Clocking method and apparatus for a storage medium
AssigneeXyratex Technology Limited
InventorsPaul H. R. Jolly, Paul A. Levin
Life of this patent
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Abstract
A clocking method and apparatus for a rotating storage medium uses a single reference frequency from which both the pattern frequency of a servo pattern signal and the rotational frequency of the storage medium are derived. During the servo track writing process, a clock track is read from the storage medium to obtain a clock signal having a clock frequency and the phase of the servo pattern signal is digitally adjusted relative to the clock signal so that the servo pattern signal is in phase with the clock signal.
Claims30
A method of writing a servo track to a storage medium having at least one clock track thereon which is used to control the phase of the servo track written to the storage medium, the method comprising the steps of:
- rotating a storage medium at a rotational frequency which is obtained from a reference frequency;
- obtaining a servo pattern signal having a pattern frequency from said reference frequency;
- reading a clock track from said storage medium to obtain a clock signal having a clock frequency;
- adjusting the phase of the servo pattern signal relative to the clock signal so that the servo pattern signal is in phase with the clock signal;
- and,
- writing a servo track in accordance with the servo pattern signal to the storage medium.
A method of writing a servo track to a storage medium having at least one clock track thereon which is used to control the phase of the servo track written to the storage medium, the method comprising the steps of:
- generating a servo pattern signal having a pattern frequency;
- and,
- reading a clock track from said storage medium to obtain a clock signal having a clock frequency;
- digitally adjusting the phase of the servo pattern signal relative to the clock signal so that the servo pattern signal is in phase with the clock signal;
- and,
- writing a servo track in accordance with the servo pattern signal to the storage medium.
A method of writing a servo track to a storage medium having at least one clock track thereon which is used to control the phase of the servo track written to the storage medium, the method comprising the steps of:
- generating a servo pattern signal having a pattern frequency from a reference signal by passing the reference signal to two amplifiers the outputs of which are separated or shifted in phase relative to each other and summing said outputs, the summed output being used to generate the servo pattern signal;
- reading a clock track from said storage medium to obtain a clock signal having a clock frequency;
- adjusting the phase of the servo pattern signal relative to the clock signal so that the servo pattern signal is in phase with the clock signal by adjusting the gain of at least one of the amplifiers;
- and,
- writing a servo track in accordance with the servo pattern signal to the storage medium.
Apparatus for writing a servo track to a storage medium having at least one clock track thereon which is used to control the phase of the servo track written to the storage medium, the apparatus comprising:
- a source of a reference signal having a reference frequency;
- a drive circuit arranged to cause rotation of the storage medium at a rotational frequency which is obtained from the reference frequency;
- a servo pattern signal generator arranged to receive the reference frequency and to output a servo pattern signal having a pattern frequency obtained from the reference frequency for use in writing a servo track on said storage medium;
- and,
- a phase adjuster for adjusting the phase of the servo pattern signal to be in phase with a clock signal obtained from a clock track on a said storage medium.
Apparatus for writing a servo track to a storage medium having at least one clock track thereon which is used to control the phase of the servo track written to the storage medium, the apparatus comprising:
- a servo pattern signal generator for generating a servo pattern signal having a pattern frequency;
- a clock track reader for reading a clock track from a storage medium to obtain a clock signal having a clock frequency;
- and,
- a digital phase adjuster for digitally adjusting the phase of a said servo pattern signal relative to a said clock signal so that a said servo pattern signal is in phase with a said clock signal.
Apparatus for writing a servo track to a storage medium having at least one clock track thereon which is used to control the phase of the servo track written to the storage medium, the apparatus comprising:
- a servo pattern signal generator comprising two amplifiers, a phase separator or shifter for separating or shifting the outputs of the amplifiers in phase relative to each other, and a summer for summing said phase separated outputs;
- a clock track reader for reading a clock track from said storage medium to obtain a clock signal having a clock frequency;
- and,
- a gain controller for adjusting the gain of at least one of the amplifiers thereby to adjust the phase of a said servo pattern signal relative to a said clock signal so that a said servo pattern signal is in phase with a said clock signal.
Dependencies are inferred from the claim text.