Difference between 16QAM and 64 QAM?

PoloMint

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What does QAM actually stand for (and mean). How does changing this increase the signal strength/quality?
 

rolfw

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It stands for Quadrature Amplitude Modulation, and is a method of sending data from one point to another, Sky digital use a system called QPSK, which is not dissimilar Quadrature Phase Shift Keying. You probably don't want to know too much detail, but needless to say it is capable of sending more information down a limited sized pipe, than standard modulation.

If you want more go to http://www.physics.udel.edu/wwwusers/watson/student_projects/scen167/thosguys/qam.html

Basically, the lower value means they are using the same bandwidth but sending slightly less information, thus giving a more robust signal and better reception
 

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leonardwolk

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I read the document located on: http://www.physics.udel.edu/wwwusers/watson/student_projects/scen167/thosguys/qam.html

BUT I didn't understand how you can read the "Phase Shifting" from a graph.

qam.gif


how can you see that the 010 graph has 1/4 phase shifting?

thanks!
 
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