SMF

[Carl-NC]

TX (current) waveform for the Equinox Park mode:

You can see 5 broad cycles (7.8kHz) and in each broad cycle there are 5 short cycles (39kHz). What's hard to see is that there is also a 2.6kHz component. So this is a 3-frequency waveform.

 

[Picketwire]

Thank you sir. What would they look like if they used say 20 frequencies. Are there detectors that do? Is there any significance that 7.8x5=39 or 2.6x3=7.8?

 

[Carl-NC]

No one uses more than 3 frequencies. More frequencies means less depth, and there's little advantage in more than 3. If you did run 20, it would look like a noisy mess.
Multifrequency detectors run the frequencies at harmonic relationships; the Equinox is 1:3:15, the Apex is 1:4, the V3i is 1:3:9, BBS/FBS is 1:8. and so on.

 

[Nauti]

I don't think i will invest the money as i'm really not convinced at all about smf.......the amount of used smf detectors on the market speaks volumes.

 

[laplander]

TX (current) waveform for the Equinox Park mode:

View attachment 27476

You can see 5 broad cycles (7.8kHz) and in each broad cycle there are 5 short cycles (39kHz). What's hard to see is that there is also a 2.6kHz component. So this is a 3-frequency waveform.

TX (current) waveform for the Equinox Park mode:

View attachment 27476

You can see 5 broad cycles (7.8kHz) and in each broad cycle there are 5 short cycles (39kHz). What's hard to see is that there is also a 2.6kHz component. So this is a 3-frequency waveform.

Interesting! Looking at the pattern rhythm it is similar although quite different. The difference in modes, is it the way the frequencies are transmitted or analyzed or perhaps even both?

 

[Carl-NC]

Interesting! Looking at the pattern rhythm it is similar although quite different. The difference in modes, is it the way the frequencies are transmitted or analyzed or perhaps even both?

Both. In both the Equinox and Legend the Beach modes alter the TX waveform to reduce the amount of 39kHz, and both do salt notching whereas the Park modes probably do not. In the Equinox the Prospecting mode runs entirely different frequencies (5+40 kHz).

 

[laplander]

Both. In both the Equinox and Legend the Beach modes alter the TX waveform to reduce the amount of 39kHz, and both do salt notching whereas the Park modes probably do not. In the Equinox the Prospecting mode runs entirely different frequencies (5+40 kHz).

Very intriguing discussion Carl. One more thought when you ground balance in for example beach 2 does it affect frequency patterns? When I say ground balance, I am running way above what would be a correct balance.
Thanks in advance
HH Jeff

 

[Carl-NC]

No, GB is entirely in software.

 

[Odanscoils]

No one uses more than 3 frequencies. More frequencies means less depth, and there's little advantage in more than 3. If you did run 20, it would look like a noisy mess.
Multifrequency detectors run the frequencies at harmonic relationships; the Equinox is 1:3:15, the Apex is 1:4, the V3i is 1:3:9, BBS/FBS is 1:8. and so on.

Hmmm
I thought the Soverigns ran 17 frequencies from 1.5-25.5 khz
And Explorers ran 28 frequencies from 1.5-100 khz

Something I've never done.
Love to see the multi freq return signal.

 

[IDXMonster]

The way I’ve understood it with my very limited and crude way is that FBS operates on base frequencies and somewhat weaker harmonics generated by said frequencies. The fact of the matter is either it works for finding what I want or it doesn’t, even though I’d like to know as many particulars as possible. If I did know, it wouldn’t change anything, it would simply satisfy a curiosity over which I have no control.

 

[Carl-NC]

The 17 & 28 frequency thing was Minelab marketing at work. All BBS/FBS models, from the first Sovereign to the CTX, use 3.125kHz and 25kHz. Here is the TX waveform:

You can see that 3kHz is dominant which is why they did so well on deep silver.

 

[IDXMonster]

Interesting….and here is where people get/have gotten REALLY CONFUSED by the information out there as it relates to FBS. On YouTube is a video from the “metal detecting skill school” with Gary using his “metal detector frequency checker” (it actually says that on the unit) and HE shows the testing unit coming up with anywhere from 16-12khz on an Explorer2, depending on which noise cancel channel he puts it on. Soooooo….whats going on there? It seems his tester is reading a composite of the 2 actual fundamental frequencies! However…at the end of his “frequency checking” he says….”well there ya go, those are the frequencies on the Minelab Explorer.” Again, this doesn’t matter in my own world, I use them because they work. It’s just a little annoying to have him present his findings in that manner and muddy things up.

 

[Carl-NC]

The only way to tell what's going on with MF detectors is to put the TX waveform on an oscope. And it needs to be the current waveform, not the voltage. What Gary is using doesn't work.

 

[JCR TX]

This is all very interesting.
Thanks

 

[Picketwire]

Thanks again for the schooling, Carl. I appreciate it almost as much as the pinpointers you designed. Problem is, of the three I own, I can't decide which one I like best. Keep up the good work.

 

[DigDog]

I don't think i will invest the money as i'm really not convinced at all about smf.......the amount of used smf detectors on the market speaks volumes.

I thought you have a Legend but maybe confused.
So you are not convinced at all the Legend and other similar are any good?
Everything i read seems to say otherwise but again im no expert.
Have not really looked at used for sale either.
I would think location might have a big impact on what works good

 

[Nauti]

Oh no bud..........they are great detectors without a doubt and will find a lot for their owners.I just don't think that they are leaps and bounds over some of the detectors I own so i won't be investing in one is what I meant.
Over the thirty plus years I have been detecting I have seen many "innovations" come and go but have yet to see a single one that really makes a big difference to overall finds rates.

 

[Monte]

Oh no bud..........they are great detectors without a doubt and will find a lot for their owners.I just don't think that they are leaps and bounds over some of the detectors I own so i won't be investing in one is what I meant.
Over the thirty plus years I have been detecting I have seen many "innovations" come and go but have yet to see a single one that really makes a big difference to overall finds rates.

 

[irnwrkr]

you have to get above it to find it, regardless if its a ctx or an ace 150

 

[pulltaboo]

When the manufacturer claims "X simultaneous frequencies", they never mention that these are transmit frequencies…
I could be wrong, but I think all SMF detectors transmit 2-3 frequencies simultaneously, the rest are just harmonic frequencies. Magic happens mostly in signal processing.