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POWER Lines


planetrobert
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I could be wrong ... I'm not a physicsist but I don't think that the presence of a magnetic field will result in errors. It may disrupt the signal and make for poor reception. Fewer clear signals may result in less accuracy but unless something can change the speed of the signal, no error will occur.

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I'm not a psychic, but I do play oone on TV, so you can believe me when I tell you that, "Yes" Lightning and Electric Lines do cause errors in your GPS (especially if there is red meat draped across the power lines).

 

--majicman (expert at everything - just ask me!)

 

maj-gps.gif

majicman

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I don't know the answer (though I am leaning toward "Tastes Great"), but I will share two experiences that MAY shed some light.

 

I found a nice spot for a cache along a trail in a park. I took a reading and made note of the coordinates. I came back the next day to verify and the first set was now 300 feet from the location (?). OK, just take another reading and try again. Went back a few days later to verify the coordinates. Same thing, way off! In a completely different direction. Clear sky, good signals. I thought maybe it was the power lines so I decided not to put a cache there.

 

On recent cache hunt the clue stated the coordinates of where the trail crossed the power lines. They were dead on.

 

So I don't think it was the power lines.

 

BUT...

 

The first power lines were on metal towers and the second ones were on wooden poles. Perhaps signal reflections were causing the problem.

 

Don't know if this helps...

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GC1427 has been around since Aug 03/2001

its name is the buzzing might be rattlesnakes

it is directly under high tension power lines

( the big metal towers) most cachers have found it with no problems the biggest problem has been bees.

So I would have to say that shoots that theory in the foot......... icon_rolleyes.gif

 

All who look are not lost

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GC1427 has been around since Aug 03/2001

its name is the buzzing might be rattlesnakes

it is directly under high tension power lines

( the big metal towers) most cachers have found it with no problems the biggest problem has been bees.

So I would have to say that shoots that theory in the foot......... icon_rolleyes.gif

 

All who look are not lost

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You really gotta remove that compass icon. It is absolutely massive! 53k and counting. It's been around since I can remember (8 years) and hasn't gotten smaller yet. I'm on a high speed connection but others will have more issues with it.

 

Jeremy

 

Jeremy Irish

Groundspeak - The Language of Location

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As a retired soldier, I have quite a bit of experience in the desert, hiking around power lines. As an electronics specialist now working for a power company, I have even more.

 

The short answer is yes, and no, and maybe.

 

First, power lines operate at a frequency of 60 cycles per second. The GPS signals are at about 1.4 Billion cycles per second. A well-designed GPSr will not be directly affected by the field of the power lines.

 

BUT... the power lines -CAN- raise the local noise floor (the ambient noise level of the area) to a level where reception of GPSr signals could be disrupted. This would be most noticable if there were a burned or arcing connection on the lines.

 

Another factor is the voltage on the line, and the field density. The two standards in out area are 115 thousand volts (kilovolts, or KV) and 345 KV. Guess which one will produce more field density.

 

Now, field density falls as a square to the distance. If you double the distance, the field density falls to 25%.

 

Bottom line, and in my experience... if you are close enough to the lines to worry about it messing with your GPSr, I think you have more to worry about first. Hope you got your grounded underware on. Hope you find this helpful.

 

Mike. KD9KC

El Paso, TX.

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Of course I don't know what I'm talking about but it seems to me that since GPS works by evaluating the times it takes for the radio signals to get to you from the several satellites, perhaps 14,000 miles away, I can't believe that any small path-length anomalies in the last few hundred feet that may be produced in some way by the power lines could make any significant difference in the total signal-travel time for the entire 14,000-mile distance.

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quote:
Originally posted by Jeremy (Admin):

You really gotta remove that compass icon. It is absolutely massive! 53k and counting. It's been around since I can remember (8 years) and hasn't gotten smaller yet. I'm on a high speed connection but others will have more issues with it.

 

Jeremy

 

Jeremy Irish

Groundspeak - The Language of Location


 

Your wish is my command, done and done.

 

(I stole it from here anyway!)

 

Always trade UP in both quantity and quality and Geocaches will be both self-sustaining and self-improving!

 

--majicman

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I was just on a cache hunt last weekend, starting my second attempt at finding Wild Arboretum, my enthusiatic six-year-old assistant leading me by 20 yards ...

 

A deep, dark cloud suddenly appeared over the tree line and quickly moved into position over us. In Portland, this usually means nothing more than you are about to look like you just went over Niagra Falls in a leaky barrel.

 

Beckoning my son to turn back, I was interrupted by one blinding fl -- what the -- make that THREE flashes of --- WOW THAT THUNDER IS LOUD! Less than a second between the flashes and the eardrum-splitting explosions, I think to myself as I notice my son no longer seems to be ignoring my weather admonitions, seeing as how he has already had the good sense to run past me on the way back to the car, leaving me for dead where I stood.

