From what I have been reading on this forum and in the literature it appears that using multiple frequencies from low Khz up thru high end such as on the Sovereigns, Quattros and Explorers would be better for gold detection. The dedicated gold detectors from Minelab are single frequency, correct? Typically above 10Khz (i.e.; 18.75Khz). At least in theory. Am I missing something on the technical side?
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Why not have FBS or BBS for Minelab's Top of the Line Gold Detectors?
- Thread starter jkasta
- Start date
The Minelab SD and GP series gold detectors being Pulse Induction operate in the time domain. The Sovereign, Explorer, and Quattro detectors are using Continuous Wave Synchronous Demodulation in the time domain.. The Pulse Induction machines actually shutdown for a few microseconds to let the general minerals decay out and then the receiver turns back on to catch the eddy currents hopefully from mostly gold. The FBS and BBS detectors never turn off just like a standard VLF. Not to say the Explorer, Quattro, and Sovereign won't find gold either. I hope this is helpful.
John Tomlinson,CET
John Tomlinson,CET
Yes, Pulse Induction puts out a pulse of EM radiation, turns off to receive any induced EM which indicates some form of metallic object was induced and re-radiated back the transmitted EM. Why not Pulse Induce at multiple frequencies? If dealing in microseconds for sequence of pulse, turn off, turn on listen (receive) then 20 (or less) different pulses with different frequencies could be feasible in under a second, yes? Now I am not schooled in electronics (my background originally was geology, now databases) but it seems to me the more frequencies one has to detect with the better???
alaskaseeker
New member
The main problem with VLFs no matter how many frequencies they have they will not work in a lot of horribly mineralized ground, hence he PIs that that will, and Minelabs have evolved into an incredible unit the GPX 4000...Geo
[quote Wirechief]The FBS and BBS detectors never turn off just like a standard VLF. Not to say the Explorer, Quattro, and Sovereign won't find gold either. I hope this is helpful.
John Tomlinson,CET[/quote]
This is totally false.
FBS and BBS have a kind of "alternate phase-square-inpulse" to drive the TX coil.
You can see with a normal oscilloscope.
John Tomlinson,CET[/quote]
This is totally false.
FBS and BBS have a kind of "alternate phase-square-inpulse" to drive the TX coil.
You can see with a normal oscilloscope.
the sover-like coil use a strange driver signal, a train of alternate square inpulse (10 uSeconds) followed by 2 large inpulse (40-50 uSeconds)
(+ - + - + - + -+ -+ -+ -+++++ ------ + - + - + - + -+ -+ -+ -+++++ ------ etc.)
In the normal condition, the coil is balanced like a IB-MD to null the RX signal, you can view only a spike on each transient.
If you analyze the RX signal is centred to zero and have the same PI shape but that spikes are alternate!!!
This idea compensate the effect of ground and mineralization and produce an inverse distortion in the shape when the target is iron.
So different, so far from VLF system that analyze phase and amplitude in the TX.
(+ - + - + - + -+ -+ -+ -+++++ ------ + - + - + - + -+ -+ -+ -+++++ ------ etc.)
In the normal condition, the coil is balanced like a IB-MD to null the RX signal, you can view only a spike on each transient.
If you analyze the RX signal is centred to zero and have the same PI shape but that spikes are alternate!!!
This idea compensate the effect of ground and mineralization and produce an inverse distortion in the shape when the target is iron.
So different, so far from VLF system that analyze phase and amplitude in the TX.
[quote jkasta] Why not Pulse Induce at multiple frequencies?[/quote]
in the perfect square impulse ther's an infinite number of armonics.
The Minelab sover-like method, only square pulse are driving the TX coil
and the multiple frequency analisys do the rest.
Subsequent from each transient the "system" collect a sample at different delay,
and the decay shape is analized using a 4 channel differential-integration.
After this block, the MotorolaMicro convert the 4 channel analog value into digital value
computing the delta deviation from the ground-null condition.
Therefore multiple frequency in the analisys only.
in the perfect square impulse ther's an infinite number of armonics.
The Minelab sover-like method, only square pulse are driving the TX coil
and the multiple frequency analisys do the rest.
Subsequent from each transient the "system" collect a sample at different delay,
and the decay shape is analized using a 4 channel differential-integration.
After this block, the MotorolaMicro convert the 4 channel analog value into digital value
computing the delta deviation from the ground-null condition.
Therefore multiple frequency in the analisys only.
[quote Wirechief]
Hi cossaro,
But what I meant is it is not a PI because the transmitter never completely turns off like a PI. This is very interesting to me and I feel I can learn from everybody and thank you for your input cossaro. Yes it is different from a VLF but I was trying to say that it's not a PI also.But I am glad you are telling me about your experience with this FBS and BBS technology. It is very nice to meet you cossaro. Ok back to you.
John Tomlinson,CET[/quote]
Don't bridle your immagination, look at forward!!!!!
If you consider the inverted square pulse as a quite condition... after each transient you can sample at desired delay to test the receved eddy current as a strange PI-detector. This technology eliminates dipole effect on mineralized soil.
This is the most beautiful idea (patented!) that differentiate Minelab from others conventionals PI designs.
BBS-FBS..... synonym of evolved Pulse Inducion analisys IMHO.
... poor gold performance are only a choice in coil and timing design, gold respond too close on transient to be commercial to build a cheap DD coil.
Hi cossaro,
But what I meant is it is not a PI because the transmitter never completely turns off like a PI. This is very interesting to me and I feel I can learn from everybody and thank you for your input cossaro. Yes it is different from a VLF but I was trying to say that it's not a PI also.But I am glad you are telling me about your experience with this FBS and BBS technology. It is very nice to meet you cossaro. Ok back to you.
John Tomlinson,CET[/quote]
Don't bridle your immagination, look at forward!!!!!
If you consider the inverted square pulse as a quite condition... after each transient you can sample at desired delay to test the receved eddy current as a strange PI-detector. This technology eliminates dipole effect on mineralized soil.
This is the most beautiful idea (patented!) that differentiate Minelab from others conventionals PI designs.
BBS-FBS..... synonym of evolved Pulse Inducion analisys IMHO.
... poor gold performance are only a choice in coil and timing design, gold respond too close on transient to be commercial to build a cheap DD coil.