[Elecraft] Planning the next filters

[Jim Brown]

On 3/8/2018 1:08 PM, Bill Frantz wrote:
> I got the 250 for eliminating loud PSK signals from wiping out weak 
> ones. It was a bunch of playing with center and width, but worked 
> quite well.

Hi Bill,

Recall my post from a few days ago about phase shift being the enemy of 
signal decoders, and that filters built with real components (and most 
digital domain filters) create phase shift in the passband. The steeper 
the skirts, the greater the phase shift, and the more it extends into 
the passband.

I don't work PSK31 and don't know about PSK31 decoders, but the authors 
of other decoding software (WSJT-X, 2Tone) recommend that radios use 
wide bandwidth and let the decoder reject off-frequency QRM. Heavy duty 
RTTY guys like W0YK recommend 500 Hz for RTTY, and K1JT recommends the 
full bandwidth of SSB channel. I follow their advice, and find it works 
well for me.

73, Jim K9YC