Discussion:
Ridiculous Wi-Fi Reception
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David Kaye
2014-07-20 03:31:41 UTC
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I'm on Treasure Island today. I have a new tablet and was looking at
various wi-fi connections. A couple Comcast business customers have
modem/routers broadcasting the "xfinitywifi" SSID. There is the free SF
wi-fi in the residential areas. But what amazed me was pulling in an
xfinitywifi signal from Alcatraz! While it's line of sight from the
northwest corner of TI to Alcatraz and we all know that RF, especially
higher frequencies carry very well over water, who ever heard of a wi-fi
signal carrying 2 1/2 miles? I drove around some more, looking for
xfinitywifi SSIDs, and except for the two I previously noted, a cafe and a
machine shop, there was nothing else until I got to a clearing between
houses and picked up the Alcatraz signal. I turned off the tablet's GPS and
looked for "me" via the location of the wi-fi, and sure enough my Google map
points to a building on Alcatraz.

Whoda thunk it?




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Bob Vaughan
2014-07-21 05:33:01 UTC
Permalink
Post by David Kaye
I'm on Treasure Island today. I have a new tablet and was looking at
various wi-fi connections. A couple Comcast business customers have
modem/routers broadcasting the "xfinitywifi" SSID. There is the free SF
wi-fi in the residential areas. But what amazed me was pulling in an
xfinitywifi signal from Alcatraz! While it's line of sight from the
northwest corner of TI to Alcatraz and we all know that RF, especially
higher frequencies carry very well over water, who ever heard of a wi-fi
signal carrying 2 1/2 miles? I drove around some more, looking for
xfinitywifi SSIDs, and except for the two I previously noted, a cafe and a
machine shop, there was nothing else until I got to a clearing between
houses and picked up the Alcatraz signal. I turned off the tablet's GPS and
looked for "me" via the location of the wi-fi, and sure enough my Google map
points to a building on Alcatraz.
Whoda thunk it?
The 2 1/2 mile range over water does not surprise me at all.. The fact that
they have Comcast service on Alcatraz does kind of surprise me..

Is there even a cable/fiber to Alcatraz? The last time I was curious enough
to look at the FCC database, I found a PacBell microwave link, which appeared to
be a DS3, which I assumed covered all of their telecom needs. I assume it is a
DS3 simply because they used a standard microwave package, not because they need
a full DS3..

I would not be surprised to find a point-to-point WiFi link to the island, given
that Ubiquiti hardware is dirt cheap, and would easily span the distance.

Speaking of islands, there is a point-to-point WiFi link out to the Farallon
Islands, built with Ubiquiti radios, and high gain dish antennas.. It's about
50km, from Twin Peaks to the lighthouse on South East Farallon Island.

http://www.pcworld.com/article/201349/article.html
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David Kaye
2014-07-21 19:36:29 UTC
Permalink
Post by Bob Vaughan
Speaking of islands, there is a point-to-point WiFi link out to the Farallon
Islands, built with Ubiquiti radios, and high gain dish antennas.. It's about
50km, from Twin Peaks to the lighthouse on South East Farallon Island.
http://www.pcworld.com/article/201349/article.html
WOW! Tim had told me about the Farallones connection from Twin Peaks, but I
thought it was some higher powered point to point channel in the fixed radio
band or something. I had no idea it was just regular wi-fi. Man am I
impressed!




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Roy
2014-07-22 00:12:47 UTC
Permalink
Post by David Kaye
Post by Bob Vaughan
Speaking of islands, there is a point-to-point WiFi link out to the Farallon
Islands, built with Ubiquiti radios, and high gain dish antennas.. It's about
50km, from Twin Peaks to the lighthouse on South East Farallon Island.
http://www.pcworld.com/article/201349/article.html
WOW! Tim had told me about the Farallones connection from Twin Peaks, but I
thought it was some higher powered point to point channel in the fixed radio
band or something. I had no idea it was just regular wi-fi. Man am I
impressed!
The biggest trick is "line of sight". That makes a lot of radio options
workable.

One of the advantages of long distance Wifi in the Southern Santa Clara
Valley is high hills with dropoffs to the valley floor. It makes for
good LOS.

A friend lives up in the eastern hills. I can't see his house even with
binoculars but one night he got on his roof with a high power flashlight
and a 10 foot pole. Darn if I couldn't see his light blinking on the
other side of the valley on my 2nd floor porch. Needless to say, that
was an easy wireless link to install.

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