The current platform-centric EW systems are limited in their ability to generate essential EW effects required to counter emerging threat system developments and employ advanced EW concepts. The adversaries are fielding increasingly sophisticated networked and agile systems, RF sensing and communications systems, including short-range tactical communications, long-range command and control (C2) communications networks, networked defensive systems, and RF seekers. This is partly due to rising commercial investments in RF materials, components, and subsystems thereby reducing the cost to deploy high power, agile systems.
The vision for distributed EW is a network-enabled, coordinated and spatially distributed EW system-of-systems to counter emerging asymmetric threat capabilities by providing time-critical situational awareness (SA) of adversary dispositions and activity, denial of the enemy’s SA of friendly force dispositions and activity, and camouflage and deception to dilute enemy engagement capacity.
One example of distributed EW operations is combined coalition EMS capability as emphasized by DOD EM Spectrum strategy. DOD unveiled its Electromagnetic Spectrum Superiority Strategy, which outlines how the U.S. military aims to dominate the electromagnetic spectrum when it is challenged by peer and near-peer adversaries. “The Department is transitioning from the traditional consideration of EW as separable from spectrum management to a unified treatment of these activities as Electromagnetic Spectrum Operations (EMSO),” Secretary of Defense Mark Esper wrote in the foreword to the publication released in October 2020.
The EMS Superiority Strategy includes five goals: develop superior EMS capabilities; evolve to an agile integrated EMS infrastructure; pursue total force EMS readiness; secure enduring partnerships for EMS advantage; and establish effective EMS governance. “U.S. military operations are rarely conducted unilaterally and are increasingly reliant on contributions from our allies and partners,” DOD experts write in the strategy. “DOD must ensure EMS enterprise development efforts are interoperable and aligned with our allies and partners and should remove barriers limiting collaboration. This requires interoperable data sources and architectures. The Department will help develop military-to-military agreements, host nation agreements, agreements with the North Atlantic Treaty Organization (NATO), and other allies and partners focused on enabling coalitions the use of their full portfolio of EMS capabilities.”
The report continues, “This requires the means (software, data standards, transport channels, etc.) to move and process data at machine speeds with allies and partners. DOD must encourage our allies and partners to adopt, build, or enhance EMS capabilities that will increase our combined coalition EMS capability and capacity with a particular focus on near-peer threats. This cooperation includes the need to expand opportunities for coalition EMS testing, training, and education in the United States and abroad.”
Apart from the coordination of distributed assets of the NATO alliance, it is also advantageous to generate distributed EMS operations within DOD. DARPA is focusing on the development of next-generation EW systems, to counter these advanced networked and agile systems using technologies such as distributed systems, coherent systems, disposable systems, providing asymmetric capabilities, and close-in remote sensing coupled with advanced jamming and spoofing.
Distributed EW can provide the following objective capabilities: wide-area, real-time location determination of adversary emitters; automated recognition of threat emitter operating modes; adaptive electronic attack response to threat emitters; wide-area camouflaging to deny target detection or cause misclassification of targets; wide-area deception through synchronized decoy control; denial or corruption of enemy sensing capabilities by synthetic generation of high-density clutter environments; seamless operability and graceful degradation of network-enabled functions in dense EM environments; and simplified scalability and ability to upgrade through modular and open systems architecture design.
John Thompson, director of EW campaigns at the Northrop Grumman Corp. Mission System’s Airborne C4ISR Systems division in Falls Church, Va., says EW underpins modern military operations. “We’re watching a drive to be as quiet as possible and when you do emit, do so in a very singular area. It’s all tied to survivability. If I’m surveilling, I want it to be very difficult for the other side to locate me — low probability of intercept, because he who emits first, dies,” he says. “When you think about EW, you have to look at electromagnetic warfare. I need to control all emissions from my radars and other surveillance systems. Emission control is the name of the game.
