Tektronix OI1125, Instruction Manual

Page: 19 / 88

Getting Started
OI1125 E/O Transmitter Instruction Manual
7
To display an eye pattern, do the following:
1. Connect the test setup as shown in Figure 2, and power on the equipment.
2. Set the BERT bit rate to 9.953280 Gb/s.
3. Set the pattern to PRBS–31.
4. Disable the adjustable duty cycle.
5. Set the mark ratio to 1/2.
6. Set the trigger to 1/32 clock.
7. Set the output mode to AC.
8. Turn the data output on and set the data amplitude to 1.0 V
p–p
.
9. Enable the transmitter laser by turning the keyswitch clockwise (to the
unlocked position). The Laser On LED and Laser Output Active LED light.
10. On the oscilloscope, press Autoset, and then adjust the horizontal scale to
display an optical eye pattern (see Figure 3).
The oscilloscope displays an optical eye pattern as shown in Figure 3, indicating
that the transmitter is functioning correctly. The internal laser source, coupled to
the laser input port, is being modulated by the electrical data stream from the
BERT. The modulated optical output signal is displayed on the oscilloscope.
W W
Figure 3: Oscilloscope display of an eye pattern
Displaying an Eye Pattern