The issue of ground plane noise can cause problems even with an optical connection.
It has to do with the transmitter, either electrical (coax) or optical, the input to the transmitter has a "threshold", a voltage at which it sees the input as changing from a one to a zero, noise on the ground pin of the transmitter causes that threshold to move up and down causing the point at which it senses the signal as changing from one to zero to change. Since signals do not change instantaneously from a low to a high value, changing the threshold also changes the time at which the transmitter sees the change taking place. This happens with both electrical and optical. The ground plane noise can also get coupled to the output as noise on the signal itself, this noise can cause the receiver to misinterpret when the change happens as well. Different receiver circuit vary significantly in how they handle noise on the signal. There is a famous example of a circuit that tried to be very immune to input noise, but they way it was implemented majorly screwed up the RF characteristics causing reflections on the line which were much worse than the noise it was trying to fix. This can also happen with optical, although because the common implementation is so poor to begin with noise on the signal is rarely noticed. John S. -- JohnSwenson ------------------------------------------------------------------------ JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=84742 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
