Patent Document

BACKGROUND OF THE INVENTION 
       [0001]    The present inventions are related to systems and methods for transferring information, and more particularly to systems and methods for determining problems related to a medium associated with a data transfer. 
         [0002]    Various data transfer systems have been developed including storage systems, cellular telephone systems, radio transmission systems. In each of the systems data is transferred from a sender to a receiver via some medium. For example, in a storage system, data is sent from a sender (i.e., a write function) to a receiver (i.e., a read function) via a storage medium. The effectiveness of any transfer is impacted by any defects associated with the transfer medium. In some cases, data loss caused by defects in the transfer medium can make recovery of data from the transfer medium difficult even for data received from non-defective areas or times. 
         [0003]    Various approaches have been developed for identifying defects in the transfer medium. Such approaches provide a general ability to identify defects, but in many cases are inaccurate. In the best case, this inaccuracy limits the effectiveness of any defect identification. In the worst case, inaccurate defect detection may actually hamper the data recovery process. 
         [0004]    Hence, for at least the aforementioned reasons, there exists a need in the art for advanced systems and methods for defect detection. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The present inventions are related to systems and methods for transferring information, and more particularly to systems and methods for determining problems related to a medium associated with a data transfer. 
         [0006]    Various embodiments of the present invention provide methods for detecting a media defect. Such methods include deriving a data input from a medium and performing a MAP detection on the data input. The MAP detection provides an NRZ output and an LLR output corresponding to the data input. A product of the NRZ output is correlated with a product of the LLR output to produce a correlated output. The correlated output is compared with a threshold value, and a media defect output is asserted based at least in part on the result of the comparison of the correlated output with the threshold value. In particular instances of the aforementioned embodiments, the methods further include delaying the assertion of the media defect output by a defined period after the correlated output transitions to a value less than the threshold value. In some cases, the above mentioned defined period is programmable, and the above mentioned threshold value is programmable. 
         [0007]    In some instances of the aforementioned embodiments, correlating the product of the NRZ output with the product of the LLR output includes normalizing the LLR output of the MAP detector, multiplying the normalized LLR output by the data input delayed in time to correspond to the LLR output, to create a multiplied LLR output, and squaring the NRZ output to create a squared NRZ output. The methods further include generating a ratio of the multiplied LLR output to the squared NRZ output. In such cases, generating a ratio of the multiplied LLR output to the squared NRZ output includes dividing the multiplied LLR output by the squared NRZ output. The created result is the correlated output. In some cases, the aforementioned methods further include filtering the multiplied LLR output and filtering the squared NRZ output prior to generating the ratio of the multiplied LLR output to the squared NRZ output. 
         [0008]    In other instances of the aforementioned embodiments, correlating the product of the NRZ output with the product of the LLR output includes multiplying the LLR output by the data input delayed in time to correspond to the LLR output to create a multiplied LLR output, and multiplying the NRZ output by the data input delayed in time to correspond to the NRZ output to create a multiplied NRZ output. The methods further include generating a ratio of the multiplied LLR output to the multiplied NRZ output. In some cases, the aforementioned methods further include filtering the multiplied LLR output and filtering the multiplied NRZ output prior to generating the ratio of the multiplied LLR output to the multiplied NRZ output. 
         [0009]    Other embodiments of the present invention provide media defect detection systems that include a MAP detector that provides an NRZ output and an LLR output based at least in part on a data signal. In addition, the systems include a correlation circuit that correlates the NRZ output with the LLR output and provides a correlated output, and a comparator that receives the correlated output and compares the correlated output with a threshold value. In some instances of the aforementioned embodiments, the systems further include a delay circuit that receives the output of the comparator and asserts a media defect flag a defined delay period after the threshold value exceeds the correlated output. In some cases, the delay circuit includes a counter that synchronously increments when the threshold value exceeds the correlated output, and synchronously resets when the correlated output exceeds the threshold value. In some cases, the aforementioned systems are implemented as part of a storage device, while in other cases, the systems are implemented as part of a communication device. Based on the disclosure provided herein, one of ordinary skill in the art will recognize other types of devices in which the systems may be implemented. 
