What the heck is this all about?

[KB4MSZ]

I hear (and see) this tone on the WWV signals fairly often. What exactly is it?

 

[k9wkj]

https://hamsci.org/publications/iontv-using-wwv-timing-reference-signals-observe-ionospheric-variation

 

[fleef]

I wonder if WindyTan has an answer. absorptions not sure where she is on social media but won't hurt to find her & include your img. It's awesome! whatever it is

 

[RFI-EMI-GUY]

I think NIST has introduced an FSK signal into the WWVB VLF signals for the newer clocks. Maybe that is same technology in HF?

 

[KB4MSZ]

And here it is at 25 MHz

 

[fleef]

https://hamsci.org/publications/iontv-using-wwv-timing-reference-signals-observe-ionospheric-variation

is that what it is?? a tool to observe ionospheric variations? That is so amazing. I did not watch the vid by OP at first, just looked at the image. Play the video, if you haven't already you guys. It's hypnotic and really something to see. The signal waterfall is a prism of the colors in the rainbow. Quite remarkable and a real scene to see.

 

[RFI-EMI-GUY]

WWV/WWVH Scientific Modulation Working Group

NIST is participating in a new project to study the ionosphere and its effects on high frequency (HF) radio propagation.

www.nist.gov