Seagate Technology Incorporated

Magnetic Peripherals Inc.

Larry J Koudele

Robert D Cronch

Stephen R Genheimer

A pulse qualification apparatus and method provides for qualifying signal pulses from a raw data signal by comparison to a variable qualification level. Pulse qualification is done on a read signal developed by moving a magnetic transducer relative to addressable portions of a magnetic disk. A qualification level generator circuit generates a qualification level signal which varies in value depending upon the addressed portion of the magnetic disk. A threshold detector is used in qualifying pulses from a transducer read signal by comparison to the qualification level signal to generate an encoded pulse signal representing occurrences of qualifying pulses.

Track dependent variable level qualification pulse detector

A raw data signal, of the type generated from magnetic storage systems, is qualified by detecting the highest peak after the raw data signal passes qualification thresholds. This peak is used to indicate the true data pulse location. The location of the highest peak after the raw data signal has passed a minimum qualification threshold may be detected using a transistor circuit for charging a capacitor connected to a comparator or through a tri-level qualification scheme. Using tri-level qualification, a set of comparators and flip flops are used to locate raw data signal peaks.

Qualification for pulse detecting in a magnetic media data storage system

A circuit for phase locking a clock signal to a series of data pulses includes a wide band signal generator, a power supply, a flip-flop, a loop filter and a voltage controlled oscillator ('VCO'). The circuit adds current or subtracts current from the loop filter which controls the voltage across the VCO. The voltage across the VCO determines the frequency of the clock signal which it outputs. During the PLO sync zone, the circuit adds or subtracts increased amounts of current from the loop filter during every other pulse to cause greater amounts of correction in the frequency of the clock signal during every other pulse. The wide band signal generator, which includes a component which decays over time, operates only during the PLO sync zone. The circuit uses a flip-flop triggered by each data pulse to either send the current from the wide band signal generator to ground or add it to the constant current level produced by the power supply.

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Louisville, CO, United States of America

Larry J Koudele