User manual

Digital Interface Tester
4-117
AM700 Audio Measurement Set User Manual
sufficient for the receiver to clearly detect whether a high or a low logic level
occurs. This separation is the eye opening of the signals, so called because of it
eye-shaped pattern.
Above the eye diagram display is a real-time readout area showing measured
parameters of the digital signal. The information displayed in this area includes the
following:
H Main sampling frequency
H Reference sampling frequency (when a reference is supplied)
H Main to reference frequency ratio
H Peak-to-peak jitter of the digital signal
H Phase difference between the main and the reference sample clock
H Main channel level
H Main channel equalization
Use the AM700 eye diagram to check data signal parameters such as amplitude, rise
time, and jitter, and to identify signal distortions such as those caused by transmis-
sion line problems.
Long Cable Simulator. Figure 4-64 shows the effects of a long cable on the signal
added by the long cable simulator. The rise time increases and the zero crossing
width increases with the added jitter. Notice the change in measurement readouts
between a good signal and the degraded signal. When adding jitter from the
generator, the AM700 eye diagram remains locked to about 0.8 UI p-p of jitter. With
that much jitter, the eye pattern appearance is nearly all random data points as the
digital data edges constantly move at the applied jitter frequency and amplitude.