Beginners chase a “good number” on the screen and walk past coins. VDI (Visual Discrimination Indicator) is a conductivity hint — not a passport for the find. Related: basic settings, newbie mistakes, choosing a detector.
VDI in plain language
The machine estimates how a target “looks” electromagnetically and shows a number or scale.
- Lower values often lean ferrous / foil (depends on model and scale).
- Mid/high values lean non-ferrous (brass, copper, silver) — still approximate.
- The same coin can read differently with depth, soil, and orientation.
Scales are not universal: Equinox/Manticore, Deus II, and Legend disagree. Learn your machine, not a chat-table from strangers.
What discrimination is for
Discrimination masks or notches part of the scale (often iron) so you dig less trash.| Approach | Upside | Downside |
|---|---|---|
| Heavy iron discrim | Fewer caps and nails | You mute masked non-ferrous and useful iron-edge info |
| Mild discrim / all-metal | More target information | More holes; needs discipline |
| Notch a band | Kill a trash peak | Easy to notch coins in the same band |
Field rule: stable ground and readable audio first, fine discrim second. Do not start the day by “notching everything under 40”.
Why the number lies
- Depth — weak signals drift on the scale.
- Iron next door — non-ferrous masks; VDI jumps.
- Shape and angle — a ring on edge ≠ a coin flat.
- Mineralization / salt — beaches and hot dirt shift ID (on Manticore, use ID Map, not only the digit).
- Caps and bi-metal — classic fakes; Legend’s Ferrocheck helps, and everyone needs repeat sweeps plus a pinpointer.
How to train properly
- Use a mode where iron is still audible (or only mild discrim).
- On a test garden: nail, cap, copper, silver — memorize tone, not only the number.
- In the field: repeat from angles + depth/pinpointer check.
- Log in Discovera: VDI/mode + photo — after ~20 outings you own a personal table, not someone else’s.
All Metal vs Discriminate
- New trashy site — more information (all-metal or low discrim).
- Clean pasture for coins — moderate iron discrim saves energy.
- Beach — ground stability first; tune discrim after the machine stops screaming at salt.
Myths
- “VDI 80 = silver always” — no.
- “Never dig iron” — sometimes non-ferrous hides beside it; sometimes the iron form matters — still subject to ethics and land law.
- “Higher discrim = more pro” — usually it means you are blind on half the scale.
How Discovera helps
Save mode and a short audio/VDI note with the photo in the find diary. You will link “drifting” ID to real targets on your soil faster. AI on photos does not replace listening, but it helps catalogue what you already dug.
Outing checklist
- Know your scale (rough ferrous vs non-ferrous).
- Discrim is not “floored” until ground is stable.
- Dig decision = audio + repeat, not one digit.
- Pinpointer on the belt.
- Diary note on questionable IDs.