Frequency question

[Mike Hillis]

Ok...so the Explorer II has 11 different noise cancel selections. Can anyone tell me which frequencies are active for each of the 11 selections?

Thanks,

Mike

 

[Captain Kirk]

Mike,

I will attempt to provide an answer that is not unduly technical.

The two basic types of detectors are frequency domain and time domain. What follows is my understanding of the basic difference between the two techniques.

In the frequency domain the transmit coil is usually excited with a single frequency at a time (sinusoidal). Some of these machine can operate at more than one frequency, but generally only one at a time. Generally, for this case the phase relationship between the transmitted and received signal is used to define the target ID.

In the time domain the transmit coil is excited with rectangular pulses. For this case there is a fundamental and a series of harmonics. When doing a NOISE CANCEL operation, then the fundamental frequency is shifted slightly by selecting up to 11 different fundamentals and associated harmonics.

For the time domain detector it is the shape of the received signal that is used for target identification.

Hope this helps,
Glenn

 

[Mike Hillis]

Thanks for the reply Glenn. That helps a little bit.

I guess a better question would be, "Would I get any benefits from manually selecting a channel based upon the frequencies being used within that channel? So for gold jewelry hunting where electrical interference isn't a real issue, would one channel provide better freqs for my desired target over another one?

Thanks again,

Mike

 

[Captain Kirk]

Mike,

I do not claim any great insight into the overall effectiveness of switching channels.

THE AMOUNT OF FREQUENCY CHANGE AVAILABLE

I believe that the NOISE CANCEL operation is intended to improve performance for a specific types of interference. I do not think that much frequency change is necessary to be useful for this objective. I think that Mine lab has selected a fundamental frequency that has been optimized for the best overall performance, but not necessarily for any particular type of target.


THE EFFECTIVENESS OF CHANGING CHANNELS

For the most part I use the NOISE CANCEL when I am hunting with companions that are also using Explorers. This is quite effective if done correctly. For electrical interference (particularly if it is broad band) the changing of frequencies is not quite so effective, but there is some improvement. With that in mind, I do not think that selecting different channels will significantly improve the performance on any given target. Be advised that I could be very wrong here.


REGARDING MANUALLY SELECTING CHANNELS

My personal preference has been to use the automatic channel selection (NOISE CANCEL). If this process does not yield satisfactory results, then one might try manually selecting a channel for better performance.

HH,
Glenn

 

[leroy1937]

n/t