Experimental error rates in a PRML channel versus asymmetry

Summary form only given. One of the most obvious distortions produced by a magnetoresistive transducer is the polarity-dependent asymmetry in its readback signal. The effects of these transfer-curve distortions on the error rate were determined experimentally using a single head and disk to minimize any confounding effects due to other normal head-to-head variations such as sensitivity and resolution. The distortion was varied by changing the bias current from 3.0 mA to 6.0 mA and by applying /spl plusmn/100 Oe external magnetic fields to produce a /spl plusmn/40% range of amplitude asymmetries. The recorded channel bit density was varied from 1.8 to 3.3 by changing the linear density from 240 kbpi to 440 kbpi, and the complex data patterns were decoded using an IBM PRML channel operating at a channel clock rate of about 280 Mbits/sec.