The solar radio noise is measured daily with amateur
theat means I use an old communication receiver AR3000 modified
for radio astronomy purposes. The detector is composed of an analoge
S042P (Siemens). The Yagi-antenna is a standard TV antennae
(BIV/V) for channel 37.
The antennae is
fixed in meridian,
but the elevation is tilted once or twice per month according
to the actual elevation of the suns orbit (Transit Meridian
The receiver is
via RS232 with a Windows compatible PC running under XP and Borland
Builder 6. This PC is also part of
the internal network, thus the data can be captured very easily. Every
month a graph and a listing will be produced and stored in the archive
Single frequency light curve AR3000.
The graph above shows the actual received signal presented in degree
Kelvin absolut aequivalent antenna noise temperature.
Every measurement-point is individually calibrated under software control
with a semiconductor noise source in
the frontend box (focal
Calibration takes place automatically
twice per minute, for equations see tables below.
The plott is updated automatically every couple of minute.
Multi frequency light curves produced by Callisto
Non calibrated data during transit of the sun.
Dynamic solar spectra are stored in FIT-files
Access to documents and data here.
Receiver AR3000, Quadratic detector (S042P) and attenuator -10dB
Integrator 6.8msec is also in the blue box
Personal Computer Windows XP
Top left: Preamplifier KUHNE +20dB, 5MHz....1500MHz
Top right: SPDT Daico (selection between calibration or antenna)
Centre: Noise source and 2 attenuators 23dB in total
Right: Calibration SPDT (selection between noise source or T0)
Bottom: cables from antenna and to receiver as well as some control
Yagi antenna for channel 36 (WIPIC) pointing to the transit position of
Tant = antenna
Tcold = reference temperature = 273.15Kelvin + measured ambient
Thot = noise source temperature = 701Kelvin
Ihot = measured digits when the noise source is applied
Icold = measured digits when the termination resistor having ambient
temperature is applied
Iant = measured digits when the antenna is switched on while pointing
the sky or to the sun
S = solar flux
expressed in sfu
where 1sfu = 10^(-22) W/m^2/Hz = 10'000FU = 10'000Jansky
Tant = antenna temperature, see
pi = 3.1416, k = Boltzman constant = 1.38E-23 J/K
G = antenna gain in the order of 14dB +/- 0.6dB
lambda = wavelength = 49.18cm at 610MHz
r/R = correction factor of sun distance to the earth (one number per
Shown left the home
analysis software tool.
Every data set of each day is read into the plot window
(white dots) and then Fourier-transformed. All higher
frequencies are set to zero and the residual spectrum
is then Fourier-transformed back into the time-domain,
see yellow plot.
By this way we get a kind of filter function. The plot
between the two green vertical lines are analyzed by
reading minimum and maximum values. This difference
is presented as DeltaT (Antenna temperature of the sun).
This temperature difference (sun-background) is then
multiplied by some system parameters to get the solar
radio flux, see equations above.