         [0010]    In various instances of the aforementioned embodiments, the correlation circuit includes a first multiplier and a second multiplier. The first multiplier multiples the LLR output by the data input delayed in time to correspond to the LLR output to create a multiplied LLR output, and the second multiplier multiplies the NRZ output by the data input delayed in time to correspond to the NRZ output to create a multiplied NRZ output. The systems further include a ratio generator that creates a ratio of the multiplied LLR output to the multiplied NRZ output. In some cases, the ratio of the multiplied LLR output to the squared NRZ output is the multiplied LLR output divided by the squared NRZ output. 
         [0011]    In other instances of the aforementioned embodiments, the correlation circuit includes a normalizing circuit, a first multiplier and a second multiplier. The normalizing circuit receives the LLR output and provides a normalized LLR output. The first multiplier multiplies the normalized LLR output by the data input to create a multiplied LLR output, and the second multiplier multiplies the NRZ output by the NRZ output to create a squared NRZ output. Such systems further include a ratio generator that receives the squared NRZ output and the multiplied LLR output and produces a ratio of the multiplied LLR output to the squared NRZ output. 
         [0012]    Yet other embodiments of the present invention provide data processing systems that include a medium, an analog signal derived from the medium, and an analog to digital converter that creates a digital signal from the analog signal. In addition, the data processing systems include a media defect detector. The media defect detector includes a MAP detector that provides an NRZ output and an LLR output based at least in part on the digital signal, and a correlation circuit that correlates the NRZ output with the LLR output and provides a correlated output. A comparator receives the correlated output and compares the correlated output with a threshold value, and a defect signal generator outputs a media defect flag based at least in part on the output of the comparator and indicating a defective portion of the medium. In one particular case, the defect signal generator includes a delay circuit that receives the output of the comparator and asserts the media defect flag a defined delay period after the threshold value exceeds the correlated output. 
         [0013]    This summary provides only a general outline of some embodiments of the invention. Many other objects, features, advantages and other embodiments of the invention will become more fully apparent from the following detailed description, the appended claims and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    A further understanding of the various embodiments of the present invention may be realized by reference to the figures which are described in remaining portions of the specification. In the figures, like reference numerals are used throughout several drawings to refer to similar components. In some instances, a sub-label consisting of a lower case letter is associated with a reference numeral to denote one of multiple similar components. When reference is made to a reference numeral without specification to an existing sub-label, it is intended to refer to all such multiple similar components. 
           [0015]      FIG. 1   a  depicts a correlation based defect detection system in accordance with various embodiments of the present invention; 
           [0016]      FIG. 1   b  is a timing diagram of exemplary signals applied to and received from the defect detection circuit of  FIG. 1   a;    
           [0017]      FIG. 2   a  a depicts another correlation based defect detection system in accordance with various embodiments of the present invention; 
           [0018]      FIG. 2   b  is a timing diagram of exemplary signals applied to and received from the defect detection circuit of  FIG. 2   a;    
           [0019]      FIG. 3  shows yet another correlation based defect detection system in accordance with various embodiments of the present invention; 
           [0020]      FIG. 4  shows yet another correlation based defect detection system in accordance with various embodiments of the present invention; 
           [0021]      FIG. 5  depicts a storage system including a media defect system in accordance with various embodiments of the present invention; and 
           [0022]      FIG. 6  depicts a communication system including a media defect system in accordance with one or more embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    The present inventions are related to systems and methods for transferring information, and more particularly to systems and methods for determining problems related to a medium associated with a data transfer. 
