The marketing firm Adnear is using drones to track cell phone users:

The capture does not involve conversations or personally identifiable information, according to director of marketing and research Smriti Kataria. It uses signal strength, cell tower triangulation, and other indicators to determine where the device is, and that information is then used to map the user’s travel patterns.

“Let’s say someone is walking near a coffee shop,” Kataria said by way of example.

The coffee shop may want to offer in-app ads or discount coupons to people who often walk by but don’t enter, as well as to frequent patrons when they are elsewhere. Adnear’s client would be the coffee shop or other retailers who want to entice passersby.

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The system identifies a given user through the device ID, and the location info is used to flesh out the user’s physical traffic pattern in his profile. Although anonymous, the user is “identified” as a code. The company says that no name, phone number, router ID, or other personally identifiable information is captured, and there is no photography or video.