How To Search an Abandoned Homestead Site Located in Remote Wooded Area
Discrimination
Using minimal or no discrimination and getting a reasonably accurate description of the buried targets is the greatest advantage to using metal detectors with Target ID systems. Knowing the various audio pitch responses and display readings of a variety of both good and junk targets gives a treasure hunter an extra edge in trashy areas.
For searching around old house foundations and cellar holes, using no discrimination and listening to all signals would be an ideal technique. This technique allows a treasure hunter to hear a high-pitched signal of extremely short duration among multiple low-pitched responses from the iron square nails.
The concentration of old iron square nails buried around the perimeter of the cellar hole is the biggest obstacle to successful recoveries of valuable coins and relics. Using discrimination to reject nails would compound the problem because of the masking effect created by the rejected nails lying in close proximity to a coin or relic.
Separating good targets from the iron junk targets can be very difficult on detectors with no visual and audio ID systems in such situations. Even non-ID detectors with good target separation can give broken or clipped audio over coins when using discrimination in areas of highly concentrated trash.
In reality, using no discrimination would drive anybody crazy because of the cacophony of audio responses from zillions of targets. That is why most people metal detect with discrimination sometimes cranked up high, thus leaving many "goodies" behind, especially if they use large search coils.
I would suggest you to use the minimal discrimination (only iron nails are rejected) with a small search coil, 7-14 inches or less in diameter, if you want to minimize the masking of good signals by nails.
Search Coils Selection
Obviously, the larger the search coil, the greater area of the ground the metal detector can cover in less time. Unfortunately, large search coils get responses from more junk targets and good targets simultaneously in addition to getting affected by more ground mineralization.
If the mineralization intensity is high and trash content is low, the 10-12 inch Double-D search coil should be used for optimum depth and coverage.
If the mineralization intensity is low and the trash content is moderate, the 8 inch search coil will give you the best depth, target separation and ease of pinpointing.
In case of high levels of both mineralization and junk, the 4-6 inch search coils will allow more accurate pinpointing and higher levels of sensitivity.
In many cases, the smaller search coils actually have a greater depth potential due to the higher level of sensitivity that can be used, higher reactivity to very small targets, and maneuverability around natural obstacles such as dense vegetation, tree roots and crevices in proportion to larger coils.
With respect to scanning speed and overlap, the small search coil's diameter imposes a certain discipline on the metaldetectorist. Not to miss the small and deep buried targets, one has to scan the ground with 25% less speed, overlap at least 50% with every new scan and pay great attention to every tiny "squeak."
When making a change in search coil size during a hunt, always check and readjust ground balance (if it is not auto tuned), sensitivity and discrimination settings, and do the Noise Cancel procedure (with Minelab detectors).
If your metal detector has a depth indicator, be sure to consider any differences in readings explored in Bench Testing (air testing). Many detectors have depth reading calibrated to only the standard size search coil, so changes in the coil diameter and its configuration may give readings over or under actual target depth.
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