El 10/02/2012 00:13, Javier Herrero escribió:
El 09/02/2012 22:28, Magnus Danielson escribió:
Consider that it is de-modulated and then low-pass filtered.
Also, it is the alternating rate and not 1400 Hz difference in DDS
setting which is the key parameter here. The 1400 Hz gives a hint of
the Q-value however, which seems to be lower on these than on any of
my larger rubidiums, but it is maybe to be expected.
Yes, you're right... I was thinking on the alternating rate (that in
fact I measured, at 416.6666..Hz, but the other number came first ;)
), and in the fact that the FRS, that uses 127Hz as alternating rate,
has notorious spurs at 127 and 254Hz (al at a lot of their harmonics),
so I was expecting someting similar for the FE5680A at 416.6666Hz and
harmonics, but seems not to be there (or the spur forest makes not
easy to see these trees :) )
I answer myself. Perhaps they are there quite notoriously, since in the
spectra plots that I took when I got mine, now it is clear why there are
two peaks at around -70/-75dBc at somewher that seems very near
+/-416.7Hz: http://www.nebulosa.org/images/FE5680A/FE5680A4.jpg Probably
in the phase noise plot they are masked by all the phase noise floor and
other spurii that are not so apparent in a quick measurement with the
spectrum analyzer
Regards,
Javier
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