if the se pro operates between 1.5 and a 100khz over 28 frequencies and the noise cancel has only 11 channels to choose from.what would the break up be,one channel = how many frequencies(28 divided by 11= ?)? so i'm thinking if i wanted to operate in a certain frequency range all i would have to know is the value of each channel and adjust to it.true or false?bye for now,emubob
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i'm confused
- Thread starter emubob
- Start date
works around + -14khz. look in yo u t ube.
emubob said:if the se pro operates between 1.5 and a 100khz over 28 frequencies and the noise cancel has only 11 channels to choose from.what would the break up be,one channel = how many frequencies(28 divided by 11= ?)? so i'm thinking if i wanted to operate in a certain frequency range all i would have to know is the value of each channel and adjust to it.true or false?bye for now,emubob
TwistedTig3r
Member
https://www.youtube.com/watch?v=xcChyUlgPIs
Not sure you will get a clear cut answer on FBS specifics. Probably get various answers on Noise Cancel as well. Time is your friend. The only way you are going to get many of the answers is by spending time with your machine. You can find a lot of information and many of times a push in the right direction on the Internet but ultimately it has to be your experience.
Not sure you will get a clear cut answer on FBS specifics. Probably get various answers on Noise Cancel as well. Time is your friend. The only way you are going to get many of the answers is by spending time with your machine. You can find a lot of information and many of times a push in the right direction on the Internet but ultimately it has to be your experience.
Chris(SoCenWI)
Well-known member
The explorers and CTX transmit square waves at two different frequencies; where they coincide can be one of the frequencies that is monitored by the machine. I believe that Charles(UpStateNY) posted oscilloscope traces of these years ago. They could go lower or higher with the frequencies or more than 28 samplings but there would be little benefit from that. When you do a noise cancel you are shifting the frequency of one of the square waves by a slight amount. If you hold the coil near your ears with your head phones on you can hear the frequency shift. So if Channel 1 had the first receive frequency at 1.5 kHz Channel 2 might have the first frequency at 1.51 Khz, not a big enough change to affect detecting ability.
Basically the reason for noise cancel, and sensitivity for that matter, is two deal with EMI. By shifting the transmit frequency slightly it might be possible to find a receive frequency with less noise at any one of the 28 monitored frequencies. I read some of the patent info years ago and if I remember correctly they completely ignore some frequencies for certain channels because they land too close to 50 or 60 hz power line harmonics.
Basically the idea that some channels are going to be more sensitive to certain metals/conditions is BS.
Basically the reason for noise cancel, and sensitivity for that matter, is two deal with EMI. By shifting the transmit frequency slightly it might be possible to find a receive frequency with less noise at any one of the 28 monitored frequencies. I read some of the patent info years ago and if I remember correctly they completely ignore some frequencies for certain channels because they land too close to 50 or 60 hz power line harmonics.
Basically the idea that some channels are going to be more sensitive to certain metals/conditions is BS.
Charles (Upstate NY)
Well-known member
Correct, the Explorer only transmits 2 square wave frequencies, it then processes the return signal of those 2 square wave frequencies AND their harmonic frequencies resulting in the 28 total frequencies advertised. The nature of a square wave vs a sine wave is that a square wave produces these harmonic frequencies. The noise cancel just shifts the two base frequencies a tad within the 11 possible choices to avoid interference, the harmonic frequencies change with them.
Chris(SoCenWI)
Well-known member
Charles,
I'm not sure about the harmonics part, the amplitude of the higher frequencies would be very small,
http://www.minelab.com/__files/f/11043
Can you make sense of this particularly 1.1.3, 2.9
I'm not sure about the harmonics part, the amplitude of the higher frequencies would be very small,
http://www.minelab.com/__files/f/11043
Can you make sense of this particularly 1.1.3, 2.9
Charles (Upstate NY)
Well-known member
Chris I think what they are saying in 1.1.3 is the Explorer not only transmits 'a' square wave which itself consists of several orders of harmonic frequencies but multiple square waves each with its own harmonic frequencies. When you look at the Explorer transmit signal on the scope you see basically two different square wave frequencies being transmitted, a long and a short in a repeating pattern, dot dot dot dash dash dash repeat. I don't know what the two base frequencies are, its highly likely they were chosen to give the machine the best of what a lower frequency can offer and what a higher frequency can offer. Higher frequencies have certain advantages and disadvantages, but don't get as much depth. Lower frequencies have certain advantages and disadvantages but go deeper. The Explorer tries to give you both in a single machine. So the two square waves effectively provides the Explorer with 28 frequencies of information, what they do with that information inside the machine is a mystery to me, the software and circuitry is where the Explorer magic happens. I had an engineer tell me once he thinks the Explorer has some elements more common with pulse induction detectors which compared to a VLF detector its like most soil isn't even there. That kind of makes sense since Minelab's high end gold detectors are pulse induction. I have also heard the soil over in Australia where Minelabs gold detectors are born is horrible, its so bad its almost a metal. In head to head comparisons in the field, on deep targets before they are dug the Explorer gets more depth and produces more accurate ID's vs the best VLF detectors. It has its limits, its no pulse induction machine and the Explorer will choke where we have heavy concentrations of volcanic black sand here in the Pacific Northwest but its better than the VLF's.
2.9 'may' be speaking to that pulse induction like behavior in the Explorer. Keeping in mind I'm no pulse induction expert but in pulse induction they are dealing with decay, the eddy currents induced in a target decay at different speeds depending on the target. Soil which produces by far the strongest signal also decays the quickest for the most part and so the timing of a pulse induction machine is tuned to allow the ground to decay and vanish before sampling for targets. Some targets like small gold also decay very quickly, iron decays slowly. So if you can get rid of the ground portion of the signal then the rates at which the eddy currents in a target are decaying tells you something about that object. Again I'm a rank amateur in my understanding of pulse induction and I know squat about the mysterious inner workings of the Explorer software and circuit. But it sounds logical that if they can get some pulse induction type of information out of the Explorer this would be useful right.
2.9 'may' be speaking to that pulse induction like behavior in the Explorer. Keeping in mind I'm no pulse induction expert but in pulse induction they are dealing with decay, the eddy currents induced in a target decay at different speeds depending on the target. Soil which produces by far the strongest signal also decays the quickest for the most part and so the timing of a pulse induction machine is tuned to allow the ground to decay and vanish before sampling for targets. Some targets like small gold also decay very quickly, iron decays slowly. So if you can get rid of the ground portion of the signal then the rates at which the eddy currents in a target are decaying tells you something about that object. Again I'm a rank amateur in my understanding of pulse induction and I know squat about the mysterious inner workings of the Explorer software and circuit. But it sounds logical that if they can get some pulse induction type of information out of the Explorer this would be useful right.