Apparatus and method are disclosed for constructing an eye pattern from a serial data signal within a receiver used in a serial data communication system. The receiver is used to receive the serial data signal and generates an internal clock signal from the serial data signal using, at least in part, a CDR circuit. Timing data corresponding to a current phase of the clock signal is also generated within the receiver using an interpolator circuit. The serial data signal is sampled by an ADC using the clock signal to generate sampled data. The sampled data and timing data are processed within the receiver by a data processor to generate the eye pattern. The resultant eye pattern may be analyzed within the receiver with respect to at least one characteristic of the eye pattern. At least one parameter of the receiver may be adjusted in response to the foregoing analysis.