Abstract: A digital equalizer with a reduced number of multipliers for correction of the frequency responses of an interleaved ADC is disclosed. An exemplary interleaved analog to digital converter with digital equalization includes a composite ADC including M time interleaved sub-ADC, a demultiplexer, samples repositioning unit, a first PreFIRs transformer, a second PreFIRs transformer, K double buffer FIR filters, a PostFIRs transformer, a samples sequence restoration unit, and a multiplexer, coupled in series and providing an equalized, frequency response-corrected output.

Abstract: An interleaved analog to digital converter with digital equalization includes a conversion-measurement-equalization unit and residual distortions reduction unit, and is operative in a calibration mode and converter mode. The conversion-measurement-equalization unit includes a composite ADC containing N sub-ADCs, equalizer, responses measurement unit and a coefficients calculator. The residual distortions reduction unit uses received measured frequency responses and equalizer coefficients, both from the conversion-measurement-equalization unit, as a base to calculate corrected frequency responses that are applied to the coefficients calculator for generation of equalizer coefficients for application to the equalizer.

Abstract: A write clock generator for use in writing data to a rotating patterned magnetic media disk is disclosed. The generator includes a magnetic read head for generating a succession of servo signals representative of succession of servo magnetization patterns detected from a corresponding succession of arcuate sectors along a circular data track on the disk. A preamble processor generates a corresponding succession of sector pair signals representative of the lengths of adjacent sectors along the data track on a rolling pair-wise basis. A next sector length predictor processor determines for a succession of pairs of sectors, a length ratio of the lengths of the sectors in the respective pairs of sectors.

Abstract: A write clock generator for use in writing data to a rotating patterned magnetic media disk is disclosed. The generator includes a magnetic read head for generating a succession of servo signals representative of succession of servo magnetization patterns detected from a corresponding succession of arcuate sectors along a circular data track on the disk. A preamble processor generates a corresponding succession of sector pair signals representative of the lengths of adjacent sectors along the data track on a rolling pair-wise basis. A next sector length predictor processor determines for a succession of pairs of sectors, a length ratio of the lengths of the sectors in the respective pairs of sectors.

Abstract: A removable cartridge for magnetic head and disk testers is disclosed. The removable cartridge includes: a base plate; a first end of an actuator rigidly fixed to the base plate; an HGA mounting block rigidly fixed to a second end of the actuator; a first end of a flexure rigidly coupled to the HGA mounting block; and a second end of the flexure rigidly coupled to the base plate.

Abstract: A system and method are described for aligning a data axis of one or more circular data-bearing tracks on an annular surface region of a magnetic media-bearing disk, with a spin axis of a spindle of a spinstand or a disk drive. The data axis is perpendicular to the surface region of the disk and the data tracks are concentric with respect to a data axis.

Abstract: A system and method are described for aligning a data axis of one or more circular data-bearing tracks on an annular surface region of a magnetic media-bearing disk, with a spin axis of a spindle of a spinstand or a disk drive. The data axis is perpendicular to the surface region of the disk and the data tracks are concentric with respect to a data axis.

Abstract: A mechanism for placing and removing a vacuum clamping device for a magnetic disk on a spinstand, comprised of automated vertical and horizontal movement arranged such that a vacuum disk chuck, comprised of a base (9) and cap (6), can be used without operator interaction. Linear actuators provide the horizontal (2) and vertical (3) movement forces to accurately move a chuck cap (6) over a magnetic disk (7) that has been placed on a chuck base (9). The same actuators remove the cap and move it away from the disk to allow quick replacement of the disk. The interface between the mechanism and disk chuck cap is designed such that the cap is securely held during motion, and does not create particles.

Abstract: A headstack locator assembly for locating and fixing a headstack on a spinstand and which mitigates the aforementioned prior art limitations. The headstack locator assembly includes a headstack locator received on a fixed locator. The headstack locator connects to a headstack, while the fixed locator is permanently secured to a spinstand. A vacuum is used to clamp the headstack locator to the fixed locator for testing of the headstack. Upon test completion, the headstack locator is released from the fixed locator by applying positive air pressure to the assembly. More generally, an apparatus and methods for generally locating and reversibly, pneumatically coupling various elements to each other.

Abstract: A headstack locator assembly for locating and fixing a headstack on a spinstand and which mitigates the aforementioned prior art limitations. The headstack locator assembly includes a headstack locator received on a fixed locator. The headstack locator connects to a headstack, while the fixed locator is permanently secured to a spinstand. A vacuum is used to clamp the headstack locator to the fixed locator for testing of the headstack. Upon test completion, the headstack locator is released from the fixed locator by applying positive air pressure to the assembly.

