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Zero Satellites on Cruise Ship?


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Howdy!

 

Just got off a cruise ship, and I was wondering if anyone had an explanation for what I was experiencing while at sea. I like to keep my GPS out on the balcony to record our route at sea while we cruise. I came back to the room the other night and found that it had stopped recording a little southwest of Key West, FL.

 

I can understand having a weak-ish signal in a stateroom since you're only getting one area of the sky, with the other half of the sky being blocked by the ship (like being on a jet). But I wasn't getting ANY satellites in view, not even a blip.

 

So I headed up to the top deck of the ship with a full view of the sky in the middle of the night, and still NOTHING. I tried using the "New Location" feature of my 60CSx, but still nothing. I was getting a bit concerned, to say the least, since I had never had any problems getting a signal in an open sky, let alone not getting anything at all.

 

So my question is whether anyone has an explanation for this? I was wondering if the ship itself would block GPS signals for some reason? We were sailing relatively close to Cuba at the time, which made me wonder if that had anything to do with it. Are GPS signals blocked in Cuba...?

 

Anyway, I've never seen anything like that before on any cruise we've taken, and I definitely know how to use the GPS... so I'm really curious to see what may have been going on here. The unit was back to normal in the morning, which was a huge relief since I had a few caches I wanted to do in Cozumel! ;)

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Are you saying that you got no bars at all on the satellite page? How long was it before you did get reception again, and how far were you from the point where you lost reception? Did reception return gradually, or suddenly?

 

I'm not certain, but it sounds like Dr. No and his giant ray gun.

Edited by Manatee87
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Howdy!

 

Just got off a cruise ship, and I was wondering if anyone had an explanation for what I was experiencing while at sea. I like to keep my GPS out on the balcony to record our route at sea while we cruise. I came back to the room the other night and found that it had stopped recording a little southwest of Key West, FL.

 

I can understand having a weak-ish signal in a stateroom since you're only getting one area of the sky, with the other half of the sky being blocked by the ship (like being on a jet). But I wasn't getting ANY satellites in view, not even a blip.

 

So I headed up to the top deck of the ship with a full view of the sky in the middle of the night, and still NOTHING. I tried using the "New Location" feature of my 60CSx, but still nothing. I was getting a bit concerned, to say the least, since I had never had any problems getting a signal in an open sky, let alone not getting anything at all.

 

So my question is whether anyone has an explanation for this? I was wondering if the ship itself would block GPS signals for some reason? We were sailing relatively close to Cuba at the time, which made me wonder if that had anything to do with it. Are GPS signals blocked in Cuba...?

 

Anyway, I've never seen anything like that before on any cruise we've taken, and I definitely know how to use the GPS... so I'm really curious to see what may have been going on here. The unit was back to normal in the morning, which was a huge relief since I had a few caches I wanted to do in Cozumel! ;)

 

My guess is that the US is selectively blocking GPS reception around Cuba.

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Are you saying that you got no bars at all on the satellite page?

 

'Tis what I'm saying! I had it on our balcony, and it was working fine. I went out to check on it in the evening, and there was nothing -- nada -- in terms of satellites.

 

I took it around to different areas of the ship, turned it off and on, took the batteries out, took the SD card out, etc., etc., with no luck at all. I eventually gave up on it and turned it off for the night.

 

When I turned it on in the morning, it acquired everything just fine as we were closing in on Cozumel.

 

I have the GPX file from that morning here if you have any interest in looking at it. The last part of the file is interesting in that the date stamps for the last few points were pretty far apart. It went from 8:08 p.m., to 8:47, to 9:44 p.m. when it's usually marking things a matter of seconds apart.

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My guess is that the US is selectively blocking GPS reception around Cuba.

 

That's what I'm wondering... do they actually block reception in certain areas? Would this be something they'd do to try to thwart Cubans from trying to navigate to the US on rafts and so forth...? I had just never heard of anything like this.

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My guess is that the US is selectively blocking GPS reception around Cuba.

 

That's what I'm wondering... do they actually block reception in certain areas? Would this be something they'd do to try to thwart Cubans from trying to navigate to the US on rafts and so forth...? I had just never heard of anything like this.

 

If that's the case, we were waaaaaay off course ;)

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I was wondering if the ship itself would block GPS signals for some reason?

 

Maybe not intentionally. The ship's radar or other equipment might interfere with your GPSr. I don't think they could jam or block the GPS frequencies because ships have to use GPS.

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My guess is that the US is selectively blocking GPS reception around Cuba.

Cuba forbids you to bring GPS receivers into the country (and toasters too), so I guess *they* aren't jamming it. If they were, it wouldn't make any difference it you had a receiver.

 

I wonder why *we* would want to black GPS around there. To send the rafters astray? These days Cuba has about as much military clout as the Grand Dutchy of Fenwick.

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i had a similar situation back in 2005 on a carnival cruise coming from aruba back northeast to san juan pr. for that matter, all throughout my cruise which took me from san juan to dominica, barbados and other islands in the southeast part of the caribbean there are numerous holes in my tracklog - some of which are tens of miles long.

Edited by Vlad
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My guess is that the US is selectively blocking GPS reception around Cuba.

Cuba forbids you to bring GPS receivers into the country (and toasters too), so I guess *they* aren't jamming it. If they were, it wouldn't make any difference it you had a receiver.

 

I wonder why *we* would want to black GPS around there. To send the rafters astray? These days Cuba has about as much military clout as the Grand Dutchy of Fenwick.

But have you forgoten that the Grand Dutchy of Fenwick won the way against the USA with their little army.

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If that's the case, we were waaaaaay off course :D

 

Well, Cuba is only a little southwest of the Florida Keys.

No, in order to block reception in Cuba they would also have to block reception in Florida and in any other area that would be in the sattelite footprint.

 

Not if they are sending out a signal to interfere with the same frequencies the satellites use. This would effectively jam the receivers, not the satellites.

 

The signal generator would not have to be powerful enough to reach all the way to Florida.

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Last week I certainly didn't have any problems getting reception, although I was a little further south and east from there. I know on cruise ships I do have times when I just don't get reasonable reception on the balcony because of the structure of this ship, but I'm definitely surprised you wouldn't be able to get it while up on deck.

 

Well, I was getting reception fine up until I killed my supposedly waterproof 60cs with water :D.

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Just to throw out something to consider (I have no idea really), perhaps it was reflections from the ship that caused the trouble.

 

Radio waves are not necessarily absorbed by metal. They could be reflected. Sand on a metal deck, and the reflections up from the deck might interfere with reception from above. Try holding the GPSR closer or farther away from the deck and see if that makes any difference.

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Anybody can jamm GPS signal and it is very simple.

Used by drivers to jamm positioning signal ( to jamm data logger).

Small devices work just in cigarette lighter.

Like this: http://www.chinavasion.com/product_info.ph...ker-in-car-use/

 

Maybe it was a joke? Someone was close to You with similar device? Just for joke? It is really not difficult.

Simple explanation.

Christopher

Edited by sokolo0
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It's not on the list of published tests, but I think they sometimes do interference testing out of Eglin AFB that might line up to where you were.

 

I've seen peculiar GPSr satellite reception in the Mobile area... very weak signal that is sporadic. Then when I got about 40 miles NE of Mobile on I-65, I immediately / instantly started receiving a strong signal, like I crossed an imaginary line.

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