Patent application number | Description | Published |
20080253012 | MAGNETIC TAPE READ CHANNEL SIGNAL VALUES DEVELOPED EMPLOYING INTERMEDIATE BITS OF THE PATH MEMORY OF A PRML VITERBI DETECTOR - Magnetic tape read channel signal values are developed employing intermediate bits of the path memory of a PRML Viterbi detector. Identification logic identifies a most likely path memory state of the PRML Viterbi detector from the path metrics of the PRML Viterbi detector. An intermediate bit sequence of the identified most likely path memory state is obtained, the intermediate bit sequence extending from an initiation point of the path memory which is intermediate the output and the input of the PRML Viterbi detector. A sample value is determined which corresponds to the obtained intermediate bit sequence. | 10-16-2008 |
20080297937 | USING A MEASURED ERROR TO DETERMINE COEFFICIENTS TO PROVIDE TO AN EQUALIZER TO USE TO EQUALIZE AN INPUT SIGNAL - Provided are a read channel, storage drive and method using a measured error to determine coefficients to provide to an equalizer to use to equalize an input signal. A read channel is incorporated in a storage device to process signals read from a storage medium. An equalizer uses coefficients to equalize input read signals to produce equalizer output signals. A detector processes adjusted equalizer output signals to determine output values comprising data represented by the input read signals. An equalizer adaptor is enabled to provide a reference measured error and coefficients used to produce the adjusted equalizer signals that are associated with the reference measured error. The equalizer adaptor computes new equalizer coefficients to use to equalize input read signals that result in a new measured error from the detector and computes a new measured error for the new equalizer coefficients. The equalizer adaptor determines whether the new measured error is degraded with respect to the reference measured error and saves the new equalizer coefficients and the new measured error in response to determining that the new measured error is not degraded with respect to the reference measured error. The equalizer adaptor provides the equalizer coefficients associated with the reference measured error to the equalizer to use to equalize input read signals in response to determining that the new measured error is degraded with respect to the reference measured error. | 12-04-2008 |
20090097535 | MULTI-CHANNEL DATA DETECTION PHASE LOCKED LOOP ERROR COMBINATION LOGIC - Phase-error combination for a multi-channel data detection system with a phase locked loop for each channel, comprises receiving phase error information with respect to each channel; combination logic configured to combine the received phase error information and generate a combined phase error; and a phase-error output configured to apply the combined phase error to at least one channel phase locked loop. Additionally, error signal combination comprises receiving error information of a signal relevant to a phase locked loop with respect to each channel; combination logic configured to combine the received error signal information and generate a combined error signal, weighting the received error signal information from each channel, for example with reliability information. An error compensation output is configured to apply the combined, weighted error signal to at least one channel phase locked loop. | 04-16-2009 |
20090097536 | MULTI-CHANNEL DATA DETECTION PHASE LOCKED LOOP FREQUENCY ERROR COMBINATION LOGIC - Frequency error combination for a multi-channel data detection system with a phase locked loop for each channel, comprises receiving frequency error information with respect to each channel; combination logic configured to combine the received frequency error information and generate a combined phase error, weighting the received frequency error information from each channel; and a frequency error output configured to apply the combined frequency error to at least one channel phase locked loop. | 04-16-2009 |
20090097603 | COMMON STATE-SPACE MULTI-CHANNEL DIGITAL SAMPLE TIMING PHASE CONTROL OF MULTIPLE READ CHANNELS FOR CORRELATED SIGNALS - Common sample timing control for sample timing of multiple read channels, wherein the signal clocking of the signals received by the multiple read channels are correlated, for example from parallel tracks of magnetic tape that have been written simultaneously. In one embodiment, a common sample timing control comprises multiple phase error inputs, each indicating phase error of one of the read channels. Logic responsive to the multiple phase error inputs is configured to weight and crosscouple the phase error indication of each phase error input with the phase error indication of each other phase error input, and to apply gain related to the variance of noise of the phase error indications. Feedback logic is responsive to the crosscoupling and is configured to provide a sample timing phase estimate for each read channel. | 04-16-2009 |
20090097604 | METHODS FOR MULTI-CHANNEL DATA DETECTION PHASE LOCKED LOOP ERROR COMBINATION - Phase-error combination methods for a multi-channel data detection system with a phase locked loop for each channel, comprises receiving phase error information with respect to each channel; combining the received phase error information and generating a combined phase error; and applying the combined phase error to at least one channel phase locked loop. Error signal combination comprises receiving error information of a signal relevant to a phase locked loop with respect to each channel; combining the received error signal information and generating a combined error signal, weighting the received error signal information from each channel, for example with reliability information. The combined, weighted error signal is applied to at least one channel phase locked loop. | 04-16-2009 |
