Marina Wireless Network
Bob Alston
Bobalston9 AT yahoo DOT com
I
own a slip at a marina where I keep my boat and have a condo nearby. During the summer of 2004, I installed a wireless
access point for the marina. Initially,
to allow wireless access via laptops within the main marina building. Ultimately, to provide wireless access to PCs
and laptops on boats throughout the 170 slip marina.
Phase I – Wireless access
to PCs/laptops inside the main clubhouse
My
implementation was fairly simple. One access point was used, a Linksys
WRT54G wireless access point and router, located on the second story of the
main clubhouse, which is almost in the center of the marina.
I
chose the "g" wireless standard (802.11g) as it covers the widely
used "b" and also the relatively new "g". We chose to
ignore the little used "a" standard (802.11a that is).
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The
"*" is the location of the antenna. The box marks the location
of slips - approximately. About 170 slips. All but a few have line
of site from the antenna.
We
also have a 2nd clubhouse, for adults only, 150-175 yards to the right on the
diagram. (“**”)
I
initially setup the system for coverage of the clubhouse only. Got an old
PC and set it up for walk-up use. Proved very popular - both adults and
kids.
I
set up the harbormaster's office PC on wireless, as it is a good way to tell if
the wireless is working or not. And, if a boater is having trouble, any
dockhand in the harbormaster's office can quickly and easily tell whether or
not the wireless access point is working.
This
worked with the access point and DSL modem on a desk right outside the
harbormaster's office. Good coverage of the clubhouse, both floors and
immediate area outside.
Phase 2 was to expand to
the boats.
The
initial system could cover the first two boats next to the clubhouse. But
that was it.
We
knew that the basic access point and stock antennas wouldn't work for coverage
to the boats. Initially we tried a +6dBi antenna that one boater has
purchased for his own use. With this antenna mounted high just inside a
2nd story window, adjacent to the access point, we could reach almost the
entire marina. We couldn't get to boats to the far left - beyond a
swimming pool bath house. And we couldn't get to the adult clubhouse on
the far right.
I
did a lot of research and purchased an outside +11 dBi antenna which was
initially mounted temporarily on 2x4s placing it in the approximate permanent
position on the front of the 2nd story. I bought the antenna from www.fab-corp.com.
Service and shipping was excellent. And excellent prices! My
research showed that you should expect to double effective power with every
+3dBi of antenna. Stock antennas are reportedly +2dBi. So I expected a lot of gain out of this
antenna. I also purchased a 5 foot long
pigtail to connect the radio to the antenna.
I
moved the access point up adjacent to the window, out which I ran the antenna
cable. Eventually we would mount it above the window on a shelf.
This keeps the antenna cable short, minimizing power loss.
Initially
I had located the DSL modem at the same place as the access point, as running
phone line is easier than coax. However, DSL requires that you use a
short, less than 14 feet, cable and preferably one that is shielded.
While it worked with a long, unshielded phone cord, the DSL speed improved
significantly when I changed its location and used only the 14 foot shielded
cable.
This
combination has proven to work just fine.
Phase 3 - Expansion to
condos
Another
issue I had was accessing the network from my condo which was behind the
clubhouse, and a parking lot. Nothing seemed to work reliably. I
could get intermittent access with a Microsoft MN-170 USB wireless
adaptor. But it was not consistent. During the first rain it
quit. So improvements needed.
http://members.cox.net/tulsaalstons/images/IMG_1571.JPG
The
above link is to a picture showing the eventual home made antenna on a tripod
pointing toward the marina clubhouse.
I
tried different adapters from a couple of companies, including a Linksys USB G
adapter and a couple of others. No better.
I
also tried the brand new Linksys wireless range extender, WRE54G. I
placed the extender in an upstairs window on the side of the clubhouse nearest
me, with a direct line of sight to me. No better. Spent lots of time
researching on the internet and working with technical support. No
resolution. Returned the range extender.
What
finally has worked for me was to build a do-it-yourself antenna - called a
"tin cantenna". Basically it is a USB "stick" or
"dongle" adapter, I used a D-Link DWL-122, inserted at the correct
point in the side of an empty 11 oz. coffee can. This is connected to my
PC using a USB extension cable that came with the D-Link USB adapter. I
set this cantenna outside the window which is adjacent to my PC.
Safety
caution - Do not look into the open end of the can with the USB adapter
connected. It could cause eye damage (so I am told).
The
latest issue I have had personally has been interference from other wireless
networks. One boater has his own, private access point. And I
recently found 4 other access points. A bit of congestion.
As
I understand it there are three non overlapping channels in the 11 available
for wi-fi use in the
What
I chose for my upstairs neighbor was a Hawking HWU54D
(http://www.hawkingtech.com/prodSpec.php?ProdID=208) USB client which includes
a small panel antenna. Approx $60. My neighbor drapes this over window blinds so
it is at the top of the window. A USB
extension maxes out the 15’ of USB cable between the laptop and the radio. I wanted a commercial device as not everyone
would want a DIY approach.
