If thermal changes could effect the signal then that would make sense though I do not recall seeing this for shots as short as we are running in the higher frequency bands we are using. I always looked at thermal effects as being a consequence only in the lower (VHF and below) bands. In my past life as a CATV headend engineer I used to have to deal with VHF co-channel interference where distant television channels in the VHF band would ride on top of one another after bouncing off the atmosphere and down onto my towers in the summer time. I guess it could happen in the microwave bands also though I never thought it was an issue outside of VHF. If anyone reads any reference materials on thermal effects of RF in the 5 Ghz bands and cares to share this would be appreciated by the group. I believe the effect is known as "tunneling" where a frequency gets locked between two thermal layers in the atmosphere and "tunnels" its way across larger distances than would otherwise be normal propagation. I once read the call letters for a VHF television station in Los Angeles here in Mt. Vernon, Illinois. Now that is some long distance interference!

Jeff Mabry wrote:

John - The links are about 60 miles due west of your location.

-----Original Message-----
Behalf Of John Scrivner
Sent: Tuesday, August 02, 2005 10:41 AM
To: WISPA General List
Subject: Re: [WISPA] 5.8 GHz PtP - weaker RSLs

We had some Trango weirdness overnight also. We had 3 different links go down at different times overnight but I do not have any specifics of why at this time. Where were you seeing this trouble?

Jeff Mabry wrote:

Good Morning, WISPA.

We have witnessed a decrease in five (5) TrangoLink10 5.8 GHz PtPs Received Signal Levels overnight. These links are deployed in various geographic locations with an average 12 miles of separation between tower sites. These links have been active for at least a year (some longer). A decrease anywhere from 3 to 8 dB has been recorded in the RSLs with the exception of one (1) link which has had a 7 dB boost in signal.

Weather this morning is about the same as yesterday's weather. Clear and 72 degrees.

Did anyone else see lower signals this morning? This is a weird issue to wake up to.

Thank you for your support.

Jeff Mabry

General Manager

SlingShot Wireless Communications

618.735.2411 x 144

618.735.2907 (fax)

618.534.6407 (mobile)

www.slingshotwireless.com <http://www.slingshotwireless.com>

WISPA Wireless List: wireless@wispa.org


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