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#1
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Fan of astronomy and VLF ?
Hi,
AAVSO requests the help of amateur radio to monitore Sudden Ionospheric Disturbances, aka SID in low bands Extract from my website. When the Sun release a CME of X-class, the D-layer see its ionisation level increases drastically, absorbing all short frequencies. The result is a deep fading of radio signals and shortly after a complete communications black-out : these are sudden ionospheric disturbances, aka SID. This phenomenon affects mainly VLF and low HF bands in degrading the MUF over about half the Earth hemisphere, the one under the sunlight. Generally the phenomeon occurs in the evening of at night and interrupts all communications on VLF, 160 and 80 m bands. During periods of high absorption, when geomagnetic storms occur, communications can be interrupted on all HF spectrum, up to the 10 m band. The attenuation is however limited to a few dB in the 20-10m band vs 20+ dB on 80m and exceeding sometimes 40 dB on 160m ! If you are interested in this activity read http://www.aavso.org/observing/programs/solar/sid.shtml Thierry ON4SKY, LX3SKY http://www.astrosurf.com/lombry/qsl-perturbation2.htm |
#2
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"Thierry" Thierry, see http://www.astrosurf.com/lombry/ wrote in message ... Hi, AAVSO requests the help of amateur radio to monitore Sudden Ionospheric Disturbances, aka SID in low bands Extract from my website. When the Sun release a CME of X-class, the D-layer see its ionisation level increases drastically, absorbing all short frequencies. The result is a deep fading of radio signals and shortly after a complete communications black-out : these are sudden ionospheric disturbances, aka SID. This phenomenon affects mainly VLF and low HF bands in degrading the MUF over Ho-Oh, my mistake. Be complete: While LF, MF and HF bands experiment blackouts, the increasing of the electronic density between 50-90 km aloft at daytime (due to solar flares) enhances VLF communications during a few days. AAVSO website offers the opportunity to fan of radio/astronomy to build a simple VLF receiver and antenna. Do it this is science ! Thierry ON4SKY, LX3SKY about half the Earth hemisphere, the one under the sunlight. Generally the phenomeon occurs in the evening of at night and interrupts all communications on VLF, 160 and 80 m bands. During periods of high absorption, when geomagnetic storms occur, communications can be interrupted on all HF spectrum, up to the 10 m band. The attenuation is however limited to a few dB in the 20-10m band vs 20+ dB on 80m and exceeding sometimes 40 dB on 160m ! If you are interested in this activity read http://www.aavso.org/observing/programs/solar/sid.shtml Thierry ON4SKY, LX3SKY http://www.astrosurf.com/lombry/qsl-perturbation2.htm |
#3
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"Thierry" Thierry, see http://www.astrosurf.com/lombry/ wrote in message ... Hi, AAVSO requests the help of amateur radio to monitore Sudden Ionospheric Disturbances, aka SID in low bands Extract from my website. When the Sun release a CME of X-class, the D-layer see its ionisation level increases drastically, absorbing all short frequencies. The result is a deep fading of radio signals and shortly after a complete communications black-out : these are sudden ionospheric disturbances, aka SID. This phenomenon affects mainly VLF and low HF bands in degrading the MUF over Ho-Oh, my mistake. Be complete: While LF, MF and HF bands experiment blackouts, the increasing of the electronic density between 50-90 km aloft at daytime (due to solar flares) enhances VLF communications during a few days. AAVSO website offers the opportunity to fan of radio/astronomy to build a simple VLF receiver and antenna. Do it this is science ! Thierry ON4SKY, LX3SKY about half the Earth hemisphere, the one under the sunlight. Generally the phenomeon occurs in the evening of at night and interrupts all communications on VLF, 160 and 80 m bands. During periods of high absorption, when geomagnetic storms occur, communications can be interrupted on all HF spectrum, up to the 10 m band. The attenuation is however limited to a few dB in the 20-10m band vs 20+ dB on 80m and exceeding sometimes 40 dB on 160m ! If you are interested in this activity read http://www.aavso.org/observing/programs/solar/sid.shtml Thierry ON4SKY, LX3SKY http://www.astrosurf.com/lombry/qsl-perturbation2.htm |
#4
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"Thierry" Thierry, see http://www.astrosurf.com/lombry/ wrote in
: Be complete: While LF, MF and HF bands experiment blackouts, the increasing of the electronic density between 50-90 km aloft at daytime (due to solar flares) enhances VLF communications during a few days. I've seen reports in ham related groups of good propagation on LF as well as 10 meters lately. |
#5
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"Thierry" Thierry, see http://www.astrosurf.com/lombry/ wrote in
: Be complete: While LF, MF and HF bands experiment blackouts, the increasing of the electronic density between 50-90 km aloft at daytime (due to solar flares) enhances VLF communications during a few days. I've seen reports in ham related groups of good propagation on LF as well as 10 meters lately. |
#6
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"donutbandit" wrote in message ... "Thierry" Thierry, see http://www.astrosurf.com/lombry/ wrote in : Be complete: While LF, MF and HF bands experiment blackouts, the increasing of the electronic density between 50-90 km aloft at daytime (due to solar flares) enhances VLF communications during a few days. I've seen reports in ham related groups of good propagation on LF as well as 10 meters lately. What happens sometimes is that during blackouts in Scandinavia regions for example (due to solar flare, etc),these hams can experiment for a few hours some exeptional openings to far DX, mainly trans-equatorial (i.e. LA to CX/PY or to pacific) due to an increasing of electrons density in D-Region. But only inhabitants of polar regions (over 60° N/S) can be the witnesses of these occurrences. AAVSO is monitoring theses openings Thierry ON4SKY |
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