Tom Van Baak wrote:
Mark,
Your 5.5 mHz is correct for the frequency difference But
note that's out of 10 MHz so the *relative* frequency error
is 5.5e-3 Hz / 1e7 Hz, or 5.5e-10 (unit-less).
The other way to look at it is this:
The nominal frequency is 10 MHz, so one period is 100 ns.
Your Lissajous pattern is seen to repeat every 182 seconds.
Frequency difference is time drift over elapsed time, so the
relative frequency difference is 100 ns / 182 s = 5.5e-10.
---
Also, see if you can repeat this a month from now. If instead
of 182 s you get, say, 188 s then you have a way to compute
the frequency drift rate.
100 ns / 182 s = 5.495e-10 on November 7
100 ns / 188 s = 5.319e-10 on December 7
So your frequency drift in this example is 1.7e-11 / month.
/tvb
Not quite, you need to take the sign of the frequency difference into
account.
ie in your example above the sign of the error measured on November 7
has to be identical to the sign of the error measured on December 7 for
your calculation to be correct.
Bruce
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