High Tension Power Lines

[+Old Bet]

Did a cache this t weekend, and the GPSr was quite bouncy, even though we had lock on 5 or 6 satellites. Reviewing the cache logs, notice many others also reported a lot of deviation in the coordinates. This cache was near a height of land, overlooking an electrical power substation fed by high tension lines. It was perhaps a quarter of a mile away, although

well below our altitude on the hill. So I'm wondering: can power lines affect GPS readings?

[+AtoZ]

YES, high voltage power line emit EMF and will interfer with you GPSr getting a good signal. Any electrical device can do this. I made a mistake when I placed a cache and put the GPSr on a telephon switch box while it averaged. I did this two time and had a fair bit of error between the tow signals which was very untypical for my GPSr. I was also doing a cache that reqiired me to walk under some HVPL and I noticed it played haveic with the signal. I even walked back and forth under the lines to confirm that it was the HVPL that were the problem. So Yes anything that is electrical has the potential to interfer with a GPSr, even a nother GPSr close to yours.

cheers

[+Timpat]

From my experience in the field using Trimble RTK GPSr's the effect is minimal, unless you are directly beneath high-voltage (230KV) transmission lines, for example. I've researched this a bit and a Google search will bring up some studies on this. If you are about 30 meters away from such high-voltage lines you will see no effect I found in some literature. My Garmin Legend and 60C show no degrading of signal if you are a reasonable distance away from any power line, again, from my experience. I can see if you have your unit too close to anything that emits strong magnetic fields you may have loss of good signal. The GPS wavelength was chosen to avoid interference from these kinds of disturbances.

[Blue Contrails]

I see powerlines affecting my GPS reception all the time. There's a road here in town with high voltage power lines along the eastbound lanes and non along the westbound lanes. When I travel east I get 3 to 4 low satellite signals. When travel west I get anywhere between 3/4 to full bars from 6-10 satellites. (Both with a high gain patch antenna mounted on the roof of the car)

Edited November 11, 2004 by Blue Contrails