Minelab and others have been developing new metal detectors based on Pulse Induction...
The trend began a decade ago. Metal Detectors operating on the basis of a "Pulse" are known to have an advantage over the common VLF or Frequency Domain Metal Detector.
Here's why;
A common VLF or Frequency Domain metal detector is designed to receive a small secondary signal in the presence of a much larger transmitting signal. The inherent problem lies in the circuitry required to cancel the large primary transmitting signal in order to detect a very small secondary signal that represents GOLD.
Pulse Induction metal detectors transmit a PULSE...

Then, they "listen" during the "quiet time" between pulses for a secondary signal. This gives a PI detector the advantage of not having to manage the process of listening while a resounding larger signal is present.
This may be a topic of interest for anyone owning or contemplating ownership of a PI detector.
AS a side-bar;
PI metal detectors are available on a towable platform that can be towed by a 4-wheeler!
PI systems can also be suspended from a Helicopter!

- Geowizard