WRIGHT-PATTERSON AFB, Ohio – US military researchers needed a company to develop broadband adaptive RF filters and compensators to allow the use of broadband access software defined radio in an overloaded and contested environment. They found their solution from the L3Harris Technologies Inc. segment. Communications Systems-West in Salt Lake City.
Employees of the U.S. Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio, announced a $ 7.2 million contract for L3Harris on Wednesday for the Broadband Adaptive RF Protection (WARP) project.
When exposed to interference and self-interference, these filters and compensating devices will sense and adapt automatically to the electromagnetic environment through intelligent control of their adaptive hardware. The idea is to reduce interference – especially in a contested environment – selectively and to protect digital broadband radio stations from saturation.
The Air Force Research Laboratory awarded this electronic warfare (EW) contract with L3Harris on behalf of the U.S. Advanced Defense Research Projects Agency (DARPA) in Arlington, Virginia. Additional WARP contracts may be awarded.
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Historically, digital receivers have been narrowband because they are limited by the A / D converter’s bandwidth, the researchers explain. For these narrowband systems, pre-scheduled filtering prevents unwanted signals from reaching the A / D converter.
In the last decade, however, A / D converter technology has achieved more than 10 GHz instantaneous bandwidth with 8-10 effective bits (ENOB).
This performance is sufficient for wideband digital receivers, but poses two challenges: broadband A / D converters typically have relatively little input voltage fluctuation available and reduced dynamic range compared to their narrowband counterparts; and as the bandwidth increases, more signals appear, which means larger voltage changes in the A / D converter.
The DARPA WARP program seeks to protect these broadband receivers against external and self-interference by adaptive input spectrum equalization to stay within the dynamic range of a digital broadband receiver.
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Today, receivers are protected from external interference by static filtering, automatic gain control or signal limiters. However, static filtering uses only part of the bandwidth of the digital receiver, which gives good sensitivity, but does not take advantage of the available bandwidth of the receiver. Meanwhile, the automatic gain control takes advantage of the system’s bandwidth, but reduces the sensitivity to small signals.
At the same time, signal limiters can cause cross-modulation distortion and reduce the overall sensitivity of the system. Adjustable filters are sometimes a solution, but can rarely be tuned to the achievable bandwidth.
Instead, WARP seeks to develop broadband, adaptive filters, and analog signal cancellers that selectively attenuate or eliminate external and stand-alone interference to protect digital broadband radio stations from saturation, ultimately allowing the use of software-defined radios in congested and congested dynamics. spectral medium.
The ideal broadband receiver will adapt to the EW attenuation or blocking to maintain dynamic range without reducing sensitivity and bandwidth. The WARP project seeks to develop adaptive filters to automatically reconfigure their frequency response to include bandwidth / stop bands and center frequency tuning and attenuation of large signals selectively when transmitting small or desired signals.
The challenge is to do this with a wide bandwidth with low insertion loss at the receiver input. Today, most adjustable chip-scale filters are limited to an adjustment ratio of 2: 1 or less, without explicit range switching.
Instead, the WARP program seeks to demonstrate adaptive RF filtering of external interference with a 9: 1 ratio to provide full-bandwidth coverage of 218 GHz with new filter architectures based on state-of-the-art components and packaging.
The WARP program consists of two four-year technical areas: broadband adaptive filtering; and canceling the broadband signal. For more information, contact L3Harris Communications Systems-West online at www.l3harris.com/capabilities/defense, The Air Force Research Laboratory in www.afrl.af.mil, or DARPA on www.darpa.mil.
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