Brian: As usual, you bring clarity to the confused. Im embarrassed to admit that Ive read the Buffers and Sampling Rate article in the KC more than once. I often think I understand what I thought I read. I failed to comprehend the importance of the DSP Buffer Size settings in the Setup Form.
The key is the setting in SETUP - DSP - Buffer Size for CW. Sure enough: Raise the RX Buffer Size from 512 to 4096 and the filters are once again razor sharp and performing as expected. I kept my FlexRadio Driver Sampling Rate, Buffers and Mode at 192K, 2048 and Normal and all seems well with the world once again. I went wrong failing to recognize that the RX Buffer Size in the DSP tab needs to be radically different from the TX size in order to keep filters sharp but not introduce confusing latency during transmit... at least with my setup. Thank you for your assistance. Forgive the bandwidth and I will resume lurking. 73 to all, Frank N. Haas KB4T Florida From: br...@lloyd.com [mailto:br...@lloyd.com] On Behalf Of Brian Lloyd Sent: Thursday, February 24, 2011 12:59 AM To: k...@kb4t.us Cc: flexradio@flex-radio.biz Subject: Re: [Flexradio] v2.0.19 RC1 CW Selectivity Issue: Bug or Confusion? On Wed, Feb 23, 2011 at 9:19 PM, Frank Haas KB4T <k...@kb4t.us> wrote: First the Rig: Flex 5000a Pentium Dual CPU E2220 @ 2.4 GHZ with 2 GB RAM Driver set to 192k, 2048, Normal DSP set to CW 512/512 This is the issue. If you increase the number of samples in the DSP buffer, you sharpen the filters. Going from 512 to 1024 will make a marked improvement. Also switching to a lower sampling rate, i.e. 96kHz will help too. When you switch up to 192kHz sampling you need to double the number of samples in your DSP buffer to keep the same filter shape. Bump up the number of samples, drop the sample rate, or both. That will get your razor-sharp filters back. The only potential problem you face is that you introduce more delay when you reduce the sample rate or increase the buffer size. This shouldn't be a problem unless you are trying to run fast QSK. Also, you only need to change the RX DSP filter, not the TX. -- Brian Lloyd, WB6RQN/J79BPL 3191 Western Dr. Cameron Park, CA 95682 br...@lloyd.com +1.767.617.1365 (Dominica) +1.931.492.6776 (USA) (+1.931.4.WB6RQN) _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
