Tektronix TDS7054, TDS7104, TDS7154, TDS7254, TDS7404 CSA7000 Series, TDS7000 Series, & TDS6000 Series Instruments User Manual 3- 157, Set measurement reference levels (Cont.)

Measuring Waveforms

CSA7000 Series, TDS7000 Series, & TDS6000 Series Instruments User Manual 3- 157

Overview Related control elements and resourcesTo take automatic measurements (Cont.)

18. To select how the instrument determines the base and

top of the waveform, touch Determine Base, Top Form

Min-Max, Histogram, or Histogram mean.

HMin-max. Uses the highest and lowest values of the

waveform record. This setting is best for examining

waveforms that have no large, flat portions at a

common value, such as sine waves and triangle

waves —almost any waveform except for pulses.

See Figure 3--35 on page 3--151.

HHistogram. Selects the most common values above

or below the midpoint. Since this approach ignores

short term aberrations (overshoot, ringing, and so

on), Histogram is the best setting for examining

pulses. See Figure 3--35 on page 3--151.

HHistogram mean. Calculates the mean value using

all values either above or below the midpoint

(depending on whether it is defining the high or low

reference level). Histogram mean is best for

examining eye patterns and optical signals.

19. To select the reference level units, touch Units Absolute

or Percentage.

HAbsolute. Sets the units to absolute values in user

units.

HPercentage. Sets the units as a percentage of the

High/Low range.

20. To set the reference levels, touch HighRef, Mid Ref, Low

Ref, or Mid2 Ref, and use the multipurpose knobs or

keypad to set the levels.