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GPS Jamming by airports?


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Today I went geocaching during my lunch hour. The cache was by an airport. I was a little less than a quarter mile away from a radar transmitter (big ugly building with a twirling red antenna). My GPS was pretty much useless and locked up (Rino 120) while in the area.

 

Link below:

 

http://www.geocaching.com/seek/cache_details.aspx?guid=e344937b-7436-4213-a283-2cd222319bd3

 

aka Grand Central Station.

 

I pretty certain it was the RF in the area. I'm just curious if anyone else here has had a similiar experience while using a GPS in an airport area? Please post your airport, model, and make of your GPS.

 

Adam P.

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Okay. Here is an update:

 

I went back to the same area (this time with 3 GPS receivers). My Rino 120 again was as useful as a paper weight. icon_mad.gif

 

However my friends Garmin III+ worked like a champ as did the Magellan Meridian. icon_cool.gif

 

My advice, stay away from the Rinos if you need to use them in RF areas (airports, radio towers, etc.). frog.gif

 

Adam P.

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adampierson - Now I got the connection... LAX.... today - read the log - BTW you should work your way down to PV - We/I have a lot of great caches here....

 

--------------------------------------------------

"If you ever go temporarily insane, don't shoot somebody, like a lot of people do. Instead, try to get some weeding done, because you'd really be surprised." - Jack Handy

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1911:

 

Yes, the unit locked up even when I had shut off the FRS - I usually do this to conserve power. My plans were to use the FRS capabilities on group hikes/group geocaching.

 

Vacman:

 

I've check out a couple of caches in the PV area (I've only found one in the area the other I was not prepared for the hike for the other). I plan to make another attempt this weekend. In fact I think I found one of yours caches!

 

Rino review:

 

I like the unit. I like the scaling on the map screen and I like the smaller compass screen and definable fields. The lockup problem IMO should not happen at all in such an environment (two other GPSes. The interface is okay, but the click stick is a little finicky.

 

I decided to go for the Magellan Meridian simply because it has the screens that I need and the memory for the mapping capabilities I want (lots of maps and memory). I would have liked to keep the Rino... IMO they still need to work out some bugs.

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This is news to me. I fly jets and we use GPS all the time to navigate. I have flown all over the world and Naples Italy is the only airport I have had repeated GPS reception problems. I do not know of anything at an airport that would jam a GPS signal. I seriously doubt there is since aviation is becoming more reliant on GPS systems every year. Aircraft are now flying GPS approaches to airports in bad weather.

 

Capt Prozac

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Having some experience in radio, I think the problem isn't so much deliberate jamming but what the consumer GPSr is getting overloaded by other signals in the microwave band. Most GPSrs are built to be used outdoors, not while standing in the path of the airport radar and guidance systems.

 

While the receivers could be built to deal with the signals, there is an added cost, size and weight for the extra parts. The manufacturer has decided it benefits too few to be wroth adding to "outdoor" units. It may also explain one of the difference between the outdoor units and the aviation units.

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Just to add a note to this. Last summer I was in Puerto Rico and was travelling across the bay on a boat with radar. I could almost see the sweeps of the radar on the signal strength on the GPSr. Some signals would go up while others would go down. I did not have the opportunity to check the signal strength against location, but I am convinced it was the boat's radar doing the dirty work.

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:o

 

Just a small note regarding radar and GPS, at least concerning marine units.

 

If you have a radar on your boat, you MUST mount the remote antenna at least 3 feet above the height of the radar dome or sweep. Otherwise the unit will be blanketed by the radar sweep.

 

Not a big surprise really, but most people never read the directions on the units.....

 

Okay. Here is an update:

 

I went back to the same area (this time with 3 GPS receivers).

 

This just goes to prove that most serious Geocachers or other nuts end up with a collection of these things. My wife now has her eye on the Rino 130, so here we go again. But this time we need at least a 120 and a 130, or maybe two 130s, bringing the current handheld total to 5. eeesssshhhh.

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my job has taken me to the roof of several traffic control towers and radar towers including the towers at newark airport. taking lats/longs was the reason i was there and had no problem with the radars or radios at any of the sites. the only place i ever got more satellites was on the ocean off of key west. i also confirmed the airport coords on a topo map later. my magellan 320 never even hiccupped, although it has in other places.

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<BR><BR>I pretty certain it was the RF in the area. I'm just curious if anyone else here has had a similiar experience while using a GPS in an airport area? Please post your airport, model, and make of your GPS. <BR><BR>Adam P.

Funny i am all over MIA Intl with mine and never a problem. Get it near trees and thats another story.

 

Objets

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Some of Garmin's fixes for the Rino addressed possible lockups. I've got a Rino 120 (with the latest software) and have used it near airports, microwave towers, etc... with no problems whatsoever. I'd check with Garmin.

 

Of course, the darn Rino doesn't include a metal detector so I still end up logging DNF's sometimes! ;)

 

I've been really happy with my Rino to date - and Garmin's customer service has been top notch. I'd recommend giving them a call and asking about the lockups.

 

Good luck!

