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A Solar Flare Monitor on VLF


Observe the Sun with Very Low Frequency Signals

Solar Flare Monitoring on VLF

Now that I am actually living full-time in my radio shack, I do find that I have time to get involved in some areas I do not ordinarily have the time for. One of those interests is the state of the Sun and the Ionosphere through observation of the Very Low Frequency (VLF) band (3-30kHz, e.g. RadioUser, February 2014: 54, September 2015: 50; November 2016: 33). A group of international hobbyists, interested as they are in propagation, venture into this area. My basic setup is a VLF Receiver, VLF Loop and ATU from the UK Radio Astronomy Association (UKRAA). The receiver monitors the 23.4kHz transmitter in Ramsloh (Germany). Because of VLF propagation, this is just about remote enough for UK hobbyists to get meaningful data. The UKRAA receiver logs the data as a voltage. This voltage reflects the ever-changing propagation conditions of the VLF signals in their environment. The output is fed to a Lab Jack U3-HV Data Acquisition Unit. The U3-HV is a USB Multifunction device with four dedicated high-voltage analogue inputs, 12 flexible I/O, and four dedicated digital I/O channels. It can be used for many other purposes too, for instance, weather data logging. Using Starbase (UKRAA), or the popular Radio Sky pipe suite (a virtual strip-chart recorder), the result can be visualised on your PC. Leave it on overnight to catch solar flares, which appear to have the characteristic ‘shark’s fin’ shape and other solar and geomagnetic events. Jeff Lashley's book The Radio Sky contains a short chapter on this area.

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