What is the difference between QPSK and 4-QAM ?

Discussion in 'Wireless & RF Design' started by yuvi1, Oct 20, 2014.

  1. yuvi1

    Thread Starter Member

    Feb 1, 2013
    37
    0
    hi everyone ...

    i have searched over the internet and still i have not found a good explenation.

    i know that these two types of modulation give the same result , but the technique is not the same, can someone
    please shed some light ?

    thanks !
     
  2. WBahn

    Moderator

    Mar 31, 2012
    17,757
    4,800
    What do you mean by "same result"? Are you claiming that the resulting waveforms are indistinguishable?
     
  3. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    qpsk is quadrature phase shift keying, the modulation is ecoded with a change in phase. 4 qam is using amplitude modulation in quadrature.
     
  4. yuvi1

    Thread Starter Member

    Feb 1, 2013
    37
    0
    thank guys !

    so in qpsk all 4 symbols have the same amplitude and in 4qam all four symbols have difference in phase and amplitude ?
     
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