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Explain phase change of an EMW in terms of photons.

  1. Jul 25, 2011 #1
    Hi Guys,

    I have a question.

    Can we attempt to explain the phase change of a carrier wave in terms of photons?

    For example consider GPS signal. It is BPSK modulated, in which phase change of 180 degrees happens for multiple of 1540 cycles of the carrier.

    How is the phase information of an electromagnetic wave carried by photons?

    Thanks for your help,
    Srini
     
  2. jcsd
  3. Jul 25, 2011 #2
    "Can we attempt to explain the phase change of a carrier wave in terms of photons?"

    Not very well, but maybe someone will surpise!!!

    unless you mean something obvious like: some groups of photons are emitted or received at dsifferent times from others in a continuous pattern. The PHASE of a classical continuous wave is a matter of time shift...like that between sine and cosine...


    And you likely you know there is nothing unique and special about one form of carrier and another regarding photons.....you'll usually see such signals discussed in terms of continous waves....just like discussing the photoelectric effect is really tough when using a continuous wave....


    see wikipedia:

    http://en.wikipedia.org/wiki/Phase-shift_keying#Binary_phase-shift_keying_.28BPSK.29
     
  4. Jul 26, 2011 #3
    in theory, if you put monochromatic wave of known wavelength through some crystal of known refractive index, and redirect the transmitted wave to the incoming wave, then the relative phase change can be deduced in terms of constructive and descructive interferance.
     
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