Counter Drone Detection Methods

Triangulation - Generally a spectrum analyzer and/or radar device are used to find the location of the drone.  The spectrum analyzer "listens" for radio frequencies between the drone's receiver and the operator's remote control.  A radar unit operates the opposite way.  It's emitting radio signs and can detect a change in frequency when the radio waves reflect off an object.  Multiple antenna are deployed in order to triangulate the drone's position. 

PROS/CONS - This method is very effective at finding the location of any aerial unmanned system; however it is very difficult to determine the location of the pilot, as buildings, landforms and other structures will obstruct the radio signals. Given the number of devices needed for a precise location, and the processing power needed to analyze the data, it's the most expensive method at 5 to 10 times the cost Decoding and Remote ID.

Decoding - Counter UAS manufacturers analyze the radio signals from each drone and "decode" the packets of information transferred within the signal.  Often times, this includes drone make, model, serial number, drone location and pilots location. 

PROS/CONS This method requires a lot of work on the counter UAS manufacturer to decode the signals of all drones and stay current with any new changes.  The Decoding method has raised legal questions in the United States, and may require a warrant to use it.  It's very effective at locating the pilot; however, if a drone's signal has not been previously decoded, it will not be detected.  It's less expensive than Triangulation, but requires a tremendous amount of labor and programming so it's more expensive than Remote ID.

Remote ID - Pilots are required to register aircraft with the FAA and broadcast a Remote ID signal from the aircraft while operating.  This signal contains the aircraft location, remote location and FAA registration number.  

PROS/CONS - This method is by far the best way to detect the drone and pilot; however, those operating maliciously will not be going through this process.  It's mainly used to detect those operators who are compliant, but operating in areas they should not be.