals. The project will be developed under the umbrella of ESA’s Navigation Innovation Support Programme (NAVISP).
Smarter antenna designs for resilience
Conventional antennas catch signals from all directions. A controlled reception pattern antenna (CRPA) can focus on signals coming from specific satellites and ignore signals or interference coming from other directions. These types of antennas are used in satellite navigation receivers to block jamming and counterfeit signals. They rely on electronics that control how they adjust their patterns (beamforming).
Under contract with NAVISP, Leonardo — together with ELT Group as subcontractor — will explore the reduction of the distance between the antenna elements to reduce the size and weight of the antenna array, and the use of machine learning to determine the best antenna setup and adjust the settings faster. This approach will lead to smaller, smarter and more effective antennas, especially useful in space-limited environments such as aircraft.
The project covers identification of the smarter algorithm for signal blocking, building and testing a real-time receiver demonstrator based on the selected algorithm, and comparing it to conventional larger antennas. The aim is to reach a Technology Readiness Level (TRL) of 4, delivering a lab-tested technology by the end of the project, in two years.
Orolia Defense & Security, provider of software-defined simulation solutions for navigation warfare, will supply a BroadSim Wavefront to the U.S. Air Force Guided Weapons Evaluation Facility (GWEF). BroadSim Wavefront is an innovative, Skydel-powered advanced GNSS simulator.
The BroadSim Wavefront simulator from Orolia Defense & Security. (Photo: Orolia)
The GWEF provides laboratory testing and simulation tools for developing precision-guided weapon technology, including a comprehensive scope of GPS plus inertial navigation systems (INS) and integrated components such as sensors, signals of opportunity and controlled reception pattern antennas (CRPAs). CRPAs are fundamental in many platforms due to their enhanced protection against electronic attacks in NAVWAR environments.
The Broadsim Wavefront simulator will be integrated into a test environment for networked, collaborative and autonomous weapon systems being developed under the Golden Horde program. Golden Horde is one of four Air Force Vanguard programs designed to rapidly advance emerging weapons systems and warfighting concepts through prototype and experimentation.
Of the several capabilities the GWEF required, features such as low-latency hardware-in-the-loop, automated calibration, and the flexibility to quickly integrate future signals and sensors were the most critical and serve as a key reason Orolia’s BroadSim Wavefront was selected. The system will also be capable of testing eight-element CRPA systems, eight simultaneous fixed radiation pattern antenna systems (FRPA), or a combination of CRPA and FRPA systems.
“When designing BroadSim Wavefront, we re-imagined every aspect for the user,” said Tyler Hohman, director of products for Orolia Defense & Security. “Though the GWEF unit contains eight nodes (corresponding to each antenna element), it can be scaled from four to 16 antenna elements. One of the greatest advancements is our continuous phase monitoring and compensation technique. It automatically monitors, aligns and adjusts the phase of each RF output continuously throughout the duration of a scenario.”
“Gone are the days of re-calibrating each frequency on your system, limiting your scenario duration or re-calibration every time you power cycle your system,” Hohman said. “Simply turn the system on, start the scenario, and your Wavefront system phase aligns and remains aligned for the entirety of the test.”
Leveraging the Skydel Simulation Engine, BroadSim Wavefront also supports high-dynamics, MNSA M-code, alternative RF navigation, open-source inertial measurement unit (IMU) plug-ins and a 1000-Hz iteration update rate.
“Because of the software-defined architecture, many upgrades don’t require additional hardware, which has been a crucial advantage for customers who are already using this solution,” Hohman said.
Spectranetix Inc., a Pacific Defense company, has announced the SX-124 ruggedized 3U OpenVPX high-performance positioning, navigation and timing (PNT) card.
With an ability to provide timing and positioning information in a GPS-denied environment through sensor fusion, the SX‑124 switch is designed for highly integrated systems with a requirement for the U.S. Army’s C5ISR Modular Open Suite of Standards (CMOSS) and alignment with the Open Group Sensor Open Systems Architecture (SOSA) technical standard.
The SX-124 can accept external sources or use its onboard GNSS receivers as reference inputs for timing and positioning data. The positioning data can be fused with internal and external inertial measurement units (IMUs). It distributes 11 100-MHz outputs and 11 1PPS outputs in a phase coherent manner.
The SX-124 provides timing and position holdover from an internal chip-scale atomic clock (CSAC) and IMU. A built-in time-of-day clock provides accurate network time stamps on system startup without GPS availability.
