Glossary
TDS 684A, TDS 744A, & TDS 784A User Manual Glossary–5
High
The value used as 100% in automated measurements (whenever high ref,
mid ref, and low ref values are needed as in fall time and rise time measure-
ments). May be calculated using either the min/max or the histogram
method. With the min/max method (most useful for general waveforms), it is
the maximum value found. With the histogram method (most useful for
pulses), it refers to the most common value found above the mid point. See
Appendix B: Algorithms for details.
Holdoff, trigger
A specified amount of time after a trigger signal that elapses before the
trigger circuit will accept another trigger signal. Trigger holdoff helps ensure
a stable display.
Horizontal bar cursors
The two horizontal bars that you position to measure the voltage parameters
of a waveform. The oscilloscope displays the value of the active (moveable)
cursor with respect to ground and the voltage value between the bars.
Interpolation
The way the oscilloscope calculates values for record points when the
oscilloscope cannot acquire all the points for a complete record with a single
trigger event. That condition occurs when the oscilloscope is limited to real
time sampling and the time base is set to a value that exceeds the effective
sample rate of the oscilloscope. The oscilloscope has two interpolation
options: linear or sin(x)/x interpolation.
Linear interpolation calculates record points in a straight-line fit between the
actual values acquired. Sin(x)/x computes record points in a curve fit
between the actual values acquired. It assumes all the interpolated points fall
in their appropriate point in time on that curve.
Intensity
Display brightness.
InstaVu acquisition mode
A mode that increases the waveform capture rate to up to 400,000 wave-
forms per second. This very fast capture rate greatly increases the probability
that runts, glitches, and other short term changes will accumulate in
waveform memory. The oscilloscope then displays the waveform at the
normal display rate using variable or infinite persistence.
Interleaving
TDS 700A Models Only: A method by which the TDS 744A and TDS 784A
Oscilloscopes attain higher digitizing speeds. The oscilloscope applies the
digitizing resources of unused channels (that is, channels that are turned off)
to sample those that are in use (turned on). Table 3–2 on page 3–19 lists
acquisition rates vs. number of channels that are on.