Tektronix CSA8000B - Manual (Page 331)

Measurement Reference Parameters and Methods
CSA8000B & TDS8000B User Manual B- 69
Low
High
Mid
ref
Mode Tracking Method
Histogram high
Histogram low
Mode (of Histogram) sets the values statistically. Using a histogram, 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), Mode is the best setting for examining pulses.
Mode Tracking Method
Min/Max Tracking Method Mean Tracking Method
Auto switches between methods. Auto method first attempts to calculate the high and low
values using the Mode method. Then, if the histogram does not show obvious consistent high
and low levels, Auto method automatically switches to the Min/Max or Mean method.
For example, the Mode histogram operating on a triangle wave would not find consistent high
and low levels, so the instrument would switch to the Min/Max mode. Consistent high and low
levels would be found on a square wave, so the Auto mode would use the Mode method.
Mid-reference Level
The mid-reference level (adjustable from the Meas Setup dialog box) defaults to
50% of the pulse amplitude. If measurement gates are enabled, the measurement
region is the area between the Start Gate (G1) and Stop Gate (G2). By default,
the algorithm searches forward from the Start Gate for the first rising edge, but
the direction can be reversed from Meas. Setup dialog box, so that the search
will be backward from the Stop Gate. See To Localize a Measurement on
page 3--83.
To Optimize the Vertical Resolution
Optimizing vertical resolution improves the result this measurement produces.
Try these methods:
H Execute Autoset (push AUTOSET on the front-panel).
H Adjust vertical scale (or increase input amplitude) to increase the overall
vertical size of the waveform, while keeping the waveform on screen.