Radar technology that has been used to track flying insects and detect explosives can also be used to discover and identify unknown or unwanted electronic devices in homes.

Beatrice Perez, a postdoctoral fellow in the Department of Computer Science, is building one such detector that can scan a space for lost or hidden electronics. Perez and her collaborators demonstrate an early prototype in a recent paper published in the journal Remote Sensing.

Their work is part of a larger research project called SPLICE. This multi-institute project led by Provost David Kotz ’86—the Pat and John Rosenwald Professor in the Department of Computer Science—analyzes and addresses issues of security and privacy in today’s smart homes.

These days, homes are overrun with devices, some of which may not even belong to their residents. “Without necessarily suspecting malice, you may want to know if there are devices installed by landlords or left behind by guests or previous owners,” says Perez. Or someone may simply be trying to locate a misplaced or long-forgotten device, she adds.

Not only are devices numerous, they also come in a wide variety, from smart refrigerators to low-power leak sensors and tiny smart tags. “We’re trying to find one method to identify any of these,” says Perez.

To achieve this, the researchers turned to radio technology. They use what is called a “harmonic radar,” a system that sends out a simple radio wave and listens for waves that are radiated back to it, akin to an echo, but at twice the frequency of the original wave.

Electronic devices, simple or complex, have components that modify radio waves and change their frequency, Perez says. “So, when we tune in at double the original frequency to listen for the re-radiation, we only hear back if the object in front of our detector is electronic,” she says.

The detector has picked up on TV remotes, smartphones, and myriad other electronics within a meter. With two cellphone-sized antennas wired to a computer, the detector is somewhat clunky, Perez concedes. A more portable version is in the works.

Now that they can identify whether objects nearby are electronic or not, the next step is to build functionality to identify what the detector discovers in its path. The long-term goal, Perez says, is to be able to scan a whole house for devices, one room at a time.