CA2143081C - Method of optimizing read channel of disk driving recording apparatus by using error rate - Google Patents
Method of optimizing read channel of disk driving recording apparatus by using error rateInfo
- Publication number
- CA2143081C CA2143081C CA002143081A CA2143081A CA2143081C CA 2143081 C CA2143081 C CA 2143081C CA 002143081 A CA002143081 A CA 002143081A CA 2143081 A CA2143081 A CA 2143081A CA 2143081 C CA2143081 C CA 2143081C
- Authority
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- Canada
- Prior art keywords
- error rate
- data detection
- disk
- data
- detection error
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
- G11B5/027—Analogue recording
- G11B5/035—Equalising
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/10009—Improvement or modification of read or write signals
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/18—Error detection or correction; Testing, e.g. of drop-outs
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/18—Error detection or correction; Testing, e.g. of drop-outs
- G11B20/1816—Testing
Abstract
The present invention relates to a disk drive recording apparatus and more particularly to a method for optimizing performance of a read channel in a disk drive recording apparatus by using an error rate. The method for optimizing performance of a read channel in a disk driving recording apparatus having a programmable low-pass filter and a control device for controlling apparatus operation includes the steps of initially assigning a filtering characteristic to the programmable low-pass filter as a predetermined initial bandwidth value via the control device; detecting and evaluating data written on a first predetermined track of a disk to calculate a first data detection error rate by the control device; comparing a reference error rate with the first data detection error rate; setting the filtering characteristic of the low-pass filter to a bandwidth indicating a lowest error rate by varying the bandwidth of the programmable low-pass filter when the first data detection error rate is greater than a reference error rate; thereafter, detecting data written on a second predetermined track of the disk to calculate a second data detection error rate by the control device; comparing the reference error rate with the second data detection error rate; outputting an error state signal indicating that the disk drive recording apparatus is in a poor state when the second data detection error rate is greater than the reference error rate; and setting a currently set bandwidth as a final set value and completing an optimization process when any one of the first and second data detection error rates is below the reference error rate.
Description
2 ~ ~ 3 0 8 1 ~
FIELD OF THE INVENTION
The present invention relates to a disk drive recording apparatus, and more particularly to a method for optimi7inp performance of a read channel in a disk drive recording apparatus by using an error rate.
BACKGROUND OF THE INVENTION
Data errors in a disk drive recording apparatus such as a hard disk drive are largely divided into "hard" errors caused by a disk defect and "soft" errors caused by a bit shift. Generally, hard errors are prevented by designating an error position as a bad sector in an initial step; however, since the error position can not be designated for soft errors, soft errors are regarded as an tmportant problem to be solved to ensure operational reliability for the disk drive rccording apparatus.
Another fundamental problem of the hard disk drive is its weakness for physical impact and shock. Head gimbals, which support a head, should be ~lexible so that the head is separated from the surface of a disk by a minute gap, which is m~in~ine(i as the disk rotates. Since the head gimbals are flexible, impacts or shocks upon the hard disk drive can cause errors when data is being read from the disk.
~8~
One invention aimed at re(1Ucin~ such errors is disclosed in U.S. Patent No.
5,327,302 entitled Data Filter Tu ung For Constan~ Density Recording A~7p1ic~rtiQns issued to Khour.,v et al. on S July 1994. In Khoury et al. '302, a tunable data filter is altered so that the filter cutoff frequency is su~s~ t;~lly proportional to a predetermined factor of an incoming data frequency, thereby creating a desired eye opening in the read data. While this invention has merit in its own respect, I believe it can be improved upon to even further reduce error rates of read data.
SUMMARY OF THE I~JVENTION
Accordingly, it is an object of the present invention to provide an improved disk drive recording apparatus and method.
It is another object to provide a method which variably optimi7es data dete~tingcharacteristics of a read channel in a disk drive recording apparatus in accordance with the characteristics of a disk and a head.
To achieve these and other objects, the present invention provides a method and apparatus for optimi7ing performance of a read ch~nnel in a disk driving recording apparatus having a programmable low-pass filter and a control device for controlling overall operation. The method includes the steps of initially ~Csigning a ~lltering characteristic to the programmable low-pass filter as a predetermined initial bandwidth value via the control device; detecting and evaluating data written on a first predetermined track of a disk to calculate a first data detection error rate via the control device; comparing a reference error rate with the first data detection error rate; setting the filtering characteristic of the low-pass filter to a bandwidth indicating a lowest error rate by varying the bandwidth of the programmable low-pass filter when the first data detection error rate is greater than a reference error rate; thcreafter, detecting data written on a second predetermined track of tfie disk to calculate a second data detection error rate via the control device; comparing the reference error rate with the second data detection error rate; outputting an error state signal indicating that the disk drive recording apparatus is in a poor state when the second data detection error ratc is greater than the reference error rate; and setting a currently set bandwidth as a final set value and completing an optimization process when any one of the first and second data detection error rates is below the reference error rate.
~1 BRIEF DESCRIPI'ION OF DRAWINGS
A more complete appreciation of this invention, and many of the ~ nC~nt advantages thereof, will be readily appar~nt as the sarne becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:
~IG. 1 is a block diagram showing construction of a read channel of read/write charmel portions of a representative hard disk drive;
FIG. 2 is a waveform diagrarn showing output states of each component in FIG.
