F75 LTD - Determining a Falsing Signal

Just to make sure I am not aware of a technique to determine if a signal is a "falsing" signal here is what I know to do.

1. Go to pinpoint mode and, if the pinpoint location doesn't agree with the discriminate mode tone location, the signal is likely a false.

2. If, after narrowing down (detuning) as much as possible in pinpoint mode, you can't get separation (tone drop out) between an adjacent target and the signal under investigation, the signal is likely a false.

Both my stock 11x6 DD and 5" DD coils false off the edges with very sweet tones quite often. Simply relying on a good 4 way repeat is too likely to result in missing a good target that is partially masked from one or more directions.

Any advice on techniques to determine "falsing" signals, other than those mentioned above, would be much appreciated.

Have you tried using the all metal mode to work the suspected signal? All metal sometimes allow you to determine if it's two closely spaced ferrous/non-ferrous targets or a single piece of iron. I use it quite often with the Omega and find it a big help after doing some digging and learning.

Tom

Thats a tuff one for me to dgc. I run into that on every hunt. I mainly look for old coins,old buttons etc. I always try to run the F-75 on 0 discrim, 4 tones sens on 85 and up. Ground ball around here is on average about 62. I basically do the same thing you do but it's never an exact determination. Like Jackpine says, I will switch to AM for another vote to dig or not, reading the numbers.

On one hunt I got a low grunt followed by a sweet high tone, followed by another low grunt in one sweep, and the same on the back sweep. The lows were about 16 inches apart with the high in the middle. I thought there might be something good between two pieces of iron. I circled and still got grunts and highs. Could only pinpoint on the outer targets so I dug only the one,pulled out a piece of iron, scaned the plug, nothing, filled the hole and swept the coil over the spot and the high tone was gone but the other undug low grunt was still there so I moved on.
The falsing does slow you down a bit because you have to stop and zero in to see if it's a false or not. The stock coil does read falsely off the sides hence the name. I don't know why they do that & if someone would explain why the supposed narrow footprint of the F-75 stock coil does that I would like to know. I know that the strongest or sweatspot of that particular coil is down the center from front to back of the coil, but I'm guessing the weaker send & recieve are off to the sides. Why do they give false high tones?? Please don't tell me to turn down the sensitivity, I refuse. I need to know Tom.



Edited 1 time(s). Last edit at 04/13/2010 01:48PM by ozzie.

AM does what you're looking for better, faster, easier. No chance of hitting the PP button near the masking target which will null the good one.....no need to retune in order to detune the over all size and in fact hearing that size in AM is very useful in figuring out what is probably below your coil. If you're using one of the high freq FT detectors, you can also adjust your AM sensitivity to be optimized for sizing and pinpointing instead of hunting.

If only the time to create another DVD.

For decades......iron has ALWAYS falsed on detectors. The least-likely to false units were.....the older/no discrim units of yesteryear. They still falsed on iron.....but with better resolve. Yes, setting todays detectors to AM mode achieves the same results.

If you are in Discrim/ID mode......and are in a fairly trashy area......you should 'nearly' never use the Pinpoint feature. And if you are in this exact config......and you ARE using ANY amount of Discrim......you should 'NEVER' use the PP feature. It's inevitable that the coil will be placed over a Discrim'd target when you invoke the pinpoint (detuning the detector).....and you may never hear the intended target. Or...EVEN WORSE......you invoke the pinpoint feature......and bring your coil over a multi-mass of targets (UNKNOWINGLY....because some of them are Disc'd out).....and the detector does not pinpoint over the correct target AND LOCATION.....and you choose to NOT recover the correct target. The intended target may pinpoint weaker than the multi-mass of targets underneath the coil; subsequently placing the pinpoint location at the strongest signal strength location....which is NOT where the intended target is located.

Confused yet??????????

So Tom are you saying dig where you hear the good signal in Disc and forget the PP?

I'm hunting a trashy 1700's homesite and had a number of these signals yesterday with the small coil on the LTD. I PP and the signal moves. Dig and forget PP?

I'm probably missing something here, I almost always use 0 discrim & 4 tone. Dozens of target tones coming thru the headphones dosen't bother me. I pinpoint only if I hear a good tone amongst the the bad...so before I pinpoint, if possible I'll narrow down the good tone with a shorter sweep then a couple inch wiggle, then pinpoint, dig that, then sweep again, if the good tone is gone after retrieving that target then I move on. In other words ... when I use pinpoint, I'm going to dig that target..when I sweep after retrieving that target and the good tone is still there, I'll repeat the procedure till there is no more diggable tones. If there is a better way, I need to know.
Will you explain "de-tune" & re-tune, thanks.

I'll add when the signal moves in PP it is no longer a good target it reads as iron. Is there a good target there I miss in PP that is being masked by adjacent iron that over powers in PP? It's always several inches or more away from the good target reading I initially get.

I had a lot of these readings so I'm hopeful these are good targets I've been missing through ignorance of how my machine works.

I'm using monotone and disc of 6.

