Can Anyone Explain This?

[bigscoop]

Ok, here's a simple test you can conduct yourself as I believe this is where the next big advancement might possibly come from.



In order to achieve the same results you'll need an Excal 800 and a small gold ring, a penny, a small piece of silver, and a small piece of iron.


Now, in theory, what is about to happen isn't suppose to happen, and yet it does. The question is, why exactly?


So let's go to the beach and step into the saltwater, set our machine to disc mode, and then adjust the sensitivity until the machine becomes unstable.


Now let's drop one of your targets on the bottom, let's start with the iron. Now when we swing the unstable coil over the iron the machine still nulls, the machine instability still allowing the processor to identify the iron.


Now lets try this same thing with our silver item and penny, pretty much the same results, the machine still identifies the silver and penny.



Now comes the real eye opener as we do this with our gold item. Suddenly our gold signal is somewhat intermittent, or perhaps we're still getting a steady response, doesn’t really matter for the sake of the experiment until the next step.


Now let's repeat this same thing with the penny and then with the silver and then with the gold, but only now we're going to use the fastest sweep speed we can muster, so fast that our unstable machine no longer has time to process the mineralization, so fast the instability goes away. Now then, what happens to our target responses?



Well, they get narrower, for sure, but yet they still retain their individual tone ID. Question is, where did the mineralization noise go and why does the machine still have time to respond with the individual tone ID, in fact, with even a stronger but narrower response?



This is something I have been playing with for a couple of years now and I can honestly say that while it makes no sense to me it is working just as I've said. I know there is something of value in these results I'm just not a techie with the required skills to pick all of this apart so I can understand exactly what is happening and why? What I can tell you is that it is sometimes very useful in field.

 

[ron lord]

The mineralized noise is still and your detector still have time to respond because it is processing at a rate of 186,000 miles per sec.

 

[lookindown]

Yeah, like in an air test, a super fast sweep gives me a couple extra inches on my AT pro and CZ21.

 

[bigscoop]

The mineralized noise is still and your detector still have time to respond because it is processing at a rate of 186,000 miles per sec.

If this is true then couldn't speed be manipulated in various ways to eliminate/reduce the effects of mineralization and also to increase send and return strength? It's very interesting to play with, speed even playing a role in helping the machine to isolate objects in that mineralization that it can't otherwise easily/clearly isolate.

 

[bigscoop]

Yeah, like in an air test, a super fast sweep gives me a couple extra inches on my AT pro and CZ21.

Exactly. This is where I first noticed it some time ago and that's what got me playing with things on the beach, pretty much the same effect there as well, even in the mineralized saltwater. But it wasn't until I created an unstable field and tried it that I learned that this same speed can also improve stability sometimes and increase send and return strength. It just seems to me that speed could be used in such a way to improve machine performance once someone with the skills has picked it apart enough to start engineering around it.

 

[Jackalope]

According to Faraday's law, “a voltage is induced in a circuit whenever relative motion exists between a conductor and a magnetic field and that the magnitude of this voltage is proportional to the rate of change of the flux”.

In other words, the increase in coil motion may increase the voltage induced on the target, which might be the reason the response was narrower (if not stronger). Another possibility is that the averaging of signals that all detectors do may not catch up when the coil is swept faster - producing a slightly better contrast against the soil matrix. These things all happen very quickly. The AC in the coil is switching polarities 15,000 per second at 15 kHz. That means in the few seconds the magnetic field is penetrating the target it is being pulses 30-40,000 times. These magnetic pulses setup the voltage across the target and electrons to move with each pulse, and a ferrous target to align its magnetic domains and relax - 30-40,000 times per second. So, on second thought it is unlikely the sweep speed affects the target's secondary field generation as much as the time-domain of the algorithms within the detector. Most manufactures recommend a sweep speed that allows the detector time to evaluate/manipulate the signal and respond. Sweeping very fast may just have the effect of clarifying the response or at least removing spurious signals or in some way truncating the tone.

 

[bigscoop]

According to Faraday's law, “a voltage is induced in a circuit whenever relative motion exists between a conductor and a magnetic field and that the magnitude of this voltage is proportional to the rate of change of the flux”.

In other words, the increase in coil motion may increase the voltage induced on the target, which might be the reason the response was narrower (if not stronger). Another possibility is that the averaging of signals that all detectors do may not catch up when the coil is swept faster - producing a slightly better contrast against the soil matrix. These things all happen very quickly. The AC in the coil is switching polarities 15,000 per second at 15 kHz. That means in the few seconds the magnetic field is penetrating the target it is being pulses 30-40,000 times. These magnetic pulses setup the voltage across the target and electrons to move with each pulse, and a ferrous target to align its magnetic domains and relax - 30-40,000 times per second. So, on second thought it is unlikely the sweep speed affects the target's secondary field generation as much as the time-domain of the algorithms within the detector. Most manufactures recommend a sweep speed that allows the detector time to evaluate/manipulate the signal and respond. Sweeping very fast may just have the effect of clarifying the response or at least removing spurious signals or in some way truncating the tone.

I've often wondered what might be possible if this field was spinning at a high rate of speed?