How is wireless data sent over the airwaves?

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Discussion Overview

The discussion revolves around the transmission of wireless data via electromagnetic radiation, exploring the underlying principles of how data is sent over the airwaves to receiving devices. Participants touch on concepts such as photons, electromagnetic waves, modulation techniques, and the mechanisms of detection.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that electromagnetic radiation consists of photons and question how these photons can be streamed to mobile devices.
  • Others assert that wireless data is essentially digital radio and suggest reviewing external resources for clarity.
  • One participant introduces the concept of the de Broglie wavelength of photons, indicating that at different frequencies, photons can be viewed as waves rather than particles.
  • There are discussions about various modulation techniques, including amplitude modulation (AM) and frequency modulation (FM), as methods to encode data onto radio waves.
  • Some participants clarify that at radio frequencies, photons behave similarly to classical electromagnetic waves, which can be detected through their interaction with charges in antennas.
  • One participant challenges the notion that the photoelectric effect is the only way to detect photons, suggesting alternative detection methods, such as molecular excitation.
  • Wi-Fi technology is mentioned, highlighting the use of spread-spectrum techniques to reduce interference, with some participants affirming its importance for wireless communication.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms of photon detection and the role of the photoelectric effect, indicating a lack of consensus. There are also multiple perspectives on the nature of photons at different frequencies and the methods of data transmission.

Contextual Notes

Some claims rely on specific definitions of photon behavior and detection methods, which may not be universally accepted. The discussion includes unresolved aspects of modulation techniques and their applications in different wireless technologies.

andy__9
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So you start with electromagnetic radiation(Maxwell) and magically send 'data' over the atmosphere to a receiving device.

EM radiation consists of photons, not electrons(I think), and the only way to detect a photon is through the photo-electric effect. I also have heard of frequency modulation.

So how can photons be streamed to a mobile device.
 
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In the end, wireless data is nothing but digital radio. I suggest perusing the Wikipedia article:

https://en.m.wikipedia.org/wiki/Radio

That should probably clear up a lot of initial questions. Feel free to ask follow-ups.
 
The effective "size" (de Broglie length) of a photon depends on the frequency. The higher the frequency the "smaller" the photon. For low frequencies (eg radio rather than light) the effective size of the photon is quite big (meters). At these frequencies it's better to think of them as waves rather than particles/photons.

There are many ways to encode or modulate data onto a radio wave. The two most commonly used for Radio stations are still variations of..

AM
http://en.wikipedia.org/wiki/Amplitude_modulation
FM
http://en.wikipedia.org/wiki/Frequency_modulation

Lots of other listed here..
http://en.wikipedia.org/wiki/Modulation
 
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andy__9 said:
EM radiation consists of photons, not electrons(I think), and the only way to detect a photon is through the photo-electric effect.

At radio frequencies, photons are indistinguishable from classical EM waves and can be detected by the effect the EM wave has on the charges in antennas. The EM wave moves them back and forth in time with the frequency of the wave, and various techniques have been developed to transmit information using these waves. Frequency modulation and amplitude modulation are two of them.
 
andy__9 said:
So you start with electromagnetic radiation(Maxwell) and magically send 'data' over the atmosphere to a receiving device.

EM radiation consists of photons, not electrons(I think), and the only way to detect a photon is through the photo-electric effect. I also have heard of frequency modulation.

So how can photons be streamed to a mobile device.
No, this is not the only way. The receptors in the retina can detect photons, for example. And there is no photoelectric effect involved. Molecules may be excited by photons without emitting photoelectrons.
 
Drakkith said:
At radio frequencies, photons are indistinguishable from classical EM waves and can be detected by the effect the EM wave has on the charges in antennas. The EM wave moves them back and forth in time with the frequency of the wave, and various techniques have been developed to transmit information using these waves. Frequency modulation and amplitude modulation are two of them.
Well, Wi-Fi (IEEE 802.11, see http://en.wikipedia.org/wiki/IEEE_802.11) uses spread-spectrum and other advanced techniques in order to minimize interference from other devices (see http://en.wikipedia.org/wiki/Spread_spectrum).
 

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