[time-nuts] Typical HP 5370B resolution ?
Poul-Henning Kamp
phk at phk.freebsd.dk
Mon Mar 4 13:54:48 EST 2013
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In message <5134DD69.1070001 at rubidium.dyndns.org>, Magnus Danielson writes:
>> Once you get to this level of detail, it is important to know that the
>> actual number is not 20ps but 19.5763ps
>>
>> See page 8-19 in the manual.
>
>Since we are in nit-picking mode, on page 8-29 it says the resolution is
>in 5/256 ns, which I get into 19,53125 ps (exact).
I doubt that difference is material :-)
I'm not sure which one is correct, at the end of the day, but it is
somewhere between 19.6078 and 19.4553 ps.
The point I tried to make was that once you start to look really
closely at good clocks, you will find that the resolution shines
through, and it will be 19.55-ish ps, not 20ps.
>One way to understand this is that the gearbox of the 5370B
>interpolators creates a virtual clock of 51,2 GHz. Not bad for a core
>design in 200 MHz and some smart ECL logic from late 1970thies.
Indeed.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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