Phase 4 - Permanent mounting of the
antenna
To
permanently mount the antenna at the clubhouse, we selected an antenna mount
from www.fab-corp.com. (select
“Accessories” and scroll down to “Universal Antenna Mount – Super Long”.) This mount allows the antenna to be
positioned above the lower edge of the roof.
We
planned to place the wireless access point near the antenna, on a shelf almost
to the ceiling. However, we noted we
would need to run an electrical outlet to that location.
I
read about “Power over Ethernet” (POE).
This involves a device at each end; one end adds power to the unused
Ethernet wires. At the other end, it
removes the power from the Ethernet cable and makes it available to the device
needing power. I selected the POE set
from Linksys to avoid compatibility issues.
http://www.linksys.com/products/product.asp?prid=582&scid=38.
Initial testing showed it worked slick.
With
power no longer an issue, and desire to make the antenna more visible to the
condos, we ultimately decided to locate the antenna on the “widow’s peak”, an
extension above the 2nd floor roof line (see picture above – note
the picture is before the antenna was mounted in its permanent position).
We
did locate the WRT54G and POE device on a small shelf about 12 inches below the
ceiling. We ran the Ethernet cable
outside and up the roofline to this location.
Then two holes in the side – one for the Ethernet cable to enter the
building and the other for the antenna cable to exit the building.
Now
I can see part of the antenna from my 2nd story condo. My neighbor above me can see almost all the
antenna. His signal strength and link
reliability has improved significantly and is no longer a concern. My signal strength increased also but I
already had a reliable signal with my tin cantenna.
With
this implementation, we have six condos with excellent line of sight to the
full antenna. Four other condos have
line of sight to at least part of the antenna.
The other 10 do not have line of sight.
Other comments
It
has also proven effective to have someone available in the marina to explain to
boaters that the wireless network is available, what equipment they should buy
and to help them if they experience problems. I have been doing this
personally for our marina. So far my batting average is 95% with all but
one boater being able to connect. (The
one who couldn’t connect was located at the extreme right of the above diagram
and had two larger boats with large fly bridges between him and the clubhouse
antenna).
I
also wrote up a document explaining our wireless network and what equipment would
work and what will not. I made suggestions on equipment to buy. I
also wrote up suggestions on anti-virus, anti-trojan, popup blocker and
software firewall, which I personally use and recommend to others to use.
All these software products are free for personal use. http://members.cox.net/tulsaalstons/Documents/antivirus-antitrojan.htm
Finally
I wrote up information on disabling file sharing on Windows PCs, activating
Microsoft XP's software firewall and disabling protocols that enable file
sharing (ex. IPX) which are likely not needed for the wireless internet access.
Our
access point uses a DSL 1.5 Mbps/384 kbps connection. We chose DSL as it was one-half the price of
Cable, given commercial pricing at the time.
We
do not have any security over access to the wireless access point. I
decided that would be more complication that I would have to deal with.
Besides we want it easy for transient boaters to be able to immediately access
the internet upon arrival at our marina.
Do It Over Again
If
I could do it over, I would like to be able to use more than one access point
and run Ethernet cable between the access points. Perhaps one at either
end of the marina. Then you could use directional antennas point all the
radiated energy toward the marina.
I
might add an amplifier to the configuration but such are expensive $300-500 or
more.
I
am also considering addition of a repeater arrangement, actually one AP to act
as a bridge and another AP connected to it.
Both at the adult clubhouse in the building to the extreme right in the
diagram. I figure $200 or so total.
We
might also run another AP to be placed on the opposite side of the clubhouse,
facing the condos. Here we might use a
panel antenna for better directional coverage.
That should give line of sight to all condos. Cost $250 or so.
Other Considerations
1)
Note that we don't guarantee access to the wireless network. Someone
could have old equipment or flakey equipment. Also we put in this network
“on the cheap” using consumer grade equipment.
But it seems to work well.
2)
We recommend that anyone interested in buying a wireless card, borrow the
laptop of a neighbor and verify connection from where they are planning to use
the laptop in their boat.
3)
We recommended using USB access points (the kind with a cable so you can move
the positioning of the access point relative to the PC). These generally have
better range and May be positioned for best reception (such as running it up
and out of a boat hatch). USB clients
may be able to make the connection workable when a PCMCIA card might choke.
4)
I just might have opted for the +14 dBi antenna from the same vendor. I thought it was overkill. Plus I was concerned about preserving
reception immediately below the antenna, in the clubhouse.
If
questions, contact the author at:
bobalston9 AT yahoo
DOT com
