Appendix B: Algorithms
TDS 684A, TDS 744A, & TDS 784A User Manual
B–9
Note that this value should never be negative (unless High or Low are set
out-of-range).
Timing measurement. The distance (time) between MidRef (default = 50%)
amplitude points of a negative pulse.
If MCross1Polarity = ‘–’
then
NegativeW idth = (MCross2 – MCross1)
else
NegativeW idth = (MCross3 – MCross2)
Amplitude measurement. The absolute difference between the maximum and
minimum amplitude.
PeaktoPeak = Max – Min
Timing measurement. Time taken for one complete signal cycle. The reciprocal
of frequency. Measured in seconds.
Period = MCross3 – MCross1
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:
Negative Width
Peak to Peak
Period
Phase
