Here is something new to be concerned about. It wasn't that long ago that tapping phone conversations required a warrant. Starting in 2001 the George W. Bush administration used new powers courtesy of the Patriot act FISA court restrictions to permit the NSA to spy directly on pretty much everyone. It's all been downhill from there.
here. They were purchased by Boeing in December of 2008.
DRT stands for Digital Receiver Technology. That very non-specific name adorns a a wholly owned subsidiary of Boeing. The industry jargon for this type of device is "Stingray." Simply put, a DRT BOX is software defined radio (SDR) used for wireless surveillance systems. In 1980, DRT was founded in Frederick, MD focusing on the development of devices for communications surveillance. If you go to their website here, you'll find a couple consumer grade wireless scanners. They also have make more specialized Stingray hardware for the feds. To my amusement I found they tacitly admit this on their site "Due to the sensitive nature of our work, we are unable to publicly advertise many of our products." More here.
The Justice Department installs these DRT Boxes on board fix-wing Cessnas so they can monitor a metropolitan area. The DRT BOX is then used to emulate a cellular base station. Because cellphones are designed to connect to the strongest cell tower available, they can just overpower the weak or distant terrestrial towers. The cell phone then transmits it's registration information to the DRT BOX. More here.
The program, used by the U.S. Marshals Service, has been in use since 2007 and deployed around at least five major metropolitan areas, with a flying range that can cover most of the US population. By flying a circuit over a city they can gather information on thousands of phones in just a couple hours of flight. This cannot be used to target individuals. Because the device must emulate a carrier it gathers information on all customers of that carrier in range. Similar Stingray-like devices have existed for decades, but flying them over American cities seems to be a new development. More here.