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Old 27-08-2014, 12:46   #1
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965 Mile AIS Range

some pretty serious AIS propagation going on in the South of Portugal
965M range..
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Old 27-08-2014, 13:09   #2
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Re: 965 Mile AIS range

Thats quite incredible! Skip, or ducting, or whatever it is.
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Old 27-08-2014, 13:15   #3
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Re: 965 Mile AIS range

Yep, ill be keeping an eye on them all for possible close quarters situations!
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Old 27-08-2014, 13:40   #4
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Re: 965 Mile AIS range

Had the same experience in the same area in 2011. Got reception for over 200 miles on either side of us.
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Old 27-08-2014, 15:39   #5
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Re: 965 Mile AIS range

Yes, summertime temp inversions along coastal areas and over areas of open ocean between land masses, etc. can introduce significant tropo enhancement, and in this case here tropo ducting....
Quote:
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some pretty serious AIS propagation going on in the South of Portugal
965M range..
But FYI, the world record terrestrial VHF (144mhz ham SSB/CW vs. 156mhz marine FM) distance for two-way contacts is 6412km!! (via Trans-Equatorial / TE F-layer prop)....

And, the Atlantic VHF tropo record is 2340km....
http://www.arrl.org/distance-records




My personal VHF tropo scatter record is ~ 820 miles (about 1250km).....and my personal terrestrial VHF record (Es) was 2075 miles (about 3350km)....
(now if you count non-terrestrial paths, bouncing my vhf signal off the moon, gives us about 480,000miles / 769,000km....but that's using the Moon, so doesn't count regarding "propagation"....)


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s/v Annie Laurie
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Old 27-08-2014, 16:32   #6
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Re: 965 Mile AIS Range

When I lived in Morocco for four years in the late 1970's we quite regularly had VHF ducting on the 2-meter amateur radio band (144-148mHz). Stations in Portugal could be heard and contacted quite often.

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Old 27-08-2014, 16:41   #7
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Re: 965 Mile AIS Range

Land based repeaters are active near the Straits of Gibraltar, Cabo St Vincent and Tarifa.
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Old 28-08-2014, 01:53   #8
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Re: 965 Mile AIS Range

The land base stations don't repeat the AIS data vessel to vessel as far as I know. They're used to receive and transmit traffic management and safety messages.
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Old 28-08-2014, 05:07   #9
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Re: 965 Mile AIS Range

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The land base stations don't repeat the AIS data vessel to vessel as far as I know. They're used to receive and transmit traffic management and safety messages.
These are land based AIS repeaters for the strait and the approaches.

And they do.

Hence the range observed.

Some areas of the world are a little ahead of others.

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Old 28-08-2014, 05:25   #10
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Re: 965 Mile AIS Range

Ah that is cool and yep, advanced. Hopefully the way of the future with ships repeating as well to give worldwide AIS coverage. Cheers for learning me something new
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Old 28-08-2014, 12:49   #11
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Re: 965 Mile AIS Range

Yep.

Had the same thought here as same technology works over smartphone networks already.

We might have problem talking the ships into it as 99% of them carry sat comms and hence they already have 100% global AIS coverage in RT.

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Old 29-08-2014, 12:14   #12
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Re: 965 Mile AIS Range

Great screen shot.

Two years ago from near Mallorca I could see AIS targets in port on the north coast of Morocco. I assumed some kind of repeater.

Later the same year I was able to see a friend's boat. We were both heading to wards and arranged meeting point from different directions) and talk to him on VHF in the Adriatic near the Greek coast on just over 100Nm.
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