> Pulse quality of single-ended RS232 over unbalanced twisted pair is going > to be pretty bad beyond a few feet. If you want to transport the 1pps over > twisted pair there are a couple of options:
Hi Brian, I suspect this is true at one level, but what would be helpful to to *quantify* it. What is "pretty bad"? What is "few" feet? You are implying that 1PPS timing is dependent in cable quality and cable length. I would agree. But please provide some numbers, even rough numbers, because what is important for modern T&F applications (picoseconds and nanoseconds) can be irrelevant for NTP, which still lives in the millisecond and microsecond world. What I'd like to see, and what would be educational for the group, is if you could take some 'scope traces at a few inches, at a "few feet", and at a few meters or tens of feet to graphically demonstrate your pont. My gut tells me 1 ns or 10 ns or 100 ns or 1 us or 10 us makes no measureable difference to the quality of NTP/PC timekeeping. /tvb _______________________________________________ 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.
