PART II: Metal Detecting Tips for Users, page 4
How To Recognize False Coin-Like Signals with XP Deus: Iron Falsing
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If the high-tone signal is "two-way repeatable" and "small", you should proceed with steps 1, 2 and 3 described on a previous page.
But, first, you should remove any dead leaves or last-year dry grass from the target spot and sweep the search coil over it again while keeping the coil flat on the ground.
The Deus sometimes responds to a small iron target with a high-pitched tone if the search coil is a little higher than necessary over the target spot, and the target is still within the Deus' operating depth range.
Other two cases of the "two-way repeatable" high-tone/iron-buzz responses may be:
2-2. Particular Small Iron Objects
Some types of small iron targets such as horseshoe and shoe nails, iron needles and wire fragments will sound off with a good high-tone/iron-buzz signal even after they are dug up, cleaned of dirt, and placed on the ground surface.
Horseshoe and Shoe Nails
Always Give Off High-Tone Signal
Fragments of Iron Needles and Wire
Also Induce a Coin-Like Responses
Also steel bolts and large washers can cause the same effect due to their characteristic ability to exhibit both ferrous and conductive properties. Consulting VDI numbers and the Signal Visualization's Vector Graph (will be described in my next article coming up) may help to identify these targets and avoid unnecessary digging.
2-3. Iron Objects of Closed-Circular or Closed-Rectangular Frame Types
Iron objects of closed-circular and closed-rectangular frame types - harness rings and various square buckles (shown with a US Dime for reference below), or objects with structural elements of rounded shapes, most likely will induce a good "two-way repeatable" high-tone/iron-buzz response and a VDI reading as high as 98. And even after you cut a dirt plug out of the target spot, the Deus' response to such a target will remain of a high-tone; however, the grunt of iron will become very pronounced, and the VDI numbers will drop into the iron range from 01 to 10.
These Iron Objects Are Most Likely To Give Off High-Tone Signal
2-4. Deep Iron Targets
Deep iron targets most likely will induce a good "two-way repeatable" high-tone/iron-buzz response and a VDI reading as high as 98. If you cut a dirt plug out of the target spot, the Deus' response should become a low-tone grunt of iron or "broken", and the VDI numbers will drop into the iron range from 01 to 10. Then it is iron.
If the detector's high-pitched response does not disappear, and the audio response's size remains small, dig up the target! If the detector's high-tone/iron-buzz response does not disappear, and the audio response becomes bigger as you dig down, then you have encountered a large iron object.
NOTE: One should keep in mind that if TOO LITTLE Conventional Discrimination is used, the Deus will respond to most iron targets with medium-pitched audio tones that may be similar to audio responses to valuable non-ferrous targets.
You can set the Conventional Discrimination level at 10 and not to worry about this effect. But if you want to keep the Conventional Discrimination at the lowest possible level, you should conduct a simple procedure in a field: reduce the Conventional Discrimination level while sweeping the coil over a shallow UNDUG iron nail until you hear a change in the signal's tone - from low to a medium pitch. Set the Conventional Discrimination level a couple of units higher. This way you could have minimum Conventional Discrimination, and the Deus' audio responses to iron will sound the way they normally do.
2-5. External metal objects such as steel toes or steel shanks inside your boots may cause false signals every time a search coil gets close to your feet. Same goes for the long-handle shovels that detectorists usually drag on a side while metal detecting, and hand jewelry that one forgets to take off before manually scanning lumps of dirt in front of the search coil.
If you have just started using the XP Deus, it is best to dig up the 'coin-like' questionable signals before you develop skills in deciphering them and master simple analytical techniques. Yes, in the beginning, you will end up digging lots of nails and other iron debris, but at least you will not pass up any valuable targets.