Time margin issues in disk drive testing

Issues in time margin analysis as an engineering tool and a method for the evaluation of disk drives are presented. Various test methods are described and contrasted. System characteristics which adversely affect peak timing are outlined. A unique test method is proposed to allow real-time differentiation of pattern-induced peak shifts. Consequences to the disk manufacturing industry are summarized. The advantage of time-domain testing over digital testing is demonstrated. With the use of a test instrumentation similar to the TSDA (time-domain spectrum analyzer) described, vital information relative to data margins, peak shifting, and error rates can be collected in relatively short amounts of time. This enables a more complete study and verification of drive R/W (read/write) channel designs and the characterization of the noise effects from heads and media