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Help: What Am I Doing Wrong?


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24 minutes ago, 67GTA said:

Wifi signals can also cause it to go crazy. Just about every house has a wireless network. You can try holding the coil in the air and noise cancel a few times to see if that helps in trouble spots. Can't remember how many frequency offsets the noise cancel has off the top of my head.

Thanks. Yes that to. We had a smart phone and was looking on som video about how to do noise canceling and ground balancing on youtube. So that might have caused it too? I did not think about that.

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9 hours ago, Hello said:

Thanks. Yes that to. We had a smart phone and was looking on som video about how to do noise canceling and ground balancing on youtube. So that might have caused it too? I did not think about that.

Powerlines and antennas can disturb some machines but usually, far enough from the interference source, nothing too bad to be not knocked down with a noise cancel step.

Forget your phone with the Nox, some friends can swear to hear it from other peoples nearby when they approach crowd.

Wet grass can be another fact...Pay attention to G.B. frequently if you are in that specific condition...

Definitely, I prefer to insulate myself with water where almost 99% I only deal with saltūü§£

 

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So I was just practicing and testing with the detector again. We tried another lawn, first we did noice cancel and ground balance. Then we took Field 1, held the detector with the coil down and had it still, it sounded a lot, the same when we held it in the air, so I guess it was EMI interference. But we changed the sensitivity from 25 to 15 and it went well and gradually tried to all the way up to 21, no noise then and tried different frequencies such as 15, worked well.

I then went back to the lawn I first wrote about which was problematic. I also first did noice cancel and ground balance, Field 1, but it sounded a lot of noise, but when I lowered the sensitivity to 15-16 it disappeared. When I tried to sweep it over the ground, it pepped sometimes and sometimes not, so that should be a sign that it worked well? It was the same on the other lawn.

Something that surprised me was when I tried to put it in the ground and hold still and sometimes lift it above ground in the air, still Field 1, sensitivity 15, and it went well in 10 KHz, 15 KHz, 20 KHz and 40 KHz, no strange sounds when still with the coil in the grass, or still in the air. But with the same sensitivity 15, it made a lot of noise at 5 KHz and in multi mode. That it would make more noise in the multi mode I had expected, but that it would make a lot noise in the 5 KHz mode surprised me. Shouldn't it be the other way around, that 40 KHz makes the most noise, 20 KHz less and 5 KHz the least?

Only when I changed the sensitivity to 11 did the 5 KHz stop making noise when I held it still, while the multi mode stopped at sensitivity 13. How can that be, should not 10 + KHz be more sensitive to EMI than 5 KHz? So the higher the frequency, the more sensitive to EMI? But here the lowest frequency, 5 KHz, seemed to be the most sensitive  and made noise while the others (except multi) were silent. How can that be?

I was maybe 50-70 meters from the powerline, when testing, but in addition, I went closer to the powerline, and tried to stand almost below the powerline just som meters from it, and it did not seem to give any EMI when I tried with 15 and 20 KHz, with sensitivity 15 and some higher. It seemed that there was less EMI, the closer I got to the powerline. Does that seem strange? Maybe it was something from the two houses by the lawn that disturbed the most, maybe satellite or similar?

Maybe the frequency in the powerline right now was weaker today maybe?

 

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Just FYI - With Equinox you have to GB separately for each mode and also, you could also  GB separately for each single frequency used if you are still hearing ground feedback.  But what you are experiencing is not ground noise due to out of whack GB but it does sound like EMI, as you surmised.  Once you go to single frequency, the multifrequency mode profile (e.g., Field 1) disappears and all you are left with is the models default or user adjusted settings. (Disc, tone settings, and recovery speed settings) associated with that mode.  IOW 5 khz in Field 1 will behave just tge same as 5 khz in Park 1 save for the mode associated tone and recovery speed settings.  Note that there is no iron bias filter when in single frequency.

2 hours ago, Hello said:

Shouldn't it be the other way around, that 40 KHz makes the most noise, 20 KHz less and 5 KHz the least?

Nope. It usually goes as you describe with the lower single frequency settings being more susceptible to typical generalized EMI.  The exception is 4khz with the newest software update which appears to run a tad quiet than 5 khz.  There are of course exceptions to this for specific narrow-band electromagnetic noise sources or strong emitters like invisible dog fences.

You are probably getting bombarded by multiple sources of EMI - power lines, cell towers, a nearby cell phone, residential WiFi, other radio transmitters, fluorescent light ballasts, etc.  All those sources interfere with each other and create local maximum and minimum noise fields.  Furthermore you detector is affected by RF noise picked up by the coil acting as an antenna and also noise that is directly absorbed by the microprocessor electronics in the control head (nearby cell phones are the typical culprit in the latter).

Finally, time of day affects load on the power lines (how much current is flowing) which translates into time dependent noise generation.  Finally,  he degree of humidity in the air can have a variable effect on noise levels as well as lightning discharges.

Try re-running noise cancel if you  change frequencies.

  HTH.

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I just got my Equinox 600 and unboxed it, charged overnight and went out in the yard to give it a try. I had the same issue I had to lower the sensitivity to 8 or less. Then it hit me I have an invisible fence to keep the dog in the yard. I went in and unplugged it and tried again. Now I am able to run up at 20-22 on sensitivity and it seems to be working ok in Park 1. I do have a bunch of junk in my yard as it was filled when the house was built and has lots of screws ,nails, bottle caps and scraps of metal but I guess this will only make me a better detector in the long run knowing how to deal with all the junk.

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When in doubt, see what Dave Johnson has to say:

http://www.fisherlab.com/hobby/davejohnson/ElectricalInterference.htm

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