Wind & EMI

[ozziii]

I read on Facebook that wind can effect EMI, like if you're near power lines & wind is blowing from your position towards power lines then EMI would effect detector less than if its blowing from direction of power line towards your position.
Like the wind is blowing the EMI away, is this true, does wind direction effect EMI.
I don't know, just read something about it so thought I would ask the clever people on this forum.

Thanks.
Paul.

 

[RedDirtDigger]

Hi Paul, don't know the science behind it, however I have noticed that a fence I have detected near many many times can interfere with my detector more on some hot windy days, and on one side of the fence you can detect close to it and on the other you had to be 20 metres away. The distance changes depending on the day.
This was with a 2200 and 4500. It does not seem to be much of issue so far with the 7000.
RDD

 

[Jon]

Don't consider myself clever but have noticed on windy days the emi in general can be worse. They say wind can affect the charge, ions, in the air. I have a mate who complained about your question of it blowing in from nearby sources, could be something in it.

 

[davent]

Was experiencing some emi problems the otherday, long way from any obvious source, maybe distant thunder storm? Anyway, out of frustration, I turned my tdi oz pro off, and back on, tuned freq and did ground balance again, all good for another hour or so.

 

[ozziii]

Could be right Jon, thats what I was trying to find out because I sometimes detect near HV power lines so if there is a little wind then I would be better off detecting on the side the wind is blowing from, being upwind would have less emi than the down wind side.
I'm not sure if wind has any effect as emi isn't actually a thing, although I guess wind can blow soundwaves so maybe emi works the same way.

 

[mbasko]

Theres definitely something to it. I've noticed the EMI worse on windy days with most machines I've used. The SDC is particularly sensitive to the wind & will start getting more erratic as the wind picks up + noticeably quietens down as the wind drops off. It's nothing that would stop you detecting most days & can be tuned out mostly although you may have to retune more often which can be annoying. It is also worse again if there is an approaching storm about.
I know that hot, dry windy days can cause issues with digital TV reception in some areas too.

 

[Jafnob]

I have always found the cooler and windless days are always better, I always try to detect early in the morning or later in the afternoon as the wind is generally calmer and temp is lower, also noticed I can really crank up the 5000 early on in the day and the machine seems to punch much deeper than later in the day, I usually reset the machina at about midday, eg get my test piece out and air test again and almost always find the machine isn't performing as well as it was early on

 

[blisters]

Just a guess but dust particles carried by the wind getting charged and affecting the coil?
Jon

 

[Jon]

Storms 100%, you can be out, blue sky all good but now and then pings and false signals of rising and dropping tones.Get home that night and on the news are thunder storms up to a few hundred ks away. Once had some dirt bike riders that every time they came within a few hundred yards of me my gpx went nuts. Sensitive things, these beepers.

 

[Moneybox]

We spent about 10 days detecting a flat patch that was miles away from any type of radio transmission. There were no hills or trees, no hot rocks, no rubbish just perfectly flat ground with nothing but fine gold. The SDC worked perfectly when it was still or very little wind but as the wind picked up so did the false signals. Every swing in one direction let out a squeal as the swing ended and another as the opposite swing started. The only way to counter it a bit was to allow the swing to slowly rise well above the ground and then swing down again. It didn't fix the problem but it made it workable because both false signals were more or less while the coil was off the ground.

We were chaining and it just seemed like the last chain mark was metallic. All the retuning and restarting did nothing to help. We discussed it with two others both using the the 7000 and the SDC. They were battling with the same problem but they were both working in a more protected area so their false signals were not as bad as ours.

I came to the conclusion that the strong wind was creating an electrical current, most likely static on the SDC's plastic housing. It had no effect on the ATX in the same conditions. If it had been the usual EMI the ATX would have felt it too even though it can be tuned out if necessary. The wind was so strong that Mrs M was wearing wet weather gear even though it was not very cold.

 

[KarlS]

We spent about 10 days detecting a flat patch that was miles away from any type of radio transmission. There were no hills or trees, no hot rocks, no rubbish just perfectly flat ground with nothing but fine gold. The SDC worked perfectly when it was still or very little wind but as the wind picked up so did the false signals. Every swing in one direction let out a squeal as the swing ended and another as the opposite swing started. The only way to counter it a bit was to allow the swing to slowly rise well above the ground and then swing down again. It didn't fix the problem but it made it workable because both false signals were more or less while the coil was off the ground.

We were chaining and it just seemed like the last chain mark was metallic. All the retuning and restarting did nothing to help. We discussed it with two others both using the the 7000 and the SDC. They were battling with the same problem but they were both working in a more protected area so their false signals were not as bad as ours.

https://www.prospectingaustralia.com/forum/img/member-images/3960/1449834987_250_nugget_patch.jpg

I came to the conclusion that the strong wind was creating an electrical current, most likely static on the SDC's plastic housing. It had no effect on the ATX in the same conditions. If it had been the usual EMI the ATX would have felt it too even though it can be tuned out if necessary. The wind was so strong that Mrs M was wearing wet weather gear even though it was not very cold.

Your conclusion is most likely correct. The wind and low humidity may create static electrocity not only on the detector but on the ground itself. Resulting discharges then create EM I .
EM I is basically same as radio waves and as such can not be carried by the wind.
Karl

 

[ozziii]

EMI is basically same as radio waves and as such can not be carried by the wind.
Karl

Thats what I wanted to know, I wasn't sure how wind could move something that physically isn't there, but was told it could.
So if that is correct, then it will not make any difference which side of HV power lines I detect on if there is a bit of wind around.

 

[davent]

Other factors that result in emi, solar flares from the sun, if they are active, then you get emi from that. RAAF in the area, semi trailer activity, mine sites , prisons, police stations, any where where a lot of radio traffic happens, HF anf VHF are probably going to be the biggest pains, VHF have multiple re trans stations that keep the signal strong, and HF is a strong signal to start with. TV stations, mobile phone towers, electrical storms (they don, t even have to be close to interfere with electronics) wind will move ionised moisture in the air, so emi can be transported by humid air via wind, in inconsistant waves.