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Better Understanding GPZ 7000 Zero Voltage Transmission ( ZVT )


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10 hours ago, DDancer said:

.........I really don't know if its a variance of machine~ mine is a pre-production one, machine set up~ I use the stock headphones~ or our native hearing.  Then there is the good old comfort zone.  Higher thresholds do cut back signal recognition for me as well.  Note that JP refers to the ground stutter he recognizes with his set ups~ for me with smoothing on and lower thresholds I hear similar patterns.  With smoothing off its just more recognizable but harder for me to process as the noise environment increases dramatically.

JP points out the interaction between three of the 4 settings I mess with most but does not address Volume Limit.  While he is speaking of the 19 inch coil similar methodology appears to be being used for increases in target recognition I feel that occurs regardless of the coil size.  ZVT is reading a window of noise where sensitivity falls behind volume and threshold limits that improve target recognition.

Thanks JP and sorry if you or anyone else feels I'm taking you out of context.

 

Audio Smoothing is a Filter, so once applied a target response or even threshold variation needs to break through the filter to be heard, problem is the Filter is digital in nature and steppy, meaning the break through stutters interfering with target info, whereas with Audio Smoothing OFF the full information is able to be heard. I always adjust my audio volume to suit the information provided, this means having a smooth stable threshold with the Volume controls set conservatively. The main aim is to be able to hear the threshold through my speakers over intrusive sounds in the environment but at the same time allowing as much space in the volume train for target information to to expand fully between threshold and max volume. The greater the range the more information is available in the audio. If I was using headphones I would be tweaking my Volume settings to suit.

The bulk of my large finds at depth have been signal responses that you could not call a target signal, I'm listening for a disturbance in the surface tension of the threshold, something that is repeatable and different to the general ground signal in the immediate area. This information can be played with so long as you do not allow the GB to drift off through repeated passing of the coil (I configure the USER button to the GB control). In Auto mode I recenter the GB nearby on typical ground indicative of the ground associated with the target signal (usually 2 coils widths or more away), by pumping the coil up and down just above saturation point. All of this is typical of a DOD or Super D coil which is down to the dual receive points. 

I should also point out that if people knew how much outright depth was being lost when applying Audio Smoothing they would not go near it. One of the main advantages of the GPZ is the ability to run the noise floor at Zero, I strongly suggest operators train their ears and brains to running Audio Smoothing on OFF, this is the reason why I recommend using conservative Volume and Sensitivity settings so I can retain the integrity of the Audio Smoothing OFF, there is no setting on the GPZ 7000 more important especially if you want to maximize your depth potential.

JP

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Yeah I feel the same way about audio smoothing, it was on when I first got the machine and since then it has been off and use sensitivity and threshold if too chattery. I love the Z for the information it is able to give you when detecting, when the ground changes it changes but also continues to give you feedback.  I have dug many deep targets this year with nothing but a pause in the threshold and by pause I mean something in the threshold that has stopped me and even after scraping the ground no real audiable signal, it is just the Z telling you something.  It was actually chasing $1 and $2 coins in the parks that has made me a better Z user as going slow and covering the ground produces more dollars and coil control and sweep speed has a huge impact when it comes to what information the Z can tell you on those really deep targets.    

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I expect there is a difference in the way one uses the 14 verses the 19.  *shrugs*  To be expected.  Variance of performance due to coil change out occurs with all detectors.  I do not intend to get a 19 but if the opportunity arose I would try one out.  With that said I would hope that does not disqualify my observations.  The 14 is plenty hot on the Zed for me with my largest find at 32 inches at one ounce and a heap of smaller stuff in extremely well pounded ground.

I do understand and respect JP's, and others, position on the use of the Smoothing Filter.  I am very aware that it is a filter and as such there is a trade off.  Hehh :) If I'm missing much well good for the next guy however I don't expect that I am.  Would a 19 inch allow me to keep the filter turned off?  Don't know but mayhap one day I'll find out. 

No excuse but while trying to train my hearing without this filter last year~ and I did~ I ran into the same problem I have with my normal hearing.  I find it almost impossible to understand a person speaking to me from more than 2 feet away when there is high ambient noise or white noise.  But strangely at night I can hear bats chirp at the camp fire.  Further more I found that I had to dull the Zed down so much that I was missing quite a bit of small stuff.  My partner last year amply proved it as he ran extremely hot settings and no smoothing.  The man has years more experience detecting and his hearing, and ability to train it, is much better.  So for me using the filter led me to the settings that I use and observations that I have made here as well as allowing me to come on par with my partner in many respects last year.  No excuses here just to each his own I reckon as it appears Norvic, for one, has great results without smoothing but similar settings.  I do explain audio smoothing to the few I have instructed on the use of their Zeds and it includes the caveat :  This is a filter try to use the machine without it on.

