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QPSK vs. 8PSK in Standard Definition

Discussion in 'Technical Talk (Closed Forum)' started by Mark Holtz, Feb 16, 2004.

  1. Mark Holtz

    Mark Holtz Day Sleeper DBSTalk Club

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    Mar 23, 2002
    Sacramento, CA
    Okay, pardon my ignorance and if I got the terms off, but...

    In the past, I thought that QPSK and 8PSK was the method of compressing HD channels, and that Dish was converting over to 8PSK in order to get three HD channels on a transponder instead of two.

    Now, I read somewhere that the recent receivers receive the SD material in QPSK, but are capable of 8PSK for additional compression without loss of quality.

    Is this correct? How long has this been true?
     
  2. boba

    boba Hall Of Fame

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    Since about mid November. All new DISH products have the 8psk built in 111,311,322,522 and HDs have the capability so at sometime in the future there may be an upgrade. Right now I certainly wouldn't trade my 301 in for a 111, that is about the only use I can figure for a 111 it is a no feature receiver DISH wants $100 for.
     
  3. rvd420

    rvd420 Legend

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    Mar 10, 2003
    QPSK and 8PSK are signal modulation schemes.

    A way to look at it is look at computer ram.
    SDRAM would be QPSK.
    DDR RAM would be 8PSK.

    But there is a catch to 8PSK.
    You need to run a higher FEC to maintain the data intgerity.
    So in real world application you only get a 33% increase of bandwidth.

    An example would be on a normal QPSK TP both providers usually run up to 12 channles per TP.

    With 8PSK they could squeeze 16 channels at the same data rate and PQ on the smae TP.


    I hope that explains it.
     
  4. Mark Holtz

    Mark Holtz Day Sleeper DBSTalk Club

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    Mar 23, 2002
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    What about the DirecTV receivers?
     

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