AMX RX

[Willy Bayot]

"..A bit more patience, we know where we are going, just try to follow and learn!!..."

Follow what?
Learn what?

I was under the impression that the work on this would be transparent. And that we will be able to follow the work on the project step by step.
Now it seems to me that a couple of you have gone "anonymous" and are working on it without the public.

We are working in the background for the sake of the AMX project. Some phases of the design are longer than others.
As Carl said, we need to make some simulations to make sure the whole system will behave as expected (not only the XMIT alone or the AFE alone)
We strongly believe that simulations are really useful to avoid unnecessary PCB generations.

If you want to take some advance on you own, you can already start preparing a good IB coil assembly and test it.
Look at the design of Tony.

[ivconic]

We are working in the background for the sake of the AMX project. Some phases of the design are longer than others.
As Carl said, we need to make some simulations to make sure the whole system will behave as expected (not only the XMIT alone or the AFE alone)
We strongly believe that simulations are really useful to avoid unnecessary PCB generations.

If you want to take some advance on you own, you can already start preparing a good IB coil assembly and test it.
Look at the design of Tony.

Who actually is "we", you keep repeating that in every of your posts?
So who is "we"?
...
I looked at the desing of Tony and I don't like it, for many reasons.
I will not name them all again here, I already posted all my reasons in several posts across the few topics.

[Willy Bayot]

Who actually is "we", you keep repeating that in every of your posts?
So who is "we"?
...
I looked at the desing of Tony and I don't like it, for many reasons.
I will not name them all again here, I already posted all my reasons in several posts across the few topics.

I meant the coil design of Tony.
If you do not like it, you do not take it, very simple!!

'WE' are all forum members having something to BRING to the project. It seems that you do not consider yourself in, you just want to GET something from the project, and QUICK.

[Tinkerer]

Who actually is "we", you keep repeating that in every of your posts?
So who is "we"?
...
I looked at the desing of Tony and I don't like it, for many reasons.
I will not name them all again here, I already posted all my reasons in several posts across the few topics.

Many different coil assemblies can be used with the AMX detector. It can be as simple as a TX coil and a separate RX coil. Or an induction balanced coil assembly. There are several different IB designs you can chose from. DD, oOo, etc. I am building a DD coil. Is this the best coil design? I don't know. It is only by building and trying different coil assemblies we will find the best coil. Coils are always a compromise between many different factors.
Which factor seems to be the most important to you?
Design and build the coil the way you like it.

[ivconic]

I meant the coil design of Tony.
If you do not like it, you do not take it, very simple!!

'WE' are all forum members having something to BRING to the project. It seems that you do not consider yourself in, you just want to GET something from the project, and QUICK.

So I have a very bad luck; because i GOT nothing so far.
I don't consider myself in because I feel left out.
By the way, I am here as an old member, since 2006, very well known for the fact that I mostly want to "grab" something useful without giving anything of myself to others.
People clearly recognize me by that. And everyone blamed me for it until now. Carl puts up with me here because he's especially patient with "predators" like me.
But luckily for the forum and especially for this project; you saw through me, you realized my true intentions and now you finally saved the project and the forum from me, with that discovery.

With my humble circumstances; I could contribute to the common cause by building a prototype very quickly and testing it.
Both on the table and in real conditions.
But I can't contribute anything because I don't have any usefull info.
We have parts of some schematics, scattered on a couple of topics, nothing concrete, that was said to be it.
One says one thing, the other says another, the debate goes on endlessly...
No one can lay out the schematic of at least one part and say "this is the final thing".
I understand that it is smarter to check everything even more than once through the simulator.
But the days pass... no one has anything new to say, there are no simulation reports...
If this is teamwork; then it is not realistic to put everything on Carl and wait for him to do everything himself in the simulator and about the calculations.
I'm the first one who doesn't love simulations... so I know for sure that there are at least 20 of you here who are "addicted" to simulations and love to play those games all day long.
Where are you now?
Why are you waiting for Carl?
In addition to the above, there is also the problem of purchasing materials. Ideally, we would have entire replacement lists for specific integrated circuits.
You keep saying "we"... so it gives the impression that "you" are some special, separate group, working on a project outside the forum. Because nothing new is published for days.
I apologize in advance, but from this moment on I will put you on the ignore list (if I manage how to do it on this new forum) because your comments always bother me and get on my nerves.
Everything you write is simply irrelevant to me.
Lest you think there is another reason, you will simply be completely ignored.
Bye!

