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Re: LF: EbNaut LF test from iz7slz

To: [email protected]
Subject: Re: LF: EbNaut LF test from iz7slz
From: Paul Nicholson <[email protected]>
Date: Fri, 20 Nov 2015 11:55:29 +0000
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Domenico wrote:
> transmission in progress (21:30 UT) is formed
> by 39 characters at 0.5s.

Sorry I was unable to decode this one.  Tried list 100k
with time offsets -0.1 to +0.9 in 0.02 second steps.

My receiving system is not very good.  You guys are doing much
better because you have proper receivers.  Here I am trying
to use the same method that I use on VLF: direct reception
through a soundcard, and it is just not working out very well.

The only soundcard I have which will clock fast enough has a
mono input which means I have to mix the PPS and LF together
into the one input.  That, and the card itself being quite
noisy,  makes it difficult to apply a precise time stamp to
the signal samples.   It is working, just not well enough and
it looks like I'm losing a dB or two at least.

It means I can't make accurate measurements of carrier phase
and although we're getting some success with EbNaut messages,
we cannot tell yet whether the band will support long distance
long duration coherent signalling when the received signal is
too weak to extract a reference phase.

Hopefully someone better equipped will be able to measure the
phase variations of a long T/A carrier.

--
Paul Nicholson
--

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