Which of the following methods is used to locate sources of noise interference or jamming?
Why Radio direction finding (RDF) uses a directional antenna, such as a small loop or a beam, plus an attenuator, to determine the bearing to a transmitting source. Taking bearings from two or more locations lets you triangulate the position of a noise source, an interfering signal, or a hidden transmitter. Hams use the same technique for fox hunts and for tracking down power line noise.
Watch out Doppler radar measures the velocity of a target by transmitting a signal and listening for the frequency shift in the echo, but it does not find the source of an unknown emission. Echolocation is a sound-based technique used by bats and sonar, not an RF method.
Finding a transmitter means finding its direction: RDF. Radar and echolocation send out a pulse, RDF only listens.