Operating Basics Monotonic Property
The TDSUSB2 application automates this process and automatically generates the results (see page 86)
and reports for the results of Chirp-K duration, Chirp-K amplitude, and Reset duration.
Monotonic Property
While performing a USB2.0 High Speed compliance test, you need to verify that the signal to b e tested is
monotonic.
The following graph shows the monotonic behavior of a USB2.0 high speed signal with a rise time
of 500 ps.
To verify the monotonic behavior of a signal, the oscilloscope must have a sample rate high enough to
capture as many sample points as possible on a rising or falling edge. In addition, the oscilloscope should
have enough bandwidth to ensure that the high frequency non-monotonic transition is not attenuated.
The application coupled with a high performance Tektronix oscilloscope automates the process and
ensures repeatability of test results.
Configuring a Measurement
To access the Configure: Measurement, go to Measurements> Configure. The application also provides a
Configure option with each measurement a rea to allow you to configure the selected measurements.
NOTE. If you select the Run button before configuring a measurement, the application displays the message
‘The selected measurements have not been configured. Do you want to continue?.’ In this case, the
application runs with the default settin
gs. If you select the Run button before configuring the measurement
and have enabled the File> Preferences> General option, the application displays the warning message
‘Warn if configuration was not changed since last run, when the run button is pressed.’
36 TDSUSB2 Universal Serial Bus Measurements Package
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