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Re: LF: All 73 Banders... wspr-x recordings

To: <[email protected]>
Subject: Re: LF: All 73 Banders... wspr-x recordings
From: "Markus Vester" <[email protected]>
Date: Sat, 14 Dec 2013 19:17:53 +0100
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Trevor,
 
thanks for this comment! It would be interesting to know how much spacing is needed between a weak WSPR signal and a relatively strong neighbouring carrier, located within the WSPR analysis range but outside the four-tone spectrum of the desired signal.
Unfortunately I can't contribute as I hadn't run recordings, and also both the desired WSPR signal and the Loran carrier were anyway too weak here for a meaningful result. Perhaps Hartmut or Victor happened to have .c2 or .wav saving enabled last night? 
 
Best 73,
Markus
 
Sent: Saturday, December 14, 2013 6:43 PM
Subject: Re: LF: All 73 Banders...

As you know WSPR-X is regarded as experimental software and as such Joe Taylor K1JT has
often asked for users to contact him with any difficulties they encounter.

So how about Marcus, Hartmut, Victor and anyone else, producing a .wav file of successful and
non successful wspr-15 decodes including all the DCF77 and other qrm. The files could be sent
to Joe direct or made available for him to download and he can analyse them to see if any
improvements can be made.

K1JT email address can be found at the bottom of this page
http://physics.princeton.edu/pulsar/K1JT/wspr.html

Trevor  G0KTN

Sent: Saturday, December 14, 2013 4:03 PM
Subject: Re: LF: All 73 Banders...
...
It's however strange that Hartmut and Victor didn't get any decodes, even though the signal seemed to be well visible for both. What looks like noise on Victor's capture must really be the WSPR-15 spectrum:
 http://dl.dropboxusercontent.com/u/26404526/pa3fny_74603_131214_0700_arrowheads.jpg

But both statiopns have a relatively strong Loran line, and Hartmut's directional antenna is pointing towards Sylt. However the nearby line frequency 74603.280 Hz should have been well outside the occupied spectrum of Bob's WSPR signal (74603.51 to 604.24), so it's not ovbvious why it should have prevented decodes. I'm speculating that the WSPR software finds the strong line, tries to sync to it, and then somehow excludes nearby real signals from further decode attempts. To prove the point and see how much spacing is needed, we could experiment with letting WSPR decode local audio signals in the presence of injected carriers. But systematic trials with WSPR tend to be time-consuming, even if such tests were accelerated by scaling to WSPR-2.
...
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