Re: wireless technology

[Jeff King]

Jeff:

Lorn Olsen at Mich.com asked me to describe what we are doing with
wireless at his ISP. We have had wireless connectivity at
Mich.com for over 1 year.

Mich.com has a 115kbaud FreeWave installed at its office
in Farmington Michigan. The FreeWave modems are 902-928mhz
frequency hopping wireless modems. At the Mich.com site
we have a comet vertical antenna feed with 9913 coax at 
about 30 feet about ground level. The FreeWave modems are
RS-232 based.

One of the fixed test sites is at my office, which is
about 1.7 miles away. At this site we are using a corner
reflector mounted at the 40 foot level on a tower.
Throughput on this link going between a LINUX machine
running PPP (at mich.com) to a windows 95 box with
trumpet/486DX66 is about 8.8kbytes a second on a FTP.
The signals are extremely strong on this link and any
outages we have had (save the first month of operation)
have been non-RF related.

We've also operated the link in point to multi-point mode
using a Livingston router running SLIP. We were able to
use both KA9Q, MAC-TCP and Trumpet winsock drivers in
the configuration. We were even able to do a demo at
a MUG meeting last year in which we got good connectivity
with a "back of the set antenna" coupled to a laptop. Was
neat sitting at the Leather Bottle (a eatery) surfing the
web portable. The present wireless coverage area covers
all of Farmington and parts of Livonia and Farmington
Hills.

Mobile I get between 2-4 miles from a car to Mich.com. The
longest fixed operation I've done with a pair of freewaves
has been from the microwave tower on North Campus (UofM) to
the Dexter schools. This I believe was about 10 miles or
so and signal strengths were extremely strong. However, I
wouldn't consider this a typical installation due to the
high height of the tower. All the FreeWave links I mentioned
above are not line of site (LOS) except for the north campus
to Dexter link.

At radio.metronet.lib.mi.us (while it was still a merit
affliate... I think it went to ATT now?) I designed a
19.2kbaud "amateur radio hamgate" wireless link. This 
spans a distance of 35 miles. Of course, this can only 
be used for non-business related traffic. Again, this
is a non-typical link.... 30 feet agl at metronet but
it went to downtown detroit at 450 feet agl.

Presently at Mich.com, they are considering using the 
technology to link in remote offices (point to point)
as well as possibly considering the technology for
service delivery to customers in a point to multi-point
mode. 

Couple comments:

I'd agree with Larry Cotton and not recommend a vertical
antenna for operation near pager sites... the antenna 
Larry is using (I believe it is made by Olde antennas
West out of Denver CO), is a much better performer to
reject interference. We had to install a interdigital
filter at mich.com to notch out the cellar towers. 

One note to those using the WaveLan cards ("KarlBridge
and "The Wave"), you can construct your own wireless router
for less if your only interested in routing IP
packets. I believe drivers for the card are available for
both LINUX and DOS KA9Q. I'm now playing with a set of
those cards and can let anyone know if they are interested
in how it turns out.





Regards,

-Jeff King
 Aero Data Systems, Inc.
 P.O. Box 9325
 Livonia, MI 48151 U.S.A.
 V 1-810-471-1787, F 1-810-471-0279

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