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Comment Re:neat idea (Score 1) 120

Well basically when you modulate a carrier (AM is modulating the amplitude of the carrier with the data signal) half the energy ends up in the carrier signal, and the other half gets split up between to sidebands that sit to either side of the carrier on the spectrum. The sidebands are mirror-images of each other.

There's techniques to suppress them (meaning you don't waste half your transmission energy on redundant signal) but broadcast AM/FM radio doesn't utilize it. Other advantages mean a more efficient use of the spectrum (ie, a whole other signal can sit where the other sideband used to be).

This article should lead you down the rabbit hole ;)

Interestingly, if you use that modulation mode specifically (AM, single sideband suppressed carrier) and tune the oscillator a hair off the mark, you sound just like the X-Wing pilots in the original Star Wars movie...

Comment Re:neat idea (Score 1) 120

Mmm true - or even just use a consistent "rotation" to do it, in that the rotation is a waveform itself that the other end can sync to - then there's no negotiation to be worried about!

Or you can send bursts of a signal (along with such a scheme or just periodically) and the other end can know what was sent (prearranged?) and with some simple subtraction it has a noise profile

Sorry. I enjoy thinking about this kind of thing. Can you see the sidebands around the AM tower as well? Or is the resolution not good enough to differentiate it from the carrier?

Comment neat idea (Score 3, Interesting) 120

The noise-cancelling scheme sounds interesting. The hardest part though is figuring out what exactly is noise - so it sounds like they would have to either invert the intended signal to cancel it out on the path to the noise measurement, or they would have to periodically turn the signal off so they can get a clean measure.

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