The SX-124 also provides enhanced location information and can be connected to an external IMU as well as a controlled reception pattern antenna (CPRA).
The SX-124 supports the standard VICTORY shared PNT services from a built-in GNSS timing receiver with an optional built-in M-code GB-GRAM receiver, CSAC and barometer to provide altitude information.
With the option for expansion to support over-the-air rekeying (OTAR), external fiber-optic gyroscope (FOG), alternative navigation (ALTNAV), and additional GNSS systems such as Galileo, the SX-124 supports the defense community’s need for a high-performance assured PNT (A-PNT) solution in the 3U VPX form factor and aligned to the latest open set of standards.
“Reliable situational awareness and cooperative, networked maneuvers demand assured PNT capability,” said Daniel Kilfoyle, CTO of Pacific Defense. “Our A-PNT solution embraces the pntOS open sensor-fusion framework and supports multiple sensor connections including GNSS receiver, GB-GRAM, IMU, FOG, CRPA and a two-channel software-defined RF receiver for added flexibility. Combined with exquisite timing and frequency performance and CMOSS alignment, this PNT card is yet another example of our commitment to CMOSS and SOSA.”
The SX-124 card is on track for production release early next year.
The CAST-5000 by CAST Navigation produces a single coherent wavefront of GPS RF signals to provide repeatable testing in the laboratory environment or anechoic chamber. The system generates up to seven independent, coherent simulations that reference a single point. With an intercard carrier-phase error of less than one centimeter, the CAST-5000 is extremely accurate, the company said.
The system generates a wavefront of GPS when its GPS RF generator cards are operated in a ganged configuration. Each generator card provides a set of GPS satellites coherent with the overall configuration. Several RF generator cards may be utilized together, ensuring phase coherence among the bank of signal generator cards.
The CAST-5000 is the only Controlled Reception Pattern Antenna (CRPA) tester that allows a full end-to-end test of the antenna system. The CRPA antenna, antenna electronics and the GPS receiver can be tested as a unit with or without radiating signals.
CAST-5000 Features
Generates single coherent wavefront of GPS
6 degrees of freedom (DOF) motion generation capability
In my April column, I introduced the basic concepts behind GPS anti-jam technology, along with a bit of history around its evolution. I knew this was a popular topic, but I didn’t anticipate the enormous amount of positive correspondence I’ve received since, including many inquiries about where to buy this technology and who is entitled to have it.
So this month we return to the controlled reception pattern antenna (CRPA) topic, to look specifically at the major suppliers of GNSS anti-jam technology in a bid to help you select the best fit for your requirements.
As mentioned in April, CRPAs can trace their roots back to military radar developments in the 1970s and 1980s. It’s no surprise, then, that the main players in the CRPA market tend to be large defense primes. But there are many smaller companies, universities and research institutions that also play in the CRPA arena these days.
What about export?
When GNSS jamming was a little-known military problem, the situation was simple: anti-jam was a military technology for military applications only. Later, as GPS evolved into a dual-use technology, critical infrastructure and civilian applications brought a new demand for anti-jam in non-military domains.
Confusion then abounded about who exactly is entitled to make use of anti-jam technology. There are two distinct factors here: security classification, and export control. Let’s clear these up.
Security classification is simple: If a product is classified, it is only available to customers who hold the appropriate level of security clearance. Usually it is the performance and vulnerabilities of a product that would attract a classified status. As you might expect for in-service military products, the military would not wish everyone to know the performance and weaknesses of its deployed technology. This is why many datasheets for CRPAs omit performance information.
The second issue is export control. This, of course, varies by country. In the U.S., a CRPA developed towards a defense program is likely to have International Traffic in Arms Regulations (ITAR) restrictions attached to it. In Canada, CRPAs are subject to the Controlled Goods Program. In the UK, CRPAs sit on the “dual-use” export control list, which recognizes that CRPAs have both military and non-military application. An export license is usually required.
Before I go any further, a little disclaimer: I am not making any product recommendations in this article. There are many things to consider when choosing anti-jam technology, and you should always consult a navigation warfare expert and carry out appropriate evaluations prior to choosing a product. You should also seek guidance from your own government regarding any restrictions on export or import.
With that out of the way, let’s look at the offerings of a few suppliers. This is by no means a complete list, but I did manage to catch up with a few of the major players to ask them about their anti-jam technology offerings.
