Topband: Noise Power Testing and Ratio Power Ratio

[Terry Posey]

...... It is primarily for transmit and receive amplifiers working at high
frequency, but I
don't know if it has ever been applied to the entire receiver, RF-to-AF.....

....I've  never seen it used on Rx just Tx as it
needs a FFT or similar process on the final signal.....

W2VJN is indeed correct in that Noise Power Testing and the Noise Power
Ratio figure of merit has been used in the communications industry for
decades.  The Marconi NPR test set that George references is used to perform
end-to-end NPR characterization of analog microwave links - from TX baseband
input to RX baseband output.  The noise generator is connected to the
microwave TX modulator input and a calibrated noise detector with
notch-filters is connected to the coordinate microwave RX detector output.
The split-site NPR test can characterize the entire microwave link providing
an NPR figure of merit that takes into account amplitude/phase/delay
distortions, signal reflections, and IMD that are introduced in the TX
modulator, waveguides, antennas, RF propagation media, RX detector,
equalizers, and in all amplifiers in both the TX and RX units.  Split-site
NPR testing can even indicate antenna mismatch problems with either TX or RX
antenna.

Noise Power testing is being used to characterize and linearize Traveling
Wave Tube amplifiers.   http://www.lintech.com/PDF/npr_wp.pdf

It seems to me with some effort a standarized test setup can be devised to
accurately characterize Topband preamps.

73,

Terry K4RX