On my mind -- Random Thoughts

NASA-Tom Wrote:
-------------------------------------------------------

> I still question: fancy displays. A display only BECOMES useful...… when the audio has already locked up your brakes...… and you are probably going to
> dig...anyway. You MUST audibly FIND a target FIRST. THEN...…. (and only then) will you look at a fancy display. The thing is...……….
>
> AUDIO = Master
> DISPLAY = Slave
>

What about a hodograph or whatever it's called?

In due time...… we're going to see enhanced display presentations.
In-works.

What about a hodograph or whatever it's called?

The Rutus 71 I had used a hodograph. I really liked it. It gave another visual dimension ( Proper word?) of the target. .Certain targets would show a string of dots, another , a curved arc, etc.

NASA-Tom Wrote:
-------------------------------------------------------
> About every Decade...… I do a inventory RATIO coun
> t. 49 years of cumulative/collected/aggregate data
> reveals...…(in a nutshell):
>
> For every 5-1/2 silver dimes found..... a "other"
> silver coin is found.
> "Other" = Trimes, Half Dimes, Quarters, Half Dolla
> rs, Silver Dollars...…. and Reales of any denomina
> tion.
>
> If I were to compare: How many silver Dimes are fo
> und.... per silver Quarter...… the Dimes ratio is
> much higher.
>
> Sooooooo…….. moral of the story is...…… silver dim
> es are the MOST 'found' silver coin. It would beho
> ove Mfr's to have (at least one) program that very
> specifically targets resonant freq



We can make a multifrequency program that is low weighted, for example at the border around 5khz ... I know that even on Equinox, such a low weighted program was also tried .....but in the end he did not get into firmware..


Spectra V3's multifrequency with sensitivity to various conductive targets works very similarly up to 1F frequency 7.5 khz ..

Perhaps that is why he is not the king of unmasking in iron ...


when I tested the Equinox-11 "DD coil - on a 5 gram 23mm silver coin..on Monte Nailboard performance test ..
Park2 program setting, recovery speed 6, iron bias F2 to-4 ... sens 20 ...


So Equinox on: ...

1F 5khz Gained only 2.5 points out of 8 points max ..

1.F 10khz gained 4-4.5 points with 8 points max ..

1F 15khz gained 5.5-6 points out of 8 max ... what I consider also the standard of separation

At frequencies of 1F 20khz and 1F 40 khz it was even better ...



Edited 5 time(s). Last edit at 06/23/2020 08:17PM by EL NINO.

possum mo Wrote:
-------------------------------------------------------
> What about a hodograph or whatever it's called?
>
> The Rutus 71 I had used a hodograph. I really lik
> ed it. It gave another visual dimension ( Prop
> er word?) of the target. .Certain targets would
> show a string of dots, another , a curved arc, etc
> .

That's what I'm talking about! So could you tell a jagged piece of trash over a coin or relic?

Cal, I no longer have it, so I don't remember all the examples. I was a coin hunter, not into relics.
Iron produced a lot of weird designs, where as a coin was usually a single line from bottom to top.
A deep coin would make a tiny short line, a shallower coin a taller line. I was able to pick out rings very well
from amongst aluminum tabs and trash. It had 120 points of VDI , ring IDs were tight, pulltab rings bounced a tiny bit.
I got fooled once in a while by a square tab.
I never really had the time to spend learning all the settings, so I ended up choosing a more turn on and go
style of detector.
That thing was also very deep. In deep mode, single audio tone, it would hit a $5 gold piece freshly buried in
fresh water beach sand at 17". Too deep for the hodograph to register, but good audio.
That was about 5 years ago. I know Rutus has come out with simpler to use machines since.

A few days ago....... I had a video conference with a prominent individual. At the end of the conversation...... what ensued was: You really should share this data with the public.

The question was: "Who do you think has the capabilities of advancing PI technology?"

My answer/response: Dimitar, Minelab and Eric Foster.
Eric Foster: Stand-alone
Dimitar: Stand-alone
Minelab: Collectively; as a body/team-effort.

I also feel the AQ is 98%......... with only a few bugs to be worked out. Politics, organizational management & foresight: inhibit. (And de-incentivize). They are SO close........ and don't know it.

possum mo Wrote:
-------------------------------------------------------
> Cal, I no longer have it, so I don't remember all
> the examples. I was a coin hunter, not into relics
> .
> Iron produced a lot of weird designs, where as a c
> oin was usually a single line from bottom to top.
> A deep coin would make a tiny short line, a shallo
> wer coin a taller line. I was able to pick out ri
> ngs very well
> from amongst aluminum tabs and trash. It had 120 p
> oints of VDI , ring IDs were tight, pulltab rings
> bounced a tiny bit.
> I got fooled once in a while by a square tab.
> I never really had the time to spend learning al
> l the settings, so I ended up choosing a more turn
> on and go
> style of detector.
> That thing was also very deep. In deep mode, singl
> e audio tone, it would hit a $5 gold piece freshly
> buried in
> fresh water beach sand at 17". Too deep for the h
> odograph to register, but good audio.
> That was about 5 years ago. I know Rutus has come
> out with simpler to use machines since.


