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Comment by dragontamer | Hacker News Reader

> Does anyone really want to process analog data?

I mean... maybe we should?

All radio waves, such as 802.11, are fundamentally analog data. And then they are converted back into digital with incredible QAM-encoding levels. If you think QLC 4-bits per Flash-cell is big, wait till you see 256-QAM (aka: 8-bits per 802.11 timeslice), or more.

I believe I saw some spec for some fiber-optic cable that is 32768-QAM (aka: 15-bits per timeslice).

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Then again, Flash (and other memory) are composed of individual cells. True-analog signals like radio-waves are truly analog, so maybe its not quite the same.

But maybe we should think of things like tape or hard-drives as an analog signal. Or maybe not, who knows? I'm not actually a storage specialist so I don't really know. (Nor am I really in communications, lol).

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"Analog" and "digital" do not refer to the physical process of transmission, such as radio waves, but the interpretation of the signal. A digital system has rules for forming and interpreting the signal, so that the transmitted and received messages are identical. These rules typically involve things like signal level thresholds and timing.

Well-engineered systems have "noise immunity" meaning that the thresholds are well above the noise floor, making the likelihood of an error negligible.

If you hang an oscilloscope probe on a "digital" signal, such as the data lines on a memory chip, it might look like a frightening mess, but so long as the rules are obeyed, data transfer occurs faithfully.

In a true analog medium, there's no way that the receiver can make out precisely what was sent, and two receivers will get different information.

All mediums are ultimately analog.

"Well-engineered systems have "noise immunity" meaning that the thresholds are well above the noise floor, making the likelihood of an error negligible."

Well-engineered systems also expect noise and compensate with error detection/correction.

256+ QAM is there but you will almost never see it in practice unless you’re next to the AP. Wifi7 defines up to 4096 so maybe the economics will drive improvements that didn’t land in 6E APs.

docsis. up to 16384

You'll see it on almost every cableTV channel these days

I was referring to Wifi but yes

256-QAM encodes 4 bits on the "phase" component and 4 on the quadrature one. They can be regarded as independent signals. Think about a sin() and a cos() being orthogonal to each other even for the same frequency.

I'm pretty sure that Einstein proved that light (including radio) is not, in-fact, analog, but rather has discrete levels of energy in quantum steps.

That turns out not to matter, because the noise is always at least several quanta at whatever frequency you’re using so you can’t get close to the quantization limit anyway.

Also our physiological sensory and processing equipment (ie, eyes, ears, brain...) translates analog / continuous input into discrete electrical signals; a given neuron fires or doesn't.

That’s not how that works.

Light is produced and consumed in quanta (photons) by reguar matter. Light itself is just radio wave. Radiowave has not such limitation. It's limitation of atomic particles.

That's not how quantum mechanics works. Radio waves are photons, and photons are radio waves. Different experiments will reveal different aspects of it, but these are not separate phenomena.

Also, the exact same thing is true of every other particle: just as photons are quantizations of the electro-magnetic waves, electrons are quantizations of waves in the electron field, quarks are quantized waves in the quark field etc. Atoms and molecules are also waves; in fact, there have been experiments showing the wave-like nature of molecules with something like 5000 atoms.

I saw water-like behavior of a wave! I have no idea, how much molecules it contains, large waves have many cubic meters of water, but I'm pretty sure that quantum behavior is not limited to 5000 atoms. Waves, even very large onses, are moving energy in "packets". 1 wave - 1 quanta. So, what?

Photon is radio-wave (EM-wave). Typical photon is produced and consumed by a electron, so properties of photon produced by an electron are limited by the electron, also, our abilty to detect photonare limited by the electron. However, EM-waves in general are not limited by electron.

On smaller scale, electron interacts with other charged particles and with EM-field (the medium) via EM-waves. I'm pretty sure that electron is not staying stil, it's vibrating because of thermal noise. Vibration of charged particle produces EM-waves. Those EM-waves are not photons.

> Vibration of charged particle produces EM-waves. Those EM-waves are not photons.

Yes, they are. In the Standard Model, the photon is the "carrier" particle of the EM field. Any EM interaction between any two charged particles is ultimately the exchange of one or more photons between those two charged particles. When a particle emits an EM wave, in any way, it emits one or more photons. It's impossible to emit 1/2 a photon or 1.3 photons - the EM field / EM waves come in quantities of whole photons.

In the same way, when two quarks interact via the strong interaction, they are emitting and absorbing gluons, the carrier particle of the strong force.

The only fundamental interaction not currently proven to be quantized is gravity. We do know gravity waves exist, but we have not been able to measure them to the required fidelity to verify whether they are also quantized, and thus to know whether they are also equivalent to an exchange of particles (we call these hypothetical particles gravitons, and many do believe that gravitational interactions also occur by the exchange of a whole number of gravitons between bodies with "gravitational charge", i.e. mass).

Unlike regular waves, photons are topologically stable, like smoke-ring kind of wave. Google hopfions for example.

If you like hydrodynamic quantum analogs (walking droplets), then you may see that droplet may escape it pilot wave sometimes. In such cases, pilot wave continue to travel in same direction for some time. IMHO, it's similar to how photons are formed: electron creates pilot wave, then escapes it, similar to Cherenkov radiation.

Anyway, photons have special configuration, so they behaves differently than regular waves.

Gravitational waves, AFAIK, are not topologically stable at all.

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