Guys, I think you have a classic case of multipath fading. The things to check are:
1. Is there enough fade margin to achieve the desired availability (99.98% - 99.998%)? 2. Is the first Fresnel Zone blocked 40% at K = 4/3? 3. Is the reflection point as close to one end as possible? Is it blocked? If you send me the following I will do a path analysis for you. Antenna gain at both ends, dBi Cable loss at both ends, dB Tx power output, dBm Rx sensitivity at BER = 10-6 Antenna height at both ends, AMSL in feet Path length in miles Mike -----Original Message----- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Marlon K. Schafer Sent: Sunday, August 09, 2009 10:31 AM To: WISPA General List Subject: Re: [WISPA] 5.8GHz Link Loss We're still guessing here. He's never told us how LONG the links are. If they are 10 miles apart it's probably not ducting. marlon ----- Original Message ----- From: "Mike" <m...@aweiowa.com> To: "WISPA General List" <wireless@wispa.org> Sent: Sunday, August 09, 2009 9:57 AM Subject: Re: [WISPA] 5.8GHz Link Loss > The way I understand it, and have worked to my advantage as a ham, is > the layers stratify at fairly definite borders in tropospheric > ducting. The layer works more like a duct with a mirror like > top. The signals can be repeatedly "reflected" back down into the duct. > > I did some experiments during one tropo opening using some long > circular polarized yagis at both vhf and uhf. The signals appear to > become more randomly polarized as the distance in the duct > increases. The signals coming from areas around the Gulf coming into > SW Fl during the events had components of both vertical and > horizontal polarization. > > Refraction is the deflection of a wave on passing obliquely from one > transparent medium into a second medium in which its speed is different. > > So, both upon entering and leaving the duct the signal can also be > subject to refraction? Not sure. > > Mike > > > At 10:52 AM 8/9/2009, you wrote: >>That is correct. So my next question: Can refraction be caused by >>thermal ducting? -RickG > > > > > ---------------------------------------------------------------------------- ---- > WISPA Wants You! Join today! > http://signup.wispa.org/ > ---------------------------------------------------------------------------- ---- > > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ ---------------------------------------------------------------------------- ---- WISPA Wants You! Join today! http://signup.wispa.org/ ---------------------------------------------------------------------------- ---- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
