Learning-Type Notch Filter for Magnetic Tape Tracking Servo
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Solution Overview
Problem
Current magnetic tape recording systems face challenges in maintaining accurate tracking of reduced recording track widths, leading to increased errors due to lateral motion, with existing servo systems struggling to effectively remove periodic and narrow-band noise, which affects data recording and reproduction accuracy.
Innovation Solution
A servo signal recording apparatus that employs a learning-type optimum notch filter control system, utilizing a servo signal reproduction unit, frequency conversion unit, and filter value generation unit to generate filter values that remove periodic noise components from position error signals, enabling precise tracking and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the recording track width is reduced to increase lateral recording density, then the recording capacity is improved, but the magnetic head cannot accurately follow the recording track due to lateral motion, causing increased errors
Solution Approach 1:
The patent implements a feedback-based servo control system that continuously reads servo signals from the magnetic tape, calculates position error signals (PES) to determine head deviation from the recording track, and adjusts the head position in real-time to maintain accurate tracking despite lateral tape motion. This closed-loop feedback mechanism enables reliable tracking even with reduced track widths.
2Device complexity
If conventional servo systems are used with reduced track widths, then the system structure is simple, but periodic and narrow-band noise cannot be effectively removed, affecting data recording and reproduction accuracy
Solution Approach 1:
The patent introduces an intermediary notch filter between the servo signal reading process and the position error signal generation. This filter specifically targets and removes periodic and narrow-band noise components from the servo signal before processing, thereby improving PES accuracy without significantly complicating the overall servo system structure.
Solution Approach 2:
The patent employs a learning-type optimum notch filter that dynamically adjusts its filter parameters (center frequency, bandwidth) based on the spectral characteristics of the periodic noise present in the system. By adapting the filter parameters to match the actual noise conditions, the system achieves effective noise removal while maintaining simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system allows for high-speed and high-precision tracking of reduced recording tracks by removing periodic and narrow-band noise, thereby reducing position error signals and enhancing data recording and reproduction accuracy.
Implementation Method 1
a frequency conversion unit that generates frequency component information by applying a Fourier transform to a position error signal generated from the servo signal reproduced by the servo signal reproduction unit
Implementation Method 2
a filter value generation unit that generates a filter value based on the frequency component information generated by the frequency conversion unit, wherein the filter value generation unit generates a filter value that enables removal of a periodic noise component included in the frequency component information
Data Source
AI summary
In the apparatus and method of the invention, a servo signal reproduction unit generates a PES from a servo signal reproduced from a magnetic tape, and a frequency conversion unit performs FFT processing of the PES to generate frequency component information. Then, a filter value generation unit generates filter values based on the frequency component information and writes these to a memory. When recording various data signals to the magnetic tape, the filter values are read from the memory and a control filter serving as a notch filter is incorporated into a feedback control for a tracking servo. This enables periodic and narrow-band noise to be removed from a PES, consequently reducing PESs. Accordingly, learning-type optimum notch filter control that allows a magnetic head to follow recording tracks at high speed and with high precision is possible even when the recording track width is reduced and the tape speed is increased.