[time-nuts] J06 HP-59992A time interval calibrator for HP-531xxcounters

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Jul 8 23:37:12 UTC 2017


The simplest solution to the divider and clock shaper is perhaps to use an LTC6954. The LTC6954 offers PECL/CMOS and LVDS outputs together with a low jitter (sub ps) programmable (SPI) divider (1-63).A couple of coax relays like those from Dow Key microwave together with some hardline and a couple of splitters could be used to implement the signal switching. 

> 
>     On 09 July 2017 at 09:53 Hal Murray <hmurray at megapathdsl.net> wrote:
> 
>     tvb at LeapSecond.com said:
> 
>         > > 
> >         The PIC dividers are good to a couple ps. I suspect the larger issue is the
> >         PCB and wiring design.
> > 
> >     > 
>     What does "good" mean?
> 
>     I'd expect the variations due to power or temperature would be easy to
>     measure.
> 
>     Delay through classic CMOS is linear with absolute temperature and inverse
>     linear with supply voltage.
> 
>     The classic way to get time-nuts level noise on FPGA outputs is to wiggle a
>     nearby pin. That shouldn't be a problem with a dedicated PIC but would
>     probably show up if you are generating multiple frequencies.
> 
>     --
>     These are my opinions. I hate spam.
> 
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