“A lot of the things we are doing today at DARPA play a critical role in integrating future EW technologies and aircraft. We want more software-defined systems, which give us more flexibility overall. It allows us to break the vendor lock and bring in third party developers, which is the path we need to go down to preserve our technical advantage in the future,” DARPA’s Javorsek says.
“Concerto [one of his programs] looks at the more advanced arrays and sensors and systems that produce a tremendous number of options,” Javorsek continues. “In the future, as we increase the diversity of the assets we have out there and the number of options within a platform and multifunction capabilities, how do we manage the high level of complexity we are imposing on ourselves so we cause the maximum number of challenges for our adversary without causing the same level of challenges for ourselves?”
UAV and UAV swarms
The UAVs are able to digitally and instantly provide the most desired and precious operational information about the battlefield. They are eyes in the skies, over a battlefield that is crammed with high-resolution optics, data links, radars, and laser-guidance systems. The UAVs’ advantage is an ability to loiter, often at a high altitude over a target, watching it ceaselessly for hours, if not days, and sometimes even weeks.30 In remote and unreachable areas, UAVs are quite effective tools because they conduct ISR without any detection by the enemy. The serious weakness of the UAV is a high-level of dependence on fair weather. As one child in Yemen said, all the kids are scared of blue skies, because that is when the drones come out.
Electronic warfare capabilities increasingly are being added to unmanned platforms, whether they are in the sky, on the ground, and even underwater. “Unmanned EW platforms can take humans out of direct conflict, which saves lives, but will limit the ability to discern nuances that only well-trained personnel can detect,” says Menlo Micro’s Leitner. “This is why EW platforms will still be required for command, control, and communications. Unmanned systems will grow more important as a complementary platform but not as a replacement to piloted ones.”
Italian defense contractor Leonardo says that it has conducted a successful demonstration in cooperation with the U.K. Royal Air Force of an autonomous swarm of unmanned aircraft, each carrying a variant of its BriteCloud expendable active decoy as an electronic warfare payload. Using the BriteClouds, which contain electronic warfare jammers, the drones were able to launch a mock non-kinetic attack on radars acting as surrogates for a notional enemy integrated air defense network.
“During the demonstration, a number of Callen Lenz drones were equipped with a modified Leonardo BriteCloud decoy, allowing each drone to individually deliver a highly-sophisticated jamming effect,” according to Leonardo’s press release. “They were tested against ground-based radar systems representing the enemy air defence emplacement. A powerful demonstration was given, with the swarm of BriteCloud-equipped drones overwhelming the threat radar systems with electronic noise.”
The general idea of using an autonomous swarm of drones to blind, confuse, and overwhelm an enemy’s integrated air defense network, or other sensor and communication nodes, is hardly new, either and is one of the most common missions envisioned for such a group of unmanned aircraft. Carrying out such missions in the open stages of conflict would make good sense as they would help clear paths for other manned and unmanned aircraft, including more vulnerable, non-stealthy types, to conduct follow-on kinetic strikes or carry out other tasks, such as intelligence, surveillance, and reconnaissance (ISR).
Mini EW Payloads
There are a variety of potential payloads suitable for mini-UAVs. These include communications & electronic intelligence (SIGINT) payloads, communications and radar jammers, electro-optic, infra-red, and MAW sensors, MTI and SAR radars, BDA sensors, comms relays, EW self-protection suites, chemical, biological, & nuclear detectors, target designators, and “horizon extenders”.
U.S. Army officials announced last year that they would move forward with an EW pod made by Lockheed Martin to be put on the MQ-1C Gray Eagle unmanned aerial system (UAS). The pod, dubbed “Air Large,” provides the Army with capabilities to jam equipment as well as provide electronics support and sense the EMS. In 2020, US Army announced a plan to defeat swarms of EW-enabled air-launched drones with its Air Launched Effects (ALE) family of systems. The Army says that its air-launched multipurpose UAS will be able to act as scouts or decoys, go on the offensive with electronic attacks, and even act as a “suicide drone.” The military branch says that the ALEs will be integrated into existing and future unmanned (and manned) platforms.