1; and FIG. 3 is a flow chart showing a process according to the present invention for optimi7ing performance of a read channel of a disk drive recording apparatus by using an error rate.
DETAILED DESCRIPIION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a block diagram showing construction of a read channel of read/write channel portions of a representative hard disk drive. In F~G. 1, a head 20 outputs an analog signal induced from a disk 10. The analog signal is received, amplified and output at a given arnplification level by a pre-amplifier 30. A variable gain amplifier 40 (hereinafter, referred to as VGA) controls amplification gain in accordance with variation of the input signal level received from pre-amplifier 30, thereby maintaining a constant output level. A programmable low-pass filter and equalizer 50 (hereinafter, referred to as programmable LPF and equalizer) removes noise from the signal output from VGA 40, compensates for the output signal, and narrows the pulse width in accordance with an input representative of a predeterrnincd bandwidth and boost lcvcl.
2S A zero-crossing comparator 60 differentiates an input signal rcceivcd from programmable LPF and equalizer 50 and then outputs a differcntiatcd signal. A
hysteresis comparator 70 sets a signal threshold level and compares the signal threshold level with the level of the output signal received from programmable LPF and equalizer 50, thcreby outputting a compared result. A flip-flop 80 reccives outputs from zero-crossing comparator 60 and hysteresis comparator 70 and gencratcs one shot data. A
clock synthesizer 90 produces a reference clock pulse by receiving a predetermined external clock pulse. A data synchronizer 100 receives the one shot data output from ~43~81 flip-flop 80, and transmits the data and a clock window signal in synchronism with the reference clock pulse from clock syntheci7~r 90. A decoder 110 ~leco~s the data and clock window signal received from data synchroni~;er 100 and outputs the decoded data as no-return-to-zero NRZ data. A serial port 120 rec~,;v~s a signal representative of the predetermined bandwidth and boost level from a microprocessor 130, and then transmits the signal to plogla-.,mable LPF and equalizer 50. Microprocessor 130 controls the overall operation of the hard disk drive and outputs an initial bandwidth value and boost level data.
FIG. 2 is a waveform diagram illu~llaling output states of each c~lllponent in FIG. 1. An explanation of the operation of the read channel in the hard disk drive will hereinafter be given with reference to FIGs. 1 and 2.
-An electrical signal induced from a surface of disk 10 by head 20 typically has a weak voltage of about 250,uV. Differences in signal voltage may be generated depending upon a flying height between disk 10 and head 20, and the quality of disk 10 and head 20. Pre-amplifier 30 receives the signal from head 20, amplifies the signal, and outputs the signal at an amplification rate of about 300 times, as shown in waveform "A" of FIG. 2. In this case, however, since noise is also amplified, the output state of pre-amplifier 30 represents an unstable output waveform, such as portion "a" indicated in FIG. 2.
VGA 40 receives the output signal from pre-amplifier 30 and varies amplification gain in accordance with variations of the input signal level, as shown in portion "b" indicated in FIG. 2, to output a signal at a constant level.
Next, programmable LPF and equalizer 50 initially establishes the bandwidth and boost level according to data received from microprocessor 130 via serial port 120.
Programmable LPF and equ~li7l r 50 filters,'comperl~es and narrows the pulse width of the output signal from VGA 40, thereby producing a stabilized analog signal, as shown in waveform "B" of FIG. 2.
Zero-crossing comparator 60 differentiates the signal output from programmable LPF and equalizer 50 to generate a differentiated output signal, as shown in waveform "C" of FIG. 2. Hysteresis comparator 70, using a predetermined signal threshold level, compares the signal threshold level with the level of the signal output from programmable LPF and equ~li7er 50 to generate a co~ )ared result signal in which the peak of the signal output from progla."n~able LPF and equalizer 50 is det~te~3.
Flip-flop 80, which receives the differenti~ted output signal from zero-crossingcomparator 60 and the compared result signal from hysteresis comparator 70, generates digital signals in a pulse pattern, as shown in waveform "D" of F~G. 2. Data synchronizer 100 receives the digital signals and transmits the clock window signal and the digital signals in synchronization with the reference clock pulse from clocksynthesizer 90. Decoder 110 receives the clock window signal and digital signals from data synchronizer 100, decodes the signals and then generates the decoded signals as NRZ data.
When executing a data read operation with the hard disk drive, however, signal qualities are different from each other due to magnetic, electrical, and mechanical characteristics of disk 10 and head 20. As a result, soft data errors such as an extra pulse or a miCcing pulse may occur. A soft data error generated by an extra pulse is aKributable to general noises, while a soft data error generated by a micsin~ pulse is attributable to a bit shift. The general noises causing an extra pulse include white noise, head noise, electric current noise, voltage noise, damping resistance noise, disk noise, PCB noise, and pre-amplifier noise. Soft data errors generated by an extra pulse can be removed by using an error correction code.
Bit shifts often recult from peak shifts attributable to patterns and noise. Peak shifts attributable to noise can be remedied by adjusting the bandwidth of the low-pass filter. Peak shifts attributable to pattems resulting from mutual interference between adjacent signals can be remedied by compensating a signal using an equalizing circuit and narrowing the pulse width of the signal in ordcr to minimize mutual interference between adjacent signals.
