NIST Technical Note 1337: Characterization of Clocks and Oscillators

ttl·010·'110 .t....,.. ,;,'"',,,,,, t' ltl.~.Je 1O~-f'.IO,0'".1504S10-w ,i1'~ ~ fila. 10,,& ~ U»w"~~,tFIGURE 12.2FM behavior mask.s the ",hite PM (with the superimposedvibration characteristic) for long averagingtimes.J8-iID 16'-0'·10'0-t1O.ott·12-120 S-(t) ~I!l~ '0-fifO 10"45.~ 10·I(,Q fa"")fa:)Hr, ~ 7141. ~ ~ tmt~~~.~FIGURE 12.4, ,"%,., 13K ~_ m- COOllll: t:nX>ESAI"F'I.£ i1I"'C,'r(,)FIGURE 12.3For example, diurnal variations in data due to dayto day temperature, pressure, and other envi ronmentaleffects can be eliminated by sampling tnedata once per day.data with only one periodic term.Thi s approach is usefu1 forFigure 12.4 shows the kind of plot one mightsee of S,(f) with vibration and acoustic sensitivityin the signal source with the deviceunder vibration.Figure 12.5 shows the translationto the time domain of this effect. Alsonoted in figure 12.4 is a (typical) flicker FMbehavior in the low frequency region. In thetranslation to time domain (fig. 12.5), the flickerFIGURE 12.5Figure 12.6 shows eXallples of plots of twopower law processes (S,«(» with a change in theflicker FM level. (Example 1 is identical to theexample given in sec. XI.) Figure 12.1 indicatesthe effect of a lower flicker FMtranslated to the time domain.level asHote again theexistence of both power law noise processes.However for a given averaging time (or Fourierfrequency) one noise process may dominate over theother.39