Servo data decoder for any amplitude dependent servo data encoding scheme

A decoder for servo data encoded with any amplitude dependent servo data encoding scheme comprising:

• means for creating one or more timing windows synchronized to appear at the same predetermined times in every frame of servo data and to sample the amplitudes of one or more servo data pulses which occur during said timing windows and to generate one or more position error signals from the amplitudes so sampled;
• and
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• wherein said means for creating timing windows includes a phase locked loop and means for synchronizing the frequency of said phase locked loop which defines the times of occurrence of said timing windows with the occurrence of synchronizing pulses encoded in said servo data;
• and further comprising:
• means for allowing the user to synchronize the frequency of said phase locked loop with a signal supplied by the user and not embedded in said servo data.

A decoder for servo data encoded with any amplitude dependent servo data encoding scheme comprising:

• means for creating one or more timing windows synchronized to appear at the same predetermined times in every frame of servo data and to sample the amplitudes of one or more servo data pulses which occur during said timing windows and to generate one or more position error signals from the amplitudes so sampled;
• and
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• wherein said means for creating timing windows includes a phase locked loop and means for synchronizing the frequency of said phase locked loop which defines the times of occurrence of said timing windows with the occurrence of synchronizing pulses encoded in said servo data;
• and further comprising:
• means in said means for creating timing windows to allow a user to set the delay between the synchronization pulse and the occurrence of the first timing window.

A decoder for servo data encoded with any amplitude dependent servo data encoding scheme comprising:

• means for creating one or more timing windows synchronized to appear at the same predetermined times in every frame of servo data and to sample the amplitudes of one or more servo data pulses which occur during said timing windows and to generate one or more position error signals from the amplitudes so sampled;
• and
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• wherein said means for creating timing windows includes a phase locked loop and means for synchronizing the frequency of said phase locked loop which defines the times of occurrence of said timing windows with the occurrence of synchronizing pulses encoded in said servo data;
• means in said means for creating timing windows to allow a user to set the delay between the synchronization pulse and the occurrence of the first timing window;
• and
• further comprising means in said means for creating timing windows for allowing the user to set the duration of each timing window.

A decoder for servo data encoded with any amplitude dependent servo data encoding scheme comprising:

• means for creating one or more timing windows synchronized to appear at the same predetermined times in every frame of servo data and to sample the amplitudes of one or more servo data pulses which occur during said timing windows and to generate one or more position error signals from the amplitudes so sampled;
• and
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• wherein said means for creating timing windows includes a phase locked loop and means for synchronizing the frequency of said phase locked loop which defines the times of occurrence of said timing windows with the occurrence of synchronizing pulses encoded in said servo data;
• and further comprising:
• means in said means for creating one or more timing windows for allowing the user to cause said window generation to stop during periods when no valid servo data exists.

A decoder for servo data encoded with any amplitude dependent servo data encoding scheme comprising:

• means for creating one or more timing windows synchronized to appear at the same predetermined times in every frame of servo data and to sample the amplitudes of one or more servo data pulses which occur during said timing windows and to generate one or more position error signals from the amplitudes so sampled;
• and
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• wherein said means for creating timing windows includes a phase locked loop and means for synchronizing the frequency of said phase locked loop which defines the times of occurrence of said timing windows with the occurrence of synchronizing pulses encoded in said servo data;
• and further comprising:
• means coupled to said phase locked loop for allowing the user to alter the frequency response characteristics of said phase locked loop.

A decoder for servo data encoded with any amplitude dependent servo data encoding scheme comprising:

• means for creating one or more timing windows synchronized to appear at the same predetermined times in every frame of servo data and to sample the amplitudes of one or more servo data pulses which occur during said timing windows and to generate one or more position error signals from the amplitudes so sampled;
• and
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• and
• an input amplifier in said means for generating which amplifies the servo data arriving from the servo head, and means for allowing the user to control the gain of said input amplifier by supplying two signals a first of which controls the range of gain the amplifier is operating in and the second of which controls the actual gain within the range set by said first signal;
• means coupled to said input amplifier for allowing the user to filter the output of the input amplifier to remove noise picked up in circuitry coupled to the input of said input amplifier and noise generated in the amplifier;
• and further comprising:
• means coupled to said input amplifier for allowing the user to have access to the amplified servo data.

A decoder for servo data encoded with any amplitude dependent servo data encoding scheme comprising:

• means for creating one or more timing windows synchronized to appear at the same predetermined times in every frame of servo data and to sample the amplitudes of one or more servo data pulses which occur during said timing windows and to generate one or more position error signals from the amplitudes so sampled;
• and
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• and further comprising:
• means coupled to said means for processing said position error signals and to said means for creating one or more timing windows for allowing a user to apply a signal indicating whether the servo data to be decoded is quadrature or nonquadrature data and for causing the appropriate changes in processing by said means for creating and said means for processing.