         [0024]    Turning to  FIG. 1   a,  a correlation based defect detection system  100  is depicted in accordance with various embodiments of the present invention is depicted. Correlation based defect detection system  100  includes a maximum a posteriori (MAP) data detector  115  that receives a media data input  105  and provides a soft log-likelihood ratio (LLR) output  116  and a hard output  118  (i.e., an NRZ output). MAP detector  115  may be any MAP detector known in the art, and LLR output  116  and NRZ output  118  may be done using algorithms and circuits known in the art. Each of LLR output  116  and NRZ output  118  are fed through respective partial response target circuits  120 ,  125  as are known in the art. This circuit regenerates y ideal  from NRZ decisions. If all NRZ decisions are correct, then y ideal  and y are almost the same. There may be some noise remaining in y, but not y ideal . Said another way, in the non-defective region, y ideal  and y are strongly correlated. In contrast, in the defective region, the correlation between y ideal  and y is substantially reduced. The output of partial response target circuit  125  is mathematically squared using a multiplier circuit  135 . The mathematically squared output is filtered using a filter circuit  140 . Filter  140  may be, for example, a low pass filter that smoothes any noise evident at the output of multiplier circuit  140 . 
         [0025]    The output of partial response target circuit  120  is mathematically normalized using a normalizing circuit  130 . In particular, the normalizing process operates to modify the range of the soft output  116  from MAP detector  115  to be consistent with media data input  105 , and in this way operates to regenerate media data input  105 . Thus, for example, regardless of the input range of media data input  105 , normalizing circuit  130  causes the output from partial response circuit  120  to go from approximately negative one to positive one during non-defective portions of the media at issue. Of note, the normalization is to values obtained during non-defective regions of the media at issue. The output of normalizing circuit  130  is multiplied by media data input  105  passed through a delay block  110 . Delay block  110  operates to provide a sample of media defect input  105  that is correlated in time with the output from normalized output circuit  130 . The multiplied output is filtered using a filter circuit  145 . Filter  145  may be, for example, a low pass filter that smoothes any noise evident at the output of multiplier circuit  145 . 
         [0026]    Filter  145  provides a correlation output  147  and filter  140  provides a reference output  142 . Correlation output  147  and reference output  142  are mathematically combined using a ratio generator  155 . In particular, ratio generator  155  is operable to provide a ratio output  157  (i.e., a correlated output) defined by the following equation: 
         [0000]      Ratio Output 157=Correlation Output 147 divided by Reference Output 142. 
         [0000]    When hard output  118  is generally correct, there will be a strong correlation between correlation output  147  and reference output  142 . Alternatively, as the number of errors in hard output  118  and soft output  116  increases, the correlation between correlation output  147  and reference output  142  will generally decrease. Ratio Output  157  is compared with a programmable data threshold  165  using a comparator  160 . Where the value of ratio output  157  is less than programmable data threshold  165 , a media defect output  170  is asserted high. Alternatively, where the value of ratio output  157  is greater than programmable data threshold  165 , media defect output  170  is de-asserted. 
         [0027]    Turning to  FIG. 1   b,  a timing diagram  101  depicts the operation of correlation based defect detection system  100  based on exemplary inputs. It should be noted that the various data inputs and outputs are merely exemplary and that circuit operation will vary depending upon the particular data inputs and system implementation. In particular, timing diagram  101  shows an exemplary data input  105  including periods where data is received from a non-defective medium  195 ,  197 , and a period  193  where data is received from a defective medium. Of note, data from the defective portion may include a DC offset that may be eliminated through use of a filter (not shown) as will be appreciated by one of ordinary skill in the art based on the disclosure provided herein. Data from the non-defective medium (portions  195 ,  197 ) exhibits a relatively high amplitude when compared with that from the defective medium (portion  193 ). Timing diagram  101  also depicts correlation output  147  and reference output  142  generated based on data input  105 . As shown, correlation output  147  exhibits a somewhat noisy signal operating around one DC level for non-defective regions  195 ,  197 , and a somewhat noisy signal operating around another lower DC level for defective region  193 . Similarly, reference output  142  exhibits a somewhat noisy signal operating around one DC level for non-defective regions  195 ,  197 , and a somewhat noisy signal operating around another lower DC level for defective region  193 . Of note, the DC level of reference output  142  for the defective region is greater than that for the corresponding region of correlation output  147 . Again, it should be noted that timing diagram  101  is merely exemplary and that different levels of noise, DC levels and the like may be possible depending upon a particular data input  105  and system implementation. Ratio output  157  is also shown. 
