"Dave Plowman (News)" wrote in message
...
In article ,
William Sommerwerck wrote:

But I'm still not sure what you mean by 'non linear group delay'.

Phase shift in which the shift is not linearly proportional to the
frequency, along a straight line that passes through the origin.

Right. And just where would you get this?

From less-than-well-designed transmission systems.

The US had microwave systems which generally had low group-delay errors. In
the late '50s, Europe had coax systems which generally did not. Which was
one of the reasons PAL was selected. According to the books, anyhow.