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LF: VO1NA CW 477.7 kHz

To: [email protected]
Subject: LF: VO1NA CW 477.7 kHz
From: Markus Vester <[email protected]>
Date: Sat, 5 Mar 2016 14:39:23 -0500
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In-reply-to: <[email protected]>
Reply-to: [email protected]
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Hi Joe,

on the spectrogram , your carrier trace was quite narrow so conditions were stable again last night. Weak sidelines at +- 4.16 Hz corresponding to the dot rate were also visible. 

Unlike Roelof, I have no chance of actually hearing your CW message here. So I made an attempt to bring it out of the noise using coherent averaging. The saved data files from 23 to 6 UT were assembled into one large array. Then the phase evolution of the AM carrier was estimated and used for synchroneous demodulation (just like in opds). Thus the modulation appears in the in-phase baseband component, allowing coherent averaging of multiple message repeats. 

From the sidelines I knew the dot duration, but I had to use trial and error to find the message length. In the end, a cycle of 208 dotlengths (25.00228 s) and 1126 averages turned up an easily readable fast-CW decode, shown in the attached screenshot (black = in-phase, cyan = quadrature).  

All the best,
Markus (DF6NM)

-----Ursprüngliche Mitteilung-----
Von: jcraig <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Fr, 4 Mrz 2016 11:49 pm
Betreff: Re: LF: MF: EbNaut: Now CW 477.7 kHz

Thank-you again Roelof. Conditions are great so I'll try 10 WPM CW
73 Joe VO1NA

On Fri, 4 Mar 2016, Roelof Bakker wrote:

> Hello Joe,
> Excellent propagation once more!
> Even better than yesterday night.
> 73,
> Roelof, pa0rdt

Attachment: VO1NA_averaged_CW.png
Description: PNG image

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