         [0028]    In part because of the strong correlation during the non-defective regions  195 ,  197 , and the reduced correlation and lower amplitudes during the defective region  193 , ratio output  142  exhibits a substantial and consistent drop-off from its highs during the non-defective regions  195 ,  197  to that exhibited during the defective region  193 . Programmable data threshold  165  is shown as a dashed line imposed over the graph of ratio output  157 . Once ratio output  157  extends below programmable data threshold  165 , media defect  170  is asserted and remains asserted until ratio output  157  again exceeds programmable data threshold  165 . By making programmable data threshold  165  programmable, it is possible to adjust the sensitivity of correlation based defect detection system  100 . 
         [0029]    Turning to  FIG. 2   a,  another correlation based defect detection system  200  is depicted in accordance with various other embodiments of the present invention is depicted. Correlation based defect detection system  200  includes a maximum a posteriori (MAP) data detector  215  that receives a media data input  205  and provides a soft log-likelihood ratio (LLR) output  216  and a hard output  218  (i.e., an NRZ output). MAP detector  215  may be any MAP detector known in the art, and LLR output  216  and NRZ output  218  may be done using algorithms and circuits known in the art. Each of LLR output  216  and NRZ output  218  are fed through respective partial response target circuits  220 ,  225  as are known in the art. The output of partial response target circuit  225  is mathematically squared using a multiplier circuit  235 . The mathematically squared output is filtered using a filter circuit  240 . Filter  240  may be, for example, a low pass filter that smoothes any noise evident at the output of multiplier circuit  240 . 
         [0030]    The output of partial response target circuit  220  is mathematically normalized using a normalizing circuit  230 . In particular, the normalizing process operates to modify the range of the soft output  216  from MAP detector  215  to be consistent with media data input  205 , and in this way operates to regenerate media data input  205 . Thus, for example, regardless of the input range of media data input  205 , normalizing circuit  230  causes the output from partial response circuit  220  to go from approximately negative one to positive one during non-defective portions of the media at issue. Of note, the normalization is to values obtained during non-defective regions of the media at issue. The output of normalizing circuit  230  is multiplied by media data input  205  passed through a delay block  210 . Delay block  210  operates to provide a sample of media defect input  205  that is correlated in time with the output from normalized output circuit  230 . The multiplied output is filtered using a filter circuit  245 . Filter  245  may be, for example, a low pass filter that smoothes any noise evident at the output of multiplier circuit  245 . 
         [0031]    Filter  245  provides a correlation output  247  and filter  240  provides a reference output  242 . Correlation output  247  and reference output  242  are mathematically combined using a ratio generator  255 . In particular, ratio generator  255  is operable to provide a ratio output  257  (i.e., a correlated output) defined by the following equation: 
         [0000]      Ratio Output 257=Correlation Output 247 divided by Reference Output 242. 
         [0000]    When hard output  218  is generally correct, there will be a strong correlation between correlation output  247  and reference output  242 . Alternatively, as the number of errors in hard output  218  increases, the correlation between correlation output  247  and reference output  242  will generally decrease. Ratio Output  257  is compared with a programmable data threshold  265  using a comparator  260 . Where the value of ratio output  257  is less than programmable data threshold  265 , an output of comparator  260  is asserted high. Alternatively, where the value of ratio output  257  is greater than programmable data threshold  265 , comparator output  267  is de-asserted. 
         [0032]    Comparator output  267  is provided to an assertion circuit including a run length monitor  282  and an edge extender  284 . Run length monitor  282  causes an output  283  to assert whenever comparator output  267  is asserted continuously for a predefined number of cycles (i.e., a programmable bit count  280 ). Said another way, whenever comparator output  267  is asserted for a continuous number of cycles equivalent to programmable bit count  280 , output  283  is asserted. This allows the circuit to filter out the occasional misreads or only limited defects regions. Output  283  is provided to an edge extender circuit  284  that operates to extend the assertion period of a media defect output  290 . In particular, media defect output  290  is extended to the left by an amount indicated by a left edge extend input  286  and to the right by a right edge extend input  288 . Extending the right and left edges allows for capture of information from the grey area surrounding a defective media region. 
