Viavi 3900 Series Operation Manual page 237

A n al og D up le x S y st em
7. 4. 13 .A .5 RF L ev el
Th e RF L ev el fiel d s ele ct s w h eth er th e R F G en e rato r O u tp ut L e ve l, w he n giv en in m V
(m icr o V o lt) is e xp res se d in a P D or E M F r efe re nc e s ys te m .
µV (P D ) = mic ro Vo lt s P o ten tia l D iff er en ce
C ircu it is cl os ed on to a m atc hin g loa d tha t is e qu al t o t he ou tp ut im pe da nc e of the
so ur ce . T he P D ref ere nc e sy ste m in clu de s a v olta g e 1 :2 div id er at t he loa d .
µV (E M F ) = micr o Vo lts E lec tr omo tiv e Fo rc e
C ircu it is o pe n, or clo se d o n to a n inf inite lo ad . T he E M F ref ere n ce sy ste m d oe s n ot
co nt ain a vo ltag e div ide r a t th e loa d, re su lting in va lu es tw o t im es lar ge r th an th os e in t he
PD r efe re nc e sys te m . F or ex am p le, -12 0 dB m is eq u al t o 0 .2 25 m V (P D) or 0.4 5 m V
(E M F) .
7 - 27