Am 2022-04-05 22:09, schrieb Mike Monett:
Joseph,
You will find it difficult to get below -170 dBc/Hz. However, you can
use
cross-correlation to get as low as -220 dBc/Hz.
Yes, it is not impossible to get these numbers. But it is cheaper to
throw dice.
U.Rohde is 30 dB more modest:
"...amplifier certainly has a higher noise figure, as it is driven with
more power and there is no
improvement possible. There is an optimum condition and some of the
measurements showing
‐190dBc/Hz do not seem to match the theoretical calculations. The
correlation allows us to look
below KT, but the noise contribution below KT is as useful as finding
one gold atom in your body’s
blood. This gold atom has no contribution to your system."
taken from the conclusion of "Phase Noise Measurements and its
Limitations – Sent to MWJ – for publication in April 2013 issue"
Gerhard
Rubiola is a wealth of information on cross-correlation. You can
download
his papers at
http://rubiola.org/index.html
See "The cross-spectrum experimental method, February 2010"
See also measurements by John Ackerman:
http://www.febo.com/pages/cross-correlation/
MRM
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