Patent ID: 7961831
Filing Date: 2011-06-14
Classification: H04L

Abstract:
1. An apparatus comprising: a primary sampler to receive an incoming signal and provide an output symbol corresponding to the incoming signal, the primary sampler controlled by a receiver clock generated from the incoming signal; a secondary sampler coupled to receive the incoming signal, the secondary sampler to generate a second symbol corresponding to the incoming signal, the secondary sampler clocked by a local clock independent of the receiver clock, wherein the local clock has a varying phase with regard to the receiver clock; a comparator coupled to receive the output symbol, the second symbol, the receiver clock and the local clock, the comparator to output an indication of whether the symbol and the second symbol are equal or different with respect to a predetermined number of clock cycles of the receiver clock or the local clock; an activity detector coupled to the comparator output to rectify the comparator output; and a duty cycle meter coupled to an output of the activity detector to provide a measurement of a horizontal eye opening of the incoming signal.