The type of locator most commonly used in HDD is a walkover system. Walkover systems, as the name implies, require that the locator operator "walk over" the top of the drill head with the receiver to determine the depth and position of the drill head.
Walkover systems consist of two major components, a receiver and a sonde. The sonde, also known as a transmitter or probe, fits inside the drill head.
The sonde sends out a signal that is picked up by the receiver. The receiver processes this signal into three important pieces of information: pitch, roll, and depth.
