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Old 17-05-2012, 21:51   #16
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Re: Google to use Satellites for real time worldwide AIS tracking

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Originally Posted by Jim Cate View Post
In this case, evading the black helicopters is pretty easy: turn off your AIS transmitter!

What's the worry about?

Cheers,

Jim
While you're at it, turn off your cell phone and don't even think about checking into this BB.

Be Concerned: "The Matrix" is Here.
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Old 17-05-2012, 22:16   #17
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Re: Google to use Satellites for real time worldwide AIS tracking

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While you're at it, turn off your cell phone and don't even think about checking into this BB.

Be Concerned: "The Matrix" is Here.
You need to put your phone into a Faraday cage, since you can't remove the battery anymore.

*Normal length was bad wording, I meant 20-40 ft. Is digital radar good enough to pick out one boat from another?
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Old 18-05-2012, 05:50   #18
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Re: Google to use Satellites for real time worldwide AIS tracking

I wonder how much of Branson's research money is going into Space Garbage Trucks.
Hey!!-somebody has to pick up the trash when these thousands of projectiles go tits up,--or the Chinese take um out with missiles.
About 35yrs ago, I was involved in a drug interdiction operation with the USCG, where a little freighter was tracked from the Straights of Hormuz, thru Suez, refuelled in Morocco, across the Atlantic, intercepted off the Carolinas, and chased to Bermuda.
USCG told me they had a photo every 90mins for the trip. 35 yrs AGO.

But if it saved my life--I'd be happy.
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Old 18-05-2012, 06:42   #19
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Re: Google to use Satellites for real time worldwide AIS tracking

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...why cant we have VHF transmissions world wide?
Actually, you can. If you have a ham radio license, you can use amateur satellites to communicate across the oceans using VHF. You have to get the timing right, and the window is narrow, but it is possible.

My guess is that we don't have complete coverage, for continuous VHF communications anywhere in the world at anytime, because it would require so many satellites that they would be bumping into each other. But that's just a guess.
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Old 18-05-2012, 06:52   #20
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Re: Google to use Satellites for real time worldwide AIS tracking

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Is that right? There are satellites sensitive enough to read AIS signals from space?
GPS signals are in the milliwatt range and we have no trouble receiving them. Because they are line of sight, and the satellite is overhead where "line of sight" covers half the globe, it takes very little signal strength for reception. As you observed, even extremely high-gain antennas send SOME small amount of signal in all directions.
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Old 18-05-2012, 07:31   #21
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Re: Google to use Satellites for real time worldwide AIS tracking

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GPS signals are in the milliwatt range and we have no trouble receiving them. Because they are line of sight, and the satellite is overhead where "line of sight" covers half the globe, it takes very little signal strength for reception. As you observed, even extremely high-gain antennas send SOME small amount of signal in all directions.
Not sure I agree, GPS signals are extremely difficult to receive. They are well below the noise floor. It is only because they are very cleverly coded with pseudo random coding and there are some very complicated algorithms built into the receiver that will recognize the coding amongst the noise and then amplify only those sections over and over again to raise them above the background noise that the receiver works at all.

It is only economies of scale that make such a complex receiver so cheap and apparently simple.

Receiving AIS VHF signals by satellite wouldn't be simple.
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Old 18-05-2012, 07:48   #22
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Re: Google to use Satellites for real time worldwide AIS tracking

If your DSC radio is hooked up to your GPS, they can poll your position without you knowing it--add that to the list of things which need to be turned off if you want to go under the radar.
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Old 19-05-2012, 11:14   #23
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Re: Google to use Satellites for real time worldwide AIS tracking

David-
Bear in mind these are data signals, not voice. Yo cna exchange data signals with the International Space Station using a five-watt handheld amateur radio, if you've got the right information and get your timing and setup exactly right.
AIS repeating by satellite? Should all be fairly simple (compared, say, to the folks at JPL getting data from Mars and points beyond!) once someone figures out how to PAY for launching the equipment and maintaining it.
Make it robust enough to compete with the 406mHz SAR system, and it might be easy to monetize. Not that big a difference in the frequency or power used, when all is said and done.
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Old 19-05-2012, 11:48   #24
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Re: Google to use Satellites for real time worldwide AIS tracking

I can't tell from the original article if Google is launching their own satellites (or have their own payload packages on someone else's satellite), or are using the data from one of the existing satellite/AIS programs. There are several existing satellite-based AIS tracking programs, all in the early demonstration / development stages. Here's a presentation from one of these (from way back in 2010): http://www.exactearth.com/assets/Upl...fing-S-AIS.pdf This briefing shows the ability to track AIS-transmitting ships on the high seas.

