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How Ground Zone Corresponds with RT, ST Channels on AKA Metal Detectors

Discussion in 'Single Frequency AKA Metal Detector Discussions' started by SuchMuch, May 24, 2017.

  1. SuchMuch

    SuchMuch Detectorist

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    ice:
    ***qte***
    It seems to me, that ground zone is very narrow in AKA detectors or gradation of the zone is rough (few steps) and therefore problems with falsings, unstable behavior of metal detector and problems with GB shifting could occur.
    ***unqte***

    Vladi:
    ***qte***
    AKA metal detectors on a physical level (hardware) are just common VLF detectors (synchronous phase metal detectors) those do not differ from VLF detectors being produced by other manufacturers.

    Conversion slope (dU/dF) of synchronous phase detector depends on F by sinusoidal rule. This means it varies from zero to to the very maximum. Therefore metal detector precisely GBed over the ground (ground signal is assigned to zero) is not able to "detect" ground. This "blind" zone could be narrowed or widen by setting levels (RT, ST channels)
    ***unqte***

    SuchMuch Remark:
    Subject Vladi's post puts dispute whether ST or Gain should be kept on high (pls check thread "
    Gain vs ST (Sensitivity), RT (Threshold)") to the end. Keeping levels on high (that is equal to keeping RT, ST on low), we widen ground zone. As we know, deep signals being impacted greatly by ground signal are shifted very close to it. With wide ground zone deep stuff will just fall into the zone and will not be sounded by AKA metal detector.
    In case of conductive grounds levels could be set on high because "salt" (its vector is orthogonal to ground signal vector) will push signals up from ground zone. Thus deep signals will be pushed up into sector of deep copper whilst falsings will be kept in ground zone
     
  2. Sam Massingham

    Sam Massingham AKA Sectarian

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    Thank you for your work on this, SuchMuch. We have had a few false moments of clarity in the past. But this seems like a more solid position.

    I am capable of testing my own preferences for ST/RT and gain, but......

    I mostly use my Signum (mft 1.0) on light grounds (around 0010-0040) Mainly pasture but some crop fields too. The fields are not trashy although they usually have some iron and scrap lead, maybe drinks cans, shotgun cartridges, small pieces of scrap bronze/brass, the usual junk. The good targets could be any depth and anything from small relics (usually clothing related, buckles, brooches, buttons etc) to silver hammered coins (likely to be less deep), to small milled silver coins, to bigger silver and copper coins. (I never aim to find modern coins or jewellery but they are a nice bonus sometimes)

    I use the 2F 9.5x12.5 6/14khz coil mostly at 14khz. I have owned and tried nearly every single AKA coil and this is the one (at 14khz) I use most for typical English conditions/targets as described above. I go down to 6khz sometimes but not often. I also have the 6x10 20khz coil for specialist sites/conditions.

    With the 14khz I would usually use something like this:

    ST 8
    RT 6
    Gain 4-5
    Econ. Off
    MM sounds

    I know it depends on the precise conditions on the day, but as a general rule, with the new confirmations in the translation above, for the same coil and ground/target type, should I instead be using something like:

    ST 11 (14 is max ST on the Signum)
    RT 9 (9 is max RT on the Signum)
    Gain low enough for no or only a little falling maybe 3, 2 or even 1
    Econ. Off (extra question = on the ground/target types I described, should I put Econ on, so I can raise gain?)

    Like I said, I can play with settings myself and I know it depends on the precise conditions on the day in the field etc.

    But with the new information in the translations, I would like to know other people's ideas for some general "rules" or "baseline settings" if possible.... Thanks.
     
  3. TS
    TS
    SuchMuch

    SuchMuch Detectorist

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    Top AKA tester (Zemleroyk) never lows ST down less than 11 even on trashy sites, he keeps ST higher than 11 on clean sites. ST could be set even on 14, but swinging should be slow and accurate.

    As to keeping RT less / equal / higher than ST, I cannot give an exact advice for Signum since I never hunted with the Sig. Try keeping RT equal to ST at least, increase RT step by step until RT starts to false. For S-Pro RT set on 2 points lower than ST makes them (RT and ST) equal in sensitivity (no falsings on both channels).

    Economy Mode, switching it on could be useful on light grounds when ground is conductive (after heavy rain lasted for a long time / spring time). With economy mode switched on detectorist can compensate light depth loose with adding more Gain. Light grounds (GS signal 00...40 indicates yr grounds are extra light/light) requires no economy switched on, pls check thread "Economy Mode and Low Conductors"
     
    Last edited: May 25, 2017
    Sam Massingham likes this.
  4. mschmahl

    mschmahl "AKA Deutschland" Group Moderator Staff Member Supporter

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    I use the signum also. I would go with these settings:

    ST on 14 (max)
    RT on 9 (max)
    Eco on
    Gain between 5-7

    This setting could be to noisy for 14 kHz, than I would lower RT to 8 or 7 and if necessary ST to 13 or 12.
    But with 6 kHz the above settings should work. Maybe you can raise gain a bit more.
     
    Sam Massingham likes this.

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