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 _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
