A Washington, D.C.-based engineer is working on the "Drone Shield" that might be able to send you text and email alerts that let you know when a drone is nearby.

The small, Wi-Fi-connected device uses a microphone to detect a drone's "acoustic signatures" (sound frequency and spectrum) when it's within range.

The company's founder, John Franklin, who has been working in aerospace engineering for seven years, says he hopes to start selling the device sometime this year, said US News and World Report.  The device will cost $69 and will be about the size of a USB thumb drive. It will use Raspberry Pi – a tiny, $25 computer – and commercially available microphones to detect drones. He says he imagines that people will attach the Drone Shield to their fences or roofs to protect their home from surveillance.

He is currently working on an open-source database of drone sounds that the detector will check what it's hearing against. Other devices with motors, such as lawn mowers and weed-whackers, will also be included to reduce false positives. Drone owners will be asked to record the sound of their drones to be included in the database. When the Drone Shield identifies a drone, it will flash and send an email and text message alert to a homeowner.

Franklin says that most commercially available drones have to come relatively close to a home in order to spy. More sophisticated drones, such as Predators, would fly too high to detect.