Frequencies is use at any one time

[Coast]

I have searched high and low for an answer to this question, maybe I’m not digesting the information right. Once a noise cancel is done, how many frequencies is the machine operating with? I know it will eliminate one or so because of noise but it would be nice to know which ones (in auto) so we can see what is being missed. I would hate to think that after a noise cancel the Ctx decides to ignore certain gold.

 

[bklein]

My understanding is that all TX and RX frequencies are just shifted, enough to reduce pickup of the nearby EMI frequencies. Bugs me that the noise cancel number rarely repeats if you retry the function. You can manually set the number and see if you notice the sensitivity of gold drop. I noticed a difference in pickup of bobbypins depending on the number but have forgotten how that worked out.

 

[Chris(SoCenWI)]

It depends.

Years ago I tried to read up on all the ML patents and white papers I could find. Not sure I ever understood it completely and the time elapsed since hasn't helped. Basically all the FBS detectors from Minelab transmit square waves at two different frequencies. One frequency is varied slightly during a noise cancel. (Fun, hold the coil up close to your earphones while you are wearing them, and hit the noise cancel button. The coil will induce a current in you headphone speaker coils and you can hear the frequency shift. You have to be a geek like me to consider this fun.)

It's looking now that Minelab's patents on multi-frequency technology other SMF detectors out there work in the same way on the transmit side.

The two transmit frequencies can be used to generate many frequencies on the receive side. What I believe I remember is that if a detecting frequency resulting from a noise cancel ends up on or close to a 50 or 60 Hz power line harmonic they just ignore that frequency because it is very likely to be very noisy.

I've seen some videos where people think that certain noise cancel frequencies can make a difference on what the detector can find. I'm pretty well convinced this is BS, and described why somewhere on this forum years ago.

Chris(SoCenWI)

 

[Coast]

Thanks for the info, I kinda figured they used some sort of shift, that is the same thing the V3I did but you had control over how much and which direction to reduce emi.