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I agree with hartclimbs about the software update. i also have noticed that the 120 does lock up or freak out a lot when there are rock faces or other natural structures that can bounce a signal. i belive that it has something to do with the double(or is it quad?)-helix antennae confusing itself. Something else i noticed is that the goto needle spins like crazy sometimes. Yes its a good produst, but it does have problems

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I too have noticed problems near SEATAC airport only it shuts off my MeriPlat on the east side of the approach lane about a 1/2 - 1 mile north of the airport. It is consistent and the only time my GPSr does an unexpected shutdown. While in the "zone" I cannot keep it on for more than a few seconds. I figured it was radar RF as well. I have seen RF at specific frequencies fry digital watches if it gets enough of a wash. I'm thankful it merely shuts down my GPSr.

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A month ago I went into a french airport (Charles de Gaulle, Paris) to wait for my girlfriend to come back from Portugal. I was in the parking lot taking fresh air outside, and planes were pretty close. The GPS not only worked fine but gave me a 3 meters precision (or so it says :bad:) without WAAS enabled, and that's the best error margin I ever got from it. The closest runway was about 100 to 150 meters from me. If planes are to use or are using GPS as position-help tool, I believe GPS works fine there :unsure:

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I have a Garmin GPSMap 76S. There was one occasion that it did freeze up at an airport. I was at the east end of the runway when it happened. I wasn't too far from the approach beacon tower. It screwed the gps up so bad that I had to re-install the software. I couldn't even turn it off without unplugging the power. It hasn't happend since, so it may have just been a coincidence <_<

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So im gonna say it is just inintended interferance.

I think it's just a matter the consumer GPS units can't deal with some of the microwave signals around the airports. The added size/weight/cost to allow the units to work around airports just can't be justified for consumer grade units.

 

I don't know what system it would be, but ground radar is one possibility. It's a radar set used to track the planes on the ground so they don't run into each other during night or bad visibility. It's quite possible that depending on how those units are mounted, the signal could be quite strong outside of the airfield. Various IFR signals are also a possibility, but I don't know if any are in the microwave range.

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I was looking for a discussion on just this topic. (interference near airports) It amazes me to read all the reasons people choose one GPRr over another. I chose my Garmin GPX 12 because it was the first chance I had to buy a GPSr for less than $200 a couple years ago (or was that just a year ago?) I figgered it was cause there were better models out and garmin made too many of these. Anyway, I like using it, have found lots o caches and don't plan to replace it anytime soon. But, I was really curious about this airport stuff.

 

I thought it would be fun to start it up on an airplane just to see how high we were and how fast we were flying; maybe even to know when I passed over places I had been before but several times I have tried and it just says acquiring and it never clicks in. I suppose everyone else's more expensive GPSr s do just fine on airplanes right?

 

- kayakman9760

email mike9760@yahoo.com

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I thought it would be fun to start it up on an airplane just to see how high we were and how fast we were flying; maybe even to know when I passed over places I had been before but several times I have tried and it just says acquiring and it never clicks in. I suppose everyone else's more expensive GPSr s do just fine on airplanes right?

I have to place my Meridian right up to the window to get a signal...if I move it more that a foot away, I usually lose the sats.

Edited by Stunod
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I suppose everyone else's more expensive GPSr s do just fine on airplanes right?

Maybe, maybe not. Keep in mind the radio signals the GPS uses isn't going to go though the metal aircraft skin. You have to place it somewhere in the airplane where it can see the skys above. If the windows have a metallic tint, you're screwed. Many car owners have the same problem.

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I just dropped a thread on this exact issue elsewhere. Was caching outside Philly airport directly under the approach for landing or departure. Not sure if planes where coming or going as they were all pretty low. Every time a plane passed overhead I could watch the directional arrow on my Garmin etrex Venture wobble a bit or swing around 180 degrees. Made locating the cache a nightmare. GPS would send me 200-500 feet in one direction then change to 200-500 feet back in the prior direction after traveling about 10 feet. Even stopping and setting the GPS down on the ground would still end end with "ranting". Eventually found the cache by just putting the GPS away and searching every likely looking spot in the area. Mystified :lol:

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Every time a plane passed overhead I could watch the directional arrow on my Garmin etrex Venture wobble a bit or swing around 180 degrees.

Since I wouldn't think a passing airplane would blot out that much of the sky, I suspect it was a radar signal reflected off the airplane messing with the GPS.

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I remember reading this topic a few weeks ago and didn't think much of it. Then yesterday, I drove by our local airport. There is a road that goes around the outside of the airport property. The radar installation is about 30 feet from this road. As soon as I drove past the dish, i completely lost the satellite signal on the GPS--it went completely blind. It took it about 10 minutes for it to find any satellites again. I was very suprised!

 

CenTex

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There is also an ILS out there. It is on both ends though. I think there are marker beacons as well. All those should be in the 108-118 mHz range though. Does it happen on 188th south of the airport or near Boeing Field?

Sorry I didn't respond to this. I lost track of the topic. It was on I-518 north of Seatac just as I am nearing the approach lights.

 

It hasn't happened the last time I went through there, so there is something that is switched on and off that causes it. I haven't corelated if it is during an expected approach but assume it is.

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