 | | The LOWDOWN This Month
In the August 2008 issue of the club publication:
- "DX Downstairs" Kevin Carey presents members' LF and VLF loggings, including NDB pictures from Kriss Larson's recent trip to Kansas.
- "On The Air" Experimenters operating on the 160-190kHz and 136kHz bands... and...
- "The Top End" MedFER and HiFER beacon lists... and...
- "The LF Notebook" Conducted by John Davis. News of LF radio happenings for, from, by, and about LWCA members.
- "News From the Old World" Alan Gale keeps us informed of LF experimentation on the "other side of the pond."
- "LowFER PA Ideas" Article by John Andrews looks as some modern variations on the popular 1W LowFER final amp design by Lyle Koehler.
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| | Magnetic Explosions? Plasma Bullets?
THEMIS mission captures the origin of an auroral substorm.
JULY 25, 2008 - NASA announced yesterday the first major discovery by the five satellites of the THEMIS mission, based on analysis of a never before witnessed but long suspected event about 80,000 miles distant in the Earth's magnetotail. The data provide an important clue to the origin of auroral substorms.
Since their discovery over 40 years ago, auroral substorms have been a source of mystery to observers of the Northern and Southern lights, including Natural Radio monitors. The auroral oval circling each pole is a smooth, calm ring of (predominantly ultraviolet) light most of the time, powered by charged particles from the sun that are captured in the planet's lines of magnetic force and directed toward the upper atmosphere around its magnetic poles. If the sun gets particularly energetic during a space weather event, the oval ring can become brighter and more turbulent.
But sometimes during the course of an otherwise calm night, there are sudden fluctuations in brightness and "dancing" of the aurorae that cannot be tied to specific solar events. The phenomenon was first recognized and named "auroral substorms" in 1964, based on study of All Sky Camera films from several ground-based stations at higher latitudes, well before there were any satellites observing the poles. It was theorized that solar wind energy must be stored in some way in the earth's magnetosphere, but just how it was released--as a disruption of the near-Earth electrical current in the magnetotail, or as a magnetic reconnection event farther out in space--was a big mystery. The five THEMIS birds were lined up just right on February 26, 2008, to receive much-needed clues to answer the question. As it turns out, the release of 1015 Joules of energy in an explosive burst of charged particles causes many interesting effects, including awe-inspiring Natural Radio signals.
Results will be published in the August 14 edition of the journal Science, under the title "Tail Reconnection Triggering Substorm Onset." Meantime, for a quick summary of the story, you can visit SCIENCE@NASA. You can also read the Mission Overview, learn more about auroral research and the history of the discovery of substorms, read about the spacecraft themselves, and view the visual aids from NASA's media teleconference about this story. (These links all open in new windows.)
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General Topics of Interest
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| | Related Longwave Sites
•William Hepburn's DX Information Centre features many kinds of DX resources, including much on services found at LF and VLF; for example, regularly updated lists of NAVTEX and TWEB (Transcribed Weather) stations, LF/VLF time signals, and longwave broadcasters. Visit the site at its new location:
DX Information Centre. Don't overlook the pages for higher frequencies, and the propagation forecasts as well.
•Radio Waves Below 22 kHz Renato Romero's eclectic collection of topics pertaining to both manmade and natural radio signals from near DC to the upper end of audibility. Includes the VLF Open Lab, and articles by many contributors...some fairly orthodox, and some not. Visit: www.vlf.it
•Whistler Receiver Online Hear a NASA Project INSPIRE receiver in near-real-time from Huntsville, Alabama. Lots of sferics, including tweaks and occasional whistlers, should be audible, particularly in the hours just before dawn at the receiving site. Listen to the receiver through the SpaceWeather INSPIRE page and get more background on whistlers and related phenomena from this NASA news headline.
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| | QRSS and WOLF Software
Rik Strobbe's QRSS software (for transmitting extremely slow CW) is usually available from our file library, but while it is temporarily out of service, you can obtain QRSS and Rik's other useful software at the ON7YD download page.
Continuing Development of Argo. Alberto di Bene regularly posts the latest version of Argo, a receiving tool for displaying slow CW, that performs FFT spectral analysis and displays it in ways optimized for QRSS. Many of the transoceanic LF amateur records were set using Argo at the receiving end. Argo has somewhat similar performance to Spectran, but interacts better with the user's soundcard and is customized for QRSS modes.
Slow CW for Linux. Claudio Girardi (IN3OTD) has released the next version of his Slow CW software for users of the Linux operating system, alpha 0.3.1. The program (called glfer) contains both transmit and receive capability, the latter including an FFT-based spectrum analyzer somewhat similar to those found in popular Windows Slow CW programs.
As with much open-source software in the X-world, you have to compile the C source code yourself. Users will also need additional code libraries. Links to those, plus downloadable source code, can be found at Claudio's glfer page.
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