At 06:42 PM 2/20/2007, Ned Johnson wrote: > Why not "resample" the 192kHz. input down to 48kHz. on the > fly as a button selectable option for receive, while leaving the > I/O stream intact to preserve the lower latency for transmit. > > Ned, K1NJ > > >Kirb Nesbitt <[EMAIL PROTECTED]> wrote: >For example, your dsp/sampling combo yield an approximate latency of 85 >ms! Utilizing the faster sampling rates of the FA-66 (192000), with a >sub-optimal dsp buffer size of 2048 equates to a total latency of 10.7 ms. >Obviously for me the perfectly in-step key-sync and change-over timing >out-weighs the ultimate shape-factor tweak (2048 vs. 4096). Just another >reason to like the flexibility built into this box! > >73, > >Kirb - VE6IV
Or, why not refactor the dsp core (which I believe is in the works) so that changeover from Tx to Rx doesn't have to occur on a buffer boundary. It's not the actual latency that causes problems (to a point), but the quantization of the changeover that disrupts the rhythm. What needs to happen is that the receive and transmit streams run continuously, in parallel, and the hardware is switched over from Tx to Rx (or reverse). The hardware switch can occur in well under a millisecond (relay closing time is the limitation, probably). The original dttsp core only changed on buffer boundaries, presumably for computational efficiency. Jim, W6RMK _______________________________________________ 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 Homepage: http://www.flex-radio.com/ FlexRadio Knowledge Base: http://kb.flex-radio.com/
