[time-nuts] Buffering a PPS signal

[Michael Tharp]

On 05/18/2012 01:33 PM, Mark Sims wrote:
>
> While you're at it,  add an ATMEGA328 processor and a 250 ps res/256 step delay line.   The processor reads the timing message,  picks off the sawtooth correction factor,  converts it to an 8-bit value that it output on a port to the delay line.  The 1PPS signal clocks the port into the delay line for sawtooth correction.   (This all assumes that the correction factor applies to the NEXT 1PPS that is output (the PPS correction is not documented...  the time field in the message  applies to the previous 1PPS pulse).

I don't need the sawtooth correction done in hardware because at least 
in my case the pulse is being fed into ntpd on a Rb-clocked computer, 
and ntpd can add the correction itself. But I'll definitely consider a 
bigger, better board that can do the correction internally, probably in 
a form more generic than this board which is just an interface to the 
Resolution SMT (and perhaps Resolution T, haven't checked if the 
mechanical aspects are the same).

-- m. tharp