Dave, in a left-handed way I just confirmed your observations. With the DSP buffer set to 2048, filters are very sharp and straight, 25 Hz setting only hears a small slice of one signal. With the DSP buffer set to 256, filter no longer has any real effect. I then hear artifacts (on CW) over 750 Hz away, despite the 25 Hz filter selection. I also did hear the difference in ability to copy weak signal better with the 256 setting as well.
Side note (no pun intended): at all settings on my SDR-1000, CW reception with narrow filters is far better with the NR turned off. 73, Carl WC0V Dave & Nancy Ridge wrote: > Thanks Dale, Bob and Lee for your thoughts. I will be looking forward to > separate DSP for transmit and receive. > > Dale, as I said in my original post, I use 2.4K filter but have tried many > other filter widths. Yes, I have tried shifting the filter up/down with no > discernible difference. > > Lee, I have used a very good set of "cans" (earphones) and have use Logitech > speakers also. The receive DSP buffer of 256 works better on both. You are > right that the human brain is a very good filter in digging out signals in > the noise. The signals that I am trying to copy is mostly in the noise except > for Meteor Scatter bursts. > > I believe that the DSP receive filter with a buffer setting of 256, with less > steep shirts, has little to do with the enhancement/advantage of this filter. > The less latency of this buffer size has no advantage to this operation. > > If you look at a CW signal on the Panadapter with the DSP buffer setting of > 256 and compare the peak of the wave form with a DSP buffer setting of 4096, > you with see that the peak is rounded off in 4096 but has a sharp tip in 256. > (Set your Panadapter to 4X) You will also hear the CW signal more discernible > in 256. (Assuming that there are not signals close to the frequency) > > The receive SSB audio in 256 DSP has a much sharper, crisper sound in 256! I > realize that in a crowded band you do not want this kind of shape factor. > Also, you do not want to transmit SSB using this DSP, thus the need for > separate transmit and receive DSP settings. I am standing by for that....what > a great radio and concept this is. Thanks to all those who contribute to the > software! > > Dave, W9DR > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/attachments/20070927/3e5a7862/attachment.html > > _______________________________________________ > FlexRadio mailing list > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > FlexRadio Knowledge Base: http://kb.flex-radio.com/ > FlexRadio Homepage: http://www.flex-radio.com/ > > _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
