On Wed, 13 Sep 2006 23:59:17 -0700, Jeff Liebermann
<jeffl@comix.santa-cruz.ca.us> wrote:
>Bob Smith <na6t@na6t.com> hath wroth:
>
>>I'm using 2 cisco 350 radios on a wireless link about 2mi in length.
>>
>>I've got the radio, 40' LMR400, 24dbi grid dish on each end of the
>>link. The power on each radio is set at 100 mw. The radios are set
>>as root and non-root w/o clients.
>
>Sounds good.
> TX power = +20 dBm
> TX coax loss = 4dB
> TX ant gain = 24dBi
> Distance = 2 miles
> RX ant gain = 24dBi
> RX coax loss = 4dB
> RX sens = -84 dBm (at 12 Mbits/sec)
> Fade margin = unknown
>| http://www.terabeam.com/support/calculations/som.php
>Calculated fade margin is 33.8dB. That's more than enough.
This is what I figured also....
I haven't had that much experience with Cisco radios but the
associated/dis-associate problem could be a radio. I was watching
the root radio and I think I was seeing a boot/reboot happen
intermittantly. All the lites would turn RED then all out, then the
radio would start to work. This is a city system and the bad thing
about it is that they don't have any spare radios that I could
substitute in to see if it's the radio.
I've tried setting the speeds from 1mb to 11mb & auto. The speed
doesn't seem to help the situation
>Depending on what speed you are selling, you might consider dropping
>the xmit power to a bit less than maximum.
>
>>I can see each antenna from the other antenna with field glasses so
>>I've got no obstructions between the links. One antenna is mounted at
>>60' and the other antenna is mounted at 40'. The antennas are
>>horizontally polarized.
>
>Fresnel zone incursion? You need 27ft clearance at midpoint. Are
>your antennas both more than 27ft off the ground? Any debris within
>27ft of the line of sight at midpoint?
The Fresnel zone looks clean with field glasses. No trees or
buildings are in the way.
>>I've checked the channels and am using channel 9, which shows NO
>>radios on that channel. I've done this with netstumbler.
>
>Yech. Ch 9 will get interference from both 6 and 11 as well as the
>other channels in between. Channels are 5 MHz wide. 802.11 is about
>25MHz wide. Try to stay on 1, 6, and 11, even if occupied.
The local computer store has started putting up hot spots. There is
one about 2000' from the Root Radio. The radio they are using is a
tranzeo panel pointed South. My antenna is pointed NW
using netstumbler I see the tranzeo radio signal strength varying from
10 to 20. it's about 60 degrees angle from the center of the 24dbi
grid feed.
On the same tower I have another cisco radio on channel one pointed
180 degrees direction( see below)
<-------------- tranzeo
channel 11
nothing /
/
/
2000' /
Cisco w/24di grid
channel 9
no wpa/no wep SSID on
cisco w/24dbi grid
channel 1
wpa on SSID off
/
/
/
/
>Netstumbler only picks up access points that respond to probe
>requests. They don't see client radios, AP's with SSID off,
>proprietary protocols (frequency hoppers), etc. At least use Kismet,
>which will see client radios and bridges. Borrow a spectrum analyzer
>and do some sniffing for non-802.11 junk. A friend recently found a
>local company doing injection molding in a small industrial park. They
>had a very leaky microwave oven setup as a a plastic pre-heater to
>remove the moisture before molding/casting. I've now found 3 over
>powered 802.11 amplifiers that were generating more pollution than
>communication.
>
>Laundry list of potential sources of crud:
> http://wireless.wikia.com/wiki/Wi-Fi#Interference
I've also used Kismet and seen nothing in the area.. The non-root
radio has no buildings arround it for at least a mile. The root radio
does have the hotspot radio shown above.
>>I've
>>checked this by driving between the two points and watching the laptop
>>for radios. Also to be sure I connected a PCMCIA card in the laptop
>>to each antenna and checked for radios showing up this way also. So
>>i'm pretty sure that I've got no other radios on channel 9.
>>
>>The link tests show about a 98% signal test at all times i've checked
>>it.
>
>OK, that's more than sufficiently strong. What about S/N ratio? If
>it's interference, it should be going up and down.
I wish there was a way to see SNR.. I don't see how to do this with
the 350 radio. They just have antenna alignment and signal strength
However, the log shows that the non-root radio without clients
>>associates and dis-associates itself from the root radio about every
>>3-5 minutes.
>WPA re-keying interval? Try it temporarily without encryption and see
>if the problem goes away.
I have turned the encryption off, and am broadcasting the SSID
>>I can supply more information about this link if needed.
>
>Contour profile using Radio-Mobile? (Never mind).
thanks jeff, maybe the above will help explain it a little be more..
Bob
Robert Smith Consulting
Fort Bragg, Ca
NA6T
Cisco BR-350 Bridge setup -- Any Help with Error Messages - Associations?? ,, thanks 
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