[time-nuts] FE-5680A results
EWKehren at aol.com
EWKehren at aol.com
Tue Nov 29 18:55:31 UTC 2011
Murray
Thank you for the info. It would how ever tie up equipment which I want to
use for other projects. I am only looking at the FE5680A once a week and
since we have right now what we call Chamber of Commerce weather the AC is
most the time off. Temperature control will be a must any way, so now is as
good a time as any to integrate it.
I am working with two other individuals on integrating the Austron
circuit with its own 100 MHz counter with LCD display, temperature monitoring and
the ability to store it on an USB memory stick or via Bluetooth to a PC.
The counter has gate times of .1, 1 10 and 100 sec. and in 100 sec. the
resolution will be E-14.
Right now the FE 5680A is just a curiosity, as to what you can get for $
40.
Bert Kehren
In a message dated 11/29/2011 12:44:15 P.M. Eastern Standard Time,
denwood at orcon.net.nz writes:
Bert,
There's a very nice way to separate diurnal thermal sensitivity from long
term ageing. It applies equally well to Rb sources as to OCXOs, which is
where I've used it.
What you do is set up to make frequency observations against a more stable
reference (of course in this case a GPSDO or a similar), and then make
several observations per day for a week or so, preferably at or about the
same time of day each day. Then you plot the results using a spreadsheet,
as
ppb offset on the vertical axis and time of day (NOT total elapsed time)
on
the horizontal axis.
What will result after several days of observations is either a zig-zag or
a
spiral, depending on the relative sizes of the thermal and ageing effects.
You can extract the ageing rate out quite nicely by adding a column with
an
estimated ageing rate which you add to the measured offset. If you then
plot
this against time of day you should end up with a static rough retraced
circle or line when the estimated offset is correct. The width and height
of
the result gives you an estimate of the thermal sensitivity with time of
day.
If you are able also to plot against ambient temperature instead of time
of
day, the same process applies, and you can extract the thermal sensitivity.
73,
Murray ZL1BPU
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