Now a critical part of worldwide defense strategy, Electronic Warfare (EW) must continually adapt in order to meet new threats. To do so, new technology together with emerging standards must be incorporated into EW system designs.
Key elements of EW systems are now often combined within a single component, such as the RF System-on-Chip (RFSoC), including signal acquisition, processing, and generation. Hardware, firmware, and software have become more complex, increasing risk and expense, and thereby increasing the need for effective, high-level development tools.
Along with emerging technology, EW systems developers must consider emerging U.S. Department of Defense (DoD) initiatives such as Sensor Open Systems Architecture (SOSA), which promotes the standardization of embedded system architectures to make systems upgradable and increase interoperability while decreasing costs and delivery times. EW systems developers can benefit from an understanding of the new technologies and standards discussed in this article.
Electronic Warfare Eclipsing Traditional Warfare
EW now often dominates the military landscape, eclipsing traditional weapons, manpower, and transport systems. EW consists of a widely varying range of military capabilities, each one focusing on different aspects of utilizing the electromagnetic spectrum to gain an advantage over the enemy. EW signals extend across nearly a dozen orders of magnitude of both frequency and power levels, using a vast array of different platforms for each application.
EW systems are ubiquitous — they are deployed on land, at sea, underwater, in the air, and in space. They often use the same increasingly congested slices of the spectrum as non-military radio activities including commercial, entertainment, government, consumer, municipal, emergency, and transportation purposes. Indeed, the electromagnetic spectrum is a finite resource that is carefully controlled, highly congested, and therefore intensely exploited by advanced technology to make the most of it.
EW is roughly divided into three major sectors:
Electronic Attack (EA): Includes classic offensive goals to disrupt, deny, degrade, destroy, or deceive.
Electronic Protection (EP): Seeks to thwart the effectiveness of EA.
Electronic Support (ES): Harvests the extensive wealth of signal information of all types to improve decision-making and strategies.
Examples of Electronic Attack, Protection, and Support
A major segment of EW, radar offers a wealth of attack, protection, and support capabilities. Benefitting from almost a century of development, radar technology provides critical support for almost all military platforms. One form of EA is jamming, used to destroy, disable, or degrade radar receivers, blinding them to enemy assets. Originally using brute force, high-power broadband transmitters, jamming has now become extremely sophisticated, with highly directed, frequency- and pulse-adaptive signals. This makes it harder to locate and disable the jamming source.
EP can be provided by clever radar transponders in aircraft, which can generate artificial reflected signals carefully crafted to simulate multiple targets as well as false location, bearing, speed, and target cross-section information. Short reaction times to synthesize these deceptive signals are vital for air-to-air combat because of close proximities.
After nearly 25 years, network-centric warfare has evolved rapidly to embrace network technology as a fast, reliable mesh of information links among all warfighting elements. By carefully acquiring signals from radar, communication, electro-optical, and other sensors and feeding those digitized streams to signal processing elements, algorithms can produce real-time representations of the battlefield for tactical and strategic decisions. Such ES functions are now greatly enhanced with artificial intelligence (AI) and machine learning technologies. Resulting orders containing precise information for the next course of action, carefully tailored for each asset, are distributed quickly across the battlefield network to soldiers and equipment.
These examples illustrate how the EW functions for EA, EP, and ES are often highly integrated and interactive within the same platform. All these operations increasingly rely upon advanced antennas, including phased array designs, and sophisticated signal processing techniques like beamforming, modulation/demodulation, AI, multi-dimensional algorithms, spread spectrum techniques, cryptography, adaptive radio, and cognitive radio.
Nevertheless, any single implementation of these strategies will eventually become less effective as new counter-measures are deployed. This self-sustaining cycle is the engine of EW, which virtually guarantees ongoing military funding and incentives for new development.
New Technologies Advance EW
Several key technologies are critical for advancing EW. Increasing the signal bandwidth accommodates higher information rates and supports spread-spectrum modulation schemes to improve channel reliability and resiliency to jamming. Another useful technology is frequency hopping, where RF carrier frequencies are rapidly changed during transmission in a predetermined pseudorandom pattern known only to the receiving device.
The increase in signal bandwidth requires wideband analog front-end RF and IF circuits, higher sampling rates for the data converters, and increased data rates for digitized signal interface links. This all greatly increases the workload for digital signal processing engines, which must now implement AI and other advanced, compute-intensive algorithms.
Phased-array antennas are linear or two-dimensional planar arrays of elements, each capable of applying independent phase shifts to a common transmit or receive signal. By precisely controlling each phase shift to achieve constructive interference, the antenna can be highly directional, both for receive and transmit. Unlike traditional dish antennas, by applying a new set of phase shifts, phased arrays can be instantly steered to a new direction with no moving parts. Additional signal processing allows simultaneous tracking of multiple targets.
Phased arrays are particularly appropriate for airborne and unmanned aerial vehicle (UAV) radars where they can be installed on a hull surface and quickly adapt to threats and targets without the bulky mechanical structures required for a directional dish. But the agility and reliability of phased arrays makes them increasingly popular for ground-and maritime-based radars as well, especially for fire-control systems and countermeasures.
