[Elecraft] K4 and Predistortion

[Jim Brown]

On 5/18/2019 4:01 PM, Phil Kane wrote:
> Those
> of us with engineering backgrounds knew that what I was referring to as
> "pre-distortion" was the pre-emphasis / de-emphasis curves commonly used
> in FM broadcast audio chains.

All of which emphasizes the need for using the right words to describe 
things. The word "distortion" is most commonly used to describe 
non-linearity, not frequency response. And, BTW, that 
pre-emphasis/de-emphasis is a Standard, not just "commonly used." You 
know the Regs far better than I, but I suspect it's there too.

As I'm sure you know, it was also common practice to go FAR beyond that, 
with multi-band dynamics processing and the tricky stuff that Bob Orban 
was doing. The engineering "rule of thumb" was that if you could see the 
modulation monitor needle move, you weren't doing enough.:)

I did some research on the Orban FM processor, which I published as an 
AES Paper in 1986. http://k9yc.com/AESPaper-TDS.pdf

73, Jim K9YC