On Sat,9/6/2014 2:28 PM, W2RU - Bud Hippisley wrote:
I believe that whether one observes monotonic improvement in ability to decipher the intelligence carried in a very weak signal as one reduces receiver BW will be a function of_how_ the BW is narrowed in the various electronic circuits and/or digital algorithms, as well as a function of our own individual hearing characteristics.
Yes. Especially if the noise is impulse noise, ringing in the filter skirts can make copy more difficult for me if I set the bandwidth too narrow. This is, of course, strongly dependent on the shaping of the filter.
From Psychoacoustics (the science of how the human ear-brain combination works), we know that we process sound in narrow chunks of bandwidth called "critical bands." The ear tends to process sounds within that band together, so when the filter gets too narrow, the filter skirts fall with the critical band and ringing begins to obscure the desired signal. The width a critical band varies with the sound spectrum, and is in the range a 1/3 octave to 1/6 octave. An octave is a 2:1 ratio of frequency.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
