Thank you GIN & PEZ;
Your post #6529
#73': On the sine qua non Core Uncertainty of AnyVNA - incl. NanoVNA - System
(the message #73 is withdrawn mainly because its conclusion is too weak)
Seems to add significant clarity to my understanding of your project overall;
I will attempt a concise summary of my understanding, and seek your confirmation on this, or clearly illuminate those components of thought where I am in error.
The One port LeastVNA equation:
[#52]
Is a reduced (one-port) expression derived from the full (two port) set of equations
[#16]
and neither of these are new, but are based on the prior works of perhaps many.
The unique property of [#52], (and [#16] as well) is that they describe calibrations of any VNA using just the nominal measurements of the SOL standards, and any nominal DUT measurements from
which the desired DUT parameters are then computed.
An additional unique (and most important property) of the equations is that they do not attempt to correct for any source of uncertainty bias. Correction parameters are intentionally ommitted.
[#16], and [#52] as a subset, are declared the Core equations for any VNA calibration, and define the variables, and computational requirements common to any VNA (All VNA's) for the following reasons:
1) The measurements are performed identically for any VNA
2) The quanity of measurements and computations are identical for any VNA
3) ALL measurement uncertainties that are not common to ALL VNA's are excluded from the computations and results.
4) The equations enable measurements made on any VNA calibrated as a "system" to be compared equally without bias. All known unavoidable uncertainties are common to all VNAs, and are
absorbed equally and identically into the calibration as the overall uncertainty of the measurement system itself.
The Core uncertainty is defined as the unavoidable deterioration of computational precision created when multiplying and dividing by indeterminately large and small quantities, the accumulation of
round-off and truncation errors, and the unavoidable number of mathematical operations required to arrive at a computed final result.
The Core uncertainty, is a computational artifact, that is objectively deterministic, and defines the UNAVOIDABLE MINIMUM boundaries of uncertainty in any VNA, that can not be improved through
the use of higher precision equipment or components. This is the objective of the DERDEI software currrently in the form of a FORTRAN calculator and wxMaxima plotting utility.
In other words...
Sine qua non F(Any)CUPOV. :-)
73
Gary, N3GO
--
73
Gary, N3GO
