Tektronix TDS 500C Graphics Tablet User Manual


 
Appendix B: Algorithms
B–12
TDS 500C, TDS 600B, & TDS 700C User Manual
Timing measurement. Time taken for one complete signal cycle. The reciprocal
of frequency. Measured in seconds.
Period = MCross3MCross1
Timing measurement. The amount of phase shift, expressed in degrees of the
target waveform cycle, between the MidRef crossings of two different wave-
forms. Waveforms measured should be of the same frequency or one waveform
should be a harmonic of the other.
Phase is a dual waveform measurement; that is, it is measured from a target
waveform to a reference waveform. To get a specific phase measurement, you
must specify the target and reference sources.
Phase is determined in the following manner:
1. The first MidRefCrossing (MCross1Target) and third (MCross3) in the
source (target) waveform are found.
2. The period of the target waveform is calculated (see Period above).
3. The first MidRefCrossing (MCross1Ref) in the reference waveform crossing
in the same direction (polarity) as that found MCross1Target for the target
waveform is found.
4. The phase is determined by the following:
Phase =
MCross1Ref * MCross1Target
Period
360
If the target waveform leads the reference waveform, phase is positive; if it lags,
negative.
Phase is not available in the Snapshot display.
Period
Phase