[amsat-bb] Re: AO-7 Mode C? (Or other reason for varying signal strength?)

Nick Pugh K5QXJ quadpugh at bellsouth.net
Wed Apr 7 03:11:13 PDT 2010

Bill there is ground reflections that can add 6db of enhancement and objects
in the foreground are important considerations.

Nick k5qxj

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Bill Dzurilla
Sent: Tuesday, April 06, 2010 10:08 PM
To: amsat-bb at amsat.org
Subject: [amsat-bb] Re: AO-7 Mode C? (Or other reason for varying signal

So, folks, does anyone have any thoughts or comments about this issue?
73, Bill NZ5N

--- On Sun, 4/4/10, Bill Dzurilla <billdz.geo at yahoo.com> wrote:

From: Bill Dzurilla <billdz.geo at yahoo.com>
Subject: AO-7 Mode C?  (Or other reason for varying signal strength?)
To: amsat-bb at amsat.org
Date: Sunday, April 4, 2010, 10:52 PM

Hi folks,

Since starting my effort to work Europe on AO-7, I've found that the very
low elevation sigs vary significantly on different 
passes.  Some mornings I can easily hear my downlink and start working 
Europe at 0.7 degrees elevation, while other days I can't hear myself 
until 5 degrees elevation, after the window to Europe has closed.  Not 
sure if this is due to band conditions, satellite polarization, 
obstructions at certain positions, operator error, local noise, or what.

Today I spoke with another experienced AO-7 op and he had an interesting
theory: on the bad days (when I don't hear my downlink until 5 degress), the
sat is in Mode C (lower power).  This seems to make sense, because there
does not seem to be any middle ground -- I start hearing my downlink at
either 0.7 degrees or 5 degrees, never at 2-4 degrees.

Anyone have any thoughts on this?  Are we able to predict when the sat will
be in one mode or another?  Or any other explanation for the signal strength

73, Bill NZ5N 


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