On Fri, Jan 10, 2014 at 10:48:15PM +0000, James Stone wrote:
> > Do you mean the spectrum analyser showed a trace at -90 dB ?
It means something... but what it means is another question.
* the noise is more or less white (if not: real trouble)
* the spectrum analyser uses an 1024 point FFT (typical),
* and a raised cosine window (also typical),
Then the full bandwidth (1/2 Fs) is covered by 512 filters,
and each of these has a bandwidth that is 1.5 times that of
a rectangular filter.
So each filter sees 1.5 / 512 of the total power.
10 * log10 (1.5 / 512) is -25.3 dB
So the noise level would be around -93 + 25 = -68 dB.
You could check this with jnoisemeter.
> With further testing, I think I can detect a similar change in gain
That could as well be due to the random alignment of the signal and
the periods of the analyser.
> I think
Unless you pay at least 10 times more they will analog pots, and they
all show this effect to some degree.
A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)
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