A clock module operates in conjunction with the generation of the bus-clock signal to provide a combination of module-clocks that can be relied upon to provide an adequate safety margin for data transfers among processing modules at the speed of the bus-clock. During a test procedure, a PAM4 transmitter is configured to repetitively transmit a PAM4 symbol test pattern, which is captured as a signal waveform. The imaging can be performed utilizing low-energy beam techniques such as scanning electron microscopy; however, more sophisticated imaging techniques can also be employed. The minimization can take the form of a least-squares minimization.