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Freq/Chan

A

Anonymous

Guest
I have a chance to drop in and see how things are going. I thought I would chime in on the topic of frequency and Time Domain and Frequency Domain.
One patents deals almost entirely with the Time Domain aspect of the Explorer. It is the retangular dirve to the coil and front end of the receiver. The block diagrams and other drawing is more concerend with ground compensation, the pulses to the TX coil, demodulators, they show three demods that are in pairs of two each for mid, low and the high frequencies. Once it leaves the demodulators and is filtered that is pretty much the end of the explanation so one would think this is just a Time Domain thing.
The second patent deal with the Frequency Domain and discriminaiton and is where you will find most of information I often talk about becaue it is the discrimination and Id that is the problem and not depth with multiple frequency or single frequency. Just about any good VLF and PI will get all the depth needed.
The third patent is fairly simple and deals with the coil. All three are listed in the back of the Owners Manual and can be looked up on the Internet. I have gone through them and "think" I understand what they are saying. As always there are areas that they don't go into as it is just how things are done with many electronic devices.
So it depend on which area you discuss as to which is best in terms of time domain or frequency domain <span style="background-color:#ffff00;">in my opinion</span>. If you look at the front end and don't get into the demodulators and the output of this section then it is time domain. Once you get past that then it is frequnecy domain.
<STRONG>The Explorer is different in that it is a groups of detectors that fall under PI or pulse induction. Minelab got past the discrimination problem by usng both frequency domain and time domain and the problem with power consumption by most PI detectors.</STRONG>
It does use 28 frequencies, it does shift these as far as the specturm is concerend with the bottom and top frequencies set. They are critical to discriminaiton and the pulse cycle, one narrow pulse and one long pulse is how they reject the soil minerals, discriminate and id metals. Noise cancel is very important and should be done over ground with no targets present.
Have a great Christmas and Holidays,
HH, Cody
 
When I say the top and bottom frequency are set it is that the top is no more than 100khz and the bottom is no less than 1khz. Each channel is a spectrum of 28 frequencies based on the one that is best for a specific detecting area. I am not sure how many variable are measured but external noise is how they are classified. A channel is just a term used to identify a particular spectrum and to interface with the user.
The only problem I see assocaited with a channel selection is if the channel is noisy. I see no difference in detetion depth or discrimination based on the channel. It is the noise that causes discrimination and depth problems so the channel with the least noise is best. I have often found that there are more than one channel that have so little noise that I cannot tell one from the other. It looks like the noise cancel will default to channel 5 but the circuits may well mesure noise that is less than I can hear so this is the best channel. If that is true than I would assume that auto noise cancel is the best way to noise cancel.
Merry Christmas
HH, Cody
 
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