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Old March 22nd 09, 07:46 PM posted to rec.radio.amateur.antenna
Richard Clark Richard Clark is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 2,951
Default Noise figure paradox

On Sun, 22 Mar 2009 06:34:03 GMT, Owen Duffy wrote:

Richard Clark wrote in
:

On Fri, 20 Mar 2009 19:46:53 -0700, "Joel Koltner"
wrote:

Say I have an antenna that I know happens to provide an SNR
of 60dB...


I've been following this saga for a while now, and I note no one seems
nonplused by the statement above. For as much that has been unsaid,
there must be a flood of presumptions that flowed from this detail.


Indeed. I addressed some in my second posting, perhaps you missed it?

Owen


Hi Owen,

I did note:
On Sat, 21 Mar 2009 03:25:39 GMT, Owen Duffy wrote:
I get 60-3.2=56.8dB.


Which appears to embrace this oddity of characterization.

And, as you offer, you say:
On Sat, 21 Mar 2009 03:43:21 GMT, Owen Duffy wrote:
It says nothing of the absolute noise power or signal power. You seem to
assume the noise power KTB noise where T is 290K.


Which still leaves an astonishing characterization accepted, if only
to seemingly fulfill a presumption.

Perhaps I should more blunt, but the quote I lifted only speaks to two
things: an antenna, and a claim for its signal to noise ratio.

60 dB ??????????????

This isn't credible leaving the gate, and how it is then used as a
source to expand the discussion is bewildering beyond compare.

The topic heading as being a paradox is certainly apt, however.

73's
Richard Clark, KB7QHC