As discussed above, peak shifts due to patterns can be remcdied by increasing a boost level, whereas peak shifts due to noise may be remedicd by an extension of the bandwidth of the low-pass filter. Hence, a trade-off is necessary between the boost level and the bandwidth of the low-pass filter. Furthemmore, since the quality of disk 10 and head 20 is variable to a large extent during the process, optimization of bandwidth of S
f~D~81 the low-pass filter and boost level of the eq~ i7in~ circuit is necessary for each disk arld head.
In co--venlional methods, however, bandwidth of the low-pass filter and boost level of the eq~ i7inE circuit are fixed. Therefore, each read channel can not be 5 utilized optimally to keep pace with the characteristic varia~ions of disk 10 and head 20;
accordingly, a rni.ccin~ pulse may occur during the data read operation.
One characteristic of a soft data error in a hard disk drive is that error generation probability varies in accordance with test conditions because of errors due to a bit shift, unlike hard errors due to a disk defect. Accordingly, in a prefcrred embodiment of the present invention, the error rate is checked while the test conditions are established to reflect a worst case scenerio. As a result, the bandwidth and boost level for optimi7in~ performance of the read channel are obtained, based upon the checked error rate.
In addition to error rate calculation methods for optimi7.ing perforrnance of the read channel, the preferred embodiment of the present invention uses a method for calculating a raw error rate for use as a judgement reference to ensure reliability.
Moreover, since an off-track read/write state changes according to the stabilityof the servo control system, the error rate is intended to be produced under a maximum off-track state.
FIG. 3 is a flow chart showing a process according to the present invention for optimi7in~ performance of a read channel of a disk drive recording apparatus by using an error rate. An operation of the preferred embodiment of the present invention will now be discussed with reference to FIG. 3 In step 301, microprocessor 130 outputs a default value for the bandwidth of thcread channel and the boost level previously established by a manufacturer in order to set programmable LPF and equalizer 50. To execute the above operation, microprocessor 130 sets the default value by providing data to programmable LPF and equalizer 50 via serial port 120.
FIELD OF THE INVENTION
The present invention relates to a disk drive recording apparatus, and more particularly to a method for optimi7inp performance of a read channel in a disk drive recording apparatus by using an error rate.
BACKGROUND OF THE INVENTION
Data errors in a disk drive recording apparatus such as a hard disk drive are largely divided into "hard" errors caused by a disk defect and "soft" errors caused by a bit shift. Generally, hard errors are prevented by designating an error position as a bad sector in an initial step; however, since the error position can not be designated for soft errors, soft errors are regarded as an tmportant problem to be solved to ensure operational reliability for the disk drive rccording apparatus.
Another fundamental problem of the hard disk drive is its weakness for physical impact and shock. Head gimbals, which support a head, should be ~lexible so that the head is separated from the surface of a disk by a minute gap, which is m~in~ine(i as the disk rotates. Since the head gimbals are flexible, impacts or shocks upon the hard disk drive can cause errors when data is being read from the disk.
~8~
One invention aimed at re(1Ucin~ such errors is disclosed in U.S. Patent No.
5,327,302 entitled Data Filter Tu ung For Constan~ Density Recording A~7p1ic~rtiQns issued to Khour.,v et al. on S July 1994. In Khoury et al. '302, a tunable data filter is altered so that the filter cutoff frequency is su~s~ t;~lly proportional to a predetermined factor of an incoming data frequency, thereby creating a desired eye opening in the read data. While this invention has merit in its own respect, I believe it can be improved upon to even further reduce error rates of read data.
SUMMARY OF THE I~JVENTION
Accordingly, it is an object of the present invention to provide an improved disk drive recording apparatus and method.
It is another object to provide a method which variably optimi7es data dete~tingcharacteristics of a read channel in a disk drive recording apparatus in accordance with the characteristics of a disk and a head.
To achieve these and other objects, the present invention provides a method and apparatus for optimi7ing performance of a read ch~nnel in a disk driving recording apparatus having a programmable low-pass filter and a control device for controlling overall operation. The method includes the steps of initially ~Csigning a ~lltering characteristic to the programmable low-pass filter as a predetermined initial bandwidth value via the control device; detecting and evaluating data written on a first predetermined track of a disk to calculate a first data detection error rate via the control device; comparing a reference error rate with the first data detection error rate; setting the filtering characteristic of the low-pass filter to a bandwidth indicating a lowest error rate by varying the bandwidth of the programmable low-pass filter when the first data detection error rate is greater than a reference error rate; thcreafter, detecting data written on a second predetermined track of tfie disk to calculate a second data detection error rate via the control device; comparing the reference error rate with the second data detection error rate; outputting an error state signal indicating that the disk drive recording apparatus is in a poor state when the second data detection error ratc is greater than the reference error rate; and setting a currently set bandwidth as a final set value and completing an optimization process when any one of the first and second data detection error rates is below the reference error rate.
~1 BRIEF DESCRIPI'ION OF DRAWINGS
A more complete appreciation of this invention, and many of the ~ nC~nt advantages thereof, will be readily appar~nt as the sarne becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:
~IG. 1 is a block diagram showing construction of a read channel of read/write charmel portions of a representative hard disk drive;
FIG. 2 is a waveform diagrarn showing output states of each component in FIG.
1; and FIG. 3 is a flow chart showing a process according to the present invention for optimi7ing performance of a read channel of a disk drive recording apparatus by using an error rate.
