Internet On a Stick
by Chad Hauris, B Street Studios, Midland,
TX. 1/31/06
At the B Street studios, we were faced with the question of how to get
internet access. John
thought, why couldn't a wireless internet link work from John's house to B Street.
Commercial wireless systems were achieving distances of several miles,
so we figured the 300 yards from the B Street studios to the house ought
to be manageable. The question was just how to do it.
We wanted a system we could put together for not a lot of money which
would still give good performance.
At the transmit end, a high gain "rabbit ear" type of antenna was
connected to the Linksys router at John's house and was set
on a ledge outside a ventilation grille in the attic area.
At first, we were experimenting with a D-Link wireless antenna in the
focus of a parabolic dish on the B street end. This was connected with
coax cable to the wireless receiver card in the computer.
We had read about people experimenting with old Primestar dishes to use
as a signal focusing device for 2.4 ghz wireless ethernet systems.
However, we found that in this case, this would not work, as the cable
length to the reciever (about 25 ft) was attenuating the signal too
much. You really can only use about 6' or less of cable between a 2.4
ghz antenna before the signal strength really drops off.
Next, John did a field strength measurement with the laptop in the
pickup truck. The same alley runs behind B Street and the house so John
drove down the alley seeing how far the signal could reach. It was
found that the laptop could receive a 2 bar strength signal from the
router on the B Street roof, so we knew that the signal was getting to
B Street.
Our next experiment was with a Linksys wireless reciever that connects
to the USB port. We tested the device at the computer and could receive
some signals, so we then did a test with the little receiver taped to a
stick outside. To connect, we spliced a Cat-5 cable into a USB
extension cable. This did not work though, as for some reason splicing
USB cables messes up the signal.
Then, we got a 16 foot USB cable and a 10 foot extension from Radio
Shack. This is the maximum USB cable length (26 feet) we found that
would work reliably. Any more extensions, and the power to the receiver
shut down. We then connected this 26 feet of cable to a USB hub, which
acts as a relay station, allowing another 10 feet of cable to run to
the computer.
Outside, we attached the wireless receiver to the top of a 25' mast
setup from Radio Shack.
The base of the mast is set into a Pedigree dog food can filled with
concrete.
Guy ropes are used to support the mast.
Here is the mast with the receiver on top. A plastic dome is used as a
radome to protect the receiver.
With this setup, we were finally able to connect to the router. We set
it up as a secured connection.
One problem though was poor signal quality. The maximum we were getting
was 18 mbps and the connection would drop often. We needed to get a
better directional beam of signal from the transmit site.
John went back to his house and stood on the ladder at the original
transmit location at the attic vent. He could see the EZ mart next to B
Street but not the antenna itself. Then, moving over to the sunporch
roof, he could see the mast:
It is important to have a direct line of sight at these very short
wavelengths. Click on the picture to enlarge and look in the circle to
spot the B Street antenna mast.
A tripod was used to secure the transmit antenna to the sunporch roof:
Here is a closeup of the antenna mounting. The duct tape will be
replaced with a permanent mount eventually:
In the background is the original transmit location, the attic vent
grille.
A plastic tool box is used to protect the router, which is housed at
the base of the mast. AC power runs in from an extension cord, and a
long ethernet cord connects to the cable modem.
This new setup really works well! The usual speed of the connection is
36 mbps with 3 to 4 bars signal strength.
Here is the result...Internet, on a stick!
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