GPX4500 - One for the EMI gurus

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GPX4500 - One for the EMI gurus

Post  Guest on Sat May 16, 2009 5:16 pm

Over in the west last year I experienced some really bad interference one particular day that defied explanation as I was detecting an area that I had been working for more than a week without interference. I mentioned it a few blokes back at camp that evening and they said that they experienced the same thing that day. One of these blokes said that he had heard that satellites could cause interference at times and I'm wondering if anyone can verify this.

I guess it could have some creedence given that satellites do transmit signals on various frequencies.

caveman

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Re: GPX4500 - One for the EMI gurus

Post  gollstar on Sat May 16, 2009 7:25 pm

It wasnt that day the plane went spastic over west oz, they reckon it was because of a RAAF rader station or some such thing,unfortunatly talbot,maryborough and dunolly are right smack bang under flight paths off to europe/asia every effing 5 minutes what may play up with the detectors would be there air search radar/weather radar/comms traffic etc think of a metal detector as a hand held radar your trying to get a return from a metal object same deal as sonar thats why they coat submarines in rubber to obsorb the sound so not giving a return,so when your pinging and there pinging {theres is bigger}and your detector plays up its prob just there rader,it would be interesting to ask some pilots if they get emi over maryborough dunolly, all though i dont think the minelabs are that powerful,

DISCLAIMER;This is only my humble opinion, by no means do i claim to be an expert
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Re: GPX4500 - One for the EMI gurus

Post  Beer Beeper on Sun May 17, 2009 12:05 pm

Maybe or maybe not, some of the EMI interference is from some kind of military base in the outback sending out and receiving strong signals ? Like the about 1000 CIA operatives outside of Alice Springs monitering international communications, etc. It is no secret and they make no attempt to hide this, as I have seen this on public TV here about 3 times, available for anyone to see. Like on the TV show "Don't Forget Your Passport", New Zealander and travel host "Ellis Emmett" explains this clearly in his TV commentary on his trip to Alice Springs.

Don't Forget Your Passport: Central Australia
http://www.yummydvd.com/safemode/cms/component/page,shop.product_details/flypage,shop.flypage/product_id,44/category_id,65/manufacturer_id,0/option,com_virtuemart/Itemid,3/
"Australia’s Northern Territory is home to many Aboriginal people, and Ellis Emmett meets some of its more artistic natives in the town of Alice Springs...."

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Re: GPX4500 - One for the EMI gurus

Post  alchemist on Mon May 18, 2009 8:12 am

G'day Caveman,
On the opposite side of the coin, the magnetic flux emanating from the sun has doubled over the last 100 years, and 40% of the increases in coronal disturbances have occurred since 1964. What this means is we could have a very bad hair day every now and then. Was there a lot of static in your hair that day?

Seriously many reputable scientists are now coming to the conclusion that this increase in solar activity is what is causing global warming and not Co2 emissions. New findings are beginning to support this theory as they show the rise in Co2 in the past has lagged temperature, not the other way around. Co2 is released as a result of the heating and it’s the earths’ cyclic response which will eventually aid in cooling the planet not heating it. Strangely many are clinging to the manmade Co2 theory with religious fervour, labelling anyone who suggests an alternate theory as heretics. It’s become such a big money cow, and so many are giving suck and depend upon it for their living that they don’t want to let go.

Anyway that’s a side point, if you can remember the date the problem happened you may be able to find on the net solar wind activity for the day in question. If it was the sun that was at fault then it will have interfered with many global communications systems on earth.

Satellites tend to have very low powered transmitters, because there aren’t any obstacles out there and power is generally conserved. The transmitters are also usually very narrow band and up into the microwave bands which at a distance and despite what many believe, have very little effect on detectors.

I’d put my money on that raging radioactive beast out there that’s going through a pretty wild phase at present.

Cheers
Grey
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Re: GPX4500 - One for the EMI gurus

Post  alchemist on Mon May 18, 2009 9:38 am

G'day Caveman,
I just checked where we’re at in the sun cycle, and we're passing through a solar minimum phase at present, which isn’t scheduled to peak again until about 2013. The last solar maximum was around 2000, so if the disturbance you experienced was fairly recent, and related to the sun, it would be from a super coronal mass ejection (CME) which can occur at any time during the sun cycle, but more often during a solar maximum period.

A CME at present can occur around every second day, however couple this with the increasing coronal flux density, the potential exists for random instability of our detectors at any time.

Some interesting reading about solar storms
http://www.foxnews.com/story/0,2933,478024,00.html
http://www.newscientist.com/article/mg20127001.300-space-storm-alert-90-seconds-from-catastrophe.html?full=true

Cheers
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Re: GPX4500 - One for the EMI gurus

Post  mulgadansa on Mon May 18, 2009 12:13 pm

Gday Caveman
I live in Dongara in WA and regularly haunt the Murchison/East Murchison with a 4500.
When you had the bad EMI day did you notice if the wind was any different to other days, especially in intensity or direction?
I've found that, together with storms of any size, even hundreds of km's away, reek havoc with the EMI levels.
Best means I've found to combat that so far has been to downsize to an 8" mono and there is a huge difference in the EMI levels then.
cheers
Brett
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Re: GPX4500 - One for the EMI gurus

Post  Tributer on Mon May 18, 2009 3:53 pm

Hi Gollstar, i cant add to the sources of EM/interference sources with any authority, however the best way to absolutely beat it is to detect late at night.

Some very noisy areas become very quiet at night and you can hear faint signals with ease. If you have an old gold patch/run where EM/interference was a problem go back at midnight and try it, you may be surprised by the results.

Night detecting is a favourite pastime of mine and the lack of noise of any kind makes detecting very pleasurable. Plus you don't wander as far at night and tend to cover the ground around you more thoroughly.

I feel its best to detect with a buddy close by at night, carry a radio each and to have a very good headlamp. Winter is a good time to detect at night as there are not many moths and bugs flying at your headlamp (which can be a problem in summer).

Cheers Tributer
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Re: GPX4500 - One for the EMI gurus

Post  Guest on Mon May 18, 2009 5:59 pm

Thanks for all the comments fellas. It was just one of those bad days I guess where everyone was copping interference - maybe the sun or distant storms that we weren't aware of. It was there one day and nothing more after that day.

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Re: GPX4500 - One for the EMI gurus

Post  GoldstalkerGPX on Mon Jul 27, 2009 11:22 pm

Hi All, Interesting reading there, I have encountered emi problems before and when it becomes overpowering or too annoying I tend to put on the DD coil and run the machine in cancel mode this usually sorts things out. Night prospecting sounds like a thing to try too, had not considered that.
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