Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data clocking
Patent
1994-11-14
1997-09-16
Psitos, Aristotelis
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data clocking
360 7708, G11B 509
Patent
active
056686781
ABSTRACT:
A discrete time servo demodulation technique incorporated within a sampled amplitude read channel to demodulate embedded servo field information stored on a magnetic medium. The servo field information is transduced by a read head into an analog signal, and converted to a sequence of sample values in the read channel. The demodulation technique is responsive to the sample values and includes a discrete time peak detector for detecting servo data, and a discrete time servo burst amplitude detector for measuring the amplitude of servo bursts. Peaks are detected in the analog read signal by sensing a change of slope from the sequence of sample values. The peaks are qualified by polarity in that a peak is detected only if its polarity is opposite in sign from the previous peak. The servo burst amplitudes are measured by interpolating, rectifying, and accumulating the sequence of sample values corresponding to the servo bursts. A plurality of registers store the amplitude measurement of corresponding servo bursts such as the four servo bursts in a quadrature system. The sample values are interpolated, squared, and the sampling frequency dithered in order to decrease the sensitivity of the burst amplitude measurement to variations in the sampling phase and to increase the effective resolution of the read channel ADC for servo demodulation. Control signals are generated in response to the detected servo data which are transferred to a servo controller over a fully digital interface, thus obviating the analog-to-digital converter found in conventional servo controllers.
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Beherns Richard T.
Bliss William G.
Reed David E.
Cirrus Logic Inc.
Psitos Aristotelis
Sheerin Howard
Wamsley Patrick
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