Mike,

I don't have any experience with the satellite internet access - those
modern systems just haven't found their way up here to Alaska yet,
where we could use it the most.  But I wonder how susceptible they are
to motion.  If you get a small wake in the harbor, or you move around
the boat and she heels a bit will you lose your connection with a fixed
dish?

For an interesting discussion on the whole 802.11 wireless LAN
phenomenon, get the latest issue of Wired Magazine (might be the
September issue).  It's their featured cover story.  With the rapid
growth of wireless networks around the country, my guess is that most
marinas, or marina residents, will have them within the next few years,
and probably with free access.

Bob Deering
Juneau, Alaska

Bob,
You are right; the system I am talking about must be sitting on stable deck
(pier or shore). I am looking for a system that will in Guatemala or an
island off over the reef in Belize.
Mike
Texas

-----Original Message-----
From: Robert Deering [mailto:deering@ak.net]
Sent: Friday, October 04, 2002 12:59 PM
To: Michael Finley
Cc: Trawler World List
Subject: Re: TWL: RE: RE: Wireless Broadband for Marinas

Mike,

I don't have any experience with the satellite internet access - those
modern systems just haven't found their way up here to Alaska yet,
where we could use it the most.  But I wonder how susceptible they are
to motion.  If you get a small wake in the harbor, or you move around
the boat and she heels a bit will you lose your connection with a fixed
dish?

For an interesting discussion on the whole 802.11 wireless LAN
phenomenon, get the latest issue of Wired Magazine (might be the
September issue).  It's their featured cover story.  With the rapid
growth of wireless networks around the country, my guess is that most
marinas, or marina residents, will have them within the next few years,
and probably with free access.

Bob Deering
Juneau, Alaska

Bob Deering wrote,

"Mike,

I don't have any experience with the satellite internet access - those
modern systems just haven't found their way up here to Alaska yet,
where we could use it the most.  But I wonder how susceptible they are
to motion.  If you get a small wake in the harbor, or you move around
the boat and she heels a bit will you lose your connection with a fixed
dish?

For an interesting discussion on the whole 802.11 wireless LAN
phenomenon, get the latest issue of Wired Magazine (might be the
September issue).  It's their featured cover story.  With the rapid
growth of wireless networks around the country, my guess is that most
marinas, or marina residents, will have them within the next few years,
and probably with free access."

Sorry I didn't respond sooner. I had to finish my homework before I could
play:).

I have investigated IEEE 802.11 wireless local area networks (WLAN) quite
thoroughly. We are looking into the possibility of using them between patrol
boats as a low cost cooperative engagement capability and to link
maintenance data to shore systems when the boats return to base (the users
always forget to plug in the landline and download the system data). We will
probably be installing a system on the companies boat, "Phantom" next year.

IEEE 802.11 is not a satellite system at all. It is intended to replace the
local area network, i.e. the Ethernet cable between your computer and the
router down the hall. There are currently three defined standards, 802.11b
is up to 11 MB/s in the 2.4 GHz band, 802.11a (which came after b) provides
up to 54 MB/s in the 5 GHz band. At the same effective radiated power levels
(ERPL) the 5 GHz band is normally slightly shorter range that 2.4 GHz,
however the allowable ERPL is slightly higher and the 5 GHz band has less
interference from microwaves and cordless phones so performance is
~comparable. The third standard is 802.11g. It is in the same 2.4 GHz band
as 802.11b, but it uses broader bands to provide 54 MB/s data rates to
compete with 802.11a. 802.11g is also backward compatible with 802.11b.

The main concern in the WLAN community is guessing which standard will
become the dominant one and be supported. To ease the concerned minds of IT
executives that are trying to make intelligent decisions for large
corporations, many manufacturers are introducing dual standard systems.
Currently you can get dual 802.11a+b and next year you should be able to get
802.11a+b/g.

The other factor to consider with 802.11 is it was originally intended for
short range, i.e. tens to hundreds of feet. Range is limited by the FCC
power levels and the gain of the antennas, however most laptop WLAN devices
use much lower power than the FCC limit to increase battery life. For a boat
to shore system you can amplify the ERPL and extend your range. Gain is
primarily a function of the broadcast pattern of the antenna. Mobile systems
prefer omni-directional antennas that allow you to turn your laptop any
direction and still get a signal. If you go with a narrow beam you can
increase the antenna gain by ~ an order of magnitude, but you have to point
it accurately. A happy median is to use an antenna that is omni-directional
in the horizontal plane but has a relatively narrow beam vertically. This
puts most of the power in the direction you need, although the vertical beam
width needs to accommodate the anticipated platform roll angles. Another
development is smart antennas or smart antenna switching. These systems
actually have several antennas and the system scans the receive signal to
determine which direction has the highest gain. It then switches all the
transmit power to the highest gain antenna. With an signal amplifier and a
high gain antenna you can obtain 25 to 30 mile range (limited by line of
sight distances and the lens effect of the Earth.)

Another thing to keep in mind is that 802.11 data rates steps down as range
and the signal to noise ratio increases. They always quote the data rate at
the shortest range and range at the lowest data rate. For example with
802.11b your data rate at maximum range will be 2 MB/s not 11 MB/s.

A useful and under utilized feature of 802.11 is the ah hoc capability or
relay mode. When the ad hoc mode is activated, each device can act as a
relay for devices that are too far from the network access point to get a
signal. For boaters this means that you might be able to get high speed data
beyond line of sight of land provided there are other relay devices between
you and shore. This will become more significant as more and more devices
become available. Cell phones are also looking into relay networking as a
economical means of eliminating dead zones.

Now, on to satellite systems. The only affordable two way MOBILE broadband
satellite service I know of is Motosat's DataStorm
http://www.motosat.com/twoway_001.htm (there is also Inmarsat, but most of
us can't afford that! refer to my wireless email presentation for more
details http://216.117.203.199/newEmail_files/frame.htm). DataStorm is a
"stationary - mobile" two-way service, which means it can be mounted on
mobile vehicles but it can only be used when they are stationary. Most
systems are fixed and must be mounted on a stationary structure. Boats
require mobile - mobile service but that isn't available and may never be
based on my last conversation with MotoSat last May. DataStorm can be
mounted on mobile vehicles, but it can only be used on a boat when the boat
was very stable, but it could be relocated to a stationary dock or
transported to shore and used there. One problem is the transmitter is 105
lbs. If the distance from boat to shore were too great for a fixed cable you
could use an 802.11 link for that.

KVH has a satellite down link and phone line uplink that is mobile (i.e. you
can use it underway) but you need to use phone line (POTS, cellular or
satellite for the uplink). Go to
http://www.kvh.com/products/product.asp?id=60. They also have coverage maps
at http://www.kvh.com/footprint/index.html. Depending on where you are, you
may need more than a 24" dish to get service in Alaska. These maps SHOULD
also apply to MotoSat DataStorm since they both use the Bell Express Vu
service. By the way, DataStorm has a ".78 Effective Area Elliptical Offset"
which equates to a 39" circular diameter, so reception should be very good.

One additional drawback of the gee synchronous satellite service is the time
delay due to the distance to Geosync orbit. If I remember correctly, it
takes about 0.25 sec for radio waves to get from here to there and visa
versa. Since a web request has to make two round trips before the page
displays this adds about a 1 second time lag every time you access the web.
This doesn't seam like much but if you are use to DSL or cable it can be
annoying.

Cheers;
Mike Schooley
Designing "Portager" a 36' trailerable trawler