How many wish the SE also had a manual ground balance option???

[digitrich]

All and all I 'd say the auto ground balance seems to work seamlessly. ML is very secretive about their auto ground balance which is, from what I read, MAYBE tied in also with the noise cancel function in mysterious ways .I don't know if the harmonics effect how the machine reacts to the ground mineralization, after all you noise cancel with the coil a foot off the ground, so I don't see the relation there. However, when the soil gets saturated during extremely wet periods and the machine starts falsing like a lying, cheating ex-wife/hooker, one has to pause and wonder if there would be a benefit of a manual ground balance option??? Or maybe at least a way of setting the tracking slower or faster like their GP machines. Because if the ground balance is truly automatic, isn't it tracking at a fixed speed? Ever rub out a likely target and wonder if the machine tracked it out? I know I have. Many who have older Explorers would complain of that as well, but they seem to have improved that on the SE version. In extreme areas, I think a manual ground balance function would be useful. Just like at certain times auto sensitivity can be useful. I guess for a newbie, the more auto the machine is the better, but for allot of guys like myself, the option of squeezing another drop out of the machine's performance to function better in a specific situation would be cool. Don't get me wrong, the options on the SE are awesome, but a part of me will always wonder if I could set or play with the ground balance setting manually, could I maybe find more or get another inch deeper on ID and turn a couple of those iron grunts into a few more silver coins??? Anybody else ever wish that?

 

[Captain Kirk]

The signal analysis the Explorers is completely different from that of VLF detectors.

HH,
Glenn

 

[Tom_in_CA]

I agree with Captain Kirk. There is something intrinsically different about the way the Explorer works, when compared to the regular VLF discriminators you are alluding to. Yes, there is a benefit to being able to "stop on the target" in VLF pinpoint mode (fixed and/or manual ground balance), but I don't think that's possible for the Exp, Sov, etc.... They are just a different beast. But I'm not sure that's a bad thing, because whatever "multiple frequency" analyze stuff makes the Exp and Sov have the characteristics it has (non manual GB), it apparently makes for overall more depth. So while I miss the days of having a ground balance I could tweek, and an all-metal mode that I could stop on top of targets, yet I prefer the depth that the Exp. has given me. I guess it's just a trade-off.

 

[SNOWY]

Digitrich, as Captain Kirk says, ~ the Explorers measure the ground differently...

And to quote Tom in CA states; ( in part.) "whatever "multiple frequency" analyze stuff makes the Exp and Sov have the characteristics it has (non manual GB), it apparently makes for overall more depth. So while I miss the days of having a ground balance I could tweek, and an all-metal mode that I could stop on top of targets, yet I prefer the depth that the Exp. has given me."

I would think that any detector that transmits 28 frequencies at once would be a nightmare to manually ground balance !!!

Nope ~ I'm very happy to leave ground compensation to my Explorer.

Our Explorers perform so well, while at the same moment, automatically compensating out the ground effect !

IMHO it just doesn't get better than that !

# Digitrich ~ good question you posed !

 

[digitrich]

So then the Explorers are not auto ground balancing as much as ignoring the ground mineralization by constantly comparing the different results of the multiple frequencies? Kind of like a PI, but to a slower degree?

 

[SNOWY]

Digitrich, this is what Minelab have to say about the Explorer ground balancing issue...

If the link works !

http://www.minelab.com/consumer/page.php?section=272&pId=5&pNm=Explorer%20SE&x=y

In particular

"Ground balancing is automatic with Minelab's advanced digital filtering.
Whatever field conditions you encounter, from dry clay to wet black sand or rich loam, Minelab will find what you're looking for."

 

[digitrich]

They are basically handling the mineralisation with digital filtering and mathematics.

 

[SNOWY]

I guess that's the sort of approach they use Digitrich...

A bit outa this little black duck's depth !!!

 

[Captain Kirk]

It is my opinion that the concept of multiple frequencies is somewhat of a marketing ploy. This concept is not well understood and does not need to be understood by the user.

A SIMPLIFIED EXPLANATION BASED UPON MY LIMITED UNDERSTANDING

Single frequency detectors:generally examine the phase relationship between the transmit and receive signals.

BBS detectors use rectangular shaped excitation pulses (fundamental frequency plus harmonics produce multiple frequencies). The electronics examines the waveshape of the received signal while continuing to stimulate the target matrix..

PI detectors generally transmit a high energy pulse (similar to radar) and shut off. After shutting off the excitation pulse, the detectors examines the "echo" caused by circulating eddy currents in the target. The process is repeated at a high repetition rate.

