[time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

MLewis mlewis000 at rogers.com
Tue Feb 14 10:31:30 EST 2017

On 14/02/2017 7:26 AM, Bob Camp wrote:
> Hi
> A direct port might be a +/- 100 ns sort of thing most of the time and a +/-10 us
> thing every so often under some OS’s. Most desktop operating systems are not
> designed to prioritize random pin interrupts. A dirt cheap MCU coded with a few
> (hundred) lines of assembly code may be a better option than a typical desktop.
> Complicating this further is the degree to which some OS’s can be directly or
> indirectly optimized. Install *this* package and it all goes nuts. Install that package
>   and not much happens ….
> Bob
Hence, wouldn't Best Practice be boxes loaded with only the bare OS and 
software for the time-related tasks?
As in:
- a dedicated machine/box for unencumbered acceptance of PPS, and
- for systems with a business need, a dedicated NTP server/box 
disciplined by the PPS source (with dedicated communication), while 
maintaining internet NTP sources as backup for when the PPS source fails?
Is there a better way?
Other considerations?


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