SID Receiver
Sudden Ionospheric Disturbances
I recently built my first SID receiver following a very inspiring article by Paul Hyde in the September 2015 edition of "Sky At Night" magazine. In the article Paul describes the basic equipment needed to receive and log those changes in the Earths ionosphere caused by X-ray flares erupting from the sun. As I knew nothing about this it seemed a good project to begin and learn the basics.
The photo on the right shows the Aerial. The one made here is simply a wooden cross 1.5M x 1.5M with 100M of 2 core solid wire wrapped around it.I have posted instructions on how this was made on my blog entry here http://digitalrust.co.uk/blogz/?p=593
The aerial output plugs into an external USB soundcard which connects to a laptop computer.
The laptop is running an item of software called Spectrum Lab. This software is used to convert the received signals into meaningful data and record this data for chart plotting.
The software does a lot more than this as I am beginning to learn.
The aerial output plugs into an external USB soundcard which connects to a laptop computer.
Once you have configured the required parameters in Spectrum Lab ( I will go into this later ) you should see something like the photo above. This will be a representation of the VLF signals your receiver is acquiring, as I am based in the U.K these frequencies are specific to this part of the world. Much of this is transient noise however you can clearly see the humps that represent the strongest signals. The horizontal ruler displays the frequency range Spctrum Lab is monitoring, in this case around 18.5kHz through 24.5kHz The spectrogram is represented as a "waterfall" in which the output scrolls down the screen, effectively in real time.
I have rendered this animation to give you an idea of what the output from my SID detector looks like over a 9 hour period with no events recorded.
The photo on the right is Spectrum Labs "View, watch list and plotter" display. This behaves like an old chart strip recorder displaying the aerials signal levels with time.
Here you can see a multiple event starting around 13:08
Interpreting these x-ray events is currently a difficult thing for me to do. Apparently this "shark fin" or inverted "shark fin" plot is a reliable indicator an event has occurred, I will go into this later.
The plot above has been generated in MS Excel from the data recorded by Spectrum Lab (exported as a text file ). This is the same data recorded in the chart strip photo previously but shows the events in much clearer detail.