DETAILED DESCRIPIION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a block diagram showing construction of a read channel of read/write channel portions of a representative hard disk drive. In F~G. 1, a head 20 outputs an analog signal induced from a disk 10. The analog signal is received, amplified and output at a given arnplification level by a pre-amplifier 30. A variable gain amplifier 40 (hereinafter, referred to as VGA) controls amplification gain in accordance with variation of the input signal level received from pre-amplifier 30, thereby maintaining a constant output level. A programmable low-pass filter and equalizer 50 (hereinafter, referred to as programmable LPF and equalizer) removes noise from the signal output from VGA 40, compensates for the output signal, and narrows the pulse width in accordance with an input representative of a predeterrnincd bandwidth and boost lcvcl.
2S A zero-crossing comparator 60 differentiates an input signal rcceivcd from programmable LPF and equalizer 50 and then outputs a differcntiatcd signal. A
hysteresis comparator 70 sets a signal threshold level and compares the signal threshold level with the level of the output signal received from programmable LPF and equalizer 50, thcreby outputting a compared result. A flip-flop 80 reccives outputs from zero-crossing comparator 60 and hysteresis comparator 70 and gencratcs one shot data. A
clock synthesizer 90 produces a reference clock pulse by receiving a predetermined external clock pulse. A data synchronizer 100 receives the one shot data output from ~43~81 flip-flop 80, and transmits the data and a clock window signal in synchronism with the reference clock pulse from clock syntheci7~r 90. A decoder 110 ~leco~s the data and clock window signal received from data synchroni~;er 100 and outputs the decoded data as no-return-to-zero NRZ data. A serial port 120 rec~,;v~s a signal representative of the predetermined bandwidth and boost level from a microprocessor 130, and then transmits the signal to plogla-.,mable LPF and equalizer 50. Microprocessor 130 controls the overall operation of the hard disk drive and outputs an initial bandwidth value and boost level data.
FIG. 2 is a waveform diagram illu~llaling output states of each c~lllponent in FIG. 1. An explanation of the operation of the read channel in the hard disk drive will hereinafter be given with reference to FIGs. 1 and 2.
-An electrical signal induced from a surface of disk 10 by head 20 typically has a weak voltage of about 250,uV. Differences in signal voltage may be generated depending upon a flying height between disk 10 and head 20, and the quality of disk 10 and head 20. Pre-amplifier 30 receives the signal from head 20, amplifies the signal, and outputs the signal at an amplification rate of about 300 times, as shown in waveform "A" of FIG. 2. In this case, however, since noise is also amplified, the output state of pre-amplifier 30 represents an unstable output waveform, such as portion "a" indicated in FIG. 2.
VGA 40 receives the output signal from pre-amplifier 30 and varies amplification gain in accordance with variations of the input signal level, as shown in portion "b" indicated in FIG. 2, to output a signal at a constant level.
Next, programmable LPF and equalizer 50 initially establishes the bandwidth and boost level according to data received from microprocessor 130 via serial port 120.
Programmable LPF and equ~li7l r 50 filters,'comperl~es and narrows the pulse width of the output signal from VGA 40, thereby producing a stabilized analog signal, as shown in waveform "B" of FIG. 2.
Zero-crossing comparator 60 differentiates the signal output from programmable LPF and equalizer 50 to generate a differentiated output signal, as shown in waveform "C" of FIG. 2. Hysteresis comparator 70, using a predetermined signal threshold level, compares the signal threshold level with the level of the signal output from programmable LPF and equ~li7er 50 to generate a co~ )ared result signal in which the peak of the signal output from progla."n~able LPF and equalizer 50 is det~te~3.
Flip-flop 80, which receives the differenti~ted output signal from zero-crossingcomparator 60 and the compared result signal from hysteresis comparator 70, generates digital signals in a pulse pattern, as shown in waveform "D" of F~G. 2. Data synchronizer 100 receives the digital signals and transmits the clock window signal and the digital signals in synchronization with the reference clock pulse from clocksynthesizer 90. Decoder 110 receives the clock window signal and digital signals from data synchronizer 100, decodes the signals and then generates the decoded signals as NRZ data.
When executing a data read operation with the hard disk drive, however, signal qualities are different from each other due to magnetic, electrical, and mechanical characteristics of disk 10 and head 20. As a result, soft data errors such as an extra pulse or a miCcing pulse may occur. A soft data error generated by an extra pulse is aKributable to general noises, while a soft data error generated by a micsin~ pulse is attributable to a bit shift. The general noises causing an extra pulse include white noise, head noise, electric current noise, voltage noise, damping resistance noise, disk noise, PCB noise, and pre-amplifier noise. Soft data errors generated by an extra pulse can be removed by using an error correction code.
Bit shifts often recult from peak shifts attributable to patterns and noise. Peak shifts attributable to noise can be remedied by adjusting the bandwidth of the low-pass filter. Peak shifts attributable to pattems resulting from mutual interference between adjacent signals can be remedied by compensating a signal using an equalizing circuit and narrowing the pulse width of the signal in ordcr to minimize mutual interference between adjacent signals.
As discussed above, peak shifts due to patterns can be remcdied by increasing a boost level, whereas peak shifts due to noise may be remedicd by an extension of the bandwidth of the low-pass filter. Hence, a trade-off is necessary between the boost level and the bandwidth of the low-pass filter. Furthemmore, since the quality of disk 10 and head 20 is variable to a large extent during the process, optimization of bandwidth of S
f~D~81 the low-pass filter and boost level of the eq~ i7in~ circuit is necessary for each disk arld head.