[ivconic]

Many different coil assemblies can be used with the AMX detector. It can be as simple as a TX coil and a separate RX coil. Or an induction balanced coil assembly. There are several different IB designs you can chose from. DD, oOo, etc. I am building a DD coil. Is this the best coil design? I don't know. It is only by building and trying different coil assemblies we will find the best coil. Coils are always a compromise between many different factors.
Which factor seems to be the most important to you?
Design and build the coil the way you like it.

Tony, sorry, but my opinion is that the coil is the last thing we should be thinking about at this point.
For prototyping purposes, a regular monocoil will do the job.

[ivconic]

Putting it on the "ignore list" is a bit complicated, but I did it!
At least I won't see a bunch of repetition of the same nonsense post after post.
In the series "Big Bang Theory" those poor people are condemned to suffer Sheldon ... but here I don't have to.

[moodz]

Putting it on the "ignore list" is a bit complicated, but I did it!
At least I won't see a bunch of repetition of the same nonsense post after post.
In the series "Big Bang Theory" those poor people are condemned to suffer Sheldon ... but here I don't have to.

well I will let you know that my simulator has been running red hot and the bipolar TX topology is going to ( suggested ) change as solving the ramp problem is easier and simpler ( less parts ) using a new topology but same results.
But there is no point publishing incremental simulation developments as you dont like it ( ... the simulation experience or the incremental publishings ).

Dont you watch star trek .. .they use the holodeck ( simulation ) all the time

moodz.

[ivconic]

well I will let you know that my simulator has been running red hot and the bipolar TX topology is going to ( suggested ) change as solving the ramp problem is easier and simpler ( less parts ) using a new topology but same results.
But there is no point publishing incremental simulation developments as you dont like it ( ... the simulation experience or the incremental publishings ).

Dont you watch star trek .. .they use the holodeck ( simulation ) all the time

moodz.

It's not a question of whether or not I like simulations. They are already extremely unclear to me.
I am not familiar with working with simulators of that type.
So it would help me a lot if the schematic from the simulation was translated into a conventional schematic,
where everything is clear, what is the input, what is the output, what are the power points, etc.
Then it would be easier for me to look at the schematic and the actual processes that are happening there.
This is simply a habit and a method I have used for decades.
I'm old, I'm used to it.
It's easier for me to understand how a circuit works when I look at a well-arranged and drawn schematic.
I understand things visually. Ask Davor, he bombarded me with simulations and I always objected to him.
Only when he translates the simulation into a clear schematic; I'm starting to understand things.
...
When someone insists so forcefully that he knows everything, that he is an "expert" in everything and has "done" everything and "understands" everything, well well...
I immediately think of Sheldon and immediately feel sick.
Star Trek I like of course!

[green]

I could contribute to the common cause by building a prototype very quickly and testing it.
Both on the table and in real conditions.

I joined this site a few years back. Owned a Heath kit VLF metal detector that we used to find arrows hidden in the grass that missed the target long time ago. I joined to learn something about metal detectors and picked PI. Had health problems about a year ago and haven't played with the metal detector since. Trying to follow this discussion. When I was active, I made a few detectors that kind of worked. What I missed was a test that I could compare my detector against some commercial or other detector. Mostly played trying to detect gold since it looked like the most difficult. Have some gold nuggets for testing. Problem was they all test different. Tried to find a test target that anyone could obtain. Tried aluminum foil (not all foil is the same thickness, TC effected by thickness and how accurate foil target was cut). Tried lead shot from shotgun shells (quite a bit of variance, maybe do to size or not being pure lead). Copper electrical wire tests consistent and suggested it could be used for a test target (TC not effected by length, amplitude is affected by length but should be able to cut accurate enough to not matter if pieces are cut 5 10 15 or 20mm. Wondering if anyone has found a good target for testing while I've been gone.

(TC) 4grain (3.1us) 10grain (6.7us) 18grain (5.7us)

[Carl-NC]

In the meantime, I reviewed the topic "My AGD analog detector work" by Auto-Mation-Assist.
And he has similar goals, to be able to detect golden flakes.
His schematics are interesting.
It may be possible to use the good things of both projects and make something third. Sublimation of both.
But also in his schematics I see some components that are not easily available in local shops.

His approach is entirely different, very little can be shared between the projects. Again, for the AMX project it will be entirely SMT and may use a lot of parts you can't get. Sorry, but that's the way it is. You are welcomed to take the design and try to build it with what you have available but that will have to be an individual effort.

