Comment by angel_j
7 years ago
What if you used the noise as the carrier wave for the signal? Like, if in an urban area you have a "stable" probability distribution of noise, modulate that.
7 years ago
What if you used the noise as the carrier wave for the signal? Like, if in an urban area you have a "stable" probability distribution of noise, modulate that.
You're being downvited because, whilst this is a clever sounding idea, unfortunately it doesn't work like that.
The noise is random, so you can't modulate it because you can't predict what it will be. A probability distribution isn't enough; say you want to modulate by XORing with a random, uniformly distributed stream of zeros and ones. Knowing that distribution doesn't enable the receiver to extract the data.
(Fun fact: GPS signals are under the noise floor, but detectable because they are encoded with a predictable pseudorandom carrier which can be found even in the noise.)
Do you know why digital pulse radios never happened?
Could you... modulate the amplitude of the PD?
Amplitude is about power, that what you want to minimize. If you can affect the amplitude of the noise, that means your signal has high amplitude: you have a high signal-to-noise ratio (SNR) and you already have won.