In co--venlional methods, however, bandwidth of the low-pass filter and boost level of the eq~ i7inE circuit are fixed. Therefore, each read channel can not be 5 utilized optimally to keep pace with the characteristic varia~ions of disk 10 and head 20;
accordingly, a rni.ccin~ pulse may occur during the data read operation.
One characteristic of a soft data error in a hard disk drive is that error generation probability varies in accordance with test conditions because of errors due to a bit shift, unlike hard errors due to a disk defect. Accordingly, in a prefcrred embodiment of the present invention, the error rate is checked while the test conditions are established to reflect a worst case scenerio. As a result, the bandwidth and boost level for optimi7in~ performance of the read channel are obtained, based upon the checked error rate.
In addition to error rate calculation methods for optimi7.ing perforrnance of the read channel, the preferred embodiment of the present invention uses a method for calculating a raw error rate for use as a judgement reference to ensure reliability.
Moreover, since an off-track read/write state changes according to the stabilityof the servo control system, the error rate is intended to be produced under a maximum off-track state.
FIG. 3 is a flow chart showing a process according to the present invention for optimi7in~ performance of a read channel of a disk drive recording apparatus by using an error rate. An operation of the preferred embodiment of the present invention will now be discussed with reference to FIG. 3 In step 301, microprocessor 130 outputs a default value for the bandwidth of thcread channel and the boost level previously established by a manufacturer in order to set programmable LPF and equalizer 50. To execute the above operation, microprocessor 130 sets the default value by providing data to programmable LPF and equalizer 50 via serial port 120.
30B-l In step 303, microprocessor 130 selects an inner track of disk 10 where minim~l hardware errors exist, writes optional data under a worst state condition and establishes an off-track level for executing a data detection operation.
In step 305, microprocessor 130 determines an error rate by repeating a read S operation to detect a small arnount of data on the selected track. The read operation is not perforrned to use the error correction code or to retry a read operation.
Furtherrnore, if more than one head exists, an error rate is calculated by an identical method for each respective head.
In step 307, microprocessor 130 compares the error rate calculated in step 305 with a reference error rate. When the calculated error rate is below the reference error rate, microprocessor 130 decign~te~ the default value as an optimization value for each head in step 319, and completes a routine for optimi~ing performance of the readchannel.
In steps 305 and 307, microprocessor 130 in the prefel~ed embodiment of the present invention evaluates 101~ bits of data through each head to calculate a data error rate. In this case, the reference error rate is established as 1/10l~.
In step 307, when the calculated error rate is greater than the reference error rate, microprocessor 130 sequentially varies the boost level of programmable LPF and equalizer S0 at step 309 and calculates the error rate of a corresponding head. As a result, the boost level corresponding to the lowest error rate is established as an optimization level.
At step 311, when the calculated error rate is greater than ~he refercnce error rate, microprocessor 130 sequentially varies the bandwidth of programmable LPF and equalizer S0 at step 313 and calculates thc er~ror rate of a corresponding head. As a result, the bandwidth corresponding to thc lowcst crror rate is established as an optimiza~ion level.
At step 315, microprocessor 130 again repcals thc operation of step 307. Here, when the calculated error rate is below the reference error rate, microprocessor 130 designates the currently established boost level and bandwidlh for each head as an ~3~8~
optimization level at step 319, and completes the routine for optimi~ing performance of the read channel.
At step 315, however, when the c~lcul~ted error rate is greater than the reference error rate, microprocessor 130 establishes a drive error state indicative of poor quality of head 10 or the drive. In this case, an output means, for instance, a host computer indicating a drive test processing state may be used as an output device for indicating the drive error state. Performance of the read channel can be optimi7~d by adjusting the characteristics of all of the low-pass filters LPFs and equalizers; but it is also possible that, after one low-pass filter LPF and equali~r is set to an established reference value, the read channel may be optimi~ed by varying the characteristics of the other components. In other words, the read channel can be optimized by variably setting the rçm~inin~E low-pass filters LPFs and equalizers in dependence upon the first established reference values, thereby elimin~ting multiple performances of steps 309 and 313.
As ~liccucce~ above, in a disk drive recording apparatus such as a hard disk drive, the present invention is provided with a method for op~imi~ing the performance of a read channel of the disk drive recording apparatus by variably setting the frequency bandwidth and boost level of the read channel in accordance with characteristics of the disk and head.
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that modifications in detail may be made without departing from the spirit and scope of the invention. By way of example, a microprocessor of a disk drive recording apparatus used to perform and control an op~imi7ing processing routine may be replaced with test equipment of the disk drive recording apparatus.
In step 305, microprocessor 130 determines an error rate by repeating a read S operation to detect a small arnount of data on the selected track. The read operation is not perforrned to use the error correction code or to retry a read operation.
Furtherrnore, if more than one head exists, an error rate is calculated by an identical method for each respective head.
In step 307, microprocessor 130 compares the error rate calculated in step 305 with a reference error rate. When the calculated error rate is below the reference error rate, microprocessor 130 decign~te~ the default value as an optimization value for each head in step 319, and completes a routine for optimi~ing performance of the readchannel.
