Viswanath Annampedu

Adaptive algorithms for asynchronous detection of coded servo signals based on interpolation

This paper presents the use of asynchronous algorithms to improve the detection performance of a coded servo channel in the presence of radial phase incoherence. The paper compares the performance of a coded servo system with both the synchronous and asynchronous algorithms. Simulation results are presented under varying amounts of radial incoherence and frequency offset errors.

Asynchronous Maximum Likelihood (ML) Detection Of Servo Repeatable Run Out (RRO) Data

A servo sector contains a preamble, servo address mark (SAM), Gray data, burst demodulation fields, a DC erase section and then repeatable run out (RRO) field. The RRO field consists of a RRO address mark (RROAM, same for every sector) and RRO data. The servo controller processes the RRO field to compensate for effects such an off center spindle rotation. We discuss the detection reliability of the RRO field, not how it is used for RRO compensation. We (i) propose a maximum likelihood (ML)asynchronous detection technique for coded servo RRO data (ii) quantify the detection.

Reconfigurable approximate pattern matching architectures for nanotechnology

Approximate pattern matching is comparing an input pattern with a target pattern with a specified error tolerance. This ability to compensate for real-world sensor errors makes approximate pattern matching an ideal choice for a wide range of applications. This paper shows that two n-bit patterns may be matched with a single stage nanotechnology architecture using 2n+1 unit area resonant tunneling diodes (RTDs) and one RTD of 1.5 times the unit area. This architecture is reconfigurable for any target pattern and any error tolerance. We analyze current and power characteristics of the architecture and develop configurations to minimize the same. The robustness of the architecture to variations in device characteristics is also investigated.

Servo ontrack/seek detection based on coding and noise prediction

This paper demonstrates the use of distance enhancing codes to improve the detection performance of a servo channel. The paper compares the performance of two example codes with an uncoded servo system. Simulation results are presented and correlated to the calculated coding gains. It is also shown that noise prediction has the potential of further improving the servo detection performance. Finally, it is shown that servo coding can also improve the detection performance in the presence of radial phase incoherence during a servo seek.

Servo detection based on coding and noise prediction

In this work, we present simulation results demonstrating the coding gains calculation and the performance can be further increased by incorporating noise prediction.