20090097606 | METHODS FOR MULTI-CHANNEL DATA DETECTION PHASE LOCKED LOOP FREQUENCY ERROR COMBINATION - Frequency error combination for a multi-channel data detection system with a phase locked loop for each channel, comprises receiving frequency error information of a signal relevant to a phase locked loop with respect to each channel; combining the received error signal information and generating a combined error signal, weighting the received error signal information from each channel, for example with reliability information. The combined frequency error signal is applied to at least one channel phase locked loop. | 04-16-2009 |
20090174964 | SERVO CHANNEL FOR TAPE DRIVE SYSTEMS - Provided are techniques for synchronous servo channel for a data tape drive. A servo reader is configured to read servo bursts from a data tape. An anti-aliasing filter is operable to output a bandlimited signal and is coupled to receive a servo channel signal comprising servo bursts from the servo reader. An analog-to-digital converter (ADC) is operable to output signal samples and is coupled to receive the bandlimited signal from the anti-aliasing filter. An interpolation and control unit is operable to output interpolated signal samples and control signals, has a first input coupled to receive the signal samples from the ADC, and has a second input coupled to receive the correlation signal samples from the dibit correlator. A dibit correlator is operable to output correlation signal samples and is coupled to receive the interpolated signal samples and control signals from the interpolation and control unit. | 07-09-2009 |
20090190250 | Robust LPOS Detection With Predictor and Bit Verifier - A tape drive system which includes the ability to reliably reproduce LPOS information even if both of the servo channels of the tape drive system could not detect the LPOS information due to defects. The system recognizes that an LPOS sequence is sequentially incremented by one if a tape is moving in a forward direction and decremented by one if the tape is moving in a backward direction. This sequential property of the LPOS information lends itself to LPOS prediction, where the LPOS prediction is the previous LPOS value plus one if the tape is moving forward and the previous LPOS value minus one if the tape is moving backward. Even if the LPOS words from the two servo channels are both bad, but not all of the bits in the LPOS word are bad. The system uses the remaining good bits from the two servo channels to verify all of the bits of the LPOS prediction word. | 07-30-2009 |
20090219645 | APPARATUS AND METHOD TO DECODE LINEAR POSITION INFORMATION ENCODED IN A SEQUENTIAL INFORMATION STORAGE MEDIUM - A method to decode linear position (“LPOS”) information encoded in a sequential information storage medium, by detecting each of one or a plurality of sequential first LPOS servo patterns encoded in a first servo band using a first servo sensor in communication with a first servo channel. While detecting that one or a plurality of first LPOS servo patterns, the method fails to detect (n) second LPOS servo patterns encoded in a second servo band. The method determines a value for (n), and then syncs the first servo channel with the second servo channel using that value of (n). | 09-03-2009 |
20090237832 | ERROR CORRECTION CODING OF LONGITUDINAL POSITION INFORMATION - A sequential data storage medium, comprising a sequence of plurality of servo patterns that provide lateral position information and longitudinal position information, wherein each of the plurality of servo patterns comprises a first burst comprising a first plurality of pulses, a second burst comprising a second plurality of pulses, a third burst comprising a third plurality of pulses, and a fourth burst comprising a fourth plurality of pulses. The spacings between the first plurality of pulses, in combination with the spacings between the second plurality of pulses, encode a first bit without affecting the recovery of lateral position information. The spacings between the third plurality of pulses, in combination with the spacings between the fourth plurality of pulses, encode a second bit without affecting the recovery of lateral position information. The sequence of plurality of servo patterns comprises a sequence of the first bits and a sequence of the second bits to form an error-correction codeword providing error-correction capability. | 09-24-2009 |
20100001772 | METHODS AND SYSTEMS FOR DELAY COMPENSATION IN GLOBAL PLL-BASED TIMING RECOVERY LOOPS - A system in one embodiment includes a global PLL circuit comprising multiple inputs, each input being for receiving an error signal associated with an individual channel; and a delay compensation circuit coupled to the global PLL circuit. A method in one embodiment includes receiving multiple error signals, each error signal being associated with an individual channel; applying one or more delay compensation signals to the error signals; and outputting phase error output signals for each of the channels. | 01-07-2010 |