Electronic Surveillance (ES) Payloads
ES and SIGINT sensors can be a source of vital information, particularly when related to imagery information to form a more complete or accurate Situational Awareness picture or when updating the Electronic Order of Battle. The key is the integration of the inputs from all of the sensors on all of the platforms. Moreover, as the sensor only has to receive and process signals it does not require large amounts of power to operate it. Consequently, ES payloads scale well to the power constraints of miniUAVs.
The more accurate sensors are nominally placed on board high-value assets and must therefore standoff at a range of 100km, whereas the less capable sensors, which are significantly smaller and cheaper, are placed on more expendable platforms and may therefore stand-in (their cost means that we are also able to afford more of them). Analysis shows that system using the less accurate sensors has errors around 50% less than those of the more expensive system.
Electronic Attack (EA) Payloads
A jamming platform must stand off at a considerable range from a target to allow for its own protection. Because it must stand off, it requires a large amount of power. By reducing the size of the platform and the need to protect it, we are able to stand in, which means that we need significantly less power to jam a given target. In addition to this, because the standin jammer is closer to its target its transmissions cover a smaller area and the potential for electro-magnetic fratricide is also significantly reduced.
The analysis shows that the achievable JSR from a 100W jammer located 10km from the radar and protecting the target at a range of 10km is equivalent to a 10kW jammer located 100km from the radar attempting to protect the same target. When one considers that many modern weapons systems have ranges in excess of 100km and that miniature UAV’s are also hard to detect (and hence target) it makes the technologies a very attractive potential alternative. In addition to this, even if the mini-UAVs are detected, targeted, and engaged, the UAVs have such small IR signatures and RCS there is still no guarantee that the weapons will fuse correctly and destroy the UAVs.
In addition to placing the sensor/processing capabilities onboard the UAV, it can be treated as a “flying antenna”. In this case, the UAV is effectively an electromagnetic “bent pipe” – comprising a receive antenna, a modest amount of processing capacity, some time stamping & signal amplification, and a (directional) transmit antenna.
Combined with knowledge of the UAV’s location and a high gain antenna on the ground (and considerably more processing power than is available onboard the UAV) we have the capacity for significant horizon extension. According to analysis even for very modest altitudes of about 500m, LOS of around 100km are achievable. Control of the UAV in the area of operations could then be undertaken either by a commander at the launch site or by one based further forward (eg. onboard a ship or tactically deployed)
If we now combine the control of these payloads with the autonomous control of the UAV’s through the use of Intelligent Agents and provide these agents with a communications architecture that allows the information to be passed from agent to agent we have a system that is potentially able to adapt to its dynamic environment. Depending upon the nature of the corporate and individual goals of the UAVs and their payloads the structure of the network may vary greatly, but it allows the strengths of the individual agents to be combined into a single cohesive team.
In a world first, a Codarra Advanced Systems Avatar unmanned aerial vehicle (UAV) achieved truly autonomous, Intelligent Agent-controlled flight in July 2007. The flight tests were conducted in restricted airspace at the Australian Army’s Graytown Range about 100 km north of Melbourne. The Avatar was guided by a JACK intelligent software agent, developed by Melbourne-based Agent Oriented Software Pty Ltd that directed the aircraft’s autopilot during the course of the mission.
The on-board JACK agent chose the best route to fly after evaluating real-time flight and weather data accessed through a direct link to the UAV’s autopilot and GPS. The agent was constantly updated with the Avatar’s position, air speed, ground speed and drift so it could intelligently The successful first flight, undertaken by DSTO and Agent Oriented Software, convincingly demonstrated both in-flight Intelligent Agent control of the aircraft and fully autonomous mission selection capabilities.
Intelligent Agents can also handle in-flight incidents such as loss of radio communications, poor landing visibility or avoiding a radar intercept by using pre-programmed contingency plans. The agents can reason about what to do in response to such events, then direct the autopilot to act. This greatly simplifies the planner’s current task of developing and validating new contingency plans for each mission – a time-consuming job that restricts operational flexibility.