Abstract: A vector signal generator with direct RF signal synthesis is disclosed. The vector signal generator comprises an RF signal synthesizer, a switch, and a memory. The RF signal synthesizer is configured for converting baseband IQ signals into a modulated digital RF signal. The RF signal synthesizer is connected to an I input, a Q input, a clock input, a control input, and an output, where the clock input is a clock input of the vector signal generator, the control input is a control input of the vector signal generator, and the output is an RF signal output of the vector signal generator. The switch is configured for selecting a source of IQ signals and is connected to an external I input, an external Q input, a stored signal I input, a stored signal Q input, the control input, an I output, and a Q output. The external I input and external Q input are external IQ inputs to the vector signal generator and the I output and the Q output are connected to the I input and the Q input of the RF signal synthesizer.

Abstract: Disclosed is a method of equalization of a vector/signal analyzer including: providing a structured test signal within a selected frequency range. The structured test signal includes a plurality of frequency components each having a respective amplitude and phase. The method includes inputting the test signal to the analyzer; the analyzer operating to condition the test signal; determining information representative of frequency distortion of the conditioned test signal introduced by the analyzer; generating a set of equalization coefficients based on the information representative of the frequency distortion, the set of coefficients corresponding to the selected frequency range; and storing the set of equalization coefficients and the correspondence of the set of coefficients to the selected frequency range.

Abstract: Disclosed is a method of measuring frequency distortions characteristics of a device under test, the device configured convert an input signal in an input frequency range to an output signal in a different output frequency range. The method includes, for each test frequency fi, where i=1, . . . , N and N a positive integer, in a selected frequency range, providing a corresponding test signal with multiple frequency components having a measurement component with a frequency fi, a first reference component with a frequency fA, and a second reference component with a frequency fB; inputting the test signals into the device under test; measuring output test signals at the output of the device under test corresponding to the input test signals; and determining, for each test frequency fi, information representative of frequency distortions based on the corresponding input test signal and the corresponding output test signal.

Abstract: A quasi-static tester is disclosed. The quasi static tester comprises: a mount configured to fix a head gimbal assembly in a given position; a camera configured to observe the head gimbal assembly when the head gimbal assembly is fixed in the mount, wherein the camera is used to position the head gimbal assembly in an observation position; and a magnet for performing quasi-static testing of the head gimbal assembly when the head gimbal assembly is fixed in the mount, wherein the observation position and a testing position in a uniform area of the magnet are a predetermined distance apart.

Abstract: A headstack locator assembly for locating and fixing a headstack on a spinstand and which mitigates the aforementioned prior art limitations. The headstack locator assembly includes a headstack locator received on a fixed locator. The headstack locator connects to a headstack, while the fixed locator is permanently secured to a spinstand. A vacuum is used to clamp the headstack locator to the fixed locator for testing of the headstack. Upon test completion, the headstack locator is released from the fixed locator by applying positive air pressure to the assembly.

Abstract: Time variant interleaving equalization of an interleaved analog to digital converter is disclosed. A high-frequency analog input signal is converted into a plurality of individual digital signals using a plurality of interleaved analog-to-digital converters. the plurality of individual digital signals are interleaved into a composite digital signal. The composite digital signal is processed in a time variant interleaving equalizer using a plurality of sets of equalizer coefficients.

Abstract: A periodic signal is sampled. The sampling frequency is less than the Nyquist rate of the periodic signal. A period of the periodic signal is determined. A phase of the periodic signal is tracked to determine a sample's position on the period of the periodic signal. A replica of the periodic signal is reconstructed. A measurement of the periodic signal is determined based on a measurement of the replica of the periodic signal.

Abstract: A spinstand having a vacuum chuck clamping mechanism for securing magnetic discs includes a cap (9) and a base (10). A disk-to-be-clamped is held between the cap (9) and the base (10). Vacuum, applied through a port (4) in a mounting screw (12) of the base, provides the clamping force. The vacuum is held constant using a circumferential seal (27) on a piston (2) of the cap, which extends into a cylindrical countering bushing (3) extending from the base. In one form, the cap (9) is centered about a spin axis (SA) extending through the base (10), using a hardened pin (1) extending from the cap and a locating bushing (19) affixed to the base. When the cap (9) is inserted into the base (10), the pin (1) prevents a piston (2) in the cap from contacting the inside walls/sealing surface (11) of the centering bushing (3) of the base.

Abstract: Analysis of a read back signal in a magnetic recording device is disclosed. The read back signal is converted to a digital read back signal, and a low frequency component of the digital read back signal is restored. A sample clock is recovered from the restored digital read back signal, and the restored digital read back signal is averaged using the recovered sample clock. A timing error is calculated based at least in part on the averaged restored digital read back signal.

Abstract: A constrained layer damping assembly for a rigid base member having a substantially planar surface comprises a gas impervious damping layer disposed on the substantially planar surface of the base member, and a load element disposed on the damping layer. The damping layer defines at least one void region extending between the planar surface and the load element, and the load element defines at least one channel for coupling a low pressure to the void region relative to the pressure external to the constrained layer damping assembly to establish a pressure differential between the inside of the void region and the outside of the constrained layer damping assembly. The pressure differential keeps the damping layer under compression and secures the load element and the damping layer onto the base member.