On-chip at-speed eye measurements of digitized signals in data and timing recovery circuits are disclosed. Eye diagrams and jitter measurements are used to evaluate signal quality and bath-tub Bit Error Rate characteristics in baseband communication systems. This disclosure describes a method and apparatus for digitally sampling a received signal at speed to produce an eye diagram of the received signal. This involves adding a small amount of circuitry to the existing prior art systems that use an interpolator for timing recovery and data recovery. In the present disclosure a temporary offset is applied to the interpolation index of the interpolator to obtain interpolated samples between the baud center and baud edge. The eye diagram can be produced from the received digitized and interpolated signal before equalization, or alternatively from the equalized signal.