When the problem happens, the rssi is "frozen" so I suspect there's actually no
connectivity any more. Definitely no data. I haven't been able to get someone
to look at the other end while it's happening, to see what they see. During
normal operation the s/n is around 30 to 35 db on the varous legs, and
bandwidth, latency, etc is as we would expect. As you probably know the CM9s
only put out around 50 mw but that's usually adequate for short-haul apps like
this.
At present I can't access the system at all, because the client has apparently
allowed palm trees to grow into the path of the 5-mile (XR5) ptp backhaul we
put in to feed it :-( and with today's rain it's killed the link. Once those
are cut I should have access again and can run more tests.
Thanks,
Tom S.
----- Original Message -----
From: Marlon K. Schafer (509-982-2181)
To: Tom Sharples ; WISPA General List
Sent: Thursday, November 01, 2012 11:00 AM
Subject: Re: [WISPA] CM9 Rx blocking problem?
Are you loosing connectivity to the client radios or only loosing data from
them?
What do your link stats show? Signal quality etc.
What are your eirp levels at normally and during the events?
----- Original Message -----
From: Tom Sharples
To: Wireless@wispa.org
Sent: Wednesday, October 31, 2012 1:46 PM
Subject: [WISPA] CM9 Rx blocking problem?
Hello all,
We're seeing an odd problem at a customer location in Honolulu. About a
year ago, we set up a pretty conventional point-to-multipoint 5.8 Ghz setup for
video surveillance - a dual-radio gateway node attached to a pair of sector
antennas, and 4 client radios (2 on each sector) attached to IP cams. The
client radios are between 1/4 to 1/2 mile away from the gateway node. This is a
multi-building industrial project in a fairly heavily polluted (RF wise) area.
There's a Home Depot and Lowes nearby with equipment on all 5.8 Ghz channels.
However our radios scan well above the noise floor.
Our equipment uses pcengines alix boards running our own linux-based OS and
CM9's using standard madwifi-style drivers. Same thing we've been using for
years.
This installation worked well at first. However, we are now seeing a
situation in which both gateway radios suddenly stop receiving data from the
downstream clients. This lasts from 5 to 20 minutes or so and then magically
fixes itself. When I ssh in during the problem, there'e no indication of
low-level driver problems or crashes, everything looks normal except for the
sudden lack of data and connectivity with the client devices.
This installation is near Pearl Harbor and there are constant overflights
from military aircraft. I'm wondering if this is a sensitivity issue to e.g.
radar or some other high-powered signals from these planes. I've seen things
like this before but never lasting up to 20 minutes. Would we see an
improvement by switching to XR5's? We don't normally use those on short hauls
like but they have better OOB filters than the CM9's. Thoughts?
Thanks,
Tom S.
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