On Nov 23, 2005, at 12:24 PM, Robert Tellefsen wrote:
Karsten
To use the NR function on cw, you need to open up the filters.
The narrower the filters, whether IF or audio, the more noise
pulses are stretched, and "white" noise begins to sound like
signal. Both cases reduce the effectiveness of the NR function.
I find that I get the best results with the IF filter set around
500 Hz
bandwidth, and the same for the DSP filter. This gives the NR
function a chance to work.
So you have a tradeoff between NR versus selectivity. You have to
experiment under any given conditions to see which gives you the
best results.
For those who think this might be a bad tradeoff, remember that
(thanks to Mr. Boltzmann) the noise power is proportional to
bandwidth, while the signal power will be generally independent of
bandwidth. Therefore, the need for noise reduction is less with
narrower bandwidths.
73, Bob N7XY
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