[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.


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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