On Tue, Feb 27, 2007 at 11:01:58PM -0800, Matt Ettus wrote:
>
> >(which makes me
> >curious, does anyone use non-differential 8PSK?).
> >
>
> Yes, satellites often do.
I might add that non differential PSK/QPSK has a theoretical
noise advantage if some mechanism exists to figure out the correct
initial rotation and not lose it later on. And this is often pretty
easy to do when using convolutional code inner FEC from the FEC
correction which works with few errors for only one of the two or four
possible rotations.
Basicly best case in differential modulation an error in
detecting a symbol causes TWO bit errors in the data while a single
symbol error in absolute phase, non-differential modulation causes only
one bit error in the data before FEC.
--
Dave Emery N1PRE, [EMAIL PROTECTED] DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."
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