HH,Glenn

 

[digitrich]

Thanks Glenn, I read Bruce Candy's white paper yesterday. I now understand how the machine is subtracting the ground signal from the equation. I just wish I could pause that math long enough to stop the machine from tracking out the iffys.

 

[digitrich]

I just wish you could pause the tracking because if you have a target that is weak and collocated with trash, if you take too long to try and isolate it, sometimes it can track out and disappear. If you throw a dime on the ground and pass your coil over the dime and then go back to your collocated target it reappears!! Most of the time the collocated target is iron falsing. However, sometimes it is a nice find. If on the first pass, the high tone sounds "scratchy, it's usually iron, if it sounds "screechy", it is usually a hot rock. If on that same first pass the tone sounds "solid" or "clean" it is usually a quality target just being masked by iron even if it doesn't repeat and slowly tracks out and disappears. That's why I wish I could pause the tracking (auto ground balance) because that would give us a longer time to make the dig or not to dig decision. Some people say "dig em all, your shovel is your best discriminator". And that's a righteous statement. Better would be to be able to dig the high percentage ones only. In some of these farm fields I might run across 40 of these types of signals an hour, so digging them all would put a serious dent in the square area I need to cover in a hunt to truly go home with some keepers. Most days, I walk an hour between coins, yeah, they are quality finds, but they are one hour of swinging apart from one another. So whenever you have a target track out, just run your coil over another target and the target that tracked out will reappear and give you another shot at isolating it, but be quick because the machine will track it out again and the whole time the iron is becoming more magnetised with each pass and it's signal is growing stronger and going to wash out your silver completely.

 

[Gyur666]

It is really. I have same experience. And...
I cut original cable and I extended it with SVHS cable. I tried more types of SVHS cable and it worked differently. Some cable made ground effect, and changed the depth and gain. Not in air, but in ground!
When I tried 15"coil, that was more contrast with different cables. The 15" coiltech coil work fine only without extension cable. So I think, perhaps an phase shifter would by useful in the first part of circuit.

 

[stasys]

It is really. I have same experience. And...
I cut original cable and I extended it with SVHS cable. I tried more types of SVHS cable and it worked differently. Some cable made ground effect, and changed the depth and gain. Not in air, but in ground!
When I tried 15"coil, that was more contrast with different cables. The 15" coiltech coil work fine only without extension cable. So I think, perhaps an phase shifter would by useful in the first part of circuit.

Gyur 666 your problem is just because your cables is to thin, use two separate coax cables and you will not get any problems.


digitrich your ideas is very right, but explorers is very old now, we can ask the same question why in etrac is no manual ground balance, but in CTX are. I think its more related to marketing and business when to making perfect products from first.

 

[hartage]

Glenn, we are both in the same boat as having limited understanding but if I may elaborate on the PI.

PI detectors generally transmit a high energy pulse (similar to radar) and shut off. After shutting off the excitation pulse, the detectors examines the "echo" caused by circulating eddy currents in the target. The process is repeated at a high repetition rate.

I gather it is not similar to radar as radar uses an actual radio frequency emission meaning the wave is sent off into space to travel like a, well, wave. I suspect PI is more like the ignition system coil of a car. A magnetic field is produced by a coil and when the power is cut that field collapses. The collapsing field induces a voltage on the very coil that emitted the field. That voltage has a rate of decay based on the field collapse in turn which is affected by the presence or lack of metal objects in the field that "charge up" from the field. The rate of decay of the field is either sped up or slowed down, not sure which, the minute differences in rate of decay is how metal is detected. Well at least that is how my understanding is with my limited knowledge of it.
So to recap.... PI uses magnetic inductance and field degradation over time vs radio frequency that radar and beat frequency oscillator detectors use.

As far as how ground balance is not affected on explorers....... I don't know how they function but I suspect they function in a manner much closer to PI mechanics than they do to the beat frequency oscillators of VLF units. Now, this isn't my field and my knowledge is very limited so take what I've said with a grain of salt. Hopefully I'm not way off.

 

[TellYaWhut]

Auto Ground Balance (Tracking) is found on some single frequency machines....I would think the multi frequency systems would be better. The only way I'd have a machine having the Auto Track is to also have the ability to Lock the GB, especially at trashy sites. I don't know of a Auto Track system that works good in salt water.

 

[cypearl]

I had a the same effect today but I do not why none of you guys have n't mention that explorers have the semi auto and lock track with the sensitivity. If turn off the auto from sensitivity I think it stops the ground balancing as well and becomes noisy.

 

[D&P-OR]

The gentleman that made/started this post has since passed away but the post lives on!-----As to no manual GB on the Explorers/Etrac--they "are what they are".------If you want this feature, the CTX no affords it.