[time-nuts] Trimble Thunderbolt 1pps

[Didier Juges]

I may have posted this link before. It is on topic, even though I was using coax cable: 
http://ko4bb.com/Test_Equipment/CoaxCableMatching.php

It would be easy to do the same experiment with cat-5 cable. I would expect the pictures to look somewhat similar.

Didier KO4BB


Tom Van Baak <tvb at LeapSecond.com> wrote:
>> 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
>
>
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