On Fri, Aug 19, 2011 at 12:44 AM, Tijd Dingen <[email protected]> wrote:
> > I'm meeting timing in a 390 MHz design with 192 taps (admittedly after a > quite a bit of messing with the tools to get P&R to do what I want). The > pipeline obviously is more stages... But maybe you guys are doing something > different. Or maybe 125 MHz is enough, and you decided you don't want design > headaches. Anyways, just curious as to why the 125 MHz sampling rate. > > 125 MHz is a natural frequency for us because the FMC carrier will in normal operation extract 125 MHz from the White Rabbit link (GbE), which will be phase compensated to account for fiber-induced delay, and will have very good long-term stability because it is derived from an GPSDO hooked to the White Rabbit master node. This TDC will then produce proper TAI time stamps, combining a integer number of 125 MHz ticks and a fractional part. We could of course double the 125 MHz and use that instead. For the time being, we are just playing. Cheers, Javier _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
