My first Solar radio spectrograms

[Kimmo]

Here are my first proper measurements of Solar radio bursts made with my radio
spectrograph.

The system is made of the following components:

1) Antenna, loq-periodic for 130-1300 MHz, from wimo.com (173 eur)
   No automatic tracking, just turning the antenna by hand from
   time to time.

2) FM trap, Nooelec Flamingo FM (20 eur)
   Yes, before the LNA. If LNA is the first component, there
   are some extra noise in the spectra.

3) Nooelec LaNA - Wideband Ultra Low-Noise Amplifier (LNA) (35 eur)

4) 500 MHz low-pass filter, eBay (22 eur)
   This is to somewhat filter out the TV and cellular signals

5) tinySA Ultra spectrum analyzer                         (141 eur)
   ( https://www.tinysa.org/wiki )

6) A Python program for controlling the tinySA and reading the data from it.
   The program is based on tinysa_scanraw.py, available at
   https://github.com/Ho-Ro/nanovna-tools

------------

I have plotted some spectrograms in the attached PDF-file.
 
I am scanning the frequency range 120-385 MHz.
At first, I used 512 data points along the frequency axis.
The channel width is then 507 kHz. With this setup, the scanning speed is about
two scans per second. The bursts number 1-4 have been observed with this setup.
But I thought that it is better to have faster scanning with fewer data points.
So, now I am using the maximum channel width of the tinySA, 850 kHz. Within a
frequency range 120-385 MHz there is then 312 channels. This also means that the
noise is smaller because the channel width is larger. With this setup, there
is about 2.7 scans per second. The burst number 5 has been observed with this setup.

My results compare well with the results of the e-Callisto instruments. However,
the quality of the e-Callisto data seems to vary a lot between different stations,
at some stations these bursts are not visible.

The burst number 4 is a bit strange... it may be that it is not a Solar burst at
all.

The tinyaSA has its own LNA, but I have not used it in these observations.

The radio bursts detected by me were not related to any X-ray Solar flare.

The antenna is designed for a much wider frequency range than what I need.
To have more gain, I am planning to keep just the boom of the antenna, and replace
the current elements with elements designed for a frequency range of 120-385 MHz.

The problem with my setup is that once or twice a day, the system gets stuck, which
means that I do not get any data from the tinySA before rebooting it.
I have to figure out what is the reason for this.

In the direction of South, at a distance of about 10 km from me, there is a high
(326m) radio/TV station. When I point my antenna towards South, the background
noise in the spectra increases by almost 10dB. This will make it difficult to
observe the Sun during the winter months, when the Sun is low in the sky.

Cheers, Kimmo Lehtinen