Metal detecting technology can be broadly categorized into two primary types: Very Low Frequency (VLF) and Pulse Induction (PI). While both are used to detect buried metallic objects, they rely on entirely different principles of operation, each suited to specific environments and target types.
Understanding how these technologies function—and knowing which detectors use them—can help you make an informed choice based on your detecting goals.
Very Low Frequency (VLF) Technology
VLF detectors operate using two continuous waveforms: a transmit frequency and a receive frequency. The coil transmits a stable, sinusoidal electromagnetic field into the ground. When this field encounters a conductive object (metal), the object generates a return signal through a process called electromagnetic induction.
The detector's receive coil picks up the phase shift between the transmitted and received signals. This phase shift provides information about the target’s conductivity and magnetic properties, allowing the detector to differentiate between different types of metals (e.g., ferrous vs. non-ferrous).
Some advanced VLF detectors use multi-frequency or simultaneous multi-frequency (SMF) transmission, emitting more than one frequency at a time to improve target identification and performance on varying soil types.
Advantages of VLF
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Excellent target discrimination
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Good sensitivity to small, shallow objects
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Typically lighter and less expensive
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Ideal for coin shooting, relic hunting, and general-purpose detecting
Examples of VLF Detectors:
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Minelab Manticore – A premium multi-frequency VLF detector offering high power, precise discrimination, target trace imaging, and excellent depth across all terrains.
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XP Deus II – A high-performance VLF detector with Fast Multi Frequency (FMF) technology, offering excellent separation and depth in a wide range of soils.
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Garrett ACE Apex – A beginner-friendly VLF detector with selectable and simultaneous multi-frequency modes.
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Nokta Legend – A rugged VLF machine with simultaneous multi-frequency operation and solid performance in wet, salty, or mineralized environments.
Pulse Induction (PI) Technology
Pulse Induction detectors operate by transmitting powerful, short bursts (pulses) of current through the search coil, creating a brief but strong magnetic field. When this field encounters a conductive target, it induces a return signal. After each pulse, the system quickly switches to receiving mode and listens for the decay of eddy currents from the target.
PI detectors do not rely on a continuous wave or frequency phase shift, and because of this, they are largely immune to issues caused by ground mineralization—making them highly effective in black sand, saltwater beaches, and hot soils.
However, PI detectors typically lack detailed target discrimination. While some offer basic ferrous/non-ferrous distinction, they do not provide conductivity-based identification like VLF detectors do.
Advantages of PI
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Excellent depth capabilities
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Superior performance in mineralized or salty environments
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Ideal for gold prospecting, deep relic hunting, and beach detecting
Examples of PI Detectors:
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Minelab GPX 6000 – A high-end PI detector designed specifically for gold prospecting, featuring automatic ground tracking and exceptional depth.
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Minelab GPZ 7000 – An advanced gold prospecting detector using Zero Voltage Transmission (ZVT), which builds on PI principles to reach extreme depths with fine sensitivity.
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Garrett Axiom – A lightweight, high-performance PI gold detector with Ultra-Pulse technology, designed for use in highly mineralized soil and optimized for fine gold in extreme conditions.
Choosing Between VLF and PI
| Feature | VLF | PI |
|---|---|---|
| Operating Principle | Continuous sine wave | Short high-voltage pulses |
| Discrimination | Strong (target ID, conductivity) | Weak (basic ferrous/non-ferrous) |
| Ground Mineralization | Can be affected | Largely immune |
| Ideal Target Types | Coins, jewelry, shallow relics | Gold nuggets, deep relics |
| Target Depth | Shallow to moderate | Deep (especially on larger targets) |
| Typical Weight and Cost | Lighter, more affordable | Heavier, higher-end pricing |
Final Thoughts
Both VLF and PI metal detectors offer distinct advantages. VLF detectors are often the best choice for beginners and general-purpose use where discrimination is important. PI detectors, on the other hand, are unmatched in depth and mineralized ground performance—making them essential tools for serious gold prospectors or deep-searching relic hunters.
When selecting a detector, your choice should depend on the ground conditions you'll be searching, the types of targets you’re after, and how much weight and complexity you’re willing to handle.
If you're not sure which direction to go, we’re happy to help you compare models and find the right tool for your detecting style.