 

Okay, about 5 seconds per mile, that makes those thunderbolts precisely, oh, about death ray range of both of us at any instant, I think inside while I try to reassure and comfort my son with my calm, trembling exterior. 1000 strikes a year in the U. S., I recollect, but only about a third of them are fatal, right? Hurrying back toward the car, another flash brings a good two-second pause before hurtling a somewhat more subdued thunder crack at our ears, which I realize are still ringing from our first death-defying (deaf-defying?) encounter.

 

Amazingly, we both arrived at and entered our comfortingly rubber-insulated-from-the-ground car before a drop of rain fell, which was good because we didn't have to wait two minutes before an amazing cloudburst absolutely rendered my windshied wipers useless on their most hysterical setting. We never witnessed another flash, but we heard another thunderclap or two.

 

It was all gone in ten minutes as suddenly as it came, but we didn't resume the hunt that morning since we assumed the trails were muddy enough to get us in serious trouble with my wife.

 

In conclusion, I don't know how or if the lightning affected the reception or accuracy of my receiver. Frankly, I don't even know how my receiver made it back to the car that day, as I have no recollection of carrying it back. I do know, however, that lightning can have a direct and dramatic effect on the geocacher.

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A cool story, but one minor nitpick... icon_smile.gif

 

quote:
Amazingly, we both arrived at and entered our comfortingly rubber-insulated-from-the-ground car

 

The tires actually have nothing to do with it. When electricity strikes a metal cage it passes along the outer surface and doesn't enter the inside. You are protected inside a car because you are in effect sitting inside a metal cage (the steel frame of the car). However if you are in contact with metal that connects to the outer frame, there is still a possibility you could get a zap. Cars that don't completely surround you with this metal cage, such as convertibles, offer absolutely no protection at all. I've heard it said that ecause of the intensity of a lightning bolt, tires would have to be a mile thick and made of solid rubber (as opposed to filled with air) to offer any protection from lightning.

 

Oh, and to keep this on topic. I have noticed that my GPSr tends to jump around like crazy any time I am hunting under power lines. icon_biggrin.gif

 

[This message was edited by scooterj on June 16, 2002 at 12:16 PM.]

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A cool story, but one minor nitpick... icon_smile.gif

 

quote:
Amazingly, we both arrived at and entered our comfortingly rubber-insulated-from-the-ground car

 

The tires actually have nothing to do with it. When electricity strikes a metal cage it passes along the outer surface and doesn't enter the inside. You are protected inside a car because you are in effect sitting inside a metal cage (the steel frame of the car). However if you are in contact with metal that connects to the outer frame, there is still a possibility you could get a zap. Cars that don't completely surround you with this metal cage, such as convertibles, offer absolutely no protection at all. I've heard it said that ecause of the intensity of a lightning bolt, tires would have to be a mile thick and made of solid rubber (as opposed to filled with air) to offer any protection from lightning.

 

Oh, and to keep this on topic. I have noticed that my GPSr tends to jump around like crazy any time I am hunting under power lines. icon_biggrin.gif

 

[This message was edited by scooterj on June 16, 2002 at 12:16 PM.]

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I would think that if lightning or power lines were causing interference that the GPS would just say "weak signal". That's why there's 24 satellites, so if you're getting a distorted signal from one or two, hopefully you'll still be picking up enough of them to get an accurate reading.

 

I think there would have to be some pretty complicated math involved that affects each satellite signal coming in to make it say it's 300 feet away from where it was yesterday. Sounds like alien intervention.

 

A friend of mine was driving up to Maine recently and got there in about 1/2 hour less time than it usually takes. And when he looked at his GPS his max speed said 196 MPH. Granted, he drives like a maniac, but a 4-cyl Jeep just won't do 196.

So, we think he was abducted by aliens and had his memory erased, and they set him down further along on his trip - but neglected to notice his GPS.

 

Anyway, this is off topic. But I'd check for crop circles around the area . . .

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As soon as I read your post, I realized you were correct. In any case, the few inches of clearance afforded by tires, even if they were perfect insulators, would not offer much protection from a bolt that spans ground to cloud.

 

It was information told to me as a child while in a similar situation in the Colorado rockies, and of course I had no reason to question it then.

 

We did have the good sense to keep away from grounded metal surfaces in the car.

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This past weekend I was driving with my GPSr on as I was heading out to check on a spot I was thinking of placing a cache. As I drove along I was getting accuracy varying between 18 and 35 feet.

 

I then hit a stretch of road that ran adjacent/parallel to high tension power lines. I noticed that the accuracy jumped and was now fluctuating between 85 and 130 feet.

 

It stayed like this during this entire stretch of road. Then, at the very moment that the power lines switched to another direction and were no longer beside me, the accuracy shifted back to 18-35 feet.

 

I'm going to have to do similar experiments on other roads to rule out factors such as trees, topography, and the orientation of the road itself.

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