Date: Fri, 2 Dec 2016 16:43:13 -0500
From: Markus Vester <markusvester@aol.com>
To: rsgb_lf_group@blacksheep.org
Message-Id: <158c17dc012-1cbc-28d9@webprd-a15.mail.aol.com>
In-Reply-To: <Pine.LNX.4.64.1612021419280.20224@plato.ucs.mun.ca>
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Subject: Re: LF: EbNaut 137.477 kHz 1 Dec
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Hi Joe,

> a fax of Tangles' forehead=20

Yes those lines on the narrow spectrogram were indeed reminiscent of cat's =
whiskers ;-)

> use the stable DOXCO to divide out or synthesise an LO signal and mix it =
in an SBL-3 as Stefan has done

But that would imply building a complete LF receiver from scratch, includin=
g an image reject filter and some gain stages. A possibly quicker alternati=
ve might be to use your existing receiver and only inject an weak pilot ton=
e from your DDS (eg. 137500 Hz) to the antenna, and then engage SpecLab's f=
requency offset detector to eliminate any receiver drift. That way soundcar=
d samplerate drift won't be corrected, but that will have little effect as =
long as the difference between the pilot and the desired signal frequencies=
 is less than a couple of 100 Hz. I have successfully employed that method =
on MF to compensate the significant drift of my freerunning FiFi-SDR, and w=
as able to decode a number of EbNaut transmissions (including yours) around=
 477.7 kHz.

Best 73,
Markus (DF6NM)


-----Urspr=C3=BCngliche Mitteilung-----=20
Von: jcraig <jcraig@mun.ca>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Fr, 2 Dez 2016 7:15 pm
Betreff: Re: LF: EbNaut 137.477 kHz 1 Dec


Hi Markus and Stefan,

Thank-you for for your efforts in receiving and decoding the message. This=
=20
is encouraging -- it's good to know everyhing still works after the=20
hardware clean-up in the shack. I'll take care of forwarding the message=20
to Poldhu.

The slope and bends in the high res bpsk specrogram were intentional.
The element period T increased as a function of time and the bends are
actually curves due to the 1/T relation of the sideband deviation
from the carrier frequency I think.

It was a (poor) attempt to send a fax of Tangles' forehead (see=20
attached). She has been reminding me that she is interested in
getting a message from Gizmo and so I've been giving some thought
about reception. An idea is to use the stable DOXCO to divide out or
synthesise an LO signal and mix it in an SBL-3 as Stefan has done,
then to feed the product and a reference into the Spectrum Lab.

73 & TNX AGN
Joe VO1NA
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<div style=3D"font-size:10pt;font-family:arial,helvetica,sans-serif;color:b=
lack;"><div style=3D"color: black; font-family: arial,helvetica,sans-serif;=
 font-size: 10pt;">Hi Joe,<br><br>&gt;&nbsp;a fax of Tangles' forehead <br>=
<br>Yes those lines on the narrow spectrogram were indeed reminiscent of ca=
t's whiskers ;-)<br><br>&gt; use the stable DOXCO to divide out or synthesi=
se an LO signal and mix it in an SBL-3 as Stefan has done<br><br>But that w=
ould&nbsp;imply building a complete LF receiver from scratch, including&nbs=
p;an image reject filter and some gain stages. A possibly quicker alternati=
ve might be to use your existing receiver and only inject an&nbsp;weak pilo=
t tone from your DDS (eg. 137500 Hz) to the antenna, and then engage SpecLa=
b's frequency offset detector to eliminate&nbsp;any receiver drift. That wa=
y&nbsp;soundcard samplerate drift won't be corrected, but that will have li=
ttle effect&nbsp;as long as&nbsp;the difference&nbsp;between the pilot and =
the desired signal frequencies is less than a couple of 100 Hz.&nbsp;I have=
&nbsp;successfully employed that method on&nbsp;MF to compensate the signif=
icant drift of my freerunning FiFi-SDR, and was able to decode a number of&=
nbsp;EbNaut transmissions (including yours) around&nbsp;477.7 kHz.<br><br>B=
est 73,<br>Markus (DF6NM)<br> <br><br>-----Urspr=C3=BCngliche Mitteilung---=
-- <br>Von: jcraig &lt;jcraig@mun.ca&gt;<br>An: rsgb_lf_group &lt;rsgb_lf_g=
roup@blacksheep.org&gt;<br>Verschickt: Fr, 2 Dez 2016 7:15 pm<br>Betreff: R=
e: LF: EbNaut 137.477 kHz 1 Dec<br><br></div>Hi Markus and Stefan,<br><br>T=
hank-you for for your efforts in receiving and decoding the message. This <=
br>is encouraging -- it's good to know everyhing still works after the <br>=
hardware clean-up in the shack. I'll take care of forwarding the message <b=
r>to Poldhu.<br><br>The slope and bends in the high res bpsk specrogram wer=
e intentional.<br>The element period T increased as a function of time and =
the bends are<br>actually curves due to the 1/T relation of the sideband de=
viation<br>from the carrier frequency I think.<br><br>It was a (poor) attem=
pt to send a fax of Tangles' forehead (see <br>attached).  She has been rem=
inding me that she is interested in<br>getting a message from Gizmo and so =
I've been giving some thought<br>about reception.  An idea is to use the st=
able DOXCO to divide out or<br>synthesise an LO signal and mix it in an SBL=
-3 as Stefan has done,<br>then to feed the product and a reference into the=
 Spectrum Lab.<br><br>73 &amp; TNX AGN<br>Joe VO1NA<br><br><br></div>
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