[time-nuts] any HP 5370B Available or other TIC

[Javier Serrano]

On Fri, Aug 19, 2011 at 12:44 AM, Tijd Dingen <tijddingen at yahoo.com> 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