how many diff. friq. does fbs use at one time?

[Wayfarer]

There's a very informative thread on another forum regarding this. the conclusion they reach is "It uses alternate bursts of 1 cycle of 3.125kHz then 8 cycles of 25kHz". The 28 frequencies is a marketing claim. Only those two frequencies are actually processed.

Thanks for the link. Great read, although much of it was over my head. I'm not an electrical engineer by any stretch, just someone who likes to tinker with radiated RF energy...aka a ham radio guy. Bottom line is what you already said: that FBS is really just two frequencies that alternate in quick pulses. The magic is in the timing of the pulses and the digital processing of the incoming signals.

The spectrum analyzer and technique I am using is better than the method the original poster in that thread was using, so maybe I can add something to the body of knowledge with my results. As soon as I get 'em, I'll post 'em up here for any and all to see and then draw their own conclusions.

Here's the link to the thread, btw: http://www.dankowskidetectors.com/discussions/read.php?2,24272

 

[jtalley007]

I think electronics guys kind of understand but nobody seems to be able to duplicate what Minelab does.

I thought for sure when I heard the sovereign patent expired, someone would be all over it.

Since that didn't happen, glad to see Minelab may meet our needs without taking out an equity line to buy their machines.

I've spent a small fortune over the years myself, bought the 3030 when it first arrived and was sick when I took it on vacation to the beach and it wouldn't work.

I won't ever buy a first run machine again, my sovereign, Excalibur, and 3030 will be fine until I know from Minelab and all the social media hype the bugs are not present.

 

[Wayfarer]

I was able to borrow a CTX *and* a Safari. Nothing new here. The CTX transmits primarily on on 3.125 kHz and 25 kHz (the strongest vertical spikes on the spectrum). The spikes at 30, 45, and 90 kHz are some kind of EMI noise and is not part of the CTX's output, so you can disregard those.

As a bonus, I measured the output as I shifted the Noise cancel channel from Ch 1 to Ch 11. You can see that the output frequency is shifted as a percentage, not as an absolute number. Very interesting and maybe a clue to how the output frequencies are generated.

 

[Ksdirt]

You seem to be very good at what you do..must have some interesting equip..... So the etrac probly does about the same thing as the ctx.
And runs on the 2 friq. ...so the 28 friq. Talked about ..what's up with that..are they just reflections off the 2 main ones used ..sorta speak..

 

[amberjack]

I know I used more than 1 frig at time when out detecting does that count as a friq

AJ

 

[Mr. Carolina]

Wayfarer:
Thank you for your time and trouble, but for me, the water is still muddy. Not sure where I see the output frequency " shifted as a percentage " . I also am not sure how you determined the spike at 90 is " some kind of EMI ". Maybe if you could draw some arrows with quotes a pee brain such as myself could grasp what you are trying to show us. I see the strongest spikes at 3.125 & 25 but can tell no difference from say 90. Also how can you disregard the other spikes as not being frequencies? Just trying to understand but maybe to much for me. Thanks again for your help.

 

[Wayfarer]

Carolina, thanks for your questions. I know those extra spikes are noise simply because they were present *before* I even turned on the detector. This is EMI from various indoor sources such as LED lights, power transformers, "wall warts," electric motors, and so on. I took a reading inside my house before the test without the detector, and it showed me the exact signals that were EMI. I attached the picture of the noise and you can see what these signal are that I disregarded.

[attachment 350562 noiselevel.JPG]

What I mean "by percentage," can be seen by how much the frequency shifts at the lower end, like the 3.125 kHz, which isn't very much, maybe 0.5 kHz, and the amount of the shift progressively grows bigger until you get up to the 25 kHz which shifts from about 23 kHz all the way up to 28 kHz (going from Ch 1 to Ch 11) for a 5.0 kHz shift. The lines at the lower part of that screen shot are a historical plot showing the last 10 seconds or so of the signal output so you can see how it changes over time. Hope that makes sense now.

