Well worked you tonight Jim on FST4-60 after engaging my 600Hz filter for a
good decode on 60.
I feel it was beneficial.


-----Original Message-----
From: Jim Brown [mailto:k...@audiosystemsgroup.com] 
Sent: Wednesday, 10 February 2021 1:46 PM
To: wsjt-devel@lists.sourceforge.net
Subject: Re: [wsjt-devel] WSJT-X v2.3.0 Oc42df.

On 2/9/2021 1:34 PM, Adrian wrote:
> Once a sought signal is known from a cluster or a random rx, then lost 
> etc on its audio freq, you can hone in on it with narrow filtering.

Last I heard, K1JT advised strongly against narrowing the IF, because the
filters create phase shift in the passband that can degrade decoding. The
top RTTY contesters have learned that -- they have abandoned dual peak
filters and now use 500 Hz bandwidth, narrowing only in the presence of very
strong signals in the passband.

Those of us working in pro audio learned nearly 40 years ago that poor phase
response created by filters we were using degraded the ability of the human
ear-brain to understand speech, causing the smart designers to develop and
users to adopt "minimum-phase" filters in our systems.

73, Jim K9YC




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