Patent attributes
It is possible to know a guideline for adjusting the levels of three voltage thresholds of a PAM4 signal. An error detection device receives a measurement pattern including a pseudo random pattern having equal appearance frequencies of four levels, decodes the measurement pattern into a most significant bit sequence signal MSB and a least significant bit sequence signal LSB, based on three voltage thresholds Vth1, Vth2, and Vth3, identifies and counts, by a level counting unit, the four levels of the measurement pattern, based on the most significant bit sequence signal MSB and the least significant bit sequence signal LSB, and displays numerical values or bar graphs indicating ratios of the appearance frequencies of the four levels of the measurement pattern so as to be in the same order as waveform levels of the measurement pattern, based on a result of the counting.