20100073800 | RECOVERING SERVO INFORMATION FROM A SYNCHRONOUS SERVO CHANNEL - Provided are a method, servo channel, and tape drive for recovering servo information from a synchronous servo channel. An interpolator reads samples of a servo signal obtained from a servo reader at a rate of one servo sample per clock interval, to produce up to M interpolated servo samples per clock interval. A first buffer buffers interpolation time instants at which the interpolator generates interpolated servo samples. The interpolated servo samples are buffered in a second buffer and the interpolated servo samples are outputted from the second buffer to a correlator to produce correlation signal samples. | 03-25-2010 |
20100172047 | System, method, and computer program product for characterizing media associated with data storage channels - A system in one embodiment includes multiple analog inputs for receiving readback signals, an analog to digital converter coupled to each of the analog inputs for converting the readback signals to digital signals, a buffer coupled to outputs of the analog to digital converters for at least temporarily storing the digital signals, and a digital processing section also coupled to outputs of the analog to digital converters for processing the digital signals for reconstructing data therefrom. A method in one embodiment includes receiving multiple channels of analog readback signals from a magnetic head, converting the analog signals in each channel to digital signals, buffering the digital signals, and outputting the buffered digital signals. A method in another embodiment includes receiving a readback waveform from a magnetic storage device, reducing a frequency offset of the readback waveform, and generating a synchronized, oversampled waveform from the readback waveform. | 07-08-2010 |
20100176865 | GAIN CONTROL WITH MULTIPLE INTEGRATORS - A system according to one embodiment includes an analog input for receiving an analog signal; a variable gain amplifier coupled to the analog input; a first integrator coupled to the variable gain amplifier for controlling the gain of the analog signal; a second integrator generating control signals for controlling functions of the first integrator; a serializer for serializing the control signals; and a deserializer coupled to the serializer for deserializing the control signals and passing the deserialized control signals to the first integrator. | 07-15-2010 |
20100177423 | DUAL GAIN CONTROL FOR MAGNETIC DATA STORAGE SYSTEM - A system according to one embodiment includes an analog input for receiving an analog signal; a variable gain amplifier coupled to the analog input; a first gain control circuit coupled to the variable gain amplifier for controlling the gain of the analog signal; an analog to digital converter for converting the analog signal to a digital signal; a first gain error generation circuit for generating a first gain error signal based on an output of the analog to digital converter, the first gain error signal or derivative thereof being received by the first gain control circuit; and a second gain error generation circuit for generating a second gain error signal based on the digital signal, the second gain error signal or derivative thereof being received by the first gain control circuit, wherein the first gain control circuit uses at least one of the gain error signals to control the gain of the analog signals. | 07-15-2010 |
20100177427 | SYSTEM AND METHOD FOR GENERATING AN AMPLITUDE ERROR SIGNAL IN A MAGNETIC TAPE RECORDING CHANNEL - A method according to one embodiment includes generating a first gain error, comprising: receiving an output of an equalizer; and comparing a magnitude of the output to a saturation threshold level; if the output is higher than the saturation threshold level, generating a first gain error. The method further including generating at least one of a second and a third gain error, wherein generating the second gain error comprises: using either a slicer or a trellis for generating the second gain error, wherein the slicer generates a gain error based on an output of an interpolator, wherein the trellis generates a gain error based on an output of a maximum likelihood detector; wherein generating the third gain error comprises: receiving an output of an equalizer; generating a threshold qualified peak from the equalizer output and a tracking threshold level; comparing the threshold qualified peak to a second threshold; and generating a third gain error based on the comparison. | 07-15-2010 |
20100177436 | APPARATUS AND METHOD TO TRANSFER DATA TO AND FROM A SEQUENTIAL INFORMATION STORAGE MEDIUM - A sequential information storage medium, comprising a plurality of servo patterns encoded lengthwise thereon, wherein each servo pattern encodes at least one LPOS bit and comprises a width less than 187 microns. | 07-15-2010 |
20110007413 | CONTROL METHOD AND APPARATUS FOR A DUAL-CHANNEL WEIGHTED LPOS COMBINING SCHEME - A method for monitoring a plurality of servo channels, providing a finite state machine (“FSM”) comprising a single servo channel mode and a combined servo channel mode, and moving a sequential information storage medium comprising a plurality of servo bands across a read/write head comprising a corresponding plurality of servo sensors. The method further asserts an acquisition flag by a servo channel if that servo channel is tracking a servo pattern, and asserts a bit flag by a servo channel if a new LPOS bit is decoded. If at least one acquisition flag is asserted, the method determines if a bit flag is asserted by a servo channel associated with said asserted acquisition flag, and if an acquisition flag and a bit flag are asserted by a servo channel, the method determines a relative positioning of each servo sensor with respect to an associated servo pattern. | 01-13-2011 |
