Method and apparatus for measuring error rate of magnetic recording devices having a partial response maximum likelihood data detection channel

摘要

A method for measuring the error rate of a magnetic recording device, such as a hard disk storing a set of data. The device has a partial response maximum likelihood data detecting channel (PRML channel) which differs from a conventional PRML channel by including a margin separator (58) which is connected between the output of A/D converter (54) and the input of a sequence detector (60). The system may contain a error counter (70) and data recovery units (66 and 68). The method consists mainly of changing the noise level in the samples received from the output of the A/D converter (54) and then counting the errors, and determining a dependence of a number of errors on a preselected criterion which characterizes a signal-to-noise ratio of the PRML channel. The above dependence can be extrapolated for an actual error rate of the channel being tested.