This is one of the latest innovations in detection metallic objects. Guards commonly use this type of detectors for detecting concealed weapons at security checkpoints. However, the technology is not very efficient in differentiating the different types of metals.
This technology relies on the simple theory of echolocation. For instance, if someone were to make a sound in a padded room, most of the sound would be lost. If they to repeat the same in a room full of hard surfaces, they would experience a very powerful echo. This is how pulse induction works. The detector usually relies on one coil or a number of coils that work as one. This is unlike other detectors that relies on two complementary coils working together. Furthermore, the detector works by sending a short burst of powerful current through the coil(s).
This pulse then disappears and the magnetic field quickly reverses. This then generates a short electric current, which then disappears. The current generate is used to generate a report on the objects present in the ground. If there is a magnetic object buried in the ground, it will undoubtedly interfere with the current generated. This model works well because the pulsing motion lets it detect only signals it has generated. The greatest impediment to using metal detectors is noise from the surrounding. Although it is more accurate at detecting objects, it is very hard to differentiate these objects. The detector remains one of the most expensive types of detectors currently in existence.