5 February 2024 – Propagation at HF: What can we learn using digital modes WSPR and FST4W? by Gwyn Griffiths, G3ZIL

The presentation

Gwyn says:

“This presentation is a story of learning-as-I-went-along with the Weak Signal Propagation Reporter (WSPR) mode within the WSJT-X digital communications package. It begins with building a simple, but successful, 7 MHz WSPR transceiver.

“My next WSPR receiver went to the Arctic on an icebreaker, receiving three spots in eight days. Why? We’ll delve into how the ionosphere affects narrowband signals like WSPR. We’ll see why frequency spread, as in auroral flutter, is important. How do we measure it? Enter the FST4W mode. Frequency spread is not just a useful measure on auroral paths. I’ll show how to identify one-hop and multi-hop signals, where the path was likely a chordal hop or a Pedersen ray, or when my 14 MHz signal from Southampton reached London via two ionospheric refractions and the Mediterranean.

“To convince you that’s quite likely we’ll look at ray trace model predictions and results of a rotating-beam experiment. To close, I’ll use these tools to show effects on the ionosphere of the 14 October 2023 annular eclipse over the USA.”

About Gwyn

I was raised on Anglesey (WAB: SH28) and it was listening to the Coastguard that first triggered a passion for things radio. Licensed as GW3ZI aged 15, amateur radio—especially benevolent and patient locals—gave me a decent grounding in practical electronics. The ionosphere, sunspots, refraction, even aircraft scatter were concepts I began to grasp.

But, in a career more concerned with sound waves—underwater—I was inactive until retirement. Modern amateur radio was a world of seemingly endless topics. I was looking for something that combined my interests in low power and making measurements, and would develop my knowledge on how signals propagated. The answer was the Weak Signal Propagation Reporter (WSPR) mode within the WSJT-X digital communications package.

The last seven years with WSPR, and lately its stable mate FST4W, have been a joy—yes, for the technical side—but primarily for the enduring friendships along the way.

Gwyn is a corresponding member of the Propagation Studies Committee.

Find out more

• More on this work
  • http://wsprdaemon.org/technical
  • http://wsprdaemon.org/presentations
• Study of effects on propagation of the 14 October 20 eclipse
• Above MUF modes
• Propagation books from RSGB
• Chen-Pang Yeang, Probing the Sky with Radio Waves – From Wireless Technology to the Development of Atmospheric Science. University of Chicago Press. Scholarly and brilliantly readable.
• Tools:
  • https://github.com/rrobinett/wsprdaemon   https://github.com/HamSCI/PyLap
  • https://rsgb.org/main/technical/propagation/propagation-prediction-programs-and-forecasts/
• Contact Gwyn: gwyn@autonomousanalytics.com

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