All these important benefits incur some complexity and cost. Each element of the phased array requires independent phase-shifts (weights). Originally done with analog circuitry, now this is performed on the digitized signals using digital signal processing (DSP) because of improved precision and speed. Thus, each element in a transceiver array requires its own analog-to-digital converter (ADC) and digital-to-analog converter (DAC), plus its own DSP engine.
To make this more manageable, the RFSoC was introduced by Xilinx in 2018 (Figure 1). Based on its UltraScale+ FPGA Zynq architecture, the RFSoC includes eight ADCs sampling at 4 GS/sec and eight DACs sampling at 6.4 GS/sec. These are connected directly to the Zynq FPGA fabric, eliminating the power, connections, complexity, and latencies of external interfaces to discrete data converters. An onboard, multi-core ARM processor acts as a system controller with control/status I/O; two 100-GbE interfaces connect the RFSoC to external devices supporting 24 GB/sec data transfers in both directions.
Introduced for commercial 5G wireless markets, the RFSoC integrates the key support functions for eight elements of a phased-array antenna and is small enough to fit right behind the phased array panel to reduce cumbersome cabling. By harvesting new technology like RFSoC from commercial markets for military applications, defense vendors are dramatically shrinking size, weight, and power (SWaP) as well as cost — especially critical for air vehicles and small EW countermeasure systems.
Because RFSoC offers a complete software radio subsystem on a chip, it opens a wealth of new military uses previously impractical with earlier technology. These include small standalone monitoring stations, more capable robots, smarter munitions, and portable adaptive radios that can dynamically change operational frequencies to avoid crowded bands or countermeasures.
New Threats and Strategies Require New Tools
Evolving EW threats increasingly require exploitation of advanced vector processing, configurable hardware for sensor interfaces, artificial intelligence, neural networks, machine learning, and scalar processing for analysis and decision-making. Each of these disciplines currently requires specific processing hardware and specialists who can program them. Even if each section is fully operational, integrating these diverse resources into a tightly coupled, functional system is daunting.
Some new initiatives offer a promising path forward. Xilinx recently announced its Versal ACAP (adaptive compute acceleration platform) family of hardware devices and supporting development tools. Members of the family provide different blends of three major resources: scalar processors (CPUs), vector processors (GPUs, DSPs) and adaptable logic (FPGAs). One even offers RF ADCs and DACs, similar to the RFSoC, and therefore highly appropriate for embedded EW. Onboard, high-bandwidth memory and flexible memory structures eliminate the need for external devices. To interconnect these resources, ACAP includes an extremely wideband network-on-chip that offers a uniform interface and protocol to simplify system integration.
Versal development tools target high-level design entry from frameworks, models, C-language, and RTL coding. Users can create a custom development environment to suit their project needs and programming preferences. Other hardware/software platforms will evolve to help speed EW development tasks to help overcome high complexity and extreme performance requirements.
SOSA: A New Embedded Open Standard for EW
A DoD May 2013 memo mandated that all acquisitions must incorporate DoD Open Systems Architecture (OSA) principles and practices defined in evolving open standards for well-defined modular hardware and software components. These include multi-vendor sourcing, reusability, and easier upgrades, reducing development risks and ensuring longer operational lifecycles.
The primary U.S. service branches (Army, Navy, and Air Force) responded to the OSA mandate by developing OSA aligned standards to meet the future procurement needs of deployed systems. Five years later, it was apparent that the three services had many common elements, inspiring the formation of the SOSA Consortium to unify these initiatives.
SOSA adopts the most appropriate subsets of existing open standards to form a multipurpose backbone of building blocks for current and future embedded systems for radar, EO/IR, SIGINT, EW, and communications. SOSA contributing members are U.S. government organizations including the U.S. DoD, Army, Navy, and Air Force as well as key representatives from industry and universities.
A major SOSA product is the Technical Standard, which draws primarily from OpenVPX and other related VITA standards, plus emerging extensions for new technologies, topologies, and environmental requirements. Now under intensive development for several years, the Technical Standard Snapshot 3 was released in July 2020 and the SOSA Technical Standard 1.0 should be released this year.
After that release, vendors who collectively have already announced dozens of “SOSA Aligned” products then may submit them for conformance certification. Interoperability demonstrations during 2020 of these early products were highly successful and well attended by defense customers.
Ahead of the release of the Technical Standard, the DoD has already issued numerous requests for proposals and information clearly favoring respondents that offer OSA-based solutions. Active participation in SOSA by the DoD, all three armed services, embedded industry vendors, universities, and research facilities gives evidence of their substantial commitments of resources and personnel. These clear signals ensure that SOSA is well on its way to setting the future course for embedded military electronics systems.
This article was written by Rodger Hosking, VP and Co-Founder, Pentek, now part of Mercury, Upper Saddle River, NJ. For more information, visit here .