In steps 305 and 307, microprocessor 130 in the prefel~ed embodiment of the present invention evaluates 101~ bits of data through each head to calculate a data error rate. In this case, the reference error rate is established as 1/10l~.
In step 307, when the calculated error rate is greater than the reference error rate, microprocessor 130 sequentially varies the boost level of programmable LPF and equalizer S0 at step 309 and calculates the error rate of a corresponding head. As a result, the boost level corresponding to the lowest error rate is established as an optimization level.
At step 311, when the calculated error rate is greater than ~he refercnce error rate, microprocessor 130 sequentially varies the bandwidth of programmable LPF and equalizer S0 at step 313 and calculates thc er~ror rate of a corresponding head. As a result, the bandwidth corresponding to thc lowcst crror rate is established as an optimiza~ion level.
At step 315, microprocessor 130 again repcals thc operation of step 307. Here, when the calculated error rate is below the reference error rate, microprocessor 130 designates the currently established boost level and bandwidlh for each head as an ~3~8~
optimization level at step 319, and completes the routine for optimi~ing performance of the read channel.
At step 315, however, when the c~lcul~ted error rate is greater than the reference error rate, microprocessor 130 establishes a drive error state indicative of poor quality of head 10 or the drive. In this case, an output means, for instance, a host computer indicating a drive test processing state may be used as an output device for indicating the drive error state. Performance of the read channel can be optimi7~d by adjusting the characteristics of all of the low-pass filters LPFs and equalizers; but it is also possible that, after one low-pass filter LPF and equali~r is set to an established reference value, the read channel may be optimi~ed by varying the characteristics of the other components. In other words, the read channel can be optimized by variably setting the rçm~inin~E low-pass filters LPFs and equalizers in dependence upon the first established reference values, thereby elimin~ting multiple performances of steps 309 and 313.
As ~liccucce~ above, in a disk drive recording apparatus such as a hard disk drive, the present invention is provided with a method for op~imi~ing the performance of a read channel of the disk drive recording apparatus by variably setting the frequency bandwidth and boost level of the read channel in accordance with characteristics of the disk and head.
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that modifications in detail may be made without departing from the spirit and scope of the invention. By way of example, a microprocessor of a disk drive recording apparatus used to perform and control an op~imi7ing processing routine may be replaced with test equipment of the disk drive recording apparatus.
Claims (19)
1. A method for optimizing performance of a read channel in a disk drive recording apparatus having a programmable low-pass filter and control means for controlling operation of said apparatus, said method comprising the steps of:
setting a filtering characteristic of said programmable low-pass filter to a predetermined initial bandwidth value via said control means;
detecting data written on a predetermined track of a disk to calculate a first data detection error rate via said control means, and comparing a reference error rate with said first data detection error rate;
setting said filtering characteristic of said programmable low-pass filter to a bandwidth value indicating a lowest error rate by varying said bandwidth value of said programmable low-pass filter when said first data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a second data detection error rate via said control means, and comparing said reference error rate with said second data detection error rate;
outputting an error state signal indicating that said disk drive recording apparatus is in an error state when said second data detection error rate is greater than said reference error rate; and setting a current bandwidth value as a final set value when any one of said first and second data detection error rates is less than or equal to said reference error rate.
setting a filtering characteristic of said programmable low-pass filter to a predetermined initial bandwidth value via said control means;
detecting data written on a predetermined track of a disk to calculate a first data detection error rate via said control means, and comparing a reference error rate with said first data detection error rate;
setting said filtering characteristic of said programmable low-pass filter to a bandwidth value indicating a lowest error rate by varying said bandwidth value of said programmable low-pass filter when said first data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a second data detection error rate via said control means, and comparing said reference error rate with said second data detection error rate;
outputting an error state signal indicating that said disk drive recording apparatus is in an error state when said second data detection error rate is greater than said reference error rate; and setting a current bandwidth value as a final set value when any one of said first and second data detection error rates is less than or equal to said reference error rate.
2. The method as claimed in claim 1, wherein said disk drive recording apparatus comprises a hard disk drive.
3. The method as claimed in claim 1, wherein said predetermined track comprises an inner track of the disk where a minimum hardware error rate exists.
4. The method as claimed in claim 2, wherein said predetermined track comprises an inner track of the disk where a minimum hardware error rate exists.
5. A method for optimizing performance of a read channel of a disk drive recording apparatus having an equalizer and control means for controlling operation of said apparatus, said method comprising the steps of:
setting a performance characteristic of said equalizer to a predetermined boost level via said control means;
detecting data written on a predetermined track of a disk to calculate a first data detection error rate via said control means, and comparing a reference error rate with said first data detection error rate;
setting said performance characteristic of said equalizer to a boost level indicating a lowest error rate by varying said boost level of said equalizer when said first data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a second data detection error rate via said control means, and comparing said reference error rate with said second data detection error rate;
outputting an error state signal indicating that said disk drive recording apparatus is in an error state when said second data detection error rate is greater than said reference error rate; and setting a current boost level as a final set value and completing said optimizing method when any one of said first and second data detection error rates is less than or equal to said reference error rate.
setting a performance characteristic of said equalizer to a predetermined boost level via said control means;
detecting data written on a predetermined track of a disk to calculate a first data detection error rate via said control means, and comparing a reference error rate with said first data detection error rate;
setting said performance characteristic of said equalizer to a boost level indicating a lowest error rate by varying said boost level of said equalizer when said first data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a second data detection error rate via said control means, and comparing said reference error rate with said second data detection error rate;
outputting an error state signal indicating that said disk drive recording apparatus is in an error state when said second data detection error rate is greater than said reference error rate; and setting a current boost level as a final set value and completing said optimizing method when any one of said first and second data detection error rates is less than or equal to said reference error rate.
