AN ALGORITHM FOR A REAL-TIME MEASUREMENT OF NONLINEAR TRANSITION SHIFT BY A TIME-DOMAIN CORRELATION-ANALYSIS

An algorithm has been developed for a real time measurement of the nonlinear transition shift in high areal density magnetic recording, by a time domain correlation analysis. By measuring SNR and a correlation coefficient of the time domain readback voltages, r[v(t), v(t + epsilon /2 + (M(1) - 1/2)T)], written by a pseudorandom sequence, we can determine the nonlinear transition shift in real time. This new algorithm not only simplifies data processing of the readback waveform, but also includes noise effects on the nonlinear transition shift measurement. This algorithm has been implemented by LeCroy Corporation into their 7200-A high-speed digital oscilloscope. The LeCroy oscilloscope measures the nonlinear transition shift in less than 100 ms utilizing this algorithm.