The Rutus 71 was a cracking machine, awesome in iron. I've been keeping my eyes peeled for a 2nd hand one.

ghound Wrote:

> The Rutus 71 was a cracking machine, awesome in ir
> on. I've been keeping my eyes peeled for a 2nd han
> d one.

Kevin at Staffs detectors has one in at the moment

[staffsmetaldetectorsonlineshop.co.uk]

Hi Tom and Fellow Forum Members,

What is depth? In Arizona we rely on having little ones...coils that is. And yes older machines are making a comeback. I recently purchased an XLT that came with the black max 5.3 coil (still looking for the 4" & 8" coils). That was the machine I first learned over 25 years ago, and have a lot to relearn. Other machines in my arsenal are: F75 with all the small coils, F44 again with the small coils, Gold Bug Pro, CZ21 8" coil, two original Bandidos (one purchased from Monte) and an Original Bandido II. So for us depth is target separation. The micro-jewelry aspect of threads is too finite for me. In Arizona we hunt old lots (coins, tokens, occasionally jewelry), ghost towns/mining camps (coins & tokens), logging camps (coins, railroad locks). I don't recall glean too much from the anecdotal aspects of some posts doing comparison wrestling, it's like those horrible political ads where somebody is saying politician X did this to me. Phoenix is in the Salt River Valley, our soil is nasty, mix in old school fertilizers and the ground on our downtown lots is hot. Usually the ground balance numbers are in the high 80s. A deep coin or token is 5-6".
Many of our ghost towns and mining camps are the same, adding in thousands of food cans, square nails etc. Logging camps in Coconino County are a different challenge, forget ground balancing a concentric coil in that volcanic dirt. Recovery speed is the key for me. On the F75 I will constantly change setting while hunting my disc is 6-10, sens 15-17, not only is the ground hot the EMI is bananas. I guess what I'm saying is there's a lot of of apples to oranges stuff in here...but we got pears! Somewhere I have a box with a lot of printed out XLT programs, Monte's Quick Out and Edge Pass Rejection tips, going old school baby!My strength as a detectorist is employing ideas from other hunters, oh and ground balancing every ten minutes...the drift is real. And as my buddy Lake Washington Steve says "Only the beach replenishes
."

Safe Digging

Jeff

Jeff........ I have hunted those conditions a few times. It is a TOTALLY different world..... as compared to Florida. Mega-educational. The biggest take-away was..... trying to get the detector to be reduced to: modestly violent reactivity to the dirt.....compounded with rusted flat tin .....topped with square-nails. A few inches of depth coupled with simply 'ferrous' or 'non-ferrous' ID was the primary target of intent. Sometimes THAT was difficult to ascertain.
Serious eye-opener.

Worth mentioning again =

A small fleck/flake of rust......say: about the size of your pinky fingernail.........,,,,,,,,,,,.......... is a fairly small target to a 11" coil. But.......... to a 6" coil........that same sized fleck/flake of rust is fairly formidable/large in size. (((Food-for-thought))).

As long as the nails/small Iron trash are not right at surface to a few inches, swamping the coil, I have always done well with a stock or even larger size coil that separates well. I probably should remember to just raise the coil at times but I'm a invertebrate scrubber.

Chris

Reiteration/reaffirmation: A few days ago....I was headed towards a specific hunt-site; but, incurred a unsuspecting in-flight-course-correction. I passed by a good (previous) hunting site whereby........ the electric company was removing a transformer.....,,,,,,......and had the local sub-station powered down.......that was directly across the street of the hunt site. I locked up the brakes...... and hit this old site.,.,.,., hard! The site (about 4 years ago).....stopped producing any coins. I clearly remember a 'medium' amount of EMI...... and the deepest coin found was 7" deep. With the sub-station powered down..... EMI was of a 'low' level. 41 more coins were found! All were found in the 6-1/2" - 10" depth range!

Moral-of-the-story = Changing local EMI conditions...... can open-up,,,or,,,shut-down old sites.

NASA-Tom -- stunning. No WONDER you are so focused on EMI mitigation in many of your more recent posts...

