Teledyne LeCroy QPHY-ENET - Manual (Page 46)

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QPHY-ENET Operator’s Manual Rev G
100Base-TX Rise and Fall Time
The rise time of the MLT-3 signal is defined as the transition time from the baseline (0 V) to either the positive or
negative going peak, while the fall time is the time for the transition from either the positive or negative pulse to
the baseline. The times are measured from the 10 to 90 % levels. They are also measured for all transitions in the
waveform, and must be between 3 and 5 ns. In addition, all measured values for a given transmitter must be
within 0.5 ns of each other.
1. Apply power to the Device Under Test. An MLT3 signal trace should be displayed on the oscilloscope
screen at this point.
2. Select 100Base-TX in the “Select Standard” field.
3. Select Rise/Fall Measurements in the “Select Test” field.
4. Check Differential Data on 2 Channels.
5. Enter C2 in the Source for + Data field and C3 in the Source for - Data field.
6. Touch the Set Up and Start Test button to begin testing.
7. Parameters P1 through P7 display the results of this test. P1 and P2 give the rise and fall times for
positive-going pulses and P3 and P4 are the rise and fall times for negative-going pulses. Parameters P5
and P6 give the minimum and maximum rise/fall measurements and P7 gives the range between these
values.
8. The Average Result checkbox is grayed out in this mode, since averaging is not applicable to this
measurement.
Figure 34. 100Base-TX Rise and Fall Time