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military radar interferring with gps?

Old 02-01-2007, 09:16 AM
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Default military radar interferring with gps?

have any of you that boat around the navy bases ever heard of this happening to rec boaters?

http://www.gpsworld.com/gpsworld/art....jsp?id=317550
Old 02-02-2007, 12:37 PM
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Default Re: military radar interferring with gps?

Phil,

An excellent article. I used to work with Dave Wolfe (one of the individuals listed at the bottom of the article), and I'll try to give him a call next week.

I have not personally experienced a Navy ship-related GPS failure. First off, the ships do not transmit their Air Search radars in CONUS ports. Another thing to note is that the ships require a minimum of a 100 yard standoff, and as the power decreases by the square of the distance, being further away is better. Lastly, the horizontal plane of radiation is much higher than the talles recreational vessel.

It appears that this issue would be more of a concern to large commercial vessels that must transit down the same channels as the Navy ships. Since their GPS antennas are usually on the bridge wings or on top of the bridge (or possibly up a mast), they are most likely more in line with the maximum radiation pattern of the Navy emitters.

My suggestion is to follow the prescribed vessel safety zone offset, and if you must transit in closer to a Navy ship that is "rotating and radiating," power down your GPS receiver.

Joe
His Doghouse Too
Master, Vessels NMT 1600 GT on Oceans
Chief Mate, Unlimited Vessels on Oceans
CDR, USN (ret)
Old 02-02-2007, 04:26 PM
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Default Re: military radar interferring with gps?

thanks Joe, I had never heard of problems with rec boats and your explanations make sense.
Old 02-08-2007, 08:27 PM
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Default Re: military radar interferring with gps?

One of the weapons few know about is a radar or EMI cannon that has been developed by the military. It's extremely directional and within it's sights extremely powerful. I'ts about guaranted to smoke the electronics in any boat or aircraft with a burst measured in miliseconds. If it has an antenna is about guaranteed. Even if not nearly so.

Had a recently retired Navy electronics weapons specialist tell me of two techs that got badly called down for playing with this type of device on an innocent private boater as a game. Apparently these two techs thought it funny to try it out on an unwitting boater in foreign waters. They spent some time in the Brig. he said.

The other thing is that the military has control over the GPS satelites and thay can play with them as needed or test their own ability to either affect the accuracy, distort, jam signals, or to even to disable the GPS system in times of war.

Personally I think I've witnessed such tests a time or two myself but they have been only momentary, and really did not effect my navigation. Maybe this explains the sudden and rare accurracy alarm when the boat is just sitting still in open water. Once I had a couple of F18's playing with each other overhead, and they gave me pretty much fits like this for a couple of hours. Many civilian units like mine might not even notice this. But then again the true position refresh rate on what mobile units we use can't be nearly as quick as that required for a jet aircraft or a guided missle.

I doubt radar has much effect but there are obviously lots of other ways to play with the signals. (Especially if you have unlimited control over what's happening and the ability to test the sucess of your control at will.)





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