Steve

(((Steve..........to the point of a sickness.,.,.,.,with sleepless nights))).

Dang Tom, those are stunning results and a memo for us to put away for the future. Question for you - were they older coins or a mix of newer and older coins at mixed (deeper) depths. Just wondering how disturbed the soil was. TIA



Edited 1 time(s). Last edit at 09/12/2021 11:09AM by Gary in Daytona.

Gary......... nearly all of the coins were modern clad......except for 6 coins that came up at nearly exactly 10" deep. These coins (the best that I could extrapolate)....... were dropped around 1967. As follows: 1966, 1961, 1959, 1959 Memorial pennies........1953D wheat penny........ and a 1963 silver Rosie! (Sandbar Florida sink-rate: sucks!)
On 5 (of the 6) deep coins....... I did one simple test. I switched from one silent EMI Noise Cancel channel...... to another quiet/silent Noise Cancel channel....... and completely lost detection of 2 (of the 5) tested coins! When I switched the Noise Cancel channel....to a channel that presented just a little bit of audible EMI...... ALL 5 of the tested coins....were completely undetectable!

Most Mfr's place considerable amounts of engineering/time/labor/effort on increasing sensitivity, boosting power, greater depth.................................................when....................................... the real answer is in atmospheric EMI ridding (or mitigation).

....... the real answer is in atmospheric EMI ridding (or mitigation).

Yes, Agreed. My first trip to VA to hunt for relics was an area mostly under hi voltage power lines, and I might as well have been swinging a stick, I didn’t find ANYTHING that trip, It’s staggering to know that being off ‘channel’ just a bit on the Nox for EMI affects the detectability of those (and many other) coins. I admit I’ve never tried adjusting the channel much, but shudder at how many nice silver coins I may have walked over largely ignoring the EMI in the area I was in (after noise canceling). Definitely give it a little more thought in the future. I remember your excellent article on target masking, it was not only great in explaining it, but best ways to deal with it. Did you ever do anything similar to that regarding EMI?

Thanks Tom.

NASA-Tom Wrote:
-------------------------------------------------------
> Worth mentioning again =
>
> A small fleck/flake of rust......say: about the si
> ze of your pinky fingernail.........,,,,,,,,,,,...
> ....... is a fairly small target to a 11" coil. Bu
> t.......... to a 6" coil........that same sized fl
> eck/flake of rust is fairly formidable/large in si
> ze. (((Food-for-thought))).


I took NASA Tom's random thought and put it in action Sunday evening. I took the Vista X with the 12X14 Demon coil to the site I dug the curtain rod ring out of the nails in with the MDT. Hunted around the less nail contaminated areas first, then moved into the heavy nails. I dug a few more non ferrous targets even in the heavier nails. This is an impressive coil & detector. I did also dig a good many small, thin nails that were deep. the bigger/shallower iron is easy to tell. On a thinned out site that is what I expect to be the price to find any deep good targets that are still to be found. This was a good learning exercise. Make use of all your tools that are available.

Chris

Gary........ it is not just the Equinox that can incur EMI. The T2/F75 platform(s) expressed the MOST EMI of all detectors. These are very hyper high-gain units that can easily be plagued with EMI. The CZ platform was one of the (if not THE) lowest EMI-plagued platforms out there. However; just because you could not hear EMI in a CZ....... did NOT mean that it was unaffected. In fact....... the CZ was most prone to 'silent EMI' whereby....... you could not hear it; yet, depth would suffer.,.,.,.,.,.,., unknowingly. Unsuspectingly.

I am unable to discuss much about current intents of EMI ridding (or mitigation thereof); yet, rest assured....... things are happening.

Kind of like noise cancelling headphones?

…I am unable to discuss much about current intents of EMI ridding (or mitigation thereof); yet, rest assured....... things are happening.

That sounds promising. Looking forward to hearing about it when it is announced.

Could there be a way to synchronize EMI with the detector or the detector to the EMI .. thus using it as an advantage, a sort of power boost .. or allowing the detector to tune out that synchronization

Beroxy ...... yes.,.,.,., yet, it's a bit more advanced than Noise Cancelling headphones. NC headphones will cancel what IS there (as noise). But....... in the detecting world...... the intent is to 'shift' operating frequency(s)..... so as to operate outside the EMI freq's. . . . . . so it does not need to be 'canceled'.

ScoTTT2....... Because of the random/asymmetrical signature of EMI....... it is impossible to electrically 'capture' and convert to usable energy. (((However...... the conductivity of saltwater can be captured/used to conduct EM energy generated from the source {coil}..... and "advance" detection))).

