Message-ID: <564A3E57.40706@abelian.org>
Date: Mon, 16 Nov 2015 20:36:39 +0000
From: Paul Nicholson <vlf0403@abelian.org>
User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130106 Thunderbird/17.0.2
MIME-Version: 1.0
To: rsgb_lf_group@blacksheep.org
References: <564A27E4.7030204@gmail.com>
In-Reply-To: <564A27E4.7030204@gmail.com>
Subject: Re: LF: COHERENT BPSK ON MF
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Status: O

Nice work.

The 22:00 message Eb/N0 is 13.8dB calculated from the symbol
error rate, but when the decode is used to reverse the
modulation so as to reconstruct a steady carrier, its S/N
corresponds to only Eb/N0 = -3.3dB.   Was there a signal on an
adjacent frequency, within the bandwidth of the baseband I/Q but
far enough away from the EbNaut signal not to upset the decode?

Two of the other messages also have suspiciously weak S/N of
the reconstructed carrier.

Adjacent signals wont upset the decoder but will give incorrect
(low) carrier S/N measurements.

The carrier S/N is used to estimate percentage of capacity,
maybe this estimate should instead use the Eb/N0 derived
from the BER so that it's not affected by signals on nearby
frequencies.

There's a big range of signal levels during this QSO, is that
normal for MF?  The phase looks pretty steady on these short
messages so I guess the amplitude should be too.

Perhaps you will try some weaker transmissions. Some of the
signals are 3dB to 15dB too strong to be a challenge
for EbNaut, it is not even having to use list decoding.

--
Paul Nicholson
--