Pirate SSB signal on the abandoned French longwave channel?
Posted: Thu Dec 31, 2020 6:16 pm
This is a purely theoretical discussion of course, I don't have the technical prowess to pull this off myself and even if I did I expect it'd draw some unwelcome attention but I've had an interesting thought:
About half a decade ago, the French supposedly shut off their longwave AM transmitter on 162 kHz because of how expensive it is to run. However, like how some of our older electricity meters depend on the BBC Radio 4 longwave signal to switch between day and night, apparently a lot of devices in France rely on the old France Inter longwave signal to operate properly (radio clocks and that sort of thing), and for this reason the carrier wave phase-modulated with time data is still being broadcast to this day just with no audio signal. You can pick it up on one of the European webSDRs to confirm, there's always a carrier but it sometimes looks deceptively like the audio still there too when it's really just getting modulated in the atmosphere by the Luxembourg longwave transmitter.
My idea is that a pirate could potentially replace one of the now empty sidebands with their own signal and end up with something that could be heard on an ordinary AM radio across quite a lot of Europe, thanks to the French transmitter completing the missing carrier needed for AM recievers to work. I'm guessing that it wouldn't be too hard to modify an SSB radio used by amateur radio enthusiasts to take a line level rather than a mic level audio signal, and the pirate would get to keep all the power efficiency advantages of SSB versus AM courtesy of the French public broadcaster. I actually looked up whether ordinary AM with one sideband missing but the carrier still intact would demodulate properly on an ordinary radio, and it turns out not only will it work but the BBC did some research back in the day about using this concept for reducing spectrum congestion! Annoyingly I can't for the life of me find the archived report but it was interesting reading (for anoraks at least!).
What does everyone else think of this idea? Would it be a viable thing for someone with too much time and money on their hands to try, or would it be a waste of time?
About half a decade ago, the French supposedly shut off their longwave AM transmitter on 162 kHz because of how expensive it is to run. However, like how some of our older electricity meters depend on the BBC Radio 4 longwave signal to switch between day and night, apparently a lot of devices in France rely on the old France Inter longwave signal to operate properly (radio clocks and that sort of thing), and for this reason the carrier wave phase-modulated with time data is still being broadcast to this day just with no audio signal. You can pick it up on one of the European webSDRs to confirm, there's always a carrier but it sometimes looks deceptively like the audio still there too when it's really just getting modulated in the atmosphere by the Luxembourg longwave transmitter.
My idea is that a pirate could potentially replace one of the now empty sidebands with their own signal and end up with something that could be heard on an ordinary AM radio across quite a lot of Europe, thanks to the French transmitter completing the missing carrier needed for AM recievers to work. I'm guessing that it wouldn't be too hard to modify an SSB radio used by amateur radio enthusiasts to take a line level rather than a mic level audio signal, and the pirate would get to keep all the power efficiency advantages of SSB versus AM courtesy of the French public broadcaster. I actually looked up whether ordinary AM with one sideband missing but the carrier still intact would demodulate properly on an ordinary radio, and it turns out not only will it work but the BBC did some research back in the day about using this concept for reducing spectrum congestion! Annoyingly I can't for the life of me find the archived report but it was interesting reading (for anoraks at least!).
What does everyone else think of this idea? Would it be a viable thing for someone with too much time and money on their hands to try, or would it be a waste of time?
