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Reference
3–22
WFM 601A, WFM 601E & WFM 601M User Manual
This section describes how to measure parameters of the Eye pattern to verify
standard signal specifications for serial digital transmission. The measurements
discussed here are amplitude, aberrations, rise time, and jitter. Figure 3–20
illustrates the initial equipment connections.
Waveform Monitor
(rear panel)
Serial source
SER A
Loop-through input
Output
75 W terminator
Figure 3–20: Connections for measuring a serial source
Setup for Measurements. Perform the following steps in preparation for the Eye
pattern measurements. Figure 3–20 illustrates the equipment connections.
1. Connect the serial source to the monitor with a 75 W cable two meters or less
in length. Use high quality, low loss coaxial cable, such as Belden 8281.
2. Connect a 75 W terminator with at least 25 dB return loss to 300 MHz on the
other end of the loop-through input.
3. Set the serial source to output a 100% Color Bar signal.
4. Press the EYE/JITTER button to select the Eye Pattern display.
5. Press the GAIN MENU button and select 1X vertical gain.
6. Adjust the vertical position so the bottom of the waveform rests on the –.1 V
line.
Measuring Amplitude. Measuring the signal amplitude can help you determine if
the signal amplitude is too low due to cable losses or other system problems. This
procedure shows you how to measure the signal amplitude using both the
graticule and the Voltage Cursors. To measure the signal amplitude, follow these
steps:
1. Perform the initial settings for Eye measurements described on page 3–22.
2. Select the desired input channel (SER A or B).
Eye Pattern
Measurements