Temporal Deviation
Measurement of the horizontal displacement of signal transitions from their ideal positions reveals the stability of a high-speed data stream. This eye diagram jitter represents the sum of all timing uncertainties within a transmission channel. Deterministic components arise from bandwidth limitations or crosstalk, while random components stem from thermal noise.
A wide opening in the center of the display indicates a clean signal with minimal timing error. High-speed serial links rely on this metric to ensure data arrives within the required setup and hold times.
Performance Margin
Bit error rates increase as the horizontal closure of the eye reduces the available sampling window. When eye diagram jitter exceeds the receiver’s tolerance, the clock recovery circuit fails to lock onto the incoming data. This condition forces retransmissions and reduces the effective throughput of the link.
System designers use these plots to evaluate the impact of termination schemes and PCB trace lengths.
Analysis Method
Oscilloscopes overlay multiple cycles of a waveform to build the visual representation of signal quality. Analysis software separates eye diagram jitter into periodic and bounded uncorrelated components. These specific measurements allow technicians to isolate noise sources within the power distribution network or the grounding structure.
Accurate characterization requires a high-bandwidth probe and a stable reference clock.
