METHOD AND APPARATUS FOR SIGNAL-EYE TRACKING IN DIGITAL TRANSMISSION SYSTEMS

摘要

METHOD AND APPARATUS FOR SIGNAL-EYE TRACKING IN DIGITAL TRANSMISSION SYSTEMS Signal-eye tracking is achieved by forming a sample at a regeneration sampling time (e,g., 404), a first sampling time (e.g., 401) and a second sampling time (e.g., 402). The first and second sampling times respectively precede and succeed the signal-eyes while each regeneration sampling time occurs within the signaleyes. The amplitude of each sample represents the amplitude of the digital signal at the sampling time relative to a reference level (e.g., 301,302 or 303) which passes through one of the signal-eyes. A first comparison signal is generated by comparing the amplitudes of the samples at the regeneration and adjacent first sampling times. Similarly, a second comparison signal is generated by comparing the amplitudes of the samples at the regeneration and adjacent second sampling times. The difference between the first and second comparison signal is then averaged to form an error signal. The error signal varies with movement of the signal-eyes relative to the regeneration sampling time. In one embodiment of the invention this error signal is used to align the regeneration sampling time with a predetermined position within the signal-eyes.