Date: Fri, 2 Dec 2016 20:27:01 -0330 (NST)
From: jcraig@mun.ca
To: rsgb_lf_group@blacksheep.org
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Message-ID: <Pine.LNX.4.64.1612022023170.21426@plato.ucs.mun.ca>
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Subject: Re: LF: EbNaut 137.477 kHz 1 Dec
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Hi Markus, group.

Just confrimed that it is indeed 4K19A being transmitted.
Sorry for the careless proofreading of my emails!

Thank-you very much for the pilot tone suggestion.  That
simplifies things greatly and with any luck there will be
an EbNaut RX here soon.

Cheers
Joe

On Fri, 2 Dec 2016, Markus Vester wrote:

> Hi Joe,
>
>> a fax of Tangles' forehead
>
> 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, includ=
ing an image reject filter and some gain stages. A possibly quicker alterna=
tive might be to use your existing receiver and only inject an weak pilot t=
one from your DDS (eg. 137500 Hz) to the antenna, and then engage SpecLab's=
 frequency offset detector to eliminate any receiver drift. That way soundc=
ard samplerate drift won't be corrected, but that will have little effect a=
s long as the difference between the pilot and the desired signal frequenci=
es is less than a couple of 100 Hz. I have successfully employed that metho=
d on MF to compensate the significant drift of my freerunning FiFi-SDR, and=
 was able to decode a number of EbNaut transmissions (including yours) arou=
nd 477.7 kHz.
>
> Best 73,
> Markus (DF6NM)
>
>
> -----Urspr=C3=BCngliche Mitteilung-----
> 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. Thi=
s
> is encouraging -- it's good to know everyhing still works after the
> hardware clean-up in the shack. I'll take care of forwarding the message
> 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
> 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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