There are other programs as well. The technical issue seems to be not so much the needed sensitivity (for signal detection), but instead overload from all the AIS transmitters in different regions using the same timeslot. AIS is designed to use coordinated timeslots so as to not have vessels interfere with each other. Timeslots are essentially re-used in regions that would not normally be able to hear each other, but the satellite hears everything over a wide area.
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Old 19-05-2012, 18:20   #25
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Re: Google to use Satellites for real time worldwide AIS tracking

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...................
Make it robust enough to compete with the 406mHz SAR system, and it might be easy to monetize. Not that big a difference in the frequency or power used, when all is said and done.
Except that 406 MHz SAR system uses many carrier frequencies (all around 406) while AIS is using only one.
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......... The technical issue seems to be not so much the needed sensitivity (for signal detection), but instead overload from all the AIS transmitters in different regions using the same timeslot. AIS is designed to use coordinated timeslots so as to not have vessels interfere with each other. Timeslots are essentially re-used in regions that would not normally be able to hear each other, but the satellite hears everything over a wide area.
Agreed, I see that as a significant problem. Again in comparison to HS's 406 analogy, AIS traffic is waaay higher than 406 traffic.
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Old 29-05-2012, 05:18   #26
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Re: Google to use Satellites for real time worldwide AIS tracking

this about the satellite f Google would be good only because is going to be free (for now) but because of that many companies serving vessel tracking services like vessel finder, vessel tracker, marine traffic and many others may bankrupt. But there is and disadvantage of the google satellite ship tracking - not real time, not like the based on ais live vessel tracking system...
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Old 27-07-2012, 09:39   #27
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Re: Google to use Satellites for real time worldwide AIS tracking

Not sure how it works,

But you can get Google to track you now, anywhere you go,
so that your friends at home know precisely where you are at all times,

I was going to set it up next year on my boat, when I am away, Sailing in the Kimberlys,

Google Maps in my Laptop.

Plus the bit I like, Is its Free,

I dont know how far off shore it would work, Or if it works off shore at all,
But the little I have seen of it, Its supposed to work any where at sea,

Some one on here will certainly straighten this info out for all of us,

It probably works the same as a car GPS. I assume that gets its info from a satellite.
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Old 27-07-2012, 10:10   #28
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Re: Google to use Satellites for real time worldwide AIS tracking

No, Google Maps can't track you. What it can do is display tracking information from other sources that actively transmit your position.

And no, Google Maps, like any other internet application, won't fully work "offshore" at all. It is an internet application, so the burden is on you to provide a LIVE INTERNET CONNECTION to the Google servers if you want to see anything displayed on the software. Without the live internet connection, the application will still run, but it will be limited to old data and whatever maps were last cached before it lost the internet connection.

Unlike your car GPS, where the maps and other information are usually stored in the unit and not accessed in real time.

You can probably get a marine internet terminal for five grand these days, pay two dollars a minute for data, and make it work over most of the world.

Or you use something like a SPOT to upload your position every hour, about $150 plus an anuual fee about the same. That won't show you anything, but anyone on shore can see where you last were.
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Old 27-07-2012, 11:05   #29
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Re: Google to use Satellites for real time worldwide AIS tracking

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No, Google Maps can't track you. What it can do is display tracking information from other sources that actively transmit your position.

And no, Google Maps, like any other internet application, won't fully work "offshore" at all. It is an internet application, so the burden is on you to provide a LIVE INTERNET CONNECTION to the Google servers if you want to see anything displayed on the software. Without the live internet connection, the application will still run, but it will be limited to old data and whatever maps were last cached before it lost the internet connection.

You're confusing two different technologies. Google CAN track you, and google maps CAN display that information to people with an Internet connection.

the "you" in this case at sea will not be able to make any use of that data without also having a separate Internet connection.

Ships at sea broadcast AIS, that VHF information is picked up by toaster sized satellites and THAT technology was recently acquired by google.

http://defense.aol.com/2012/05/17/go...cluding-us-na/
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Old 27-07-2012, 11:28   #30
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Re: Google to use Satellites for real time worldwide AIS tracking

"You're confusing two different technologies. Google CAN track you, "
This is why Hollywood makes people think a handheld GPS transmits your position UP to the satellites and cen be used to track you.

No, it can't. No, Google doesn't track you, even though it "tracks" you. Google agglomerates data, and when you sign in it knows the probable location of the IP address you are signing in from. Or the location of the WiFi router you conected through. And IF you have a GPS attached to your device, like a smartphone, and IF you have locaiton services enabled, yes, Google tracks that data.
But Google itself does not "track" you the same way that an actual tracking device or system would, using an active technology to report back on where you are.

In the same way, Google Maps can use these technologies to report your position back to Google--but only and if you have an active internet connection. All by itself? Google Maps will only "track you to the exentof displaying your position on whatever maps it has cached. And once you are off the cache, all it does is report whatever position information it has--typically liimited the the GPS or cellular tower information is is getting on your smartphone.

Very limited abilities, dependent on outboard hardware and outboard data systems. Not at all a "tracking" system in any conventional sense of the word, which is kinda evident in Mr. B's confusion. I can stick pins in a map, does that make the map itself into a tracking system? Can the map track me? No, not really. Not without a lot of outside help.

AIS from ships at sea relayed by satellites...nice, but that's still only input to the land-based servers.
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