[time-nuts] 5 MHZ PIC PPS Divider?

Pete peterawson at earthlink.net
Tue Apr 15 16:13:02 EDT 2008


Jitter measurements of moderately high frequency
sources can be made directly with relatively cheap
used instruments.

Older sampling 'scopes from H-P and TEK appear
on *Bay frequently. The H-P 54120 family boxes
are down to US$500 to 800 with sampling heads 
capable of 12.4GHz measurements. These show up
about once per month. If you're trying to buy one,
wait for a complete system (mainframe+sampling 
head) which is listed as operational & you have
confidence it's actually working. These things are
HEAVY & having to return a junker is painful;
even if you get your money back.

These mainframes have jitter capture & analysis
built in. The internal trigger jitter floor is about 1ps,
good enough for most measurements. The internal
timebase delay feature allows measuring multi-
cycle jitter out to many screens width of data.
Obviously, long delays will introduce added
jitter floor contribution, but it's still quite good.

Pete Rawson

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