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18-2
Measure Commands
Measure Commands
The commands in the MEASure subsystem are used to make parametric measurements on
displayed waveforms. The 86100C has four modes: Eye/Mask, Jitter, TDR/TDT, and Oscillo-
scope. Each mode has a set of measurements. In Eye/Mask mode, all of the measurements
are made on the color grade/gray scale data, with the exception of average optical power and
histogram measurements.
Measurement
Setup
To make a measurement, the portion of the waveform required for that measurement must be
displayed on the analyzer.
• For a period or frequency measurement, at least one and one half complete cycles must be dis-
played.
• For a pulse width measurement, the entire pulse must be displayed.
• For a rise time measurement, the leading (positive-going) edge of the waveform must be dis-
played.
• For a fall time measurement, the trailing (negative-going) edge of the waveform must be dis-
played.
• A valid source for the measurement must be designated. This can be done globally with the
MEASure:SOURce command or locally with the optional source parameter in each measure-
ment.
User-Defined
Measurements
When user-defined measurements are made, the defined parameters must be set before actu-
ally sending the measurement command or query.
Measurement
Error
If a measurement cannot be made because of the lack of data, because the source signal is
not displayed, the requested measurement is not possible (for example, a period measure-
ment on an FFT waveform), or for some other reason, 9.99999E+37 is returned as the mea-
surement result. In TDR mode with ohms specified, the returned value is 838MΩ. If
SENDvalid is ON, the error code is also returned.
Making
Measurements
If more than one period, edge, or pulse is displayed, time measurements are made on the
first, left-most portion of the displayed waveform. When any of the defined measurements
are requested, the analyzer first determines the top (100%) and base (0%) voltages of the
waveform. From this information, the analyzer determines the other important voltage values
(10%, 90%, and 50% voltage values) for making measurements. The 10% and 90% voltage