21 MHZ DX pile up - screen shot and WAV file
Posted: Tue Feb 03, 2015 3:10 pm
They are going absolutely nutty on 21 Hz! and I have no idea who they are working - I suspect the DX station is working split frequency - but it makes a good screen shot!
https://app.box.com/s/abmzflx8dd555m3pa4crw0yj7b1dp2iz
Also an 11 second long .wav file of the pile up. It is rather large as it is a full 5 MHz bandwidth. You'll have to zoom in to see it. It was recorded from HDSDR
https://app.box.com/s/ky6l6dd6joqnlzy9f220vu931ofqzco2
If you look at the full bandwidth you'll see a very strong signal spanning 21.58 to 21.71 MHz. It looks like a sub-harmonic of a DAB signal - which I'm trying to track down - but the shape of the signal doesn't match any of the DAB Muxes. I have a DAB pre-amp (12dB gain) and I when unplug all the aerial leads from the output it is still 25dB above the noise floor - but disappears as soon as the power is switched off. So I suspect it is the pre-amp - and has nothing to do directly with breakthrough. Although some of the signals are peaking over 60dB above the noise level no sign of them appearing on the other side of the centre frequency and no signs of this on SDR Sharp or SDR Console.
Rgds
David
https://app.box.com/s/abmzflx8dd555m3pa4crw0yj7b1dp2iz
Also an 11 second long .wav file of the pile up. It is rather large as it is a full 5 MHz bandwidth. You'll have to zoom in to see it. It was recorded from HDSDR
https://app.box.com/s/ky6l6dd6joqnlzy9f220vu931ofqzco2
If you look at the full bandwidth you'll see a very strong signal spanning 21.58 to 21.71 MHz. It looks like a sub-harmonic of a DAB signal - which I'm trying to track down - but the shape of the signal doesn't match any of the DAB Muxes. I have a DAB pre-amp (12dB gain) and I when unplug all the aerial leads from the output it is still 25dB above the noise floor - but disappears as soon as the power is switched off. So I suspect it is the pre-amp - and has nothing to do directly with breakthrough. Although some of the signals are peaking over 60dB above the noise level no sign of them appearing on the other side of the centre frequency and no signs of this on SDR Sharp or SDR Console.
Rgds
David