MnGCA

RJ

I've read many logs about how high voltage power lines play havoc on people's gps receivers.

I've seen, "I was zeroing out but there were some powerlines close by so maybe I was not getting a good reading."

I thought it might be interesting to see what a very limited and brief search on Google might find. Here's a summary of what I've found after 10 minutes of searching the web. Here's the page I copy and pasted this from.

Q. What is the effect of powerlines on the GPS signal? Can GPS be used under or in near proximity to strong magnetic fields?

Etherington: Magnetic fields have no effect on the GPS signal, nor do power lines; even electric transmission towers and their stronger EMF emissions have minimal effect.

Lange: In North America the energy from powerlines is 60 Hz and the harmonics of 60 Hz, (50 Hz in Europe) with the harmonic energy falling off rapidly as the frequency increases. Magnetic field power line harmonics are not a factor at GPS frequencies.
However, certain computers radiate electromagnetic energy at the GPS frequency and can interfere with a GPS receiver. This can be verified by moving the GPS antenna closer to the suspect electronics and observing the GPS receiver SNR values. If the SNR decreases with the GPS antenna near the suspect electronics, then the electronic device is radiating measurable GPS interference. The remedy is to move the GPS antenna away from the offending electronics.

Stenmark: Overhead power transmission lines create electromagnetic fields. We have seen little or no effect of powerlines on the GPS signal. Overhead telephone lines pose no problems. Operation of GPS receivers near strong magnetic fields (e.g. electromagnetic cranes) also shows little difficulty.

Maybe something to think about the next time you're under some. Next time I'm going to do a test of my own.
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Joelcam · Posted: Wed Apr 07, 2004 9:25 pm Post subject:

Good Topic RJ!
I've had some experience getting a good signal under the real high voltage power lines, like the ones along I494 in the west metro.
I've also experienced interference from those same lines while transmitting a video/audio TV signals back to downtown Minneapolis from the Plymouth area. The field is strong at a considerable distance, the masts on our trucks will not go up because the sensor can detect that field from distances greater than 800 feet from the power lines.
I know one of our engineers had the compass on his dash mounted GPSr spin out of control when he parked on top of a live downed power line in Siren WI. after the tornado 2 years ago. Luckily he was not hurt and moved the truck without incident.

15Tango · Posted: Thu Apr 08, 2004 2:56 am Post subject:

My "Down in the Valley" cache is near some powelines, and I get constant gripes about how inaccurate the coordinates are, and I've been out to double check them a few times and usually get a variation of about 0-50 feet, which I feel is well within the norms of other people's caches I've sought (I'll place my GPSr on the cache itself, and it'll sometimes read right on, or up to 50 feet away).
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Lyverbird · Posted: Thu Apr 08, 2004 6:06 am Post subject:

I've been to caches that are real close to power lines and have had no problem and yet at others with the powerlines, it hops about abit. So it's a coin flip for me. I'm more incliend to blame the Witch Lines.

What are Witch Lines I hear you all ask.

Witch lines occur all over the globe and may strech a few hundered miles or a few thousand. A guy in England found them and studied them about 30 years ago. He wantted to know why is car stereo always gave static in the same spots on his travels. So he started plotting each static spot on his map. Lo and behold, lines started apearing on his map from his dots.
He got others to help, and a grant from a universcity, and expanded his maps and well all these lines showed up with no explanation. No powerlines, above or below ground no other reasaonable explanation.

Hence they became know as Witch Lines. At the time, I remember maps being published in the papers.

Liverbird, WWPP
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Moe the Sleaze · Posted: Thu Apr 08, 2004 6:40 am Post subject:

towlebooth · Posted: Thu Apr 08, 2004 6:56 am Post subject:

Marsha and Silent Bob · Past MnGCA President Joined: 02 Sep 2003 Posts: 6261

I have several caches (Size Twenty-two Tennisioux, Ruudee Ruudee Ruudee, some others that are ?) that are located in close proximity to powerlines...

I find that they are better to use as a scapegoat and less as a true fact Smile

I need as many excuses as I can get Wink

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Sad state of affairs.

Lyverbird · Posted: Thu Apr 08, 2004 7:54 am Post subject:

I have heard of lay lines and rift lines, but I don't remember there being a connection. I would strongly discount the Roman roads. Many of Englands roads, and I would therefore also assume Europes roads, still follow the exact path of the origional Roman road. Thousands of Roman mile markers still are in place (even though loads were removed during WWI and WWII so the Germans couldn't find their way if they did invade). Since they built very straight roads, there was never a need to change them. I can see no reason for them having a higher metal content than the surounding ground. They used local stone and gravel where and if they actually built up a road out side of a city. Of course, they did build stone roads in the cities and again local stone was used.

On a different path of thought, I can give you the reason the romans decided how large the booster rockets on the space schuttles are.
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Lyverbird · Posted: Thu Apr 08, 2004 8:10 am Post subject:

Warning Off Topic But technical.

The Space shuttle's booster rockets had to travel via train, through a mountain tunnel. the tunnel was dug to fit the the train, the train was built to fit it's axles. A few hundered years ago, horse wagon makers started making axels for these new fangled iron horses. Now the Wagon builders had being making their wagon axels to a standard size from hunderds of years. They were made to this size for a very good reason. There were ruts in the roads from hunderds of years of wagon wheels being made to the same size. If they changed the size, the wheels would not fit and so the axles would break. Who put the ruts in the roads. The Romans did. They were the first mass producer of wagons and they had more of a need to carry mass quantities of stuff long distances. The old English and Europeans didn't travel so far or carry so much. The Roman wagons and charriots needed to be built to a standard so that replacement parts could be more easily had. This standard was ofcourse the width of 2 Roman horse behinds.

This is why the booster rockets size was determined by the width of 2 roman horse rumps.

And so ends todays history lesson.
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Save the earth.
It's the only planet with chocolate.

Kitch · Posted: Thu Apr 08, 2004 8:59 am Post subject:

Size Twenty-two Tennisioux--NO PROBLEM WITH POWERLINES...but fun to walk under them to "hear" them hum......

....I forgot all about the mess of "something with juice" underground at the centris bug bank...something there played all kind of tricks on my gps.

I also had all kinds of tricks going on up at the "indian mounds" ..but I get creeped out there.......spirits and all.....

Marsha and Silent Bob · Past MnGCA President Joined: 02 Sep 2003 Posts: 6261

KC0GRN · Past MnGCA Board Joined: 22 Feb 2004 Posts: 1424

Interesting stuff on the ley lines, I'll haveta look those up. Wonder if they're just in europe, or if they're global?

Would be interesting to place a cache on one Wink

Difficulty: 5 stars

Kitch · Posted: Thu Apr 08, 2004 12:04 pm Post subject:

don't give CAG any ideas...

KC0GRN · Past MnGCA Board Joined: 22 Feb 2004 Posts: 1424

good point. And here I thought I only had a couple caches left in hidden falls, that area is lookin to be another Saturday trip for me. Though not for a couple weeks, too many events and such.

Lyverbird · Posted: Thu Apr 08, 2004 12:21 pm Post subject:

I read up on the ley lines and it reminds me that many Myan ruins are in a line with Egyption pyramids. But, I digress, again. Nothing is mentioned about electrical or radio interferance on ley lines, but a search of the net reveals nothing of Witch lines. Now, what I'm remembering was 30 years ago and my memory is not that great. Perhaps they are related. Though I don't remember histroical sites being invloved.
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Save the earth.
It's the only planet with chocolate.