Jump to content

Power Lines,


Recommended Posts

IIRC, we've not ever had any problems with power lines.


That's not to say that it couldn't happen if it's an older unit and the EMI filters aren't working properly.


The best thing to do is actually get out there and experiment in your spot. If you are walking around the unit does some flaky things, then it might not be a good spot.

Link to comment

I have found that power lines do cause some GPS reception problems, but it varies with the GPSR. I have an old Apelco marine GPS that will refuse to work at all under some very high voltage transmission lines (e.g., 500kV). My Garmin GPS76 does a lot better, but the lines still cause some problems.

Link to comment

All logic and reasoning tells me it shouldn't interfere but the truth of the matter is that I have been to one cache in North Dakota see link where I had a hard time pinning down the signal - some report going to a museum area 120 feet to the east and some like me ended up about 150 foot west of the posted coords. There are a number of high voltage lines directly overhead.


Later a friend told me that the power company had come through and replaced old wire and insulators and now I see that virtually everybody is finding the cache with ease.


Seems to me that something in those lines was causing problems. Bad connection, loose wire, swaying tower - something.........

Link to comment
Why dont you post a question in the "GPS and Ham Radio" forum?  Some of those guys may have some information on this.

There's this thread in the Geocaching Topics fourm. But, I hadn't posted it since it wandered way off topic and didn't seem to reach an answer.


Then there's this short thread from when I posted the same question last summer.

Edited by Thot
Link to comment

Yes, it's true that the power in overhead lines runs at 60hz and normally should not interfere with your GPS but, in most urban areas there are a lot of transients from intermitant power surges and marginal connections at the pole, plus the RF interference from traffic signal switching circuitry etc. etc. I would imagine that, the more populated an area is, the more problems you will have. :D

Link to comment

Even though the frequencies are so different, the problem with the EMI is that the field is so large around some of those lines and the interference wreaks havoc on the internals of the GPS, not just the incoming signal. If you measure the field, it seems fairly insignificant, but in such close proximity and with a sensitive device like a GPSr, it will have an impact.


I would just note in the cache description that the coordinates may be suspect due to this issue.

Link to comment

Electronically speaking the 60HZ power lines ARE a HARMONIC (albiet a distant one) of the 2.4Ghz GPS signal. Theoretically speaking it is so distant the energy at that harmonic is not measurable. (Typically a harmonic is not measurable or significant beyond the 63rd harmonic (In this case 3780hz.) Therefore the powerline cannot be affecting the signal as they are at the 400,000,000 th harmonic. In practicality, the powerlines outside my house (125kv) drive my GPSr absolutely NUTS. I can move 100 ft away and it's fine. Go figure.

Link to comment

Any device that emits an electromagnetic field may affect a compass. It depends on how strong the field is relative to the earth's magnetic field. I have found that my GPSR can affect my compass if I hold it too close. But I have used my compass in proximity to high voltage transmission lines and did not notice a problem ... but I was not directly under the lines. The lines seem to affect the GPSR more than the compass. I would suggest you set the compass then walk under the lines and see what happens. It would be really interesting to try this with a DC transmission line, but those are very rare, most are AC. I don't think you will see much deviation, if any. But a steel transmission tower could cause a large deviation.

Edited by CharlieP
Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...