VLF vs Pulse Induction: What's the Difference?

VLF (very low frequency) is the two-coil transmit-and-receive design behind almost every detector reviewed on this site. It measures how a target's signal compares to the transmitted one and converts that into a target ID number and a discrimination setting — see how a metal detector works for the full mechanism.

This is why VLF detectors can tell you roughly what's buried before you dig, and why you can set them to ignore iron and foil. It's the right choice for the overwhelming majority of detecting — parks, beaches, fields, relic sites.

Pulse induction (PI) works differently: it sends strong pulses into the ground and times how long the returning echo takes to fade, rather than comparing frequencies. This makes PI almost completely immune to ground mineralization and salt water — the two things that hurt VLF depth the most.

The trade-off is real: PI detectors have little to no meaningful discrimination. Every metal signal sounds roughly the same, so you dig everything, iron included. That's an acceptable cost in the specific situations PI is built for, and a genuine downside everywhere else.

Saltwater and wet beach sand — salt confuses VLF ground balance; PI shrugs it off entirely, which is why serious surf and underwater detecting leans PI.

Heavily mineralized goldfields — the same immunity that helps with salt helps in iron-rich prospecting ground where VLF ground balance struggles to keep up.

Meteorite hunting — see can a metal detector find meteorites — since PI's lack of discrimination is actually the point when every metallic signal needs digging.

For the vast majority of detectorists — coins, jewelry, relics, general beach and park hunting — a good multi-frequency VLF like the Minelab Equinox 800 covers salt water and mineralized ground well enough that a dedicated PI machine isn't worth the discrimination you'd give up.

We don't currently carry a full-size PI detector in our review lineup — the closest is the Nokta PulseDive, a PI pinpointer built for underwater recovery rather than as a primary detector. If serious PI prospecting or surf hunting is genuinely your focus, that's a specialist purchase beyond what a general buying guide should talk you into.