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Slide 1
Very Low Frequency Astronomy Or how to observe at work on a
cloudy day!
Slide 2
The Radio Spectrum
Slide 3
D Layer E Layer The Ionosphere VLF are opaque to the ionosphere
Therefore VLF Astronomy is by its nature an indirect method of
observing
Slide 4
Quiet Sun Low level of Sky-wave signal Vs. ground-wave
Slide 5
At Night Erratic level of Sky-wave signal Vs. Constant
ground-wave
Slide 6
Active Sun High level of Sky-wave signal received during
flare
Slide 7
Most people think radio astronomy think is complicated Colin
Clements 4Ghz Radio Telescope But it doesnt have to be...
Slide 8
Radio Equipment Receiver RecorderPC Antenna Larger the better
More turns the better I have three 128 turns 400x400 square tuned
antenna 25 turns 600mm Diameter circle un-tuned 150 turns 600mm
diameter circle untuned Receiver Two approaches 1.radio receiver
tuned to a specific station, outputs signal strength 2.PC sound
card Recorder Two approaches 1.Data logger 2.PC
Slide 9
My UKRAA VLF Receiver Antenna Aerial Tuning Unit Receiver Data
logger/controller
Slide 10
Starbase Observatory Software
Slide 11
My Natural Radio Spectrum Set-up Soundcard Antenna
Slide 12
SpectrumLab Freeware Running on an old laptop Win98 (first
Edition) 192MB RAM Pentium II 400MHz processor 6GB Harddisk Live
power spectrum, peaks are radio transmitters Waterfall shows how
the power changes with time Up to 100 plotters can be set to record
the power at specific frequencies / bands of frequency
Slide 13
Radio Stations 19.6kHz GBZ, Anthorn,UK 20.27kHz ICV, Isola di
Tavolara, Italy 20.9kHz FTA, Sainte-Assise, France 21.75kHz HWU,
Rosnay, France 22.1kHz GQD, 22,.1kHz Skelton, UK 23.4kHz DHO38
Rhauderfehn, Germany 24Khz NAA, Cutler, Maine, USA 37.5kHz, NRK/TFK
Grindavik, Iceland 62.6kHz, La Regine, France 81kHz, Inskip,
UK
Slide 14
VLF receivers currently monitored
Slide 15
Recording & Interpreting Results Amplitude of event
Corresponds (usually) to the flare class, but will be specific to
conditions and observer Start, Peak & End of event Recorded as
an importance level ClassEnergy X10 -4 -10 -3 W/m 2 M10 -5 -10 -4
W/m 2 C10 -6 -10 -5 W/m 2 B10 -7 -10 -6 W/m 2 A10 -8 -10 -7 W/m 2
DurationImportance 126 min3+ A text book SID Importance = 2+
2011-02-28 12:46 12:54 13:48 Corresponded to a M1 event Increasing
Energy
Slide 16
Typical Quiet Day Transmitter is turned off at 07:00 08:00
every day
Slide 17
SID
Slide 18
Raw Data can be a little confusing
Slide 19
Removing signals after sunset and the signals that are not
showing useful information can make it easier to see what is going
on.
Slide 20
SIDs come in many shapes
Slide 21
Results
Slide 22
Next Steps for VLF Get laptop set-up in shed and connected via
wifi to main PC Get lap-top controlling UKRAA controller Build VLF
set-up for CMHAS observatory Experiment with different antenna
configurations Automate logging and access via web
Slide 23
Future Projects for Radio Astronomy Meteor Detection Solar
activity monitor (21Mhz) Radio Jove (21Mhz) Radio Imaging