         [0033]    Turning to  FIG. 2   b,  a timing diagram  201  depicts the operation of correlation based defect detection system  200  based on exemplary inputs. It should be noted that the various data inputs and outputs are merely exemplary and that circuit operation will vary depending upon the particular data inputs and system implementation. In particular, timing diagram  201  shows an exemplary data input  205  including periods where data is received from a non-defective medium  295 ,  297 , and a period  293  where data is received from a defective medium. Of note, data from the defective portion may include a DC offset that may be eliminated through use of a filter (not shown) as will be appreciated by one of ordinary skill in the art based on the disclosure provided herein. Data from the non-defective medium (portions  295 ,  297 ) exhibits a relatively high amplitude when compared with that from the defective medium (portion  293 ). Timing diagram  201  also depicts correlation output  247  and reference output  242  generated based on data input  205 . As shown, correlation output  247  exhibits a somewhat noisy signal operating around one DC level for non-defective regions  295 ,  297 , and a somewhat noisy signal operating around another lower DC level for defective region  293 . Similarly, reference output  242  exhibits a somewhat noisy signal operating around one DC level for non-defective regions  295 ,  297 , and a somewhat noisy signal operating around another lower DC level for defective region  293 . Of note, the DC level of reference output  142  for the defective region is greater than that for the corresponding region of correlation output  247 . Again, it should be noted that timing diagram  201  is merely exemplary and that different levels of noise, DC levels and the like may be possible depending upon a particular data input  205  and system implementation. Ratio output  257  is also shown. 
         [0034]    In part because of the strong correlation during the non-defective regions  295 ,  297 , and the reduced correlation and lower amplitudes during the defective region  293 , ratio output  242  exhibits a substantial and consistent drop-off from its highs during the non-defective regions  295 ,  297  to that exhibited during the defective region  293 . Programmable data threshold  265  is shown as a dashed line imposed over the graph of ratio output  257 . Once ratio output  257  extends below programmable data threshold  265 , run length monitor  282  starts a count to determine whether to assert output  283 . Once the count value exceeds that of programmable bit count  280 , media defect output  290  is asserted and remains asserted until an extension region (i.e., the combination of left edge extend  286  and right edge extend  288 ) beyond the point where ratio output  257  again exceeds programmable data threshold  265 . By waiting a period corresponding to programmable bit count  280  before asserting media defect output  290 , false positives are avoided. Further, by making programmable data threshold  265  and programmable bit count  280 , it is possible to adjust the sensitivity of correlation based defect detection system  200 . Left edge extend  286  and right edge extend  288  allow for the period of assertion of media defect  290  to be extended to capture the period where ratio  257  first extends below programmable data threshold  265  and after ratio  257  extends above programmable data threshold  265 . In some cases, left edge extend input  286  and right edge extend input  288  are each individually programmable. In some cases, left edge extend input  286  may be increased to provide a left edge extension and to compensate for the delay programmed via programmable bit count  280 . 
         [0035]    Turning to  FIG. 3 , yet another correlation based defect detection system  300  is depicted in accordance with various embodiments of the present invention. Correlation based defect detection system  300  includes a maximum a posteriori (MAP) data detector  315  that receives a media data input  305  and provides a soft log-likelihood ratio (LLR) output  316  and a hard output  318  (i.e., an NRZ output). Hard output  318  is provided to a normalize circuit  319 . As an example, the output of normalize circuit  319  may go from approximately negative one to positive one during non-defective portions of the media at issue. MAP detector  315  may be any MAP detector known in the art, and LLR output  316  and NRZ output  318  may be done using algorithms and circuits known in the art. Each of LLR output  316  and NRZ output  318  are fed through respective partial response target circuits  320 ,  325  as are known in the art. The output of partial response target circuit  325  is multiplied by media data input  305  passed through a delay block  310  using a multiplier  323 . Delay block  310  operates to provide a sample of media defect input  305  that is correlated in time with the output from MAP detector  315 . The multiplied output is filtered using a filter circuit  340 . Filter  340  may be, for example, a low pass filter that smoothes any noise evident at the output of multiplier  323 . 