20110013312 | METHOD AND APPARATUS TO POSITION A HEAD MODULE COMPRISING SERVO ELEMENTS AND A PLURALITY OF DATA ELEMENTS - A method to position a head module, where the head module comprises at least one servo element and a plurality of data elements, where the servo element and each of the plurality of data elements can detect a servo signal, wherein the method includes moving a sequential information storage medium having a servo band encoded therein across the head module and detecting the servo band using the at least one servo element or any one of the plurality of data elements. | 01-20-2011 |
20110013313 | METHOD AND APPARATUS TO SET A WRAP ANGLE OF A READ/WRITE HEAD - A method is presented for setting a wrap angle of a read/write head having a servo element and multiple read elements, where the servo element and the read elements can detect a servo signal. The method includes moving a sequential information storage medium having a longitudinal axis and a servo band encoded therein adjacent to the read/write head. The longitudinal axis and a flat upper surface of the read write head define the wrap angle. The method further includes detecting the servo signal using one of the read elements. If the read element is unable to detect the servo signal, then the remaining read elements are sensed to detect the servo signal. | 01-20-2011 |
20110228424 | DUAL GAIN CONTROL FOR MAGNETIC DATA STORAGE SYSTEM - A system according to one embodiment includes an analog input for receiving an analog signal; a variable gain amplifier coupled to the analog input; a first gain control circuit coupled to the variable gain amplifier for controlling the gain of the analog signal; an analog to digital converter for converting the analog signal to a digital signal; a first gain error generation circuit for generating a first gain error signal based on an output of the analog to digital converter, the first gain error signal or derivative thereof being received by the first gain control circuit; and a second gain error generation circuit for generating a second gain error signal based on the digital signal, the second gain error signal or derivative thereof being received by the first gain control circuit, wherein the first gain control circuit uses at least one of the gain error signals to control the gain of the analog signal. | 09-22-2011 |
20120014010 | DETERMINING A REFERENCE WAVEFORM USED BY A CORRELATOR IN A SERVO CHANNEL - Provided are a method, servo channel, and tape drive for determining a reference waveform used by a correlator in a servo channel. Sequences of servo signal samples are provided from read servo signals read from a servo pattern on a recording medium. A determination is made of a reference waveform based on the sequences of servo signal samples and the reference waveform is forwarded. Interpolated servo signals are generated. The interpolated servo signal samples and the forwarded reference waveform are received to generate correlation output samples. Position and velocity information are calculated from the correlation output samples. | 01-19-2012 |
20120126876 | GAIN CONTROL WITH MULTIPLE INTEGRATORS - A method according to one embodiment includes receiving an increment signal at a first integrator when a second integrator overflows; receiving a decrement signal at the first integrator when the second integrator underflows; and incrementing or decrementing a gain applied to an analog signal based on receipt of the increment or decrement signal. A system according to one embodiment includes a first integrator configured to cause incrementing of a gain applied to an analog signal based on receipt of an increment signal when a second integrator overflows, the first integrator being configured to cause decrementing of the gain applied to the analog signal based on receipt of a decrement signal when the second integrator underflows; and the second integrator. | 05-24-2012 |
20120200952 | Apparatus and Method to Transfer Data to and from a Sequential Information Storage Medium - A sequential information storage medium, comprising a plurality of servo patterns encoded lengthwise thereon, wherein each servo pattern encodes at least one LPOS bit and comprises a width less than 187 microns. | 08-09-2012 |
20120212852 | DETERMINING A REFERENCE WAVEFORM USED BY A CORRELATOR IN A SERVO CHANNEL - Provided are a method, servo channel, and tape drive for determining a reference waveform used by a correlator in a servo channel. Sequences of servo signal samples are provided from read servo signals read from a servo pattern on a recording medium. A determination is made of a reference waveform based on the sequences of servo signal samples and the reference waveform is forwarded. Interpolated servo signals are generated. The interpolated servo signal samples and the forwarded reference waveform are received to generate correlation output samples. Position and velocity information are calculated from the correlation output samples. | 08-23-2012 |
20120212853 | Method and Apparatus to Position a Head Module Comprising Servo Elements and Plurality of Data Elements - A method to position a head module, where the head module comprises at least one servo element and a plurality of data elements, where the servo element and each of the plurality of data elements can detect a servo signal, wherein the method includes moving a sequential information storage medium having a servo band encoded therein across the head module and detecting the servo band using the at least one servo element or any one of the plurality of data elements. | 08-23-2012 |