Charles, I've noticed that the shape factors of all filter bandwidths always vary with buffer settings, at least since December last year when I bought my SDR-1000.
This is easily seen in spectrum display mode. In my opinion, this behavior allows you to balance performance vs. CPU load and/or latency. 73, Guy Atkins Puyallup, WA www.sdr-1000.blogspot.com Sent from my BlackBerry® wireless handheld -----Original Message----- From: Charles Greene <[EMAIL PROTECTED]> Date: Wed, 01 Nov 2006 12:36:12 To:<[email protected]> Subject: [Flexradio] Filter Bandwidth and DSP Buffer size. Hello, I noticed the SDR-1000 25 Hz filter seemed to have grown while operating CW. I had set the DSP buffer size to 2048 as part of the process in optimizing for CW. I am running a Firebox on a 1.8 GHz P4, SDR 1.63 SVN 732. So I ran Spectrogram, hooked up a white noise generator to the antenna input and plotted the filter at various filter and DSP buffer settings. Some results: Filter 25 Hz, Buffer 4096 (This is what it should be) sig level (from peak) filter width -6dB 25Hz -40dB 100Hz Filter 25 Hz Buffer 2048 sig level (from peak) filter width -6dB 62Hz -40dB 164Hz I couldn't get a meaningful reading at -60 dB; don't know why, but -40 dB is a pretty good operational limit. I copied the screen and I will send these two files to who ever would like to see them. Each file is 80-90 kb each. Conclusion: Be careful reducing the DSP buffer size as it will affect your narrow CW filters. 73, Chas, W1CG _______________________________________________ FlexRadio mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com _______________________________________________ FlexRadio mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