         [0036]    Similarly, the output of partial response target circuit  320  is multiplied by media data input  305  passed through a delay block  310  using a multiplier  322 . Delay block  310  operates to provide a sample of media defect input  305  that is correlated in time with the output from MAP detector  315 . The multiplied output is filtered using a filter circuit  345 . Filter  345  may be, for example, a low pass filter that smoothes any noise evident at the output of multiplier  322 . 
         [0037]    Filter  345  provides a correlation output  347  and filter  340  provides a reference output  342 . Correlation output  347  and reference output  342  are mathematically combined using a ratio generator  355 . In particular, ratio generator  355  is operable to provide a ratio output  357  (i.e., a correlated output) defined by the following equation: 
         [0000]      Ratio Output 357=Correlation Output 347 divided by Reference Output 342. 
         [0000]    When hard output  318  is generally correct, there will be a strong correlation between correlation output  347  and reference output  342 . Alternatively, as the number of errors in hard output  318  increases, the correlation between correlation output  347  and reference output  342  will generally decrease. Ratio Output  357  is compared with a programmable data threshold  365  using a comparator  360 . Where the value of ratio output  357  is less than programmable data threshold  365 , a media defect output  370  is asserted high. Alternatively, where the value of ratio output  357  is greater than programmable data threshold  365 , media defect output  370  is de-asserted. The outputs of correlation based defect detection system  300  are similar to those depicted in  FIG. 1   b  above. Again, it should be noted that the timing diagram of  FIG. 1   b  is merely exemplary and that significant changes may occur due to a change in the media data input and the particular implementation of the correlation based media defect detection system. By making programmable data threshold  165  programmable, it is possible to adjust the sensitivity of correlation based defect detection system  300 . 
         [0038]    Turning to  FIG. 4 , yet another correlation based defect detection system  400  is depicted in accordance with various embodiments of the present invention. Correlation based defect detection system  400  includes a maximum a posteriori (MAP) data detector  415  that receives a media data input  405  and provides a soft log-likelihood ratio (LLR) output  416  and a hard output  418  (i.e., an NRZ output). Hard output  418  is provided to a normalize circuit  419 . As an example, the output of normalize circuit  419  may go from approximately negative one to positive one during non-defective portions of the media at issue. MAP detector  415  may be any MAP detector known in the art, and LLR output  416  and NRZ output  418  may be done using algorithms and circuits known in the art. Each of LLR output  416  and NRZ output  418  are fed through respective partial response target circuits  420 ,  425  as are known in the art. The output of partial response target circuit  425  is multiplied by media data input  405  passed through a delay block  410  using a multiplier  423 . Delay block  310  operates to provide a sample of media defect input  405  that is correlation in time with the output from MAP detector  415 . The multiplied output is filtered using a filter circuit  440 . Filter  440  may be, for example, a low pass filter that smoothes any noise evident at the output of multiplier  423 . 
         [0039]    Similarly, the output of partial response target circuit  420  is multiplied by media data input  405  passed through a delay block  410  using a multiplier  422 . Delay block  410  operates to provide a sample of media defect input  305  that is correlated in time with the output from MAP detector  415 . The multiplied output is filtered using a filter circuit  445 . Filter  445  may be, for example, a low pass filter that smoothes any noise evident at the output of multiplier  422 . 
         [0040]    Filter  445  provides a correlation output  447  and filter  440  provides a reference output  442 . Correlation output  447  and reference output  442  are mathematically combined using a ratio generator  455 . In particular, ratio generator  455  is operable to provide a ratio output  457  (i.e., a correlated output) defined by the following equation: 
         [0000]      Ratio Output 457=Correlation Output 447 divided by Reference Output 442. 
         [0000]    When hard output  418  is generally correct, there will be a strong correlation between correlation output  447  and reference output  442 . Alternatively, as the number of errors in