Fast eye diagram analyzer uses nearest neighbor transverse to quickly discover basic eye diagrams

Abstract

The time needed to perform an eye diagram measurement is minimized by initially randomly investigating the (X, Y) that lie on a “starting” line crossing the sample space and expected to intersect any eye diagram. This finds a location on the eye diagram. Then the eye diagram is traversed as it is discovered by investigating nearest neighbors of locations found to belong to the eye diagram. Two arrays E and L of bits are established. The bits of E represent “eligible” (X, Y) , while those of L represent “likely” (X, Y) . At the very start of the measurement all bits in the eligible array E are set and all those in the likely array L are cleared, except that the starting line is established by setting in L and clearing in E locations for the corresponding (X, Y) . Thereafter, locations in L that have 1s are measured in a randomly selected order. The presence or absence of activity is duly recorded by the conventional data collection mechanism for use in the resulting eye diagram, and the measured location is then deleted from L by setting the corresponding bit to 0. However, if there was some activity, the nearest neighbors for that (X, Y) are promoted from E to L. Promotion means that the corresponding bits are cleared in E and set in L. When no further set bits remain in L, promote from E to L any remaining locations in E on the horizontal rows corresponding the maximum and minimum voltages thus far discovered for the signal. After that the measurement can stop when no further set bit remain in L, or, if desired, any remaining (i.e., unmeasured) locations identified by E can subsequently be measured by promoting them to L.