Tektronix DPO2304SX, Printable Help

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Missing or out-of-range samples
If some samples in the waveform are missing or off-scale, the measurements will linearly interpolate between known samples to
make an appropriate guess as to the sample value. Missing samples at the ends of the measurement record will be assumed to
have the value of the nearest known sample.
When samples are out of range, the measurement will give a warning to that effect (for example, CLIPPING) if the measurement
could change by extending the measurement range slightly. The algorithms assume the samples recover from an overdrive
condition instantaneously.
For example, if MidRef is set directly, then MidRef would not change even if samples were out of range. However, if MidRef was
chosen using the % choice from the Set Levels in % Units selection of the Measure menu, then MidRef could give a CLIPPING
warning.
NOTE. When measurements are displayed using Snapshot, out of range warnings are NOT available. However, if you question
the validity of any measurement in the snapshot display, you can select and display the measurement individually and then check
for a warning message.
Measurement warnings
The following measurement warnings can be generated by the instrument. They may be generated in various situations such as
those described below. In general, measurement warnings produce measurement results that are uncertain.
Warning Description
Not yet computed Displayed until a measurement is completed. This is displayed if you hit the clear button and the
instrument is waiting for a trigger.
LTGT This is a measurement warning that’s only generated in some cases where null samples are
present in a waveform, such as an ET waveform or a math waveform generated by arbflt()
functions. It is a warning that strictly speaking a measurement might be larger then or less then the
reported value because some samples were null in measured waveform.
Uncertain This is a generic warning regarding an uncertain result and can result for measurements that
depend on multiple sub-measurements to generate a result (such as area, or rms that need to
measure times and voltages). If one of the sub-measurements generates a warning the
combination of warnings may be combined to simply report ‘uncertain’ to the user.
Low signal amplitude This is reported when the measurement system tries to find a cross for a waveform less then
50 digitizing levels high.
Unstable histogram This is generated for histogram measurements when the resulting histogram size is too narrow to
perform an accurate measurement. It might show up for some eye measurements.
Low resolution This is a common warning that can occur when there is insufficient horizontal resolution to get
accurate timing measurements.
Uncertain edge This warning is generated in eye diagram measurements when there isn’t sufficient resolution to
determine an edge to measure.
Clipping positiveClipping
negativeClipping pos neg These are generated in response to any input waveform that has generated an over range or
under range DAC value, indicating the waveform went off screen.
Oscilloscope reference
DPO70000SX, MSO/DPO70000DX, MSO/DPO70000C, DPO7000C, and MSO/DPO5000B Series 699