A typo.... It should have read 5.280GHz...
Sorry for the confusion.
Jack Unger wrote:
Blair,
Well, because the 5.180 GHz range is only legal for indoor use in the
U.S., your problem could be one of the following.
a) The signal over the 1 km indoor path is bouncing off too many
interior walls and creating unpredictable multipath effects. Check to
see if any new interior walls have been constructed recently and, if
so, order them removed immediately. If they are in the "critical path",
don't hesitate to immediately knock them down yourself! In the future,
plan to cover such long indoor paths with at least 3 hops.
b) Somebody moved some large item somewhere in the 1km-long warehouse
(or whatever other HUGE building) that you have deployed inside of.
That huge moved item (perhaps a large crane or boat) is partially
blocking the signal path. The item may be closer to one end of the link
thereby causing the lower RSSI at the other end of the link. Walk the
path to locate any large objects and have them relocated.
c) The building may have become overheated at one end causing the cm9
at that end to overheat and go out of spec causing low transmitter
output power. Check the building temperature at the end OPPOSITE the
end where the RSSI is low and correct it.
d) A bird may have gotten into the building (don't laugh, I've seen it
happen before, especially in very large buildings) and built a nest in
the feedhorn of one grid antenna thereby introducing 9 dB of
attenuation of the signal strength on receive. Visually inspect both
antennas and remove any bird nests. Try to humanly trap the bird if at
all possible and release it outdoors with a firm verbal command to "go
home and don't come back".
e) The clear and cold weather outdoors may have caused a buildup of
static electricity indoors causing static damage to the front end of
the cm9 which is experiencing the RSSI decrease. The chances of this
are high especially if you failed to install lightning arrestors on
both ends of the indoor link.
f) Last but not least (and this is VERY IMPORTANT) - don't even think
about trying to figure out what might have happened to cause the RSSI
decrease until you go into that warehouse (or whatever that building
is) and CHANGE OUT EVERY PIECE OF EQUIPMENT ON BOTH ENDS OF THE LINK.
Many, many WISPs have been using this method to "fix" bad links for
many years. If so many WISPs are using this ("swap before you stop")
method, there must be a very good reason why!
Good luck and good birding!!
jack
Blair Davis wrote:
Hi all...
All of a sudden, a PtP link that has been stable, -79 rssi or so
bi-directional has become very asymmetric.
I now get -79 rssi/-98 noise floor at one end and -88 rssi/-95 noise
floor at the other...
Link is a pair of cm9's, 20db grids, 5.180GHz, range 1km, clear LOS.
3ft lmr-400 radio to antenna at one end, 60ft lmr-400 radio to antenna
at other end.
Any ideas?
Clear and cold here, 27F. Dry since last Thursday...
Thanks.
Blair
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--
Jack Unger - President, Ask-Wi.Com, Inc.
Serving the Broadband Wireless Industry Since 1993
Cisco Press Author - "Deploying License-Free Wireless WANs"
WISPs - Do you know where your customers are?
For wireless coverage mapping see http://www.ask-wi.com/mapping
FCC Lic. #PG-12-25133 LinkedIn Profile <http://www.linkedin.com/in/jackunger>
Phone 818-227-4220 Email <[email protected]>
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