A Pulse Induction Metal Detectors use electronic pulses to generate a brief magnetic field. It is not uncommon for this system to use a single coil for the receiver and the transmitter. Some models have two or three coils simultaneously working together. Each coil receives a short blast of current and makes a short magnetic field. An electrical spike is received when the short blast ends, resulting in a polarity shift that reverses the magnetic field.
These electrical spikes only last for one millionth of a second and it generates more current to run into the coils. This is known as (reflected pulse) also very brief and just lasting for microseconds. The system repeats itself with these short pulses of current hence the name pulse induction metal detector system. The average (PI) system can send 100 pulses for every second. Some of the best pulse induction metal detector (PI) systems are more sophisticated with 24 pulses a second to well over a 1000 pulses per second. Like the Garrett ATX pulse induction metal detector.
How Does It Work?
If you think of a pulse induction metal detector circuit acts like an echo, it makes more sense. If you’re surrounded by limited hard surfaces and dense matter, the echo will be very brief. If you shout at the top of your lungs where hard surfaces are in multiple direction the sound waves reflect off each one of them, thus causing the echo effect. When you place the (PI) detector over metal, the pulse generates a reverse magnetic field. The pulse of the magnetic field will end, producing a reflected pulse in the magnetic field. The target metal objects in the magnetic field adds an echo to the pulse allowing the (PI) metal detector to read the presence of a metal object.
The pulse induction metal detector uses a sampling circuit to determine the reflected rate of the pulse being sent. When the length is compared, the system can analyze if a different magnetic field is present in the reflected pulse making the signal longer to end. If the end of the signal takes longer to recognize than what the system is programmed to receive there is a pretty good chance there is some type of metal object in the way. You just learned how a (PI) system is used to find metal by using pulses that work like an echo.