On 8/27/2018 10:01 AM, Bob McGraw K4TAX wrote:
Per one authority on receiver performance, the optimum receiver performance occurs when the no signal band noise is about 10 dB above the receiver noise floor.
Not quite -- when the noise from the antenna is 10 dB above the receiver noise, the combined noise is fractional dB greater than the antenna noise alone. As the ratio increases (13 dB from the antenna, for example), that fractional dB becomes even smaller.
A common misunderstanding is that 1 dB is the smallest change in loudness that average listeners can hear, but the ear is FAR more sensitive to differences between signal and noise at low signal to noise ratios, so fractional dB improvements can make the difference between no copy and just enough to get the rare DX in the log. :)
Another manifestation of this is mixing multiple mics that pick up the various parts of a band or orchestra. Anyone who's done much live mixing will tell you that when the balance relative to the rest of the band of a vocal or instrument is not quite right, the volume slider for the mic in question rarely needs to move more than a dB or two. In other words, the ear-brain is far more sensitive to differences between sounds than to absolute loudness of the combination of the sounds it hears.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