NovAtel
I spoke with Peter Soar, business development manager, Military and Defence, at NovAtel about NovAtel’s offerings.
Peter Soar: “The GAJT-710 series are retrofittable GPS anti-jam products that combine a seven-element controlled reception pattern antenna (CRPA) and the antenna electronics in a single unit. The GAJT-AE-N is a GPS anti-jam antenna electronics system that supports a separated four-element antenna.”
Photo: NovAtel
Photo: NovAtel
Photo: NovAtel
Main features: “All three products protect the GPS L1 and L2 bands simultaneously, and are suitable for military (SAASM) receivers as well as open-signal receivers, normal civil receivers and ‘survey grade’ receivers. The wideband design means that the units are ready for M-code. In the GAJT-710, there are seven antenna elements for up to six independent nulls on both frequencies, and the GAJT-AE-N supports four antenna elements, for up to three independent nulls. All products use space-frequency adaptive processing for increased degrees of freedom. System messages provide an indication of jamming presence, even when the nulling is defeating the jamming.”
Intended market: “GAJT-710ML is optimized for land use, while GAJT-710MS is used for maritime and littoral applications. Both types are currently in use on mobile platforms and fixed installations. The GAJT-AE-N is optimized for smaller platforms such as unmanned air vehicles, and is currently in use on a variety of platforms. GAJT products have been shipped to customers in 16 countries to date.”
Example customers: “The GAJT-700ML (a predecessor to the 710ML) was selected for trials by the Canadian Army through the Build in Canada Innovation Program, with exercises performed on the Artillery Observation Post Vehicle (LAV III OPV). Both GAJT variants were selected for field testing by the U.S. Army Communication-Electronics Research Development and Engineering Center (CERDEC) through the U.S. Army Rapid Innovation Fund. The United States Naval Observatory (USNO) selected the GAJT-710ML to satisfy a requirement at sites throughout the Department of Defense Information Network (DoDIN). The GAJT-AE-N is deployed on the Schiebel Camcopter S-100, and was also selected for testing on the M777C1 Howitzer by the Canadian Army.”
Situation with regards to export: “All GAJTs are designed and built in Canada. As such, they are subject to the Controlled Goods Program of Canada, but they are free from ITAR for non-U.S. customers.”
Raytheon UK
Some Raytheon products were mentioned briefly in the April column; I caught up with Alan Wright, business development executive, Force Protection, to get the latest information.
Alan Wright: “Raytheon UK offers a range of anti-jamming products ranging from high-performance products with multiple-element CRPAs to low size, weight and power products. Our current product lines utilize either analog or digital technologies to suit specific end-user requirements.”
Product
Image
Key Features
GAS-1
Analog technology, 7 antenna elements, switchable L1/L2 protection, minimal quiescent time delay, nulling, J/N, M-code signal bandwidth, AE/antenna integrated variant, fiber optic output variant.
Digital technology, 5 antenna elements, simultaneous L1/L2 protection, low size, weight & power, STAP, nulling, J/N, direction finding, anti-spoof, jamming flag, M-code signal bandwidth.
Landshield
Digital technology, integrated 4-element antenna, simultaneous L1/L2 protection, low size, weight and power, STAP, nulling, J/N, direction finding, anti-spoof, jamming flag, M-code signal bandwidth, switched antenna variant.
MiniGAS
Analog technology, integrated 4-element antenna, simultaneous L1/L2 protection or L1 with L2 passthrough, low size, weight and power, minimal quiescent time delay, nulling, jamming flag.
MicroGAS
Analog technology, integrated 2-element antenna, simultaneous L1/L2 protection, very low size, weight and power, minimal quiescent time delay, nulling.
Intended market: “With over 25 years’ experience, Raytheon UK is a world leader in the development, production and supply of GPS Anti-Jamming (GPS-AJ) systems to the majority of the world’s military forces (including the U.S. DoD and UK MOD), with solutions developed and certified for air, maritime and land applications. Raytheon UK has designed and manufactured in excess of 10,000 GPS anti-jam units for the worldwide market.”
Situation with regards to export: “GAS-1, ADAP and SAS are subject to U.S. ITAR restrictions. Landshield, MiniGAS and MicroGAS are free from ITAR and subject to UK export control.”