Flying Ad hoc Networks
An ad hoc network is the cooperative disposition of a collection of dynamic (mobile) nodes without the necessity of existing infrastructure or any centralized access points. Recently, ad hoc networks have aroused great scientific curiosity and have led to wide-scale research works into this field. FANET implies creating an ad hoc network between multi-UAV systems, which is connected to the base station. The base station can be remotely ground based or an aircraft. In FANET, communication between UAVs is dependent on node mobility and topological changes. Development of FANETs poses many demanding challenges in terms of quality of service, energy efficiency, scalability, and adaptability.
MANETs are networks composed of mobile devices such as laptops, cellular phones, sensors, etc. Similarly to vehicle ad hoc networks (VANETs), whose components are cars, buses, ambulances, etc., incorporating embedded communication devices, in FANETs, UAVs are wirelessly interconnected, either directly or using intermediate nodes. Thus, only a small set of nodes need to be connected to the BS/satellite. Even though it is clear that FANETs share common features with MANETs and VANETs, there are several unique characteristics that makes them different, namely, mobility, topology changes, radio propagation, and energy constraints.
Another critical technology to implement these Intelligent agents is embedded AI. Due to resource-constrained UAVs, issues of latency, reliability and the security it is not possible to use large servers or GPUs for implementing machine learning algorithms. Therefore, there is need for embedded AI using special purpose chips. The continued advancement in performance of A/D and D/A converters the higher the performance of FPGAs and concepts like heterogeneous computing which combines an FPGA with onboard processing and a general-purpose processor all setting on the same silicon are other enablers.
Electronic warfare platforms also are following military and aerospace industry trends in embracing open-systems standards. Standardization also is of significant importance in making EW ubiquitous on manned and unmanned aircraft, as is the growing use of data processors like field-programmable gate arrays (FPGAs). The increasing emphasis on open-systems standards has been called one of the single biggest changes enabling EW. Open Architecture is essential weather to take advantages of commercial developments or implementing a Network centric EW.
“We’re seeing a lot of advances in commercial technology making its way into the DOD marketplace. That is feeding the ability to reduce the volume of our systems — weight and power as well as price — putting added capability into the hands of the warfighter,” says Max Pelifian, senior program manager for airborne EW at the Lockheed Martin Rotary and Mission Systems segment in Owego, N.Y. Open standards and a closer partnership with industry also have dramatically reduced the development time for upgrades. Lockheed Martin’s Ottaviano says what was up to a 24-month cycle as little as five years ago has now been shortened to 30 days.
Open standards make it easier to build highly integrated, scalable EW systems that can keep up with changing application requirements,” says Curtiss-Wright’s Bateman. “For example, increased sensor bandwidth could be accommodated by upgrading the RF and data converter board(s), while upgrading to newer DSP or GPGPU boards satisfies increased processing requirements.
“The use of open standards eases integration between different pieces of the EW system technology chain,” Bateman continues. “So, you can have a tuner outputting data in a standardized form, such as VITA 49 (VITA Radio Transport) to an FPGA-based device or SBC. The receiving device can then ingest that data in a standardized way then process that data. So, integration of components from different parts of Curtiss-Wright or even different companies is eased by that standardization.” Bateman says that Sensor Open Systems Architecture (SOSA) standards help build upon existing VITA VPX standards.
“SOSA also eases the integration of different types of processing in an EW system, so that you can leverage a wide variety of processing types, for example, FPGA, SBC or GPU processing,” says Bateman. “Different types of hardware can be easily and more readily applied in the same physical environment thanks to standardized and defined pin-outs, etc. That means, too, that you can more easily change the system configuration in the future if needed, if, for example, a new higher-performance FPGA or DSP becomes available. Upgrades are simplified because of standardization.
“EW by its very nature is a protean challenge that is continually evolving as adversaries develop new techniques and technologies. To keep up with these ever-changing requirements you need a smooth path for upgradeability, which is why open standards are so attractive,” concludes Bateman.