I was thinking something... the TC for a small gold nugget was said to be 1uS.
Is that strictly so? Can certain nuggets be stretched to 2-5uS?
In other words; what to expect from a detector with the ability to set the delay to not below 5uS, or 10uS?

Gold nuggets are all over the place. Sub-us up to 100s of us. Even two nuggets of 1 gram can have quite different taus.

A few more interesting questions...
Whether and to what extent; good GEB and DISC depend on minimum TC?
Logic says that what is more "extracted" data from one delay period; the more reliable both GEB and DISC will be.
Or does it have nothing to do with each other?
On the other hand; GEB should not depend on it.
Unrelated to TC, the moment you put the coil on the ground; the state of the signal in coil will change due to the influence of the earth.
Does the number of samples improve GEB or does it not matter.
Further next question;
What will DISC look like?
Will Disc work on the simple principle of "rejecting" everything in the signal that is longer than 1uS, 2uS... etc.
That is; if iron is present in the first uS but still too in the next 20uS (for example) and the gold nugget is not, it is present only in the first uS:
how will the difference between iron and gold in that first uS be expressed? By amplitude?

My goal for GB is to use alternating long & short pulses and do a subtractive GB. I'm not sure what you mean by minimum TC, but GB can be accomplished whether you design for sub-grain nuggets or multi-grain nuggets.
There are 2 definitions for multiple samples: a given sample delay from multiple pulses, or multiple sampled delays within a given pulse. The former always helps as it improves SNR. The latter may or may not be as useful.
Disc will not work on sample delay, it will work on target curvature by distinguishing between exponential target and power-law ground responses. This is why we need multiple samples in each pulse.

[ivconic]

His approach is entirely different, very little can be shared between the projects. Again, for the AMX project it will be entirely SMT and may use a lot of parts you can't get. Sorry, but that's the way it is. You are welcomed to take the design and try to build it with what you have available but that will have to be an individual effort.



Gold nuggets are all over the place. Sub-us up to 100s of us. Even two nuggets of 1 gram can have quite different taus.



My goal for GB is to use alternating long & short pulses and do a subtractive GB. I'm not sure what you mean by minimum TC, but GB can be accomplished whether you design for sub-grain nuggets or multi-grain nuggets.
There are 2 definitions for multiple samples: a given sample delay from multiple pulses, or multiple sampled delays within a given pulse. The former always helps as it improves SNR. The latter may or may not be as useful.
Disc will not work on sample delay, it will work on target curvature by distinguishing between exponential target and power-law ground responses. This is why we need multiple samples in each pulse.

Thanks! Educational again!
....
How the GEB is done on detectors with uniform pulses? You gonna use long&short pulses and do a subtractive GB, alright, But how is done in simpler way when all the pulses are the same, uniform?
Isn't it the similar subtraction taking place too?
Disc. You said it will work on target curvature by distinguishing between exponential target and power-law ground responses. It's misty to me, can't grasp it. Maybe longer post/topic with details?
And again, what about the idea of using TC for discrimination? Say... everything above 1uS is cut and that 1uS is compared to what lasts up to 5uS, then both compared to what lasts up to 50uS etc...
Sort of a "scale" from 0 to 100uS and redistribution of the signals in it. Ultra small flake will probably appear in first uS and fast diminish in next one or few. But iron will last much longer.

[ivconic]

I joined this site a few years back. Owned a Heath kit VLF metal detector that we used to find arrows hidden in the grass that missed the target long time ago. I joined to learn something about metal detectors and picked PI. Had health problems about a year ago and haven't played with the metal detector since. Trying to follow this discussion. When I was active, I made a few detectors that kind of worked. What I missed was a test that I could compare my detector against some commercial or other detector. Mostly played trying to detect gold since it looked like the most difficult. Have some gold nuggets for testing. Problem was they all test different. Tried to find a test target that anyone could obtain. Tried aluminum foil (not all foil is the same thickness, TC effected by thickness and how accurate foil target was cut). Tried lead shot from shotgun shells (quite a bit of variance, maybe do to size or not being pure lead). Copper electrical wire tests consistent and suggested it could be used for a test target (TC not effected by length, amplitude is affected by length but should be able to cut accurate enough to not matter if pieces are cut 5 10 15 or 20mm. Wondering if anyone has found a good target for testing while I've been gone.

(TC) 4grain (3.1us) 10grain (6.7us) 18grain (5.7us)

I like the method!

