Low Frequency Radio Transmission

Connect one end of the wire, any insulated wire, to the centre pin tag of a 3.5mm jack plug. Via a capacitor if you wish, a 1.8µF capacitor as can be found in a BT master-socket etc should be ok. Plug into the Mic input of the pc or laptop. Try and get the wire up as high as you can, or say from an upstairs window to a shed roof or similar.


I found that with the SAQrx program running, but without the wire connected, whistling into the built in Microphone will produce activity on the screen.  Once the wire is connected, there are other Very Low Frequency signals around which you should see on the screen. Most of these are phase-shift keying, just a warbling noise, but there is a Russian station which sends Morse using frequency shift keying. Which even to a professional ear is not easy.


I use a high impedance e-probe as an aerial. The actual aerial being a piece of copper foil about the size of a standard UK postage stamp. This has two transistors, one to impedance match the other to drive the coax cable to the receiver which is a Software Defined Receiver, an SDR-IQ manufactured by RF-Space which I bought from the USA about 13 years ago and associated software which gives me a spectrum of the range of frequencies that I am "looking" at.
http://ancient-mariner.co.uk/public/2018.07.01%20-%20SAQ%20Alexanderson%20Day.bmp  You can see the Morse code running vertically beneath 17.2 kHz and at 60.0 kHz The UK MSF radio time-signal and similarly at 77.5 kHz the German DCF77 radio time signal. Either of these are used by radio controlled clocks and watches to maintain an accurate time display.   The other transmissions are all naval. (VLF penetrates water, LF less so; say no more!)

Connect one end of the wire, any insulated wire, to the centre pin tag of a 3.5mm jack plug. Via a capacitor if you wish, a 1.8µF capacitor as can be found in a BT master-socket etc should be ok. Plug into the Mic input of the pc or laptop. Try and get the wire up as high as you can, or say from an upstairs window to a shed roof or similar.


I found that with the SAQrx program running, but without the wire connected, whistling into the built in Microphone will produce activity on the screen.  Once the wire is connected, there are other Very Low Frequency signals around which you should see on the screen. Most of these are phase-shift keying, just a warbling noise, but there is a Russian station which sends Morse using frequency shift keying. Which even to a professional ear is not easy.


I use a high impedance e-probe as an aerial. The actual aerial being a piece of copper foil about the size of a standard UK postage stamp. This has two transistors, one to impedance match the other to drive the coax cable to the receiver which is a Software Defined Receiver, an SDR-IQ manufactured by RF-Space which I bought from the USA about 13 years ago and associated software which gives me a spectrum of the range of frequencies that I am "looking" at.
http://ancient-mariner.co.uk/public/2018.07.01%20-%20SAQ%20Alexanderson%20Day.bmp  You can see the Morse code running vertically beneath 17.2 kHz and at 60.0 kHz The UK MSF radio time-signal and similarly at 77.5 kHz the German DCF77 radio time signal. Either of these are used by radio controlled clocks and watches to maintain an accurate time display.   The other transmissions are all naval. (VLF penetrates water, LF less so; say no more!)