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Wind farm affect on GPS?


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I visited Walla Walla Washington this week and noticed an anomaly with the GPS in my car. A few minutes before getting off of Route 12 coming into town, the GPS got very confused, showed me quite far off the route itself. Cleared up just before I got to my exit to pull into town. I was puzzled as to why but pretty much forgot about it -- until a few days later when the GPS did the exact same thing in pretty much the same spot as I was LEAVING town.

 

The only obvious, visible source of interference was a nearby wind farm. BUT... there are numerous wind farms along the route took between Portland and Walla Walla, and I only had this problem in one location. And searching online for wind farm effects on GPS didn't turn up anything conclusive.

 

Anybody else live near one of the facilities seen anything similar? Or have other ideas about that one spot in Washington?

Edited by Portland Cyclist
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I visited Walla Walla Washington this week and noticed an anomaly with the PS in my car. A few minutes before getting off of Route 12 coming into town, the GPS got very confused, showed me quite far off the route itself. Cleared up just befe I got to my exit to pull into town. I was puzzled as to why but pretty much forgot about it -- until a few days later when the GPS did the exact same thing in pretty much the same spot as I was LEAVING town.

 

The only obvious, visible source of interference was a nearby wind farm. BUT... there are numerous wind farms along the route took between Portland and Walla Walla, and I only had this problem in one location. And searching online for wind farms affecting GPS didn't turn up anything conclusive.

 

Anybody else live near one of the facilities seen anything similar? Or have other ideas about that one spot in Washington?

I have found a couple of places in Kansas where that happens. After I stopped and looked around carefully the second time it happened I discovered that the highway had been moved about 100 yards and the GPS was showing me where I was but the highway where it used to be.

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Interesting anecdote but this was different from a map error. It wasn't that the GPS thought I was following a line offset from the road.. The error had my position fluctuating widely from one side of the road to the other, as well as ahead of and behind my real position.

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I was wondering about the dates? When were the errors noticed.

We have recently had two large solar flares and cautions about effects of that on GPS was mentioned in the news, but it would have been a real coincidence for anything to occur in one location exactly when you were traveling thru that exact location...

 

I think I would be considering other things, but I can't say what it would be... mountains or were the Power lines really close to the road there?

Interesting subject. I use APRS as a Ham, and have seen some weird tracks caused by something or other while people drive around the country... perhaps they have a local jamming device for security reasons.

 

Doug 7rxc

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Hmmm, interesting. It does seem to be site specific so the answer must lay there. I looked up the radio frequency our GPSrs use and found it is 1575.42 MHz. Perhaps this wind farm facility is emitting radio waves of this or near this frequency? Either as part of the electric generation, or some other random consequence? I understand the DOE picked this frequency to avoid such issues.

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Hmmm, interesting. It does seem to be site specific so the answer must lay there. I looked up the radio frequency our GPSrs use and found it is 1575.42 MHz. Perhaps this wind farm facility is emitting radio waves of this or near this frequency? Either as part of the electric generation, or some other random consequence?

 

Possible, but wouldn't that rather cause the GPS to lose signal completely instead of giving false readings?

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Cacheholic: Typos corrected, thanks.

 

MtnHermit: You're thinking the same direction I was, constantly changing multi-path reflection from lots of blades. Radio equivalent of flicker vertigo. But why only near that one spot, while there were so many other wind farms along the route? Maybe having an exact line of sight to just that one stand of windmills? Another possibility is perhaps only that one group was in full operation and oriented for a specific wind direction that day. Along the drive I noticed many in other locations had their blades feathered, not spinning.

 

I don't have a GPS track of the events, but I wish I had. Maybe someone else in or around Walla Walla could go for a drive and see if they can reproduce the error? Guess I could go ask for that experiment in the NW forum*.

 

* Edit to add: Done! http://forums.Groundspeak.com/GC/index.php?showtopic=269751

Note to mod: Hope you don't frown on the cross-post. This one is the "real" discussion, the one in the regional forum is just to get some folks over there to participate in this one.

Edited by Portland Cyclist
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This is looking to be the most likely answer so far. Guess I owe NicknPapa an apology -- he suggested the same thing early on (post #2) but I dismissed the notion (post #3) because it seemed like the GPS was trying to position me all over the place, not just get me back on the road. But there may be enough variations in direction in the new Hwy 12 to account for that, it's not just a line paralleling old Hwy 12. So the TomTom app would see me going towards and away from the "correct" route a few times.

 

Thanks!

Edited by Portland Cyclist
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So here are two pictures of the area in question.

 

ScreenHunter_02Mar051923.jpg

 

This is the track log in mapsource over the roads my Gps thinks are there.

Your track log reflects the way Highway 12 looks now. The problem isn't your GPS - it's the map. Even the most recent (865) TomTom (Teleatlas) maps are out of whack for the current routing of US 12.

 

In some parts of the world, Teleatlas has more current coverage. In others, NavTeq wins.

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"The problem isn't your GPS - it's the map" ...

 

It should be interesting to see how soon the corrections make it into the TomTom app. Apart from the regular updates offered several times a year, the app itself can download incremental updates/corrections every time you use it. Or as TomTom puts it on their website: Map Share™ technology -- Make changes to your own map and benefit from thousands of updates made by TomTom users every day – on-demand, wherever you are, free of charge.

 

They must not have enough contributors from Walla Walla -- I *did* download the most current updates the morning I left and still got this surprise.

Edited by Portland Cyclist
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"The problem isn't your GPS - it's the map" ...

 

It should be interesting to see how soon the corrections make it into the TomTom app. Apart from the regular updates offered several times a year, the app itself can download incremental updates/corrections every time you use it.

While the MapShare corrections can come at any time you make a computer connection to your TomTom, new roads are NOT part of the deal. Corrections to existing map features can be 'patched' using MapShare (much as you do it yourself), but even if you add a road on the TomTom yourself, it isn't part of your map set, can't be used, and is only used for reporting purposes back to Teleatlas. Major realignments like that, and new roads (which is essentially what US12 is up there), come only with the quarterly map updates. The most recent (865) just arrived a couple of weeks ago, so wouldn't expect the next one until the middle of May.
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On a side note, check out what your car compass (if you have one) does ...

Heck, I don't even own a car -- just rent when I need one :)

 

But this bridge is "the longest continuous truss bridge in North America" -- an awful lot of steel in interesting shapes might mess with a compass.

 

800px-Astoria-Megler_Bridge01_2008-02-26.jpg

Edited by Portland Cyclist
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Last fall, when we traveled on US 12 west of Walla Walla the same thing happened to us. Our Nuvi 550 with no new maps also indicated we were traveling through fields.

When the new road got back on the old road every thing looked OK.

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On a side note, check out what your car compass (if you have one) does ...

Heck, I don't even own a car -- just rent when I need one :)

 

But this bridge is "the longest continuous truss bridge in North America" -- an awful lot of steel in interesting shapes might mess with a compass.

 

800px-Astoria-Megler_Bridge01_2008-02-26.jpg

Yeah, we find the problem is at the north end where is far less superstructure.

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...we find the problem is at the north end where is far less superstructure.
Interesting. What's your typical compass behaviour there? Wandering aimlessly, or a specific offset? With a near four mile long stretch of steel running away from you, I'd guess the compass would want to line up in the direction of the bridge.
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...we find the problem is at the north end where is far less superstructure.
Interesting. What's your typical compass behaviour there? Wandering aimlessly, or a specific offset? With a near four mile long stretch of steel running away from you, I'd guess the compass would want to line up in the direction of the bridge.

The compass always says we are going east as we drive toward Washington.

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