It's called an electromagnetic method radiodetección allowing pinpoint buried pipes and cables.
Basically, its operation is to detect the resulting magnetic field of an electric current flow. Therefore the basic possibilities of operation are:

• The detection of cable assets that any current flow,
• When cables or pipes are not active, induces a signal in an accessible pipe or cable to detect and locate the signal in the study area to locate your position.

The location will be both surface and depth.
Radiodetección teams are composed, therefore, a receiver and a transmitter. The receiver detects the magnetic field resulting from the flow of electric current induced in a line. This field is called a signal. The transmitter emits a signal connection, induction or by some accessories.
Both the sender and receiver have different ways of operating (power signal, radio signal, signal to 8 kHz, 33 kHz signal, passive scanning, active scanning, tracking, peak response, no response, etc.). And some accessories allow the introduction of a "fish issuer" within the pipe / collector, and so on. to be followed by the receiver surface.

APLICATIONS:
Basically, the detection and location of buried cables and pipes, be they active or passive. Location and tracking of collectors, pipelines, galleries visited abandoned and / or accessible, etc. .. It is very useful to detect urban services before tasting, polls, etc..