CTX3030 noise cancel vs detection

[bklein]

When the CTX first came out people had issues with it at the beach. Minelab then came out with a firnware upgrade called seawater to fix these issues. Works awesomely. I havent tried enabling ground balance there....
I am not looking for the ultimate quiet detector - i am looking for ways to eliminate me digging aluminum, bottle caps, and bobbypins. These all have looked like good targets per ID's."

[Funfinder]

> i am looking for ways to eliminate me digging aluminum, bottle caps, and bobbypins

OK, if the Minelab beach setting works good enough it's fine.
But what you wanna eliminate is really not possible.
Bottle-caps and alu-stuff is in the middle of precious ID-values.

Even if you have a detector with 100 different ID values and you can sort (notch) out
every single one seperatly you will lose good stuff depending in what position and
how deep certain finds are.

Easier would be if you only hunt for special stuff where you know after different tests
within what ID-range it is and you discriminate completly the whole rest.

[bklein]

The bobbypins tend to come in at extremes like 35 so it is due more to curiosity and "dig everything" mentality that I dig them now - but if they get annoying I can try setting NC higher. Aluminum and bottlecaps come in just as you say - right in "good ID" ranges! FerrousCoin mode bumps bottlecaps into the 12 range so I think there may be something about them that Minelab firmware guys can still do to discriminate out. A few weeks ago I worked an area near here that was an old creekbed cleared off by water company tractors. I thought I might find something really old but just found a multitude of aluminum cans chewed up by the tractors, two feet down. All sounded like gold. At the beach, it really is amazing how deep small melted nuggets of aluminum detect with the standard 11" coil. I havent found anything that helps with aluminum.

[Carl-NC]

The next and even more important thing is that you must not cancel the noise completly because
still good and valuable find-signals "modulate the noise"!
It may disturb you but if you walk around with a completly quiet detector you will miss alot stuff.

I doubt this. EMI noise masks targets, not only in the audio noise that reaches your ears, but also in the way EMI screws up the integrators. It's always best to eliminate as much EMI as possible.

[Carl-NC]

I did a quick look at the NC on an Explorer. Frequency goes down with increasing channel number. Channel 1 is about 3.5kHz/28kHz and Channel 11 is about 2.75kHz/22kHz. In the middle is the nominal 3.125kHz/25kHz that I usually cite. This is a lot more than I expected, generally the whole range of NC is a few percent, not each NC setting. CTX may be different, both in direction and amount, but the center channel is identical to the Explorer as I recall.

[Funfinder]

> I doubt this. EMI noise masks targets, not only in the audio noise that reaches your ears, but also in the way EMI screws up the integrators. It's always best to eliminate as much EMI as possible.

Too much noise for shure and its also the question of how e-smog resistant is a detector -
how fast the sensitivity must be reduced so not completly every metal-signal at all gets rendered inaudible by the EMI-chatter.

But some moderate level of around 15-35% ambient noise - depending on how much somebody prefers - will reveal
very weak and deep stuff by repeated sweeps while they would never be heared if the MD was made completly quiet
by setting the sensitivity to some low enough level.

Another good method to reduce noise is using a smaller coil while still being able to search with very high sensitivity
settings, but that also depends for what kind of targets someone searches and if they are within the coils range.

thx for the frequency info, this is already an useful ten times kHz spectrum.



@bklein
> I thought I might find something really old but just found a multitude of aluminum cans chewed up by the tractors, two feet down.

Be glad it was just on a sandy beach!
I digged exactly the same stuff out on the edge of concrete hard forest-roads, 30cm thick compressed gravel-layer.

So what do you think now might help you out of that beach dilemma?
Perhaps you make some test-diggings at different locations there first until you
find one with the fewest junk? Or you use a large coil and look for the big stuff first.
Perhaps you even have to visit some different beach so the motivation remains high.

[Skippy]

Quote Carl:"CTX may be different"
It is. The sequence is reversed. The CTX (and ETrac) have the frequencies as I mentioned in my earlier post.

[Carl-NC]

Quote Carl:"CTX may be different"
It is. The sequence is reversed. The CTX (and ETrac) have the frequencies as I mentioned in my earlier post.

I missed that, thanks.

[Skippy]

I'm using this thread on NASA-Tom's Forum (which both you and I contributed to) as my reference:
http://www.dankowskidetectors.com/di...2,24272,page=1

Note to Mr.Klein: this Tom's Forum thread contains plenty of 'erroneous opinions', don't pay too close attention to it.

[Carl-NC]

I'm using this thread on NASA-Tom's Forum (which both you and I contributed to) as my reference:
http://www.dankowskidetectors.com/di...2,24272,page=1

Note to Mr.Klein: this Tom's Forum thread contains plenty of 'erroneous opinions', don't pay too close attention to it.

Yeah, there's a fair amount of wrong in that thread.

[bklein]

>
So what do you think now might help you out of that beach dilemma?
Perhaps you make some test-diggings at different locations there first until you
find one with the fewest junk? Or you use a large coil and look for the big stuff first.
Perhaps you even have to visit some different beach so the motivation remains high.

Well, judging by my experience a couple days ago, if all I find are aluminum nuggets it is time to leave for another beach or home. The beach in some areas was depleted of sand - you could find lead weights but nothing good. I was sticking to this one beach because it is convenient and I wanted to "learn" it - when it is bad it is time to move on.

[Funfinder]

Right choice; you may try your luck 100-200 meters away from there to look if the situation improves.
If not, you'll find some other lucrative opportunities for shure.

A good principle for life is:
Try your luck and realize precious chances but if it doesn't works, don't waste your time with it.
(or only then again for another try, when the cards have been mixed newly)