Agilent Technologies HP 8719D Service Manual page 452

Transmission Uncertainty Equations
Transmission Magnitude Uncertainty (Etm)
An analysis of the error model, located at the end of this appendix, yields an
equation for the transmission magnitude uncertainty. The equation contains
terms under the radical are random in character and are combined on an RSS
basis. The terms in the systematic error group are combined on a worst case
basis. In aII cases, the error terms are treated as linear absolute magnitudes.
Transmission magnitude uncertainty (forward direction) = Etm =
Ert = Systematic + d(Random)2 + (Drift and Stability)2
=
Systematic Efc
= S21d(Ctm1)2 +
Ct
= S21d(C~tl)~ + (Crt2)2 + (CrrlS11)2 +
Rt
where
Efnt = effective noise on trace
Efnf = effective noise floor
Crtl = connector repeatability (transmission)
Ctml = cable 1 transmission magnitude stability
Dmsl = drift magnitude/°C source to port
Efs = effective source match error
Eft = effective transmission tracking error
Efl = effective load match error
Efc = effective crosstalk error
Determining System Measurement Uncertainties
+ + EfsSll
Random = d(Ct)2 + (Rt)2 + (Nt)2
Nt = d(EfntS21)2 + Efnf2
Drift and Stability = Dm2b2S21
+ EflS22 + EfsEflSBlSlX + Ab2)
+ (CrmlS11)2 +