Propagation | The SWLing Post

ionosphere-earth-radio-waves Two weeks ago, at the W4DXCC conference in Tennessee, I met Lyle Juroff (K9FIK). Not only did I find that Lyle and I had many radio interests in common, but he also told me a story about hearing, recording and analyzing a double echo on the HF bands. I asked if he would explain in an email and include the recording so that I could share it on the SWLing Post. He kindly agreed!

Lyle writes:

I worked a DX station [9A1A] on 10 meters this past spring. As the band improved, I heard an echo develop on his signal and guessed it might be long path so I began recording the audio. I then began to hear a double echo and looked at the waveform on AUDACITY. The timing marks on AUDACITY indicated 140 milliseconds between echos.

I went to Wolfram Alfa, one of my go-to sights for things I can’t remember, and looked up the earth circumference. It not only gave me the distance but also the time to travel it at the speed of light, 133 milliseconds. Not sure if everyone working DX has heard this sort of thing, I played the recording at the next East Tennessee DX Association meeting. Nobody said they had heard that kind of double echo.

Click here to download an mp3 of Lyle’s recording or simply listen via the embedded player below (note that the second recording is .WAV format):

Have you heard a double echo this profound? Please comment.

Many thanks to Lyle (K9FIK) for sharing his story!

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Photo Source: NASA

News sources are publishing information regarding new scientific research which puts our sunspot cycle into question. How does this affect the average shortwave listener? Periods of high sunspot numbers generally produce excellent DX conditions. In other words, with modest equipment, listeners can hear even weak signals around the world. Amateur radio operators find that they can communicate around the world with very low power.

Our current cycle (cycle 24) has been relatively uneventful compared to the past–but the prediction for Cycle 25 is scary. Indeed, it may not even happen on schedule. The news sources below explain in detail.

Spaceref.com:
A missing jet stream, fading spots, and slower activity near the poles say that our Sun is heading for a rest period even as it is acting up for the first time in years, according to scientists at the National Solar Observatory (NSO) and the Air Force Research Laboratory (AFRL).

As the current sunspot cycle, Cycle 24, begins to ramp up toward maximum, independent studies of the solar interior, visible surface, and the corona indicate that the next 11-year solar sunspot cycle, Cycle 25, will be greatly reduced or may not happen at all.

From Yahoo:
For years, scientists have been predicting the Sun would by around 2012 move into solar maximum, a period of intense flares and sunspot activity, but lately a curious calm has suggested quite the opposite.

According to three studies released in the United States on Tuesday, experts believe the familiar sunspot cycle may be shutting down and heading toward a pattern of inactivity unseen since the 17th century.

Science Mag:
Things may be about to get very dull on the sun. Three different measurements of solar activity, reported by scientists at a press conference today, suggest that the next 11-year-long solar cycle will be far quieter than the current one. In fact, it may not happen at all: Sunspots, the enormous magnetic storms that erupt on the sun’s surface as the cycle builds, might disappear entirely for the first time in approximately 400 years.

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