OmniTek OTR 1001, Руководство пользователя

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OmniTek OTR 1001 User Guide, v3.1 M-12
Rise and Fall Times
Rise and Fall Times measure the time taken to rise/fall between the 20% and 80% signal levels.
Markers on the screen indicate these signal levels.
Control Panel Mouse & Keyboard
To measure the Rise time:
1. Use the Properties control to display both the Time Cursors and the Voltage Cursors (needed
in order to display the 20% and 80% level markers).
2. Position one Time cursor where the 20% level marker crosses a rising trace and position the
other Time cursor where the 80% level marker crosses the same rising part of the trace.
3. The rise time is given by the dx value quoted in the top right corner of the screen.
Similar steps are used to measure the Fall time, positioning one cursor where the 80% level
marker crosses a falling trace and the other where the 20% level marker crosses the same falling
part of the trace.
Overshoot/Undershoot
Control Panel Mouse & Keyboard
To obtain a measure of the degree of overshoot:
1. Use the Properties control to display the Voltage Cursors.
2. Position one cursor in line with the peak of any overshoot.
3. Position the other cursor in line with the bottom of any ringing etc. associated with the upper
signal line. The difference between the cursors is the ‘thickness’ of the upper signal line.
4. The overshoot is given by the dy reading.
Similar steps may be used to measure undershoot by using the cursors to determine the thickness
of the lower signal line.
Transmission Integrity
A measure of whether the signal can be expected to be correctly interpreted at the receiver is
given by the degree to which the eye of the diagram appears open.
In making this assessment, the user will typically judge the height and width of the eye at a
‘Decision point’ approximately half-way across the eye.
There are, however, no hard and fast measures that can be applied. Determining the
characteristics of the Eye diagram at the point at which reception stops being sufficiently error
free is a matter of experience.