[ivconic]

... Gold nuggets are all over the place. Sub-us up to 100s of us. Even two nuggets of 1 gram can have quite different taus...

I didn't register this well on the first read.
If the situation with the gold nuggets is like that, as you say; then designing a PI detector with the possibility of setting a delay up to 1uS ... is not mandatory,
it is not the main goal, it is not a mandatory part of the criteria to be fulfilled.
If it is like that; and achieving the ability to adjust the delay up to 1uS is a big challenge... then it is not a big problem if a detector is made with the ability
to adjust the delay from 5uS to more or even 10uS to more.
The point is; if it will reduce the material requirements, expensive and rare opamps and ADC circuits, processors... then the whole project could be divided into several versions.
I repeat; only if the differences in material and work are significant, otherwise it makes no sense.
My personal view is that I am not interested in such PIs in the least. Because I have no application for such a detector here in my fields. I have absolutely no interest or need.
The Pulse Star II is absolutely the best detector for my conditions and my terrain.
With a smaller coil, it would also be interesting for smaller targets. But the Pulse Star 2 has no GEB and has a very debatable Disc.
And of course, why not say it when it's true; not an ideal solution for very small targets.
That's why I became interested in this "your" project.
Not because of the TC of 1uS... but because of the functional GEB circuit and additionally the functional and accurate Disc circuit.
I don't know what the TC would be for an ancient Roman bronze coin... say 1.5-2cm in diameter.
But it is also the "minimum" TC that interests me in the whole story.
All TCs below that: I'm not interested in the least, therefore a detector that is capable of that as well.
Why PI when I already have Deus?
Well, because PI detectors generally behave better in situations with target "masking" problems.
Deus overcomes that problem to a good extent, but times have come when all such finds have been dug up a long time ago.
And on the fields there are (often very valuable) findings that are totally masked by surface material. Even Deus doesn't help here.
Well, I finally revealed to "you" my motives and interest in this project.
My list of criteria would be somewhat milder than the one set, in that sense.

[Carl-NC]

How the GEB is done on detectors with uniform pulses? You gonna use long&short pulses and do a subtractive GB, alright, But how is done in simpler way when all the pulses are the same, uniform?
Isn't it the similar subtraction taking place too?

On a monopolar design you take a late sample, amplify it, and subtract from an early sample. Just the right amount of gain will cancel ground. But this causes a target hole because, somewhere, there is a target that will also subtract to zero. And other targets near the hols are also diminished.

You can also use monopolar pulses with 2 pulse widths, and subtract a gained-up narrow pulse sample from a wide pulse sample. But you still get a target hole. What I plan is to use multiple pulse widths combined with multiple samples to eliminate ground with (hopefully) no target hole.

Disc. You said it will work on target curvature by distinguishing between exponential target and power-law ground responses. It's misty to me, can't grasp it. Maybe longer post/topic with details?

Eddy targets have an exponential decay (e^-at), which is a straight line on a log-linear plot (see the hundreds of images Green has posted). Ground has a t^-a response, which is a power law response. Their curvatures are different. Iron targets exhibit a collapsing B-H curve response, which also looks different. If you grab a minimum of 3 points then you can distinguish these curves. Pulse width also affects amplitude responses, which offers another dimension. A third dimension is the temporal response; that is, what is happening as the coil passes over the target. This is useful in identifying flat steel, such as bottle caps.

And again, what about the idea of using TC for discrimination? Say... everything above 1uS is cut and that 1uS is compared to what lasts up to 5uS, then both compared to what lasts up to 50uS etc...
Sort of a "scale" from 0 to 100uS and redistribution of the signals in it. Ultra small flake will probably appear in first uS and fast diminish in next one or few. But iron will last much longer.

Using tau for discrimination means you throw out all the silver coins along with the iron. I'm looking for a way to throw out just the iron.

If the situation with the gold nuggets is like that, as you say; then designing a PI detector with the possibility of setting a delay up to 1uS ... is not mandatory,
it is not the main goal, it is not a mandatory part of the criteria to be fulfilled.
If it is like that; and achieving the ability to adjust the delay up to 1uS is a big challenge... then it is not a big problem if a detector is made with the ability
to adjust the delay from 5uS to more or even 10uS to more.

I don't plan on having a variable sample delay. I want several fixed sample times for each pulse, with first sample as early as possible. Keep in mind that even a 5us-delayed sample can detect a 1us target, just not as well as a 2us delay.