Wanted: In-flight Drone Charging, Itty-Bitty Spy Cams, and More

Icons of biohazards, video cameras, and microchips
Illustration: Randi Klett; Icons: Shutterstock

Every year, the U.S. Combating Terrorism Technical Support Office puts out a “Broad Agency Announcement” that describes technologies that it wishes it could purchase, but which don't yet exist. It's a sort of to-do list for technologists and engineers, and it can turbocharge research in these areas.

The agency issued its latest draft in November, and it includes some doozies. Among the items described are a wireless recharging station for drones in flight, a low-power mini-spy camera that can be worn on the body, and a portable scanner that can find tunnel entrances under a floor or behind walls. 

None of these technologies are easy to create, and that’s the point. “I think it is very challenging and that's usually what the BAAs are geared for,” says Albert Titus, a biomedical engineer at the State University of New York at Buffalo. “When you read them the first time, it's kind of, 'Oh my, my.'”

As a whole, the list speaks to the tech priorities of a U.S. military faced with new demands in both its counterterrorism and counterinsurgency efforts, says Dylan Lee Lehrke, senior analyst with IHS Jane’s. Today’s military officials want to gather as much intelligence as possible through technology, to reduce their use of force and target it more efficiently.

“Technology can act as a force multiplier, providing information that enables a limited number of forces to maintain situational awareness in large complex environments and allows them to act with precision,” he says.

The items on this year’s draft BAA can help officials achieve that objective in a number of ways. Among other technologies, the military is seeking a method to wirelessly recharge drones in flight. Drones have become increasingly important for surveillance, but the battery life of most commercial models is still limited to under 30 minutes.

That short flight time means drones aren’t very useful for monitoring areas over time, which can be a serious problem. “Any gaps in surveillance are gaps in information. These gaps can be exploited by an adversary, for example to plant an improvised explosive device.” Lehrke says. 

In the draft, the agency requests a way to wirelessly transmit power over a range of one to three kilometers to a fixed-wing Puma and an Instant Eye drone, which has four rotary wings. The transmitter should be capable of sending enough power to keep the drones in flight for at least 24 hours. It must run from a silent generator operated from the back of an SUV, and be capable of automatically shutting itself off within 1 to 10 milliseconds if a foreign object passes in front of it while it’s transmitting.

Of course, there are many places where drones simply can’t fly, so the military is also requesting high-tech tools that will help agents gather information on the ground, or stay in touch with soldiers. These tools include a low-cost sensor that can send an email or text to a central command center whenever it’s moved, and a wearable health monitor for first responders.

The military also seeks a low-power mini-spy camera that can be worn on the body and send live audio and video for surveillance purposes. The military specifies that the device should be no larger than one inch by one inch by 3/8 inch (2.5 x 2.5 x 1 centimeter), not including the battery. (It’s unclear from the announcement whether those specifications are meant to include the antenna, microphone, and camera. A representative from the agency could not be reached for comment.)

Despite its small size, the wearable device must be able to transmit information including live video across a distance of at least 500 meters at microwave frequencies within the S Band (2.2 GHz to 2.29 GHz) or C Band (4.4 GHz to 4.8 GHz). It must encrypt everything it sends with 256-bit keys described in the Advanced Encryption Standard. And it should do all of this without heating up so much that it burns the person who is wearing it.

The challenges of building such a capable yet itty-bitty transmitter are significant. “What I think about when I read that is really, what they're looking for is a television studio that you can fit in the palm of your hand,” Titus says.

To understand why that's so difficult, it helps to start with the basics. A transmitter that generates and modulates a signal that can be broadcast from an antenna is made up of many components, including transistors, capacitors, and resistors mounted to a circuit board. To fit all that onto a single mini-unit, each component must be made as small as possible.

The good news is that the size of these basic components has shrunk considerably. Some years ago, the smallest transmitters for S and C bands measured roughly 2.5 x 2.5 centimeters, says Josep Miquel Jornet, an electrical engineer at SUNY Buffalo who works on radiofrequency miniaturization projects. Today, transmitters as tiny as 5 millimeters by 5 millimeters are commercially available, and researchers are pushing to make them at the sub-millimeter scale. Antennas, too, have become more compact, and Jornet says it’s now possible to buy antennas for the S or C bands which measure just 2 to 4 centimeters in length.

However, the military wants a device that not only emits a signal, but also encrypts that signal and processes live video streams. Jornet estimates that a system that can compress and stream videos requires at least two orders of magnitude more processing power than one which can simply generate and transmit a low-bit-rate signal. To lighten the burden, he says researchers may consider sending uncompressed video data and leave compression and other processing to the receiver. "I believe all of the elements are feasible," he says. "I think the real big challenge will be, they really want all of them in a one-by-one-inch space."

One way to make transmitters even smaller is to further integrate, or combine, their components. For those elements that can’t be easily integrated, such as capacitors and resistors, Titus says embedding components within multi-layered circuit boards can help to conserve space. Unfortunately, that approach adds manufacturing costs and causes heat to become trapped in the middle of the boards. “It comes down to manufacturing and heat dissipation, essentially,” he says.

Antennas could also be made much smaller, Jornet says, if the military were to switch from the S and C bands to high-frequency millimeter waves or even terahertz waves. However, such frequencies are limited in performance by various physical factors, so a device that handled them would almost certainly require an antenna array or some form of advanced signal processing to boost those signals—which could wind up taking up even more room than a slightly larger microwave antenna.  

The greatest challenge in creating a mini wearable spy camera as described in the BAA, Jornet says, will be finding a way to integrate all of the components that the device would need to process video, encrypt information, and generate signals, without causing it to overheat. Though miniaturized solutions exist for many of these functions, combining them on the same wearable device has never been done.   

The beauty of the BAA, Jornet says, is that it forces researchers working on their own projects to think about how they would bring all of their efforts together. “I think it's a good time for this announcement because in my opinion, the technology is here,” he says. “These types of announcements are the ones that tell you, go fetch the results on that paper and go make that real. So that's exciting.”

And just in case you’re wondering, the colorful Snap spectacles would not satisfy the military’s requirements. The spectacles transmit recorded video over a few meters to a smartphone through WiFi or Bluetooth, but cannot transmit live video over the 500-meter range specified by the military.  

The new BAA document is still in draft form. Once finalized, the agency intends to issue six to 24-month contracts for fiscal year 2018 for researchers to develop these and other technologies. To apply, applicants must submit a one-page quad chart outlining the specifications and costs of their proposals. A deadline for the application has not yet been set.  



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