Sudden Ionospheric Disturbances ( SID’s) are rapid changes in the Earths ionosphere caused by X-ray flares erupting on our nearest star, the sun.
When the material from these flares leaves the sun and hits our atmosphere, it causes changes in the way low frequency radio waves from terrestrial transmitters are reflected.
Following a guide in the September 2015 “Sky at Night” magazine, I set about building a detector that makes it possible to see and record these events.
Please bear in mind I have no prior knowledge about this type of device and have approached this project as an absolute beginner, relying completely on the magazine articles author “Paul Hyde“.
The first task is to build the detector to receive the low frequency radio signals in the 15 – 30 kHz range. My detector / Aerial was made using a wooden cross 1.5 M x 1.5 M with 100 M of 2 core solid copper wire. The article states the detector receiver should be a minimum of 1.0 M x 1.0 M and use 100 M of solid core Bell wire.
Unfortunately I was unable to source the recommended Bell wire, however I found a reel of the item in the photo below which seemed to be a reasonable alternative;
I first made the wooden cross and secured the 2 halves using a couple of the largest tywraps I had in the shed. It is also easier to cut a V shaped channel into each limb of the cross to help keep the wire in position.
Please note that I have subsequently discovered that the cable should not be wound like this, and as per the S@N article needs to be kept flat
After wrapping the drum of cable around the wooden cross it needs to be terminated. I used a “choc-block” type connector shown in the photo below. Take care to connect your marked cable cores correctly so as to make one large loop. So in my case I connected a bare copper to one of the blue cores ending up with just 3 connections into the choc-block;
I used a tywrap every 10 cm to help the wire loop keep its shape.
The next step is to connect the receiver to the interface that will provide a USB output to the computer. The S@N article recommends an external USB soundcard that can be attached to one of the legs of the wooden frame. Below is the one I ordered off Amazon for no other reason that it was reasonably priced and had lots of positive comments. As I have never built a device like this before I had no further information to base my decision on. Below is a photo of the unit I purchased;
At this point you should insert the USB soundcard and ensure your computer installs it correctly before continuing, you dont want to be chasing potential problems here later on.
Ensure the computer soundcard settings for your particular device used here in the project are exactly as the S@N article instructs;
In the microphone recording section the sample rate should be 48,000 Hz or higher
The AGC should be switched on
The input level slider should be set to maximum
The sound card should have at least one stereo input and one stereo output port. Mine uses standard 3.5 mm audio jacks. Get hold of a stereo audio cable with the correct size connector for your audio port and plug it in;
Cut the other end of the cable and dress it in such a way as you have two separate mono outputs going into your soundcard. This is only to help you connect the correct input later, you have a 50/50 chance of getting it right first time and it is way easier to fault find later on;
Connect one of the mono inputs (going to the soundcard) to the choc-block connector on your receiver as shown in the photo above ( the 2 red arrows ).
Connect a USB extension cable from the sound card and connect it to your computer;
The next step is to get a copy of “Spectrum Lab” software available from http://www.qsl.net/dl4yhf/spectra1.html
This blog post is not able to go into the full operation of the software suffice to say there are some good on-line resources to help.
The S@N article provides links to a page where you can download some preconfigured settings to load into spectrum lab, optimised for SID detection.
The links are available from here http://bit.ly/howto124
The file you need to load into Spectrum Lab is RAG_SIDv1.USR
When you first start the software you will hopefully see something like the screenshot below;
The top graph with the yellow trace shows the input signal level from the receiver I made. The blue “waterfall” trace below should be slowly scrolling downwards and the window at the bottom will show the incoming data logged against time.
There are lots of reasons why you may not be getting a trace however in the first instance you need to verify the correct mono input wires are going into the choc-block connector described earlier. I had the left/right input cables to my soundcard the wrong way round so had to switch them around.
After that I got a very small signal as in the photo above.
Remember the receiver is directional as stated in the S@N article, in real-time you can move the receiver around to get an optimum signal on your display. Mine was best positioned vertically with the winding’s aligned North to South.
Below is a photo of the final receiver in operation;
Below is a screen capture of an event that took place during 28th August 2015. I am still trying to get confirmation this is an SID however it does have the “shark fin” shape associated with such events. On this date the earth was exposed to a number of Geomagnetic events as recorded by the NOAA website here at http://www.swpc.noaa.gov/communities/space-weather-enthusiasts
Below is the graph recorded by Spectrum Lab of the event which can be found in the “view, watch List and Plotter” section:
I will update this section as I learn more about SID monitoring and please check out my website for more information at http://www.digitalrust.co.uk/astrophotography.html
Thanks for looking