Rockwell Collins
I spoke with Al Simon, business development for navigation products/solutions, to get the latest on Rockwell Collins’ offerings. Rockwell’s portfolio includes some CRPA products aimed specifically at weapons. Al kindly provided the following table to summarize:
Product
Image
Platform
Key Features
Integrated GPS Anti-Jam System (IGAS)
Weapons (Embedded)
GPS receiver + AJ, nulling and beamforming, spatial, 20 in3, <2 lbs, up to 4 RF antenna inputs, 90+ dB J/S performance *, GPS (simultaneous L1 & L2), path to M-code
Strategic Anti-Jam Beamforming Receiver (SABR)
Weapons (Embedded)
GPS receiver + AJ, nulling and beamforming, STAP, 46 in3, <3 lbs, up to 7 RF antenna inputs, 120+ dB J/S performance*, GPS (simultaneous L1 & L2), path to M-code
NavStorm+
Weapons
Nulling, spatial, 6.9 in3, <.6 lbs, up to 5 RF antenna inputs, 20,000 G shock, 90+ dB J/S performance*, GPS (simultaneous L1 & L2), path to M-code
NavFire
Weapons
Nulling, spatial, 2 in3, <.2 lbs, 1 or 2 RF antenna inputs, 25,000 G shock, 85+ dB J/S performance*, GPS (L1 or L2), path to M-code
DIGAR-200
Airborne, Maritime, Ground
Nulling and beamforming, spatial, 218 in3, <11 lbs, up to 7 RF antenna inputs, 110+ dB J/S performance*, GPS (simultaneous L1 & L2), path to M-code
DIGAR-300
Airborne, Maritime, Ground
Nulling and beamforming, STAP/SFAP, 69 in3, <5 lbs, up to 7 RF antenna inputs, 125+ dB J/S performance *, GPS (simultaneous L1 & L2), path to M-code
Small Platform AJ (Pre-Production)
Ground, Airborne
Nulling and beamforming, STAP/SFAP, 45 in3, <3 lbs, up to 7 RF antenna inputs, 95+ dB J/S performance*, GPS (simultaneous L1 & L2), path to M-code
STAP (Space Time Adaptive Processing); SFAP (Space Frequency Adaptive Processing)
* Beamsteering mode. Actual performance is classified
Situation with regards to export: All listed products are unclassified, but are subject to U.S. ITAR restrictions.
Roke Manor Research
This column wouldn’t be complete without a few words on my own organization. Roke has been developing anti-jam CRPAs since the 1980s, but rarely offers its own products. Typically Roke develops bespoke anti-jam and anti-spoof technology for other defense organizations, including for some products already listed above. Examples of bespoke developments for more specialist markets include Gincan and the Helium antenna.
Photo: Roke
Photo: Gincan
Main features: Both these products are aimed at the commercial civilian market, but do also have defense interest. The Gincan is a very basic low-cost CRPA, with just two antenna elements. The Helium is a conical spiral design, using four antenna elements, and is primarily aimed at protecting GNSS in critical infrastructure. The Helium has excellent low-elevation performance. Both antennas feature very low latency, making them particularly suitable for timing receivers.
Intended market: The Gincan is primarily aimed at providing a basic level of anti-jam capability to the automotive mass market, including cars and trucks, but also has been adopted by some lightweight UAV platforms. The Helium is aimed directly at timing receivers for critical infrastructure, including mobile base stations, digital TV networks, stock exchange and financial institutions, and power and utility grids.
Example customers: Gincan has been delivered to 42 countries, with a mixture of commercial, defense and national security customers. Helium is a relatively new product, and is being trialed on infrastructure in two countries.
Situation with regards to export: Both products are unclassified and suitable for commercial use. They are subject to UK export control as dual-use items, and are ITAR-free.
Others
There are many other suppliers of CRPA technology — unfortunately, too many to cover in this column. Mayflower Communications offer a good range of CRPA products in the form of their NavGuard range. Some other suppliers include Cobham Antenna Systems, BAE Systems Rokar, Thales, Harris Corporation, L-3 Interstate Electronics and Lockheed Martin. I encourage you to contact these companies for the latest information if you are contemplating a CRPA product. If you’re a CRPA supplier and I’ve missed you, please feel free to post a link to your products in the comments section below.
So, that was a bit of a whirlwind tour through some of the products currently around. CRPAs come in all shapes and sizes, and they all have their own particular characteristics and subtleties.
I conclude by reiterating my earlier point. Always conduct a threat analysis, seek the help of a navigation warfare expert if necessary, and properly evaluate your choices. Happy choosing!
