Comparing Measurements To References - Tektronix 11801C User Manual

Comparing
Measurements to
References
11801C User Manual
You can establish reference values for your measurements and have the
11801C display the measurement readouts as the amount of variance from
the reference value. For example, you can store the propagation delay
through the cables that connect to your device under test. Then, by turning
on compare mode, you can measure the delay through the device under
test with the cable delay automatically removed from the measurement
result. You can also use this feature to compare measurements on several
different tests or parts.
You can also tell the 11801C to save the current measurement readouts as
the reference values for those measurements. If you then turn on the
compare feature, you can observe how much the signal deviates from those
references as you tune the circuit under test.
If you change the axis units on a trace, for example from volts to
rho, the reference values are not changed to match the new units.
Be sure the reference value is stored with appropriate units.
When the compare mode is on and measurement readouts show difference
values, the measurement readouts show a delta ( D ) in the selector label to
remind you that difference values are being displayed. For example, the
RMS measurement readout in the major menu area becomes the DRMS
readout when compare mode is turned on.
Measurement reference values are stored separately for each trace. The
reference values you establish for one trace will not affect the reference
values for other traces.
The compare feature affects all measurements on all traces. When you turn
on compare mode, all measurement readouts show D comparison values,
even if you select a different trace.
Compare mode is turned on or off using the Compare & References pop
up menu in the Measure major menu.
You set the reference values to the current measurement values by touching
the Save Current Meas Values as References selector. See Figure 3 69.
When you touch this selector, all the reference values for the measurements
established on the selected trace are copied from the current measurement
readouts.
NOTE
Measurements
3 145