[time-nuts] Precision Freq Measurement in Short Time

Poul-Henning Kamp phk at phk.freebsd.dk
Sat Jul 30 09:06:33 EDT 2005

In message <004001c59506$0bedbf80$eb12f204 at computer>, "Tom Van Baak" writes:
>OK, here's the second part of your answer.
>> I tried this method several time before by feeding the A 
>> and B input the same 10MHz source, and the result is not 
>> as good as promised. It always jump more than 25ps and 
>> sometimes more than 50ps. When I look at the Jitter:Allan 
>> (for every second), it something like 20ps. Until today
>I suspect this jumping will occur when the two
>channels are highly synchronous; 

There's a lot of electronics in the 5370B to handle
exactly that and it is very tricky to calibrate it correctly
in my experience.

If you look in the manual, there are oscilloscope pictures of just
how fuzzy the signals have to be at certain places etc.

But if you get it top-tuned according to those pages, it will be
inside spec.

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.

More information about the time-nuts mailing list