Cell phones and EMI

[signal_line]

Do cells phones affect depth?

If EMI is present, does it help to aim the detector in that direction when doing a noise cancel?

Thanks.

 

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[signal_line]

I'm kinda under the impression that nobody around here knows. i read somewhere that if a cell phone causes interference you probably won't even know.

 

[bleeohio]

Not to sure about emi, (I believe it does affect it though) , but I leave my phone in the truck because when I'm detecting it seems like everyone I know is trying to call me. Like they all have an app that lets them know I've turned on my detector.

 

[kenpodetector]

I always turn the cell to OFF when metal detecting it can cause interference. Lots of people leave there Bluetooth on IE interference, leaving the WiFi on interference. Depending on the phone band it always checks in with local cellular towers ie interference can happen. So leave it off but of course carry it with you in case you need it.

 

[GeoW]

Several years ago I experienced erratic behavior in an area that was on the fringe of cellular service.
It seems that the cell phone was continuously searching for its signal.
Long story short, turned the phone off, problem solved!

g

 

[Darke]

Look up GSM or LTE interference. The phone and the towers can interfere with anything in their bandwidth. They raise havoc with OTA tv channels and speakers without a filter.

 

[Possum]

I remember reading a thread a while back by I believe by Vferrari regarding cell phones and he suggested turning it off or placing it in airplane mode. Sorry my memory sux as I get older... "D"

 

[vferrari]

I remember reading a thread a while back by I believe by Vferrari regarding cell phones and he suggested turning it off or placing it in airplane mode. Sorry my memory sux as I get older... "D"

D that was with the Equinox which tends to be more affected by nearby cell phone EMI (I still keep my cell phone on when using Equinox, I just make sure it is nowhere near my Equinox control head while swinging, usually stuffing it in my left rear pocket).

I have never experienced nearby cell phone EMI with Deus and very little EMI under "normal" conditions that can't be handled by a frequency change (higher frequencies are less susceptible) and slightly lower sensitivity. I just initialize the Deus holding the coil at waist height for noise cancellation until I hear it start to chatter, select my mode, then adjust sense as needed and swing away. For severe noise situations, such as a nearby electric dog fence, you can crank notch up high (e.g., dial in notch to cover from the top of the disc range up to 80 or 90) and just attempt to cherry pick high tones. Not ideal, but at least it gives you a chance to pull a silver keeper out of the ground without dialing sensitivity way down. Sometimes, you just have to walk away from the site, though, and move on. Some sites are really noisy only at some specific times of the day or during periods of high humidity and you can work around that by properly timing your visit.

As far as depth is concerned, obviously, if you have to use higher frequencies and/or lower sensitivities to mitigate EMI, that is also going to advesely affect maximum detection depth. But that is what detecting is all about, proper management and balancing of all these trade-offs to find something that works for the situation at hand.

HTH

 

[DizzyDigger]

Depending on the bandwidth of the EMI, you may be able to
mitigate it as Vferrari has suggested. Truth is, cell phones
operate at 800-2100 MHz, which are much higher frequencies
than detectors operate at.

A cell phone, being an intentional transmitter, will transmit even when on,
but not in use, it will still stay in contact with the local cell towers.

 

[vferrari]

Depending on the bandwidth of the EMI, you may be able to
mitigate it is Vferrari has suggested. Truth is, cell phones
operate at 800-2100 MHz, which are much higher frequencies
than detectors operate at.

A cell phone, being an intentional transmitter, will transmit even when on,
but not in use, it will still stay in contact with the local cell towers.

That's true regarding the relationship to detector operating frequency but, especially with the Equinox, the phone appears to interfere with the control box electronics and microprocessor (which is operating at similar frequencies to the cell phone but should be shielded from RF EMI). Putting the phone closer to the coil and away from the control box seems to have less of an affect, as long as the coil is not picking up the phone metal itself.