6. The method as claimed in claim 5, wherein said disk drive recording apparatus comprises a hard disk drive.
7. The method as claimed in claim 5, wherein said predetermined track comprises an inner track of the disk where a minimum hardware error rate exists.
8. The method as claimed in claim 6, wherein said predetermined track comprises an inner track of the disk where a minimum hardware error rate exists.
9. A method for optimizing performance of a read channel of a disk drive recording apparatus having a programmable low-pass filter, an equalizer, and control means for controlling operation of said apparatus, said method comprising the steps of:
setting a filtering characteristic of said programmable low-pass filter to a predetermined initial bandwidth value and setting a boost level of said equalizer to an initial value via said control means;
detecting data written on a predetermined track of a disk to calculate a first data detection error rate via said control means, and comparing a reference error rate with said first data detection error rate;
setting said equalizer to said boost level indicating a lowest error rate by varying said boost level of said equalizer when said first data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a second data detection error rate via said control means, and comparing said reference error rate with said second data detection error rate;
setting said filtering characteristic of said programmable low-pass filter to a bandwidth value indicating a lowest error rate by varying said bandwidth value of said programmable low-pass filter when said second data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a third data detection error rate via said control means, and comparing said reference error rate with said third data detection error rate;
outputting an error state signal indicating that said disk drive recording apparatus is in an error state when said third data detection error rate is greater than said reference error rate; and setting a current bandwidth and a current boost level as final set values and completing said optimizing method when any one of said first, second and third data detection error rates is less than or equal to said reference error rate.
setting a filtering characteristic of said programmable low-pass filter to a predetermined initial bandwidth value and setting a boost level of said equalizer to an initial value via said control means;
detecting data written on a predetermined track of a disk to calculate a first data detection error rate via said control means, and comparing a reference error rate with said first data detection error rate;
setting said equalizer to said boost level indicating a lowest error rate by varying said boost level of said equalizer when said first data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a second data detection error rate via said control means, and comparing said reference error rate with said second data detection error rate;
setting said filtering characteristic of said programmable low-pass filter to a bandwidth value indicating a lowest error rate by varying said bandwidth value of said programmable low-pass filter when said second data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a third data detection error rate via said control means, and comparing said reference error rate with said third data detection error rate;
outputting an error state signal indicating that said disk drive recording apparatus is in an error state when said third data detection error rate is greater than said reference error rate; and setting a current bandwidth and a current boost level as final set values and completing said optimizing method when any one of said first, second and third data detection error rates is less than or equal to said reference error rate.
10. The method as claimed in claim 9, wherein said disk drive recording apparatus comprises a hard disk drive.
11. The method as claimed in claim 9, wherein said predetermined track comprises an inner track of the disk where a minimum hardware error rate exists.
12. The method as claimed in claim 10, wherein said predetermined track comprises an inner track of the disk where a minimum hardware error rate exists.
13. A method for optimizing performance of a read channel of a disk drive recording apparatus comprising a programmable low-pass filter and an equalizer, said apparatus connected to an external control device for controlling operation of said apparatus, said method comprising the steps of:
setting a filtering characteristic of said programmable low-pass filter to a predetermined initial bandwidth value and setting a boost level of said equalizer to an initial value via said control device;
detecting data written on a predetermined track of a disk to calculate a first data detection error rate via said control device, and comparing a reference error rate with said first data detection error rate;
setting a characteristic of said equalizer to said boost level indicating a lowest error rate by varying said boost level of said equalizer when said first data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a second data detection error rate via said control device, and comparing said reference error rate with said second data detection error rate;
setting said filtering characteristic of said programmable low-pass filter to a bandwidth indicating a lowest error rate by varying said bandwidth of said programmable low-pass filter when said second data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a third data detection error rate via said control device, and comparing said reference error rate with said third data detection error rate;
outputting an error state signal indicating that said disk drive recording apparatus is in an error state when said third data detection error rate is greater than said reference error rate; and setting a current bandwidth and a current boost level as final set values and completing said optimizing method when any one of said first, second, and third data detection error rates is less than or equal to said reference error rate.
setting a filtering characteristic of said programmable low-pass filter to a predetermined initial bandwidth value and setting a boost level of said equalizer to an initial value via said control device;
detecting data written on a predetermined track of a disk to calculate a first data detection error rate via said control device, and comparing a reference error rate with said first data detection error rate;
setting a characteristic of said equalizer to said boost level indicating a lowest error rate by varying said boost level of said equalizer when said first data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a second data detection error rate via said control device, and comparing said reference error rate with said second data detection error rate;
setting said filtering characteristic of said programmable low-pass filter to a bandwidth indicating a lowest error rate by varying said bandwidth of said programmable low-pass filter when said second data detection error rate is greater than said reference error rate;
detecting data written on said predetermined track of the disk to calculate a third data detection error rate via said control device, and comparing said reference error rate with said third data detection error rate;
outputting an error state signal indicating that said disk drive recording apparatus is in an error state when said third data detection error rate is greater than said reference error rate; and setting a current bandwidth and a current boost level as final set values and completing said optimizing method when any one of said first, second, and third data detection error rates is less than or equal to said reference error rate.
