A really big thanks JimB!
This is exactly what I was looking for and more.
You are welcome.
A frequency analyzer is pretty nifty if I can say so myself
Yes, a spectrum analyser is one of those things which you wonder how you ever managed without. Especially when it has an add-on called a tracking generator.
The 23:00 vs the 16:00 readings really intrigues me, is it that more broadcasts are happening at night or does it have something to do with the atmosphere and how some signals bounce back easier at night?
Radio propagation changes through the day.
During daytime, the sun ionises the various layers in the ionosphere, very noticably the medium waveband is practically empty during the day with just local (100 miles or so) stations being audible. This is due to absorbtion by the D (from memory) layer.
At night the D layer disappears and the F layers can reflect the signals back to earth, and so then medium wave stations from all over Europe and North Africa can be heard quite easily.
I don't know how the medium waveband is in South Africa, but in UK and Europe is is completely full up with stations every 9kHz, and frequencies re-used so that there can be several stations which are on the same frequencies in different countries.
Similar sorts of things happen with the shortwave frequencies where higher frequencies will propagate during the day than during the night. Again from memory I think this is due to changes in the F layers. (Propagation theory is not one of my strong points).
So, more or less stations, stronger and weaker reflections from the ionosperic layers make for more or less signals on the antenna.
In theory I could actually take a small snippet of data from the oscilloscope and feed it into a PC and conduct a Fourier Transform to obtain the spectrum analyzer results?
In theory, maybe, in practice most unlikely.
But having said that, google for "Software Defined Radio".
With an SDR it is possible to convert the RF signals to "baseband" and feed them into a PC soundcard to create a quite reasonable receiver.
To do this you need to convert the incoming signal to two audio signals with a 90 degree phase shift between them.
Feed the audio into the two channels (left and right) of the sound card and the software can filter the signal and tune up/down the frequency band a few kHz.
How far you can tune is limited by the frequency response and sampling rate of the sound card.
JimB