US Patent 11496282 Horizontal centering of sampling point using vertical vernier

Methods and systems are described for measuring a vertical opening of a signal eye of a pulse amplitude modulated (PAM) signal received over a channel to determine a vertically-centered voltage decision threshold of a sampler receiving a sampling clock, determining channel-characteristic parameters indicative of a frequency response of the channel, determining a correctional vernier value from the channel-characteristic parameters, and generating a horizontally-centered voltage decision threshold that introduces a horizontal sampling offset in the sampling clock in a direction closer to a horizontal center of the signal eye by combining the vertically-centered voltage decision threshold and the correctional vernier value.