[TangerineSDR] Dawn Chorus Event 4/10/2022

[Jonathan]

In the early morning hours of April 10th, there were some strong
geomagnetic storms that peaked with a K index of 7! There were many reports
of weak aurora at low altitudes, including the northern US. Here in
Northeast PA, Nathaniel and I were treated to a beautiful electromagnetic
event that is just as amazing as aurora. I checked the detected events on
my VLF SDR and was greeted to this beautiful surprise:


These are spectrogram thumbnails of a beautiful daw chorus event that was
over two and a half hours long with the first riser appearing at 08:18 UT!
The event detector looks for rising frequency components in the spectrum
using principal component analysis that matches rising frequency components
and colors those features white. Here are some full spectrograms:
This is a beautiful example of risers from such an awesome dawn chorus
event!

The footprint of this chorus event was quite large! In this stacked
spectrogram, the top shows the event from a VLF receiver in Virginia. On
the bottom is our receiver in Northeast PA:

Here is a movie I made by combining 10 second spectrogram stills with the
audio sample. This is the peak (peak signal intensity) of the event! It
sounds absolutely beautiful:

https://drive.google.com/file/d/1r5kE3SYV3UQzDfuQoMA_b7Dh8OWXy_aM/view?usp=sharing
2022-04-10_09-45-00-09-55-00_10m_04102022_chorus_peak_spectrogram10s.mp4

Paul was able to remove a lot of the local interference and sounds much
better in this sample:

https://drive.google.com/file/d/1oykH8JmbZxJ1bYIbjKkdWl8ZuLPRdVgZ/view?usp=sharing
au220410-vlf44.mp3

Using a sferic blanker utility, the audio was further filtered:

https://drive.google.com/file/d/175HxZkswJMVv5ev0mLxTFYUXE2w2msS8/view?usp=sharing
au220410-vlf44b.mp3

For those interested, this is the whole chorus event:

https://drive.google.com/file/d/1ka14XfVZKeZ3IWslhSUjX_PDdXRbjhZF/view?usp=sharing
2022-04-10_08-18-20-11-00-00_2-41-40_04102022_chorus.mp3

Jonathan
KC3EEY
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