Readback signal comparison between DSMR & SAL/MR heads

In this work, we present a comparison study of read-back signals between DSMR and SAL/MR heads. Using the reciprocity principle and the boundary-element method, we studied read-back signals, including voltage amplitudes, spectra and roll-off curves. Results show, if we allow the same temperature rise above ambient, the peak voltage produced by the DSMR head is about 1.4 to 2.0 times as large as that by the SAL/MR head. The high signal amplitude is attributed to the absence of current shunting and more magnetic flux entering the DSMR head. Results also show that both DSMR and SAL/MR heads have exactly the same characteristic behavior in square-wave spectra within normal application regime, although the spectrum of a DSMR head has a gap null at a very high linear density.