I have enjoyed detecting for over five decades, and will wrap up my 52nd year and start #53 in March. Along the way I have been a very avid enthusiast at not just using a detector, but
learning detectors and how to get the best performance out of them. In doing so I have learned, used and taught some of the techniques that have benefitted me, and have named some terms that describe the techniques I use, and have used these terms in instructing folks in club meetings, working at dealer friend's shops, or with customers when I was a detector dealer starting in '77, and in MD Seminars I have been hosting since 1981.
I have used terms like:
ATC ..
Audio Target Classification or methods to 'classify' some targets as probably ferrous-based or non-ferrous, and also other functions. Two of the techniques mentioned are
'Quick-Out' and
'EPR.'
'Quick-Out' .. I started using this technique in '83. It is a technique that works
sometimes with a motion-based Discriminator, especially a slower-sweep type using a 2-filter or 3-filter circuitry, that allows you to make a very brisk [size=small]
('Quick')[/size], but short-length sweep across a located questionable target, that might degrade or reject the audio signal to 'classify' [size=small]
(knock 'Out')[/size] the target as probably being a ferrous-based piece of junk. An example would be a rusty, crimp-on bottle cap. It can even help a TID model provide a more correct visual TID of ferrous trash. Sometimes either the detector, the coil used, or the problem trash ferrous junk might not kick-out using this technique, so I then employ
'EPR.'
'EPR' .. This is a technique that I was using back in the early days of conventional TR detectors in '71, before Discriminators were popular, to help 'classify' probable iron targets. It worked great with the good TR's I used, and still do with my Compass Coin Hustler and Yukon 99B, and can work with other Discriminators. It is especially useful with out modern, motion-based Discriminate models that often have more trouble with some iron, nickel, steel and other challenging-shaped magnetic metal targets, especially things like crimp-on bottle caps.
'EPR', short for
'Edge-Pass Rejection', is a technique where you isolate or pinpoint the location of a questionable target that gives you a good or iffy audio response and, if you have visual TID, a jumpy or unsteady read-out. Then, you continue to make a side-to-side sweep across the target. Not a long-length sweep, just enough for the search coil to just completely cross the located target.
While doing so you work the search coil back towards you so that the targeted location is swept across with the front 'edge' of the search coil. This is not always going to work the same from detector-to-detector or from one type and size search coil to a different one due to the differences in the shape and effect of the EMF, the coil's internal positioning, and how the detector's circuitry processes the received signal.
Usually, the
'EPR' technique works well with a Concentric search coil when the target is about ½" to 1" inside the coil's diameter towards the center from the outer 'edge' of the coil. NOT right at the very 'edge' of the coil but close to it. Most often, a Double-D coil might not display a proper
'EPR' until the targeted spot is near the
outer edge to maybe 1" or so away from the outer coil's edge.
What does it do? Many problem iron-based targets cause us problems because man has shaped them into a more conductive shape. Again, a rusty or even unused bottle cap is a prime example. While many early conventional TR-Discriminators could reject a bottle cap, the modern motion-based units we use today might have problems with those and some other iron-type targets. Both coil types, but especially DD's seem to be challenged by them and 'false signal' a lot. We sweep over a bottle cap or other annoying targets and get a reasonably good audio response and maybe a so-so good TID. Reasonably good, but kind of a questionable audio or somewhat inconsistent TID that
hints to a
potential ferrous based piece of junk.
Time to use
'Quick-Out' and, if that doesn't work or to add an extra measure of classification, we employ the
'EPR' technique. If the target is a non-ferrous metal coin, such as a US 1¢, 5¢ 25¢ or other coin, you will continue to get a good repeatable audio response and an OK TID as you draw the coil back towards you while just sweeping across the targeted spot until you get to the 'edge' area and lose detection of the coin.
If the target is a bottle cap, piece of rusty tin, an iron bolt or washer, etc., then when you find the functional 'edge' area of your detector/coil doing an
'Edge-Pass' you will get an obvious 'Rejection' of the iron target. If your Discrimination is low for more iron targets, then more will be heard with a low tone [size=small]
(if your detector is working in a 2-Tone, 3-Tone or other multi-tone function that can indicate iron with a lower tone)[/size]
and will also display a proper 'Iron ID' range visual response. I Relic Hunt most of the time, but use this technique a lot for both Relic Hunting and Coin Hunting needs.
Power Balance .. This is a technique I have used since about 1980, teach in seminars since '81, and have especially relied on since mid-'83 using many [size=small]
(not all)[/size] motion-based detectors to adjust for a most efficient working Ground Balance while in the silent-search Discriminate mode. It has been most useful with
most Tesoro Discriminators, many brands that used or copied the Tesoro type circuitry, or others that had a tie-in between the motion-based Disc. mode GB and the Threshold-based All Metal mode GB adjustment.
volpe said:
Please explain "edge-pass rejection"
I occasionally get an iron signal, then a null, and again an iron signal when passing over sheet metal.
If you hear an Iron Audio signal, then a NULL, and then the iron signal again after passing the target, and it is sheet iron, that is not totally uncommon depending upon the detector model used, the settings used and the search coil used.
Iron has a different effect on the EMF than a same-size and shape piece of non-ferrous metal and the coils used and settings can create different results. When Relic Hunting sites with a lot of rusty tin type trash, I prefer to use the Racer 2, CoRe and Relic in their 3-Tone Discriminate mode instead of any 2-Tone mode. This provide me a little better ability to hear a low-Tone before, after or both when I encounter challenging sheet metal, and remember, I hunt with a high Gain setting and a low Disc. setting that lets me hear ferrous junk in an area. When it gets bad like that, I also tend to use the Racer 2 or Relic because I can reduce the Iron Audio Volume.
Sorry for the delayed response but we've been dealing with bitter coil [size=small]
(it was -19° F last night)[/size] and a lot of snow. I just partially shoveled my driveway, but it tired this old phart out and I need a breather to finish. This was a 4" dump and I already shoveled 5" to 6" total earlier this afternoon in two trips outside.
Enjoy the Racer 2 as it is one of the best multi-purpose detectors out there today.
Monte