Abstract
The recording performance of a new prototype magnetic tape based on
perpendicularly oriented strontium ferrite particles is investigated
using a 29 nm wide tunneling magnetoresistive reader. At a linear
density of 702 kbpi, a post-detection byte-error rate of 2.8e-2 is
demonstrated based on measured recording data and a software read
channel. The read channel uses a 64-state implementation of an extended
version of a data-dependent noise-predictive maximum-likelihood
detection scheme that tracks the first and second order statistics of
the data-dependent noise. At the demonstrated post-detection byte-error
rate, a post-error-correction-coding byte-error rate of less than 1e-20
can be achieved using an iterative decoding architecture. To facilitate
aggressive track-density scaling, we made multiple advances in the area
of track following. First, we developed a new timing-based servo pattern
and implemented a novel quad channel averaging scheme. Second, we
developed a new field programmable gate array prototyping platform to
enable the implementation of quad channel averaging. Third, we enhanced
our low disturbance tape transport with a pair of 20 mm diameter air
bearing tape guides and a prototype track-following actuator. Fourth, we
developed a novel low friction tape head and finally, we designed a set
of tape speed optimized track-following controllers using the
model-based H∞ design framework. Combining these
technologies, we achieved a position error signal (PES) characterized by
a standard deviation ≤ 3.18 nm over a tape speed range of 1.2 to 4.1
m/s. This magnitude of PES in combination with a 29 nm wide reader
enables reliable recording at a track width of 56.2 nm corresponding to
a track density of 451.9 ktpi, for an equivalent areal density of 317.3
Gb/in2.