On 2/25/2021 5:16 PM, John Kaufmann via Topband wrote:
The P3 averages power, not amplitude, so using longer averaging times just
smooths the display and doesn't reduce random noise.
It has nothing to do with power. Last I looked, the P3 is reading and
displaying the instantaneous voltage in the IF, and can be calibrated to
voltage at the input.
I've been doing swept measurements of complex quantities for nearly 40
years, first at audio frequencies and now at RF. Averaging DOES cause
random contents of a bin to approach zero (or the noise floor), making
correlated signals stand out. This has long been well understood.
I the principle to measure the dynamic response of broadcast signal
processing in a peer-reviewed paper to the Audio Engineering Society in
1986. The test signal was a swept sine embedded deep in musical program
material to the point that it was barely audible to a trained listener,
and detected by a synchronized swept narrowband detector. Because the
swept excitation and swept detector are synchronized, the measurement
produces the complex response of the system, and program material, being
non-coherent, averages out.
http://k9yc.com/AESPaper-TDS.pdf
73, Jim K9YC
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