HP 37717C Calibration Manual page 198

Performance Tests
STM-1 Transmitter Output Waveshape (Options US1, [US5], A1T, [A1U],
A3R [A3S], 120)
Figure 3-38
STM-1 All Zeros Mask
11. Select STM-1 TEST PATTERN [OFF] on the OTHER DEBUG FUNCTION
display.
12. Select PATTERN [2^23-1] on the display.
TRANSMIT
13. Adjust the Oscilloscope controls to display the eye diagram as shown in Figure
3-39, STM-1 Eye Diagram Example. Check that the waveform meets the STM-1 eye
diagram mask. It may be necessary to adjust the V/div gain on the Oscilloscope.
3-89