I agree. Please, Paul, start a new thread, and we'll be there.
Volker
Am 28.11.2012 08:10, schrieb Hal Murray:
You might get better answers by starting a new thread rather than hiding your
question in an existing thread. (Use your New message button rather than
Reply, and cut-paste the To address from an old message, then type in the new
Subject.)
Using a useful Subject also helps people find things in the archives.
paul.destef...@willamettealumni.com said:
We have an application in which we plan to travel 7 hours with an SR620
turned off, then turn it on for 1 hour and take measurements we expect to
be accurate to less than 1ns. I would appreciate more information about
how to get reliable data out of this instrument.
What do you mean by "accurate to less than 1ns"? What are you trying to
measure?
The internal clock in the SR620 may be off a bit. The specs should be in the
users manual. In general, you have to wait a while for it to warm up and it
will depend on which options you have. (Some units have good crystals. Some
have low cost crystals to save $$ if they will normally run off an in-house
reference clock.)
Suppose it's worst case 1 part in 1E9, just to pick a handy number to work with.
If you measure the width of a 1 microsecond pulse, the error from the clock
will be 1E-15 seconds or 1E-6 ns.
If you measure the time between 2 consecutive PPS pulses, the error from the
clock will be 1E-9 seconds or 1 ns.
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