A pulse induction (PI) metal detector is a type of electronic instrument that uses electromagnetic fields to detect the presence of metals or other conductive materials buried underground or hidden within objects. This type of metal detector works by emitting a series of rapid, high-voltage pulses of electricity into the ground, and then measuring the changes in the electromagnetic field that are caused by the presence of metallic objects.

PI metal detectors operate on the principle of electromagnetic induction, which is the phenomenon that occurs when an electric current flows through a conductor and produces a magnetic field around the conductor. In the case of a PI metal detector, the electric current is provided by a battery or other power source, and the conductor is a coil of wire that is wrapped around a metal rod or other support structure.

When the PI metal detector is turned on, it emits a series of rapid, high-voltage pulses of electricity into the ground through the coil of wire. These pulses generate a brief, but intense, electromagnetic field around the coil, which extends outwards from the coil in all directions, and extends downwards into the ground. As the PI metal detector is moved over the ground, the electromagnetic field encounters any metallic objects that may be buried underground, such as coins, relics, or other valuable items.

When a metallic object comes into proximity with the electromagnetic field generated by the PI metal detector, it becomes magnetized by the field. This causes the object to generate its own magnetic field, which interacts with the field generated by the metal detector. The interaction between these two magnetic fields causes a disturbance in the electromagnetic field, which is detected by the metal detector.

The PI metal detector measures the disturbance in the electromagnetic field and uses this information to determine the presence and location of a metallic object. This information is then displayed on the metal detector's display screen, typically in the form of a visual or auditory signal, such as a change in the tone or volume of a beeping sound, or a change in the color or intensity of a light on the display screen.

One advantage of PI metal detectors over other types of metal detectors is their ability to detect deeply buried objects. Because PI metal detectors emit high-voltage pulses of electricity into the ground, they are able to generate a powerful electromagnetic field that can penetrate deep into the ground, allowing them to detect metallic objects at greater depths than other types of metal detectors.

Another advantage of PI metal detectors is their ability to discriminate between different types of metals. Some PI metal detectors are equipped with advanced algorithms and signal processing techniques that allow them to differentiate between different types of metals, based on the characteristics of the electromagnetic field disturbances that they produce. This allows the user to selectively search for specific types of metals, or to exclude certain types of metals from the search. It is the author's opinion that all targets need to be dug regardless of exclusion signal (aka discrimination).

In summary, a pulse induction (PI) metal detector is a type of electronic instrument that uses electromagnetic fields to detect the presence of metals or other conductive materials buried underground or hidden within objects. PI metal detectors emit rapid, high-voltage pulses of electricity into the ground, and measure the changes in the electromagnetic field that are caused by the presence of metallic objects. These changes are then displayed on the metal detector's display screen, allowing the user to locate and identify metallic objects. PI metal detectors are known for their ability to detect deeply buried objects and to discriminate between different types of metals.