[TangerineSDR] [HamSCI] Merry Christmas! SAQ Grimeton Christmas Eve Transmission

Jonathan emuman100 at gmail.com
Tue Dec 28 07:54:32 EST 2021

Hi John,

I believe 329 is accurate to what you were able to squeeze out from my recording. I use sox quite a bit, but I wasn’t aware of the benefit of the filter in this case. The brick wall filter of vtfilter isn’t always the best choice. In sox, the bandpass filter is a 2-pole Butterworth and worked much better. 

I’ll definitely give Baudline a try, especially with the autonotch feature. I’m in the process of trying to identify the source of those harmonics and mitigate them in my receiver. Unfortunately, they raise the noise floor, so weak signals can easily be missed. 

Thank you again for all of your help and contributing to a successful copy! I submitted the information for an eQSL card.


> On Dec 25, 2021, at 9:03 PM, John Magliacane <kd2bd at yahoo.com> wrote:
> Hi Jonathan.
> When you see stations giving 549 and 339 RST signal reports from EUROPE, you know copying SAQ from across the Atlantic isn't going to be easy...
> I'm glad the SoX filtering worked out well. It's a fantastic tool that I use quite often for all sorts of things.
> Incidentally, Baudline can also plot spectrum averaged over any region of a recording (see attached plots), and SoX can make spectrogram plots as well.
> It may not improve matters much, but you can measure the frequency of those powerline harmonics and notch them out with SoX using multiple "bandreject" filters. That might clean up some the background "growl".
> I think the slow QSB phenomenon that can heard in your recording (especially due to the low SNR) is normal consequence of nighttime propagation at VLF and LF.  I have seen it in both amplitude and phase with WWVB at 60 kHz, and it appears in the daily 24 kHz NAA plots taken at the University of Louisville (http://moondog.astro.louisville.edu/naa/archive/plots/20211224.png).
> 73 de John, KD2BD
> <spectrum.png>
> <spectrum_average.png>

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