White Paper

WHITE PAPER The Need for Direct RF in an Evolving Defense Environment mrcy.com 2 mrcy.com 2 A CONNECTION BETWEEN ANALOG AND DIGITAL WORLDS Humans experience the world with analog senses: smell, taste, touch, hearing and vision. However, our senses are limited as to what we can transmit or receive. In the world of defense and aerospace, we extend these senses via radar and radio so we can penetrate complex adversarial activities and systems and provide our forces with timely, critical and actionable information gathered from around the world and in space. We accomplish this via different uses of the electromagnetic spectrum. For example, we use sensors to capture intelligence such as radio or microwave signals, radars to produce and bounce signals off distant objects to detect their size and location, and advanced software to modify and retransmit an adversary 's signals as an act of electronic warfare (EW). Accomplishing these tasks requires the conversion of analog signals into digital ones (and vice versa). This process has traditionally required several analog and electronic components and is known to cause latency and interference issues. Direct RF processing technology, however, removes these risks by providing a new type of connection between these analog and digital worlds — one that is also high performance; size, weight and power (SWaP) friendly; and primed to unlock a world of new capabilities. Importance of the RF spectrum and bandwidth Radio frequency exists in the lowest portion of the electromagnetic spectrum and covers a wide range of frequency bands between 3 kHz and 300 GHz. The 2 GHz to 18 GHz and higher bands are commonly used by defense applications such as radar, 5G and other communications. For example, commonly used radar bands such as S‐band (2–4 GHz), C‐band (4–8 GHz), X‐band (8–12 GHz) and Ku‐band (12–18 GHz), any of which might be the best performance choice depending on the detection objectives, all fall within this range. Ka‐band radars such as those used by traffic police to detect speeders, on the other hand, operate in the 26–40 GHz range. A radar 's ability to use these bands depends on its frequency coverage (i.e., how much spectrum can be sampled at one time) and the ability to support complex modulation schemes that exploit the target. Among other characteristics, radars must be able to detect target location, size, direction of travel, speed, shape, and even movable parts such as propellers or jet engines. These detections often require transmit/ receive radar signals with different frequencies, waveforms, bandwidths, and signal processing strategies that are best suited for each task. The extreme flexibility of direct RF radars allows them to handle wideband target exploitation signals located across a wide span of operating frequencies, and to adapt to multiple targets and evolving mission requirements. Legacy and heterodyne receivers and the down‐conversion of RF signals Traditional systems require more than just converting analog signals to digital. Legacy data converters can only sample about 4–6 giga samples per second (GSPS), and handle analog signal frequencies no higher than 6 GHz and signal bandwidths less than 2.5 GHz. As a result, higher frequency RF signals must be translated to a lower IF frequency capable of being handled by these converters. These analog RF frequency translation stages, often called heterodyne receivers, include mixers, local oscillators, amplifiers, filters and other discrete analog circuits to ensure IF bandwidth is typically less than half the sample rate of the data converter. To avoid aliasing, which creates signal artifacts, the IF signal must fall within a single Nyquist sampling zone. We also sell these kind of frequency conversion solutions. Next‐generation direct RF technology removes the need for this down‐conversion entirely because it uses vastly improved digital converters that can sample up to 64 GSPS. They still must use amplifiers and simple filters to avoid aliasing, but these components are far simpler, smaller, less expensive than The Department of Defense (DoD) vision of connected and well‐informed armed services depends on the ability of industry to develop and provide revolutionary digital and RF microelectronics. Direct RF is a crucial technology for transforming defense platforms. The next generation of this technology is here and ready to redefine what's possible in radar and software radio, from jamming to electronic intelligence to significant performance increases in bandwidth capture. This white paper explores why it is important to move toward direct RF, discusses its capabilities and applications, and shows how innovative products like those from Mercury Systems can help make the DoD's vision a reality.

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