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AND with postage stamp sized antennas. That one blows my mind regularly.
by jcims 6y ago
AND with postage stamp sized antennas. That one blows my mind regularly.
- jacquesm 6y agoFrom under the noise floor. If anything that is the impressive feat.
- jcims 6y agoI heard this in a podcast recently, imagine working at Bell Labs mid 20th century and calling a meeting with Nyquist, Hartley and Shannon. Even if they didn’t show the invite would be a keepsake.
- jacquesm 6y agoIt would be hard to tell the names apart from the various tech bits and pieces named after the participants in the meeting. Shannon: "But what about the Nyquist frequency? Nyquist: "My trembling is much reduced, thank you." ...
- batsigner 6y agoNothing special about the noise floor, it's just the point where you can only transmit around one bit per second per hertz
- giomasce 6y agoLink to the proof? Or at least, does the theorem has a well-known name?
- tripletao 6y agoThe Shannon–Hartley theorem. It assumes additive white Gaussian noise (which is a good model for most kinds of thermal-ish noise), and provides a bound on the channel capacity that practical codes closely approach. https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theore...
- labawi 6y agoFrom an information-theoretic POV, yes, you can squeeze information from less, but the definition I found is based on signal levels not transmission capacity, and it seems to have other notable consequences. AFAICT it's around this point that you can't tell whether there is a transmission, unless you know what it looks like; tuning requires decoding and/or fancy math, not a spectrometer; communication works just fine (with proper transmission modes), but there are nontrivial practical consequences as you approach or go below the noise floor. I wouldn't expect to see analog equipment operating below the noise floor.