Ask HN: AM, FM, What else?

2 pointsaaronsnoswell2 comments

I'm seeking a novel and new means for encoding information within a wave medium; perhaps something exploiting pulse modulation or polarization. Comments? Thoughts?

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AM and FM are time and frequency-modulated respectively, of radio signsls. If you look at any other form of energy, such as optics, copper, even just rolling marbles down a hill, you'll see the same separation.

Are you wanting something that might be done by today's spies, today's clever children or clever children in 10-20 years?

There is a lot of other modulation techniques... start by understanding them. You can start with Wikipedia, follow the links in the sidebar. http://en.wikipedia.org/wiki/Amplitude_modulation

Analog modulation: AM / FM / PM / QAM / SM / SSB

Digital modulation: ASK / APSK / CPM / FSK / MFSK / MSK / OOK / PPM / PSK / QAM / SC-FDE / TCM

Spread spectrum: CSS DSSS FHSS THSS

See also: Capacity-approaching codes / Demodulation / Line coding / Modem / PAM / PCM / PWM

There are limits to how much information can be transmitted on a channel with a given signal/noise ratio. http://en.wikipedia.org/wiki/Shannon_limit

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