It is actually amazing how immune to EMI the Deus is considering the whole design is built around wireless signal transmission. I guess the engineers were forced to innovate to make it more EMI immune than traditional wired detectors due to wireless' natural susceptibility to interference. Also, the target signal processing in Deus is done in the coil unlike traditional detectors, like Equinox, that process signals in the control box. That means with Deus, the signal processing electronics are further away from any cell phones or other interference causing electronics (e.g., GPS, walkie-talkie) you may be carrying on your person.

 

[Bodkin]

That's true regarding the relationship to detector operating frequency but, especially with the Equinox, the phone appears to interfere with the control box electronics

I was having issues earlier with my 800 signals bouncing around and remembered a reply on Tnet from vferrari regarding such and that an "on" cell phone could be one of the problems. I turned off my cell phone and it instantly went away! I keep the phone with me but now off.

 

[signal_line]

Thanks much for the info.

 

[trdking]

I keep the cell phone in my back pocket There is no better RF Blocker than the human body. Well that of course is not true there is water and lead but the body is 2/3 water so pretty darn good blocker. I can't say that I have ever experienced any interference But RF is RF so anything is possible.

 

[Possum]

D that was with the Equinox which tends to be more affected by nearby cell phone EMI (I still keep my cell phone on when using Equinox, I just make sure it is nowhere near my Equinox control head while swinging, usually stuffing it in my left rear pocket).

I have never experienced nearby cell phone EMI with Deus and very little EMI under "normal" conditions that can't be handled by a frequency change (higher frequencies are less susceptible) and slightly lower sensitivity. I just initialize the Deus holding the coil at waist height for noise cancellation until I hear it start to chatter, select my mode, then adjust sense as needed and swing away. For severe noise situations, such as a nearby electric dog fence, you can crank notch up high (e.g., dial in notch to cover from the top of the disc range up to 80 or 90) and just attempt to cherry pick high tones. Not ideal, but at least it gives you a chance to pull a silver keeper out of the ground without dialing sensitivity way down. Sometimes, you just have to walk away from the site, though, and move on. Some sites are really noisy only at some specific times of the day or during periods of high humidity and you can work around that by properly timing your visit.

As far as depth is concerned, obviously, if you have to use higher frequencies and/or lower sensitivities to mitigate EMI, that is also going to advesely affect maximum detection depth. But that is what detecting is all about, proper management and balancing of all these trade-offs to find something that works for the situation at hand.

HTH

Thanks V for clearing that up, I knew I read it some where's before, but kinda had my wires crossed between the Nox and the Deus, that comes with old age I suppose... LOL "D"

 

[HuntinDog]

Hey Sam,
These guys here know their stuff.
Glad to help.

and Welcome to TreasureNet

 

[GeoW]

Welcome Sam!

 

[signal_line]

The other day I was getting some chatter and decided to turn off the detector and see if the noise cancel helped upon re-starting. What I noticed was when i turned off the RC the chatter went silent (still had headphones on). I had my cell phone on in my front pocket. Any ideas why I was getting no chatter through the headphones?

 

[vferrari]

The other day I was getting some chatter and decided to turn off the detector and see if the noise cancel helped upon re-starting. What I noticed was when i turned off the RC the chatter went silent (still had headphones on). I had my cell phone on in my front pocket. Any ideas why I was getting no chatter through the headphones?

It takes about 30 seconds for the wireless headphones to pick up and lock onto and start receiving the coil detector signal directly once you turn off the remote controller (RC), during that time the headphones are silent. If you did allow the headphones the time necessary to start receiving signals directly from the coil and were able to detect just using the wireless headphones and there seemed to be less EMI related chatter, then the probable explanation is that the RC, being in close proximity to your phone may have been picking up phone related EMI. Once you switched to a direct wireless connection between the coil and headphones, the phone EMI went away because the headphones are further away from the phone than the RC. This is just speculation though, based on your description of what you observed. Hard to be sure without seeing (and hearing) what is actually going on first hand. EMI is complex often difficult to pin down the source and how that noise is getting into the system.

 

[Cyberdeus]

I believe firmly that cellphones can cause EMI. I have decided that from now on, I will just leave my cellphone in my car while metal detecting or at least I will try to put the airplane mode ON. At least to reduce the EMI