Jackpine Wrote:
-------------------------------------------------------
> Have you tried using the all metal mode to work
> the suspected signal? All metal sometimes allow
> you to determine if it's two closely spaced
> ferrous/non-ferrous targets or a single piece of
> iron. I use it quite often with the Omega and
> find it a big help after doing some digging and
> learning.
>
> Tom

As obvious as going to AM mode to check the signal is, I'll have to admit I didn't think about it. So Tom (jackpine) am I correct that after switching to AM, you either should have no tone or a tone with a poor VID if the signal was a false to begin with?

Yes, dig where there is a good ID......which may not be congruent with where it pinpoints. THERE IS A LEARNING CURVE HERE. Yes, nails will 'false' to other tones other than the correct low-tone. Usually......in general.....the iron false is a high-tone. You MUST go through a learning curve as to which signals are a iron 'false'......and which are a good non-ferrous audio hit in between/amongst iron targets. It is quite difficult to explain (using words only) as to 'preamble' and 'postamble' (the key to which determines "success") audio 'sharpness' whilst detecting iron infested sites.

De-tune = When the coil is partially (or fully) over a piece of metal when the pinpoint mode is invoked.......causing the detector to (now) use this condition/signal-strength to establish it's "zero reference"; subsequently, dramatically reducing the detectors sensitivity to any other metal object thereafter...................and .......... any other target of LESSER signal strength...will go 'undetected/undetectable' whilst remaining in this 'level of detune' status. Releasing the pinpoint mode.......and trying again.........by invoking pinpoint mode again......but.......this time with the coil NOT near any metal objects.....and you will have much better success. XXXXXX IF YOU ARE USING SOME DISCRIMINATION......AND YOU BRING YOUR COIL OVER A PIECE OF 'DISCRIMINATED-OUT' METAL (you would never know it......because the detector is silent.....as this target is being discriminated)........THEN YOU INVOKE THE PINPOINT FEATURE....THIS IS WHERE PROBLEMS ENSUE! This is a VERY common 'operator-error'.

Thanks Tom. That really helps me. I tried it on my own today experimenting with what you just posted and dug 3 CW cuffs with very erratic signals using the small coil. Hope to be unearthing much more from here out. Thanks again.

Tom, are you saying it's best to invoke pinpointing in clean soil before going over the intended target (target just found & wanting to pinpoint)? And if you have some discrim set, while wanting to pinpoint over clean soil, the area may not be clean because a discrimed target may be below... so when you go back to the intended target the pinpoint may not be effective or is de-tuned.

Now I see why not using pinpoint may be a better/faster way to locate good targets amongst the junk. You would hear a good tone between the bad, determine at what point it is on the ground by matching the tone with the center of the coil, then dig a plug in that area, not using the pinpoint feature.
Can you re-tune in the air or does the coil have to be over clean ground?

Yes, you can invoke pinpoint in the air. I use this method occasionally. However, in time..... the Minelab Soverign 'wiggle'....whilst in the ID mode.......never invoking pinpoint.......is the best method ESPECIALLY in very trashy areas............,,,,,,,,,,,,,.............even over invoking pinpoint in open air. Don't forget, the Minelab Soverign is a DD coil also. This so-called 'wiggle' over a target is much more pronounced with DD style coils. You will begin to respect and appreciate the exceptionally tight footprint of the F75/T2 coils. So much so......that you may never use (or need) the pinpoint feature ever again.....AND.......will learn that the pinpoint feature in trashy areas......can be more of a hinderance!

NASA-Tom Wrote:
-------------------------------------------------------
> Yes, you can invoke pinpoint in the air. I use
> this method occasionally. However, in time.....
> the Minelab Soverign 'wiggle'....whilst in the ID
> mode.......never invoking pinpoint.......is the
> best method ESPECIALLY in very trashy
> areas............,,,,,,,,,,,,,.............even
> over invoking pinpoint in open air. Don't forget,
> the Minelab Soverign is a DD coil also. This
> so-called 'wiggle' over a target is much more
> pronounced with DD style coils. You will begin to
> respect and appreciate the exceptionally tight
> footprint of the F75/T2 coils. So much
> so......that you may never use (or need) the
> pinpoint feature ever again.....AND.......will
> learn that the pinpoint feature in trashy
> areas......can be more of a hinderance!


Thanks Tom for confirming the value of a tight wiggle over a suspected target. The F75 manual says "shoulder width" swings are best, but from what I have seen that just doesn't work well in heavy trash. I'll practice the wiggle next time out. I'm hunting an extremely iron infested old house site and need a good "signal isolation" technique.

dgc

I keep it kinda simple when using all metal to isolate a target next to trash/iron. By sweeping the coil over the suspected good signal from different directions it will usually show up. If the detector sees the iron first it may not signal on the good target. Sometimes the wiggle works but it's not always perfect, any time I'm not sure I dig. The main objective (to me) is eliminating digging as much iron as possible, it's more a matter of ID'ing falsing iron rather than isolating good targets... all metal does this best. Another thing... in instances like this I dig as wide a hole as possible or widen it 'underground' because very often under these types of co-locate conditions the good target is off to the side, not where you think it is. You probably all ready know this.. but before giving up on a target make sure you remove all the loose dirt from the bottom of the hole and DIG at least another couple inches more out of the bottom. If I did not do this I know for a FACT that I am leaving at least 50% of the good stuff at my pounded sites.

Tom



Edited 1 time(s). Last edit at 04/16/2010 10:22AM by Jackpine.

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