Hello Angus,
That is roughly what I want to do, a plausibility check if what I see is
caused more by the GP22 or already present on the signal I am trying to
measure.
Very clearly there is no principal problem, the data I get from the GP22 is
pretty decent and with enough filtering already useable. I have the feeling
the GP22 does not add very much noise/jitter and all I want is get a handle
on how much in reality.
If we take this approach further we will have to invest in some additional
kit, but apart from that I am also rather taken by the capabilities of the
GP22 as a timer, and my own curiosity wants to find out how good a homebrew
counter/timer could be built from it.
As I said I will feed back anything I can establish in this respect.
Best regards,
Thomas.
-----Original Message-----
From: Angus
Sent: Thursday, November 26, 2015 1:54 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] ACAM GP22 Chip
I wouldn't expect the noise to
be in the ns range, but i wouldn't surprised if it was a few 10ps.
I have never done any measurements though, and I don't think i've
ever seen any jitter measurements for 32kHz oscillators, so take
this value as rough guestimate.
On the GP21 board I used it was more like 10ns+. I don't know if
that's typical, but it wasn't a even particularly cheapo crystal as
the original one was faulty and I had to replace it. The official acam
board might be better, but the data sheet specifically talks about the
32K osc having a lot of jitter.
One of the problems of the data sheet is that it is really tailored
for those using it as a flow converter - some of the text does not
even make sense otherwise. That was one of the reasons I was planning
to test it more as a TDC, but just getting back to doing that now.
Angus.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