Ksdirt, he two strongest frequencies are 3.125 kHz and 25 kHz because they are the two tallest spikes. All the other frequencies are likely harmonics, although I'm not sure which ones are the true fundamental frequencies without looking a lot closer. The two strongest frequencies 3.125 and 25 are not necessarily fundamental freqs since the signal strength of each freq can be increased or decreased using filters and other electronic circuitry. But the fact that those two are the strongest, shows that those are the main two that the detector uses since ML wouldn't've designed it that way without a reason.

But it's still muddy, even for me, because there's really no telling which of the additional frequencies the detector uses without knowing "what's under the hood" in circuit design and software. But at least it's a start and shows the main two freqs...and shows how the Noise cancel actually affects the frequency.

Once I get the Equinox in hand, I'll be able to run the same kind of tests.

 

[amberjack]

would make sense if what they have us believe, 25 ground cancel 3 for finding targets , and why FBS is good on silver/copper...

thinking the EQ is based off a xterra platform as FBS dosnt fit in a small box so just reading between the lines no proof, but it sure sounds like a 705 and about the same depth just hope they have fixed the coils as while the 705 can be an inch deeper than FBS its minelab coils are well bad, only run after market coils on 705 , granted their newer coils are getting better (FBS-CTX) so fingers crossed hey.

if it is based on the 705 it should be a good all-rounder if I was just looking to have one detector maybe this could be it, but then I have a lot of time on the ones I have do I want to waste all that time and trade down and learn again, not at this point but keep an open mind and see what unfolds..

I see the monster was a flop here and the go fiddle even worse so lets hope they have upped their game only one success in 5 years GPZ so fingers crossed for them

AJ

 

[Mr. Carolina]

Wayfarer:
Thanks for the expination as it is becoming somewhat clearer maybe. If I were to take a guess, would channel 8 be the closest to 17kHz according to the graph?

 

[D&P-OR]

Hey AJ------Where you been in all this??----and---why was the monster a flop in oz?

would make sense if what they have us believe, 25 ground cancel 3 for finding targets , and why FBS is good on silver/copper...

thinking the EQ is based off a xterra platform as FBS dosnt fit in a small box so just reading between the lines no proof, but it sure sounds like a 705 and about the same depth just hope they have fixed the coils as while the 705 can be an inch deeper than FBS its minelab coils are well bad, only run after market coils on 705 , granted their newer coils are getting better (FBS-CTX) so fingers crossed hey.

if it is based on the 705 it should be a good all-rounder if I was just looking to have one detector maybe this could be it, but then I have a lot of time on the ones I have do I want to waste all that time and trade down and learn again, not at this point but keep an open mind and see what unfolds..

I see the monster was a flop here and the go fiddle even worse so lets hope they have upped their game only one success in 5 years GPZ so fingers crossed for them

AJ

 

[amberjack]

Hey Del, keeping a low profile don't want to annoy too many people there is a constant flow of monsters used a few times on to ebay so people buy try and sell , just a guess but they probably are not handling the ground to well as all VLF's will do here, its only a guess as not used one, but its pretty hot out there in most of the gold fields. in the air and on the ground well unless its winter then it can get real cold

minelab seem to be caught in some sort of limbo or twilight zone right now they are having a crisis of who they are and what they want to be, and just guessing that trying to keep everyone happy isn't working so well for them, and in the process are a bit lost in the transitional phase of moving to new minelab, no doubt there are some smart people there, but I think they are trying to hard...

just how I see it..

hope all is well.

AJ

Hey AJ------Where you been in all this??----and---why was the monster a flop in oz?

would make sense if what they have us believe, 25 ground cancel 3 for finding targets , and why FBS is good on silver/copper...

thinking the EQ is based off a xterra platform as FBS dosnt fit in a small box so just reading between the lines no proof, but it sure sounds like a 705 and about the same depth just hope they have fixed the coils as while the 705 can be an inch deeper than FBS its minelab coils are well bad, only run after market coils on 705 , granted their newer coils are getting better (FBS-CTX) so fingers crossed hey.

if it is based on the 705 it should be a good all-rounder if I was just looking to have one detector maybe this could be it, but then I have a lot of time on the ones I have do I want to waste all that time and trade down and learn again, not at this point but keep an open mind and see what unfolds..

I see the monster was a flop here and the go fiddle even worse so lets hope they have upped their game only one success in 5 years GPZ so fingers crossed for them

AJ