In telecommunication, an eye pattern, also known as an eye diagram, is an oscilloscope display in which a digital signal from a receiver is repetitively sampled and applied to the vertical input, while the data rate is used to trigger the horizontal sweep. It is so called because, for several types of coding, the pattern looks like a series of eyes between a pair of rails. It is a tool for the evaluation of the combined effects of channel noise and intersymbol interference on the performance of a baseband pulse-transmission system. It is the synchronised superposition of all possible realisations of the signal of interest viewed within a particular signaling interval.

1. Eye diagram

2. Then define it….
 The eye diagram is a technique to view the time waveforms out of the
matched filter.
 The eye diagram is a repetitive plot of the matched filter output
either I (real) or Q (imaginary) channel over one symbol in time of
the stream modulation.
 With eye diagrams you can see signal quality with one display, you
can diagnose problems, such as attenuation, noise, jitter, and
dispersion that arise or characterize specific parts of the system.

3. Jitter and drift
 Jitter is the deviation from ideal timing of an event, and is
typically measured from the zero crossing of a reference signal.
 Clock drift occurs when the transmitter’s clock period is slightly
different from that of the receiver. After many clock cycles
these difference becomes noticeable and causes loss of
synchronization and signal errors.

6. A – Eye rise time
B – Eye fall time
C – Maximum overshoot
D – Noise margin
E – Jitter
F – Optimal sampling time

7. Closure
point

8. Logic level
“High” or “1”
Logic level
“Low” or “0”

9. PAM2 ( 1 bit data)
PAM4 (4 bit data)

10. Steps involved in calculating eye
diagram

11. IMPORTANT terms
 EYE AMPLITUDE
 EYE HEIGHT
 EYE LEVEL
 QUALITY FACTOR
 JITTER
 EYE WIDTH
 EYE RISE TIME
 EYE FALL TIME
 EYE CLOSURE

12. Thank you….