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infrared/heat radio


fredreload
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2 hours ago, fredreload said:

Is there a radio that works based on infrared? If that is the case does heat works as a radio? But then it would require modulation. Using infrared camera we could modulate these waves.

Infrared and radio are different parts of the spectrum, so it would not be a radio, as such.

However, you can modulate and detect IR and send a signal. Often along a fiber optic, with a laser (which is not a thermal source, so it’s not heat).

Thermal radiation would just be noise, and any modulation of it would have a very limited bandwidth, depending on how fast you could heat or cool the source.

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Most current T.V. remotes are based on consumer infrared.

About 15 years ago I had wireless headphones that used infrared (what we use bluetooth for nowadays).

So yes, signals can be modulated onto an infrared carrier.

Way less flexible than bluetooth etc, not sure why it'd be a choice now for "radio". You'd need to be close to the transmitter and in good line of sight.

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12 hours ago, fredreload said:

Is there a radio that works based on infrared? If that is the case does heat works as a radio? But then it would require modulation. Using infrared camera we could modulate these waves.

By radio I assume you mean speech communications ?

You have not distinguished between digital systems and analog systems but I am guessing that you mean analog ones.

Here are 200 pages of an Engineering Masters thesis on how to do this with microwaves, which sit between what we call 'radio' in the spectrum and infrared.

https://open.uct.ac.za/bitstream/handle/11427/8363/thesis_ebe_1987_marsden_m.pdf?sequence=4

 

Note microwaves are also heat radiation of a sort.

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1 hour ago, studiot said:

Note microwaves are also heat radiation of a sort.

Only if they come from a thermal source. The microwaves in an oven of that type do not emit thermal radiation (heat), they do thermodynamic work.

(this is an area where the terminology is often used in a rather sloppy fashion. Also a shortcoming of thermodynamics, where you have heat and work as your two options. I don’t think non-thermal radiation sources existed when thermodynamics was being developed) 

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1 hour ago, fredreload said:

Can you apply an alternating current on tungsten to produce light wave for communication? I am trying to mimic how radio wave works, which uses alternating current on an antenna.

Modulation on a wire would be radio, if the signal is RF. It would not produce visible light. 

 

1 hour ago, fredreload said:

P.S Seems like someone got it to work already @@, respect. https://en.wikipedia.org/wiki/Li-Fi

These are not the same thing. That’s not modulating signal on a tungsten wire, it’s modulating an LED.

Are you interested in learning the science, or are we chasing another fiction?

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19 hours ago, fredreload said:

Is there a radio that works based on infrared? If that is the case does heat works as a radio? But then it would require modulation. Using infrared camera we could modulate these waves.

Since you evidently don't wish to talk to me I will bow out.

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19 hours ago, swansont said:

Modulation on a wire would be radio, if the signal is RF. It would not produce visible light.

Yes, your logic is correct. You do not need an alternating current to produce light from tungsten.

18 hours ago, studiot said:

Since you evidently don't wish to talk to me I will bow out.

Hi Studiot, I am just curious on the data modulation from an electrical current onto the radio wave. Reading a 200 pages paper for this might be a bit too long.

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1 hour ago, fredreload said:

Yes, your logic is correct. You do not need an alternating current to produce light from tungsten.

But it can produce it; that's how an incandescent light bulb works. The AC current heats the tungsten filament. The (50 Hz or 60 Hz) frequency is much too high for there to be a modulation of the thermal output.

Quote

I am just curious on the data modulation from an electrical current onto the radio wave.

If you modulate a current you will emit EM radiation at the modulation frequency - up to a point. Eventually you can't get the electrons in your antenna to respond, and also have difficulty in generating a signal to drive them at the frequency. (These may be related phenomena)

The generation and modulation of electromagnetic waves in this [Terahertz] frequency range ceases to be possible by the conventional electronic devices used to generate radio waves and microwaves, requiring the development of new devices and techniques.

https://en.wikipedia.org/wiki/Terahertz_radiation

So you aren't going to generate light signals from an antenna with a THz input signal, and this is several orders of magnitude below optical frequencies. And you aren't going to modulate a signal at those frequencies, either. What you can do is modulate a light source like an LED or laser, at much lower frequencies. (I've sent sound signals across the room this way - modulate a laser with the headphone jack output, capture the light on a photodiode, remove the DC component, and send the signal into an amplifier and speaker) 

 

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2 hours ago, fredreload said:

 

Hi Studiot, I am just curious on the data modulation from an electrical current onto the radio wave. Reading a 200 pages paper for this might be a bit too long.

Then perhaps you might like to address my original comments as you OP was too vague.

As to 200 pages, I seem to remember that the manuals for the Tellurometers I worked with were longer than that.

But never fear, you can rest your poor weary eyes, you only need to read the chapter on the voice communications part and the Thesis contains full circuitry for a simplified Tellurometer.

You were asking about infrared, but seem now to be talking about visible light.

Wikipedia has Themal Radiation as extending from the top of the radio spectrum, though microwave infrared and visible radiation.

https://en.wikipedia.org/wiki/Thermal_radiation

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One should note that thermal radiation will be a blackbody spectrum (or close to it), so you get the whole thing.

You could, in principle, get amplitude modulation by heating and cooling your source. This would be extremely limited in therms of modulation, as it will take time to cool the source down. You could so some sort of frequency modulation, but then the blackbody radiation would tend to mask it as it would appear as noise. Neither approach has any real utility as far as I can see.

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