Many thanks to SRAA contributor, Matt Todd, who shares the following short clip of the Ham Sci Ionospheric Scientific Modulation Test:

Date of recording: 3/10/2022

Starting time: 1908

Frequency: 15

Your location: Hu

Your receiver and antenna: SDRplay RSPdx with wire loop around perimeter of attic

Mode: AM

Notes: Ionospheric Scientific Modulation Test on WWV recorded March 10, 2022 at 1908UTC on 15Mhz in Hugo, MN.

Information about the signal from the Hamsci website: HamSCI's WWV/H Scientific Modulation Working Group is exploring possibilities for additions to WWV and WWVH's modulation that can be used for science purposes.

https://hamsci.org/wwv