On Sun, 09 Jul 2006 00:44:26 GMT, Owen Duffy wrote:

It seems to me that what I am doing in statistical terms is taking a
limited set of samples and using it to estimate the population
variance (and hence the noise power in a resistor).

Seeing that the RMS voltage is applied fully to the resistance,
shouldn't that be signal + noise power in a resistor? The noise in
this sense only describes the deviation from the distributions' shape.

In this case, the KTB noise due to the loads own resistance is so
small as to be insignificant and not require a correct to be applied.

Hi Owen,

I was not thinking of thermal noise (actually, I've been quite deeply
involved in studying phonon interaction, but not to this purpose).
Rather, I was offering that if you integrate under the curve of the
gaussian distribution, and compare to the computed/measured noise
power, then and only then through that difference would you resolve
error. Of course, this may be a description of what you have already
offered in previous discussion.

What are you using as a source of noise?

Noise from the real world which I understand is not exactly white, but
I figure that if I understand the behavior from a white noise point of
view, the answer will be very close for noise that resembles white
noise.

The noise is audio output from an SSB receiver (operating below AGC
gain compression threshold) that, if you like, is acting as a linear
downconverter with a narrow pass band filter. Typically, the passband
is 300-2400Hz. The sampling is done in a PC sound card at a rate of
11kHz. The application here is using these samples to synthesise a
"true RMS voltmeter".

I've used both biased Zeners and weakly illuminated Photomultiplier
Tubes. The PMT doesn't offer much power, but it is flat out to the
100s of MHz. Another precision method is to load each output of a
ring counter (as big a ring as possible) with a random selection of
resistor values and feed them into a summing junction. This is
especially useful in the AF region.

73's
Richard Clark, KB7QHC