Many thanks to SWLing Post contributor, Jock Elliott, who shares the following guest post:
You and the ionosphere . . . a reader participation post
By Jock Elliott, KB2GOM
Here’s a shocker for you: we live at the bottom of the sky. Above us there are multiple layers of the atmosphere, pressing down on us at 14.7 pounds per square inch.
Of particular relevance to us as shortwave listeners and hams, there is a special layer of the atmosphere, not shown on the chart above called the ionosphere. The ionosphere starts around 30 miles above us and extends up to about 600 miles and includes parts of the layers above.
The Sun’s upper atmosphere, the corona, is very hot and produces a constant stream of Ultra-Violet and X-rays, some of which reach our atmosphere. When the high energy UV and X-rays strike the atmosphere, electrons are knocked loose from their parent atoms and molecules, creating a layer of electrons.
Now, here’s the cool part: this layer – the ionosphere – is important because radio waves bounce off of it.
The sun, however, is not constant in its action on the ionosphere. The amount of UV and x-ray energy (photon flux) produced by the sun varies at by nearly a factor of ten as the sun goes through an 11 year cycle. The density of the ionosphere changes accordingly, and so does the ability of the ionosphere to bounce radio waves. When the sun is at peak activity, and the ionosphere is “hot,” SWLs and hams are likely to experience excellent long-range propagation. When the sun is quieter, long-range propagation diminishes.
The results can be spectacular. Decades ago, during a particularly hot solar cycle, I once spoke from my station near Albany, NY, to a station in the state of Georgia on a mere 4 watts. On another occasion, I conversed with a ham in Christchurch, New Zealand – a distance of over 9,000 miles – with 100 watts single sideband transmit power. During that same period, I would routinely listen to shortwave stations halfway around the world.
And now, it’s your turn – what’s your favorite long-range propagation story, either as an SWL or ham? Please comment!
Predictions for Solar Cycle 25. Blue is the “official” prediction of a weak cycle. Red is a new prediction based on the Termination Event.
Feb. 26, 2022: Something big just happened on the sun. Solar physicists Scott McIntosh (NCAR) and Bob Leamon (U. Maryland-Baltimore County) call it “The Termination Event.”
“Old Solar Cycle 24 has finally died–it was terminated!” says McIntosh. “Now the new solar cycle, Solar Cycle 25, can really take off.”
The “Termination Event” is a new idea in solar physics, outlined by McIntosh and Leamon in a December 2020 paper in the journal Solar Physics. Not everyone accepts it–yet. If Solar Cycle 25 unfolds as McIntosh and Leamon predict, the Termination Event will have to be taken seriously.
Radio Waves: Stories Making Waves in the World of Radio
Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers. To that end: Welcome to the SWLing Post’sRadio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!
Many thanks to SWLing Post contributors Ron, Mike, and the Southgate ARC for the following tips:
Giant flares and eruptions from the sun can cause space weather, and stormy space weather can interfere with everything from satellites to the electrical grid to airplane communications. Now, though, there’s good news for people who monitor the phenomenon — the sun has passed from one of its 11-year activity cycles into another, and scientists predict that the new cycle should be just about as calm as the last.
That doesn’t mean, however, zero risk of extreme weather events. Even during the last, relatively weak solar cycle, drama on the sun triggered occasional weirdness on Earth like radio blackouts, disruptions in air traffic control, power outages — and even beautiful aurorae seen as far south as Alabama.
Over each solar cycle, the roiling sun moves from a relatively quiet period through a much more active one. Researchers monitor all this activity by keeping an eye on the number of sunspots, temporary dark patches on the sun’s surface. These spots are associated with solar activity like giant explosions that send light, energy, and solar material into space.
Counting of sunspots goes back centuries, and the list of numbered solar cycles tracked by scientists starts with one that began in 1755 and ended in 1766. On average, cycles last about 11 years.
