Measurement System
TDS 620A, 640A, & 644A User Manual
Table 3-5: Measurement Definitions (Cont.)
Name Definition
Delay Timing measurement. The time between the MidRef crossings of two different
traces or the gated region of the traces.
Fall Time Timing measurement. Time taken for the falling edge of the first pulse in the
waveform or gated region to fall from a High Ref value (default = 90%) to a Low
Ref value (default =10%) of its final value.
Frequency Timing measurement for the first cycle in the waveform or gated region. The
reciprocal of the period. Measured in Hertz (Hz) where 1 Hz = 1 cycle per sec-
ond.
High The value used as 100% whenever High Ref, Mid Ref, and Low Ref values are
needed (as in fall time and rise time measurements). Calculated using either
the min/max or the histogram method. The
min/max method uses the maxi-
mum value found. The
histogram method uses the most common value found
above the mid point. Measured over the entire waveform or gated region.
Low The value used as 0% whenever High Ref, Mid Ref, and Low Ref values are
needed (as in fall time and rise time measurements). May be calculated using
either the min/max or the histogram method. With the min/max method it is the
minimum value found. With the histogram method, it refers to the most com-
mon value found below the mid point. Measured over the entire waveform or
gated region.
Maximum Voltage measurement. The maximum amplitude. Typically the most positive
peak voltage. Measured over the entire waveform or gated region.
Mean Voltage measurement. The arithmetic mean over the entire waveform or gated
region.
Minimum Voltage measurement. The minimum amplitude. Typically the most negative
peak voltage. Measured over the entire waveform or gated region.
Negative Duty
Cycle Timing measurement of the first cycle in the waveform or gated region. The
ratio of the negative pulse width to the signal period expressed as a percent-
age.
Negative Over-
shoot Voltage measurement. Measured over the entire waveform or gated region.
Negative Width Timing measurement of the first pulse in the waveform or gated region. The
distance (time) between MidRef (default 50%) amplitude points of a negative
pulse.
Peak to Peak Voltage measurement. The absolute difference between the maximum and
minimum amplitude in the entire waveform or gated region.
Phase Timing measurement. The amount one waveform leads or lags another in time.
Expressed in degrees, where 360 cycle.