[amsat-bb] Modulation levels on AO-85

Tom Schuessler tjschuessler at verizon.net
Tue Aug 15 02:47:21 UTC 2017

The issue with quieting vs. Modulation level is that if a station has enough
power to do full quieting FM into the AO-85 bent pipe, than even if he is a
weak talker, or his radio has low modulation gain, he will be heard because
the background noise is minimal.   Having enough power to get to that point
is a good thing, but there are many stations, like myself sometimes, that
are using HTs for uplink and downlink.  5 watts, not the right transmit
polarization and a slightly deaf RX on AO-85 due to an antenna not quite
what it should've been (Documented shortly after AO-85 launch) and you have
a number of things lined up against you.   This presents a situation where
this combination results with a station barely coming through the noise and
thus being hard to hear.  Again remember that AO-85 is a bent pipe after it
is tuned on via hearing a station transmitting a 67 Hz tone so that is why
you can hear FM noise through it when no RX of uplink signal is present.  It
has no squelch to prevent weak signals from getting through.  

I have a little Chinese radio that definitely even on "Wide" mode, is
quieter than another radio I own.  Most HT's give no option to adjust this
value.  Yelling into these radios does not help as they seem to have some
level of high signal limiting or compression, as simple as plane old peak
clipping.  I know that Yaesu does allow for mic gain adjustments on some of
their Fusion radios but most FM only handhelds have no option for fine

My suggestion to little pistols like myself (When learning to work FM
satellites like AO-85), is to just not try during a busy pass but wait for a
lesser trafficked pass so you can learn how best to manipulate your
transmitting circumstances to hear yourself and be heard.  

Jerry Buxton, the Fox series daddy, assures us that the newer iterations of
the AMSAT Fox birds will have a little better ears and hopefully that will
help immensely.  

Have patience with the little guys.  You probably were one once yourself.

Tom Schuessler
n5hyp at arrl.net


Message: 3
Date: Mon, 14 Aug 2017 19:27:29 +0200 (CEST)
From: jerry.tuyls at telenet.be
To: amsat-bb <amsat-bb at amsat.org>
Subject: Re: [amsat-bb] Modulation levels on AO-85
	<1165542169.90891698.1502731649191.JavaMail.zimbra at telenet.be>
Content-Type: text/plain; charset=utf-8

Spending some time here by telling several times on AO-85 passes about bad
modulation to the same stations, but they DON'T listen.

Just ignoring them, because i cannot understand them on my TS-790/FT-847.No
narrow FM and no PL tone. Never got a problem.

And please...why do some stations upload logs with DWNlink freq on sat qso's
instead of the UPlink freq?
Always having some rejected qsl's because qso's don't match due to wrong
band. I log with VQlog, uplink and dwnlink freq etc, so i think the TX-freq
is most important for logging sat'qso's and not the RX-freq? 



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