[time-nuts] Looking for Wavecrest Visi
SAIDJACK at aol.com
SAIDJACK at aol.com
Sun Apr 8 15:42:15 EDT 2007
In a message dated 4/8/2007 04:02:38 Pacific Daylight Time,
bruce.griffiths at xtra.co.nz writes:
The Wavecrest instrument only has a single shot resolution of 25ps not
as you claim 800fs (this is only achieved after averaging)
The above counters can only be compared for this purpose if their single
shot resolution and linearity are known.
Hi Bruce,
again, I did say in my original post that my math only works if their noise
is Gaussian, and that I did not know if it was.
Also, please note that they do claim 25ps Accuracy , and 800 femtoseconds
Hardware resolution, not the other way around.
They claim +-25ps accuracy with 3-sigma confidence. The user manuals are
available on the Wavecrest website.
There is no mention in their documents that averaging is needed to make use
of their 800 Femtoseconds hardware resolution; quite the contrary in some
older white-paper documents they show how they achieve this single-shot
resolution (when looking inside one of these units it's quite amazing technology).
Keep in mind that these instruments are on a totally different level than
the 53132A or SR-620: these units cost anywhere from $50,000 to $90,000 new.
BTW: the only point I was trying to make is that you sometimes can get these
things for <$500 and they are a lot better than the above mentioned
instruments for time-interval measurements.
Bye,
Said
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