Areal-Density Capability Measurement Based on 747 Test in Magnetic Recording Systems
A method is presented for determining the areal density (AD) capability of a magnetic recording system based on a set of 747 tests taken over a range of linear densities. By fitting the measured results with a suitable functional form, we can readily predict off-track capability (OTC) at any combination of linear density and track density. Conversely, for a given OTC requirement, we can immediately find the maximum AD that can be reached and the bit aspect ratio required to achieve it. Our results also reveal the effect of skew angle on AD and match well with previous results for perpendicular magnetic recording.
Empirical Determination of Areal Density Capability
A method is presented for determining the practical areal density capability of a magnetoresistive head/disk design from two quick error rate measurements. The method is generally independent of write width and track pitch and facilitates the direct comparison of MR readers or disk media.
Selection of modulation code parameters for maximum lineal density
The relative performance capabilities for many known run-length-limited binary modulation codes useful in digital magnetic recording are placed in perspective. The criteria for grading is relative maximum achievable lineal recording density under conditions of quasi-optimal spectral shaping. The results are based upon a linear system analysis in which superposition is applicable in modeling saturation recording systems where the media is indeed fully saturated at the termination of each transition. The maximum relative achievable lineal density is shown in terms of code parameters for maximum theoretical information rate with run constraints. The results show which binary modulation code to select for maximal lineal density and how its performance compares with the maximum theoretically achievable for any binary modulation code.