The N2100B PXIT Digital Communications Analyzer (DCA) implements a coherent patented vector under-sampling technique which combines the benefits and measurement capabilities of a real time scope with the bandwidth of a sampling scope. This PXI instrument uniquely combines the functionality of several traditional instruments in a single PXI module. The N2100B performs accurate eye diagram analysis to characterize the quality of transmitters from 155 Mb/s to 10.3125 Gb/s.