A decoder for servo data encoded with any amplitude dependent servo data encoding scheme comprising:

• means for creating one or more timing windows synchronized to appear at the same predetermined times in every frame of servo data and to sample the amplitudes of one or more servo data pulses which occur during said timing windows and to generate one or more position error signals from the amplitudes so sampled;
• and
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• wherein said means for creating timing windows includes a phase locked loop and means for synchronizing the frequency of said phase locked loop which defines the times of occurrence of said timing windows with the occurrence of synchronizing pulses encoded in said servo data;
• and further comprising:
• means coupled to said phase locked loop for outputting a signal each time a synchronization signal from the recorded servo data is to appear and means coupled to said means for creating timing windows for providing access to the user to the synchronization pulse read from the servo data input such that the user can determine for each data frame in the servo data whether or not a synchronization pulse occurred for that servo data frame.

A decoder for servo data encoded with any amplitude dependent servo data encoding scheme comprising:

• means for creating one or more timing windows synchronized to appear at the same predetermined times in every frame of servo data and to sample the amplitudes of one or more servo data pulses which occur during said timing windows and to generate one or more position error signals from the amplitudes so sampled;
• and
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• wherein said means for creating timing windows includes a phase locked loop and means for synchronizing the frequency of said phase locked loop which defines the times of occurrence of said timing windows with the occurrence of synchronizing pulses encoded in said servo data;
• and further comprising:
• means coupled to said means for creating one or more timing windows for supplying to the user the high speed clock signal of the voltage controlled oscillator of said phase locked loop so that the user may use it for a write clock or for any other purpose.

A decoder for servo data encoded with any amplitude dependent servo data encoding scheme comprising:

• means for creating one or more timing windows synchronized to appear at the same predetermined times in every frame of servo data and to sample the amplitudes of one or more servo data pulses which occur during said timing windows and to generate one or more position error signals from the amplitudes so sampled;
• and
• means for processing said position error signals or signals to generate a gated position error signal having predetermined characteristics and a velocity and a track crossing signal therefrom;
• wherein said means for creating timing windows includes a phase locked loop and means for synchronizing the frequency of said phase locked loop which defines the times of occurrence of said timing windows with the occurrence of synchronizing pulses encoded in said servo data;
• and further comprising:
• means in said means for creating one or more timing windows for allowing said phase locked loop to be synchronized to either single or double pulse synchronization signals.

A servo data decoder for decoding servo data recorded on a media and for generating control signals to control a head positioning servo system comprised of:

• means for receiving servo data in any amplitude dependent servo encoding format and detecting peak amplitudes of pulses therein;
• a phase locked loop for generating a local clock signal;
• means coupled to receive said servo data and to process it to allow either recorded synchronizing pulses in said data to be separated from said data or a user defined input signal to be used to synchronize said phase locked loop;
• timing generator means to generate sample window timing signals from said local clock signal for use in sampling the output of said means for receiving and for allowing the user to define the delay between the synchronization pulse and the first sample window and the width of each sample window;
• sample means for sampling the peak amplitude stored by said means for receiving at each of a plurality of times and for generating at least one position error signal from said samples;
• means for receiving said position error signals and for generating a velocity signal to indicate head velocity, a gated position error signal to indicate head position error and a track crossing signal to indicate when the head is within a predetermined distance of a track center.

An apparatus for generating a gated position error signal, a velocity signal and a track crossing signal for a magnetic head passing over servo data recorded in frames of either the tri-bit or quadrature format on the magnetic surface of a magnetic media having data tracks comprising:

• means for detecting the peak amplitudes of analog pulses derived from said servo data;
• means for sampling and holding the amplitudes of said analog pulses and for generating a plurality of outputs indicating said amplitudes;
• means for subtracting the outputs of said means for sampling and holding to generate at least one position error signal;
• position error calculating means for receiving a first signal indicating whether tri-bit or quadrature servo data is recorded on said magnetic media and for receiving said position error signal and for receiving a reference voltage and a second control signal indicating whether the magnetic head is in a track following mode or a seek mode and for receiving a third control signal indicating the direction of travel of said magnetic head in nonquadrature format servo data, said position error calculating means for generating a gated position error signal for indicating the degree that said magnetic head is located away from a track centerline for a data track in the track following mode;
• velocity calculating means coupled to said position error calculating means and to said meanss for sampling and holding and coupled to receive said first signal, said velocity calculating means for generating a velocity signal;
• and
• track crossing calculation means coupled to receive said first signal and said position error signal for generating said track crossing signal.