Based on recent sunspot data, researchers can now say that so-called “Solar Cycle 24” came to an end in December of 2019. Solar Cycle 25 has officially begun, with the number of sun spots slowly but steadily increasing.[…]
Iconic AM station just celebrated the 100th anniversary of its first broadcast
It was shortly after World War I that Clarence Thompson, a partner of Lee de Forest, formed a new company Radio News & Music Inc. in New York. His goal was to encourage newspapers to broadcast their news reports by wireless, using de Forest transmitters.
The franchise offer — available to only one newspaper in each city — offered the rental of a de Forest 50-watt transmitter and accessories for $750. Just one newspaper signed up for the deal; it was the Detroit News, led by publisher William E. Scripps.
He had been interested in wireless since investing in Detroit experimenter Thomas E. Clark’s wireless company in 1904. Scripp’s son, William J. “Little Bill,” was an active ham radio operator, operating a station in the Scripps home.
People Might Laugh
Scripp proposed accepting the Radio News & Music offer and building a Detroit News radio station in 1919, but he met resistance from his board of directors. It was not until March of 1920 that he was given the go-ahead to sign a contract.
The de Forest transmitter was shipped to Detroit on May 28, 1920, but was lost in transit; a second transmitter was constructed and sent on July 15. This delayed the installation of the station until August.[…]
NOTE: This is a machine translation of the original post in Czech.
Czech Radio has entered another, important phase of radio digitization. To date, the ?Ro DAB + multiplex signal has reached 95% population coverage. Ten new transmitters were launched in Bohemia and Moravia. You can find a detailed description of them below.
DAB + technology is becoming a common distribution channel for Czech Radio, which will be placed on the same level as analogue FM / FM broadcasting. All marketing activities will already include the “DAB + More Radio” logo. ?eské Radiokomunikace is planning to start certification of receivers next year in order to protect customers and facilitate orientation in the range for them and retailers.
According to the CEO of Czech Radio, René Zavoral, the public service media is proceeding in accordance with a long-term strategic plan. The head of communication and press spokesman Ji?í Hošna describes the step as a turning point that can affect the direction of the entire radio market.[…]
The RSGB Examinations Standards Committee (ESC) report covering 2019 is now available for anyone to download
The report contains statistics for the both the RSGB amateur radio exams and the Air Cadets Organisation (ACO) exam which Ofcom considers to be equivalent to the RSGB Foundation.
Ofcom has been concerned about the participation of women in amateur radio and STEM disciplines. They requested the ESC to publish figures for the number of women taking the exams. Unfortunately the results are disappointing with only 9.9% of all exams being taken by women.
Many thanks to SWLing Post contributor, Dave (K4SV), who shares this video courtesy of NASA Goddard:
The Sun is stirring from its latest slumber. As sunspots and flares, signs of a new solar cycle, bubble from the Sun’s surface, scientists are anticipating a flurry of solar activity over the next few years. Roughly every 11 years, at the height of this cycle, the Sun’s magnetic poles flip — on Earth, that’d be like the North and South Poles’ swapping places every decade — and the Sun transitions from sluggish to active and stormy. At its quietest, the Sun is at solar minimum; during solar maximum, the Sun blazes with bright flares and solar eruptions. In this video, view the Sun’s disk from our space telescopes as it transitions from minimum to maximum in the solar cycle.
The orbits of Venus, Earth and Jupiter may explain the sun’s regular 11-year cycle, a new study suggests.
A team of researchers from Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a research institute in Dresden, Germany, showed that the magnetic fields of those three planets influence the cycle of solar activity, resolving one of the bigger questions in solar physics.
“Everything points to a clocked process,” Frank Stefani, a researcher at HZDR and lead author of the new study, said in a statement. “What we see is complete parallelism with the planets over the course of 90 cycles.”
The researchers compared observations of solar activity — like sunspots, solar flares and coronal mass ejections — from the last thousand years with planetary alignments in order to show that there was in fact a correlation, according to the statement.[…]