I still ise a Nautilus 2b detector for Civil War relic hunting. It's the Harley Davidson of metal detectors. By that I mean its an old design, hand made, not pretty......but the results are staggering. With the 10 inch coil I can easily dig bullets at 12 inches. This used to be the detector of choice for hard core relic hunters in the south.

I still have a heart/place for the DMC-2b! It 'set-the-pace' for a couple of Decades.

On another note: I've gotten carried away.....again.,.,.,.,.,.,., with Beating-a-Dead-Horse to a newer/higher order-of-magnitude. All related to EMI. ((EQX-800...... Park Mode-1)). For Decades ...... on multiple hunts/occasions. , . , . , . , . , . a long-since 'dead' site.....would "suddenly" produce. I've had plenty of suspicion/hunch/gut....... but genuinely needing scientific data for the big: "why" question. This past weekend....... I went to a 'dead' site.....and hunted it the old-fashioned way. After about 2-1/4 hours of hunting; yep. It's dead. Sparing the details...... I spent about 18-minutes manually finding the best EMI Noise Cancel Channel. Within a few minutes...... I found a 100+ year old penny (1919 Wheat). BEFORE I DUG....... I had a plethora/battery of tests to perform. First..... I jumped the Noise Cancel Channel 'up' one-increment. Penny was no longer detectable. I lowered the Noise Cancel Channel one-increment. Again..... penny was no longer detectable. (Those two Noise Cancel channels were indeed...a bit more EMI 'chatty'). Soooooo............ I found another 'like item' Noise Cancel Channel..... that was ALSO very 'quiet'. Penny still remained undetectable. Hmmmmmmmmm. "Silent EMI" in full play! AND..... demonstratable! I then tried ALL of the Noise Cancel Channels....... to see: go/no-go. Dig/no-dig. There were 2 acceptable channels that allowed detection of the penny. The original channel that the coin was found.......and another channel that (for some crazy/curious reason) expressed a mild amount of EMI; yet, did indeed detect the penny .... fairly clearly (audibly). I then switched the unit back to the original (best) Noise Cancel Channel....... and could clearly detect the penny..... to include up to (but not beyond) about a 1-1/4" air-gap above the ground. THEN......... I switched over to Field Mode-2....... for more data-collection. The same Noise Cancel Channel for Field Mode-2.... did not produce the same resultant. But...... I did find one (and only one) Noise Cancel Channel that did detect the penny in Field Mode-2. Then...... all of a sudden...... the quietist Noise Cancel Channel.....suddenly became a chatter-box. Nothing in Field Mode-2 would ever detect the penny again. I switched back over to Park Mode-1...... only to find the original 'best channel' would no longer detect the penny. The 2nd 'acceptable' Noise Cancel Channel still worked. I then played/tested Target Recovery Response speed, Iron Bias settings.....Ground Balance settings. Then....... whilst in the middle of testing different Ground Balance settings...... something happened...... and the penny was gone. No longer detectable under any circumstance. Some pump, A/C unit, motor, electrical load.......,,,,,,,,,........ something kicked 'on' and caused just enough EMI to NEVER detect the penny again. Good thing I had the exact pinpoint location marked...... and had 'certainty' to dig-and-recover (with pinpointer)...... the penny.
I hunted for another 1-1/4 hours...... in an exercise of futility. No more coins/targets found. I then went to lunch..... and came back 50-minutes later. Park Mode-1...... and a completely different Noise Cancel channel.... worked! The EMI noise-generating source..... had secured. I found 27 more 'curious/suspicious' targets....... and tested/played with each one...... for about 8-11 minutes each.

Summational closure: Many times (unsuspectingly)....... EMI can be FATAL.

Ground tracking which has been around for decades.......now we need emi tracking. Yeah we talked about it before. A detector that changes frequencies or offsets frequencies in the background while we hunt. An automatic mitigation capable of keeping up with an ever changing situation. We have all been noise canceling for decades as well. A snapshot in time that is worthless a few minutes later. From 4 to 40 kHz. A single coil can do the entire range. Let the detector and automation do the work and maximize depth.



Edited 1 time(s). Last edit at 09/21/2021 01:00AM by goodmore.

NASA-Tom,

Wow. I am literally shocked at your results here. Truly amazing.

Question -- when you say you are using "the best" noise-cancel channel, I assume you are using the procedure you have outlined before, where at the start of your hunt, you "air test" a coin, at the site you are hunting, on each of the available channels, and then choose the noise-cancel channel that allows you to ascertain the greatest air-test distance as your "hunt channel?"

Steve

Am I correct to assume that simultaneous multi frequency is more susceptible to EMI than a single frequency?

Chris