14. The method as claimed in claim 13, wherein said disk drive recording apparatus comprises a hard disk drive.
15. The method as claimed in claim 13, wherein said predetermined track comprises an inner track of the disk where a minimum hardware error rate exists.
16. The method as claimed in claim 14, wherein said predetermined track comprises an inner track of the disk where a minimum hardware error rate exists.
17. A disk drive apparatus, comprising:
first means for exhibiting a bandwidth value and a boost level used to process electrical signals in said disk drive apparatus;
second means for reading data from an inner track of a disk driven by said disk drive apparatus; and third means for calculating a first data error rate from said data read by said second means from said inner track of said disk and comparing said first data error rate with a reference error rate, said third means adjusting said boost level exhibited by said first means and then calculating a second data error rate from said data read by said second means from said inner track of said disk and comparing said second data error rate with said reference error rate when said first data error rate is greater than said reference error rate, said third means adjusting said bandwidth value exhibited by said first means and then calculating a third data error rate from said data read by said second means from said inner track of said disk and comparing said third data error rate with said reference error rate when said second data error rate is greater than said reference error rate, said third means indicating an error state of said disk drive apparatus when said third data error rate is greater than said reference error rate and controlling said first means to exhibit said boost level and said bandwidth value according a current state when any one of said first, second and third data error rates is not greater than said reference error rate.
first means for exhibiting a bandwidth value and a boost level used to process electrical signals in said disk drive apparatus;
second means for reading data from an inner track of a disk driven by said disk drive apparatus; and third means for calculating a first data error rate from said data read by said second means from said inner track of said disk and comparing said first data error rate with a reference error rate, said third means adjusting said boost level exhibited by said first means and then calculating a second data error rate from said data read by said second means from said inner track of said disk and comparing said second data error rate with said reference error rate when said first data error rate is greater than said reference error rate, said third means adjusting said bandwidth value exhibited by said first means and then calculating a third data error rate from said data read by said second means from said inner track of said disk and comparing said third data error rate with said reference error rate when said second data error rate is greater than said reference error rate, said third means indicating an error state of said disk drive apparatus when said third data error rate is greater than said reference error rate and controlling said first means to exhibit said boost level and said bandwidth value according a current state when any one of said first, second and third data error rates is not greater than said reference error rate.
18. The disk drive apparatus as claimed in claim 17, wherein said first means comprises a programmable low pass filter and equalizer.
19. A method for optimizing performance of a read channel in a disk drive recording apparatus having a component and control means for controlling operation of said apparatus, said method comprising the steps of:
setting a characteristic of said component to a predetermined value via said control means;
detecting data written on a first predetermined track of a disk to calculate a first data detection error rate via said control means, and comparing a reference error rate with said first data detection error rate;
setting said characteristic of said component to a value indicating a lowest error rate by varying said value of said component when said first data detection error rate is greater than said reference error rate;
detecting data written on a second predetermined track of the disk to calculate a second data detection error rate via said control means, and comparing said reference error rate with said second data detection error rate;
outputting an error state signal indicating that said disk driving recording apparatus is in a poor state when said second data detection error rate is greater than said reference error rate; and setting a current value as a final set value when any one of said first and second data detection error rates is below said reference error rate.
setting a characteristic of said component to a predetermined value via said control means;
detecting data written on a first predetermined track of a disk to calculate a first data detection error rate via said control means, and comparing a reference error rate with said first data detection error rate;
setting said characteristic of said component to a value indicating a lowest error rate by varying said value of said component when said first data detection error rate is greater than said reference error rate;
detecting data written on a second predetermined track of the disk to calculate a second data detection error rate via said control means, and comparing said reference error rate with said second data detection error rate;
outputting an error state signal indicating that said disk driving recording apparatus is in a poor state when said second data detection error rate is greater than said reference error rate; and setting a current value as a final set value when any one of said first and second data detection error rates is below said reference error rate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019940009013A KR970010637B1 (en) | 1994-04-27 | 1994-04-27 | Lead channel optimization method using error rate in disk driver |
| KR9013/1994 | 1994-04-27 |
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| CA2143081A1 CA2143081A1 (en) | 1995-10-28 |
| CA2143081C true CA2143081C (en) | 1998-06-23 |
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| CA002143081A Expired - Fee Related CA2143081C (en) | 1994-04-27 | 1995-02-21 | Method of optimizing read channel of disk driving recording apparatus by using error rate |
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| JP (1) | JP2868707B2 (en) |
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1995
- 1995-02-08 US US08/386,906 patent/US5610776A/en not_active Expired - Lifetime
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- 1995-03-29 DE DE19511587A patent/DE19511587B4/en not_active Expired - Fee Related
- 1995-04-10 JP JP7084340A patent/JP2868707B2/en not_active Expired - Fee Related
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| KR970010637B1 (en) | 1997-06-28 |
| US5610776A (en) | 1997-03-11 |
| JPH07296529A (en) | 1995-11-10 |
| JP2868707B2 (en) | 1999-03-10 |
| KR950030118A (en) | 1995-11-24 |
| CA2143081A1 (en) | 1995-10-28 |
| DE19511587A1 (en) | 1995-11-02 |
| DE19511587B4 (en) | 2006-04-20 |
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