Tektronix TDS7254 Stereo System User Manual


 
Measuring Waveforms
CSA7000 Series, TDS7000 Series, & TDS6000 Series Instruments User Manual
3- 151
High/Low Method. The levels that the automatic measurement system derives as
the High (Top) or Low (Bottom) for a waveform influence the fidelity of
amplitude and aberration measurements. You can select among the modes the
instrument provides for determining these levels. You can set the modes
differently for each measurement:
H Histogram. Sets the values statistically. It selects the most common value
either above or below the midpoint (depending on whether it is defining the
high or low reference level). Since this statistical approach ignores short
term aberrations (overshoot, ringing, and so on.), Histogram is the best
setting for examining pulses. See Figure 3--35.
High (Histogram)
Low (Histogram)
Low (Min/Max)
High (Min/Max)
High (Mean)
Low (Mean)
Mid reference
Figure 3- 35: High/Low tracking methods
H Min-max. Uses the highest and lowest value s of the wavef orm rec ord. This
setting is best for examining wavefor ms that have no lar ge , fla t portions at a
common value, such as sine waves and triangle waves almost any waveform
except for pulses. See Figure 3--35.
H Histogram mean. Sets the values statistically. Using a histogram, it selects
the mean or average value derived using all values either above or below the
midpoint (depending on whether it is defining the high or low reference
level). This setting is best for exa mining eye patterns and optical signals. See
Figure 3--35.