HP 8753E manual Transmission Uncertainty Equations, Efnf = effective noise floor

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 all of the first order terms and some of the significant second order terms. The 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 all cases, the error terms are treated as linear absolute magnitudes.

Transmission magnitude uncertainty (forward direction) = Etm =

Ert = Systematic + J(Random)2 + (Drift and Stability)2

Systematic = Efc + (Eft + EfsSll + EflS22 + EfsEflSBlSl2 + Ab2) S21

Random = &Ct)2 + (Rt)2 + (Nt)2

Ct = S21J(Ctml)2 + (Ctm2)2 + (CrmlS11)2 + (Crm2S22)2

Rt = S21d(Crt1)2 + (C~d2)~ + (CrrlS11)2 + (Crr2S22)2

Nt = -\/(EfntS21)2 + Efnf2

Drift and Stability = Dm2b2 S21

where

Crt2 = Connector repeatability (transmission) port 2 Crr2 = Connector repeatability (reflection) port 2 Efnt = effective noise on trace

Efnf = effective noise floor

Crrl = connector repeatability (reflection) Crtl = connector repeatability (transmission) Ctml = cable 1 transmission magnitude stability Ctm2 = cable 2 reflection magnitude stability Crm2 = cable 2 reflection magnitude stability Dmsl = drift magnitudePC source to port

Efs = effective source match error

Eft = effective transmission tracking error Efl = effective load match error

Efc = effective crosstalk error

The detailed equation for each of the above terms is derived from the signal flow model, located at the end of this appendix.

Determining System Measurement Unseertsinties B-6