Bill, You can probably get a good mathematical explanation from Bob or Frank. I like to think that the window smooths out the edges of a set of data to eliminate high frequency false info caused by the sharp transitions.
Practically, some of the window functions provide nice narrow spikes but tend to widen out with a big signal as you get lower in level. Others, like my personal favorite, the Blackman-Harris series, provide great dynamic range but tend to be a bit wider at the peak. The Hanning is nice for typical radio use since the signals are in the less than 90 dB level. Making measurements with large level signals over 100 dB level, the Blackman-Harris works better. The rectangular window is really no window at all. Try it on a big signal and you can see why some window is useful at most times. Tune to where you have large cw signals and switch the different filters. Some of the spreading that you see near the bottom of the signal is caused by the keying of the signal itself; it did not stop or start where it could get smoothed by the window function. You see the spreading intermittantly since it depends on whether or not the signal started or stopped in the tiome of the current data buffer. Regards, Richard W5SXD "Bill Nagle" <[EMAIL PROTECTED]> wrote: (02/23/2006 15:15) >Do you have a description of the various filters like the hanning default and >what is best for what mode? > > >Bill Nagle > > > >_______________________________________________ >FlexRadio mailing list >FlexRadio@flex-radio.biz >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >Archive Link: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/ >FlexRadio Homepage: http://www.flex-radio.com