Breaks in my threshold give me pause as well and often with good result.  Breaks in threshold are something most anyone who has been detecting for years will appreciate regardless of the type of machine used.  I wont say I get the breaks you are JP however when they occur I look into them just like you do ;).  I do not qualify myself as a professional~ just an experienced Joe Shmoe  who enjoys a good prospect and sharing with like minded people.

Understanding ZVT seems to boil down to effective utilization of your comment JP:

18 hours ago, Jonathan Porter said:

One of the main advantages of the GPZ is the ability to run the noise floor at Zero,

In PI's its timing and sensitivity.  In ZVT its about the noise.  Yes? No?

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Makes good sense to me JP.  I am not mistaking your passion nor your advice/instruction or the why's.  I witnessed it, the passion, first hand many years ago in Stanton AZ and have never forgotten.  I'm the same way in my own profession in aviation so your professionalism, and that of others, are understood and appreciated as are your approaches to the technical details.  I do thank you for the debate and your views. Knowledge is indeed power.  Hahh!

I have used what has been given here and given it a Good Go.  So what I'm giving back is just my return on all of our members advise and instruction.  Pay back if you will.  If I seem argumentative its only in a good way as I see it as debate and really am not looking to win anything but knowledge.

This year I put the Zed in with the 2300 myself thinking it would be a good combination. Though its comparing apples to oranges I ended up reselling the 2300 as I found that there was very little that I could do with the 2300 that I could not with the Zed.  If ML can ever make a smaller coil, something I'm doubting can be done *kind or like the Garret GTI never being able to come up with a imaging coil smaller than 8 inches*,  we will all be talking about another set of tweaks to get the most out of that coil as well.  Me I'm considering dragging the 3000 with the Joey and 11 DD back out of retirement for use as a pin pointer with the Zed.  That's about all the 2300 was really good for with me aside from being able to push into grass and bushes the 14 inch could not be worked in.

Settings aside I have to wonder on the subject of Pin Pointing which is probably the most irritating subject with the Zed in the field.  I wonder if it would be possible to get ML to make a Zed set up so that it could operate much like a PI in cancel/mono mode~ ie turn off one of the receive coils and operate similar in manner as is done with DD coils.  That function helped me so many times on deep stuff with my 3000 as to be a no brainer for the Zed.  Almost every picture I see of deep finds shows a PI in the background and that was so in my experience as well.  Having to call a mate over to figure out where the nugget is in the calcrete so we didn't have to blast a hole to find the nugget required a PI.  I could find no way to dull the Zed down enough to get accurate pin pointing.  You literally have to get the target out of the hole or trench as it were.  Funny enough you can tell a Zed hole from a PI hole very easily ;)

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OK, I`ve revisited a patch found with the Z 14", flogged with the Z and a 5000 with a new age 14" coil,(two of us) revisited it with the 19", spent 9 hours for ziltch with my hot settings I used with the14", went back this morn for a 3 hour detect with the 19" used JPs conservative settings and I`m stoked. Is the 19" worth its weight in gold, you bet.

Tis magic but this old fella is knackered, pick and crowbar holes in 45deg heat at 8 in the morn. Don`t feel sorry for me it was bloody magic, Thank You JP.

DDancer we may need to rethink our settings, especially volume, operating the Z at low noise may be more productive, certainly has shown to me to be so with the 19", reminds me a bit of the VLF hot or conservative debate days.

Pinpointing was no drama, dug directly over nuggets (coil centre), finished off digging them out last couple of " using pinpointer and pick point carefully.

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Do not take this wrong mate but your dealing apples and oranges messing the 14 with the 19 and I make no bones about it.  At that I'm going to point you back to the posts:  JP is speaking from experience with the 19 and I am most certainly not.  I have also intoned that there will be variance between the two coils just like any other machine.  No false thinking there mate.  As to pin pointing its a desire I have and something I think, remotely, that the Zed is capable of.  You dug a HOLE :)) and got the reward but it was a big arse Hole ;) *I'm betting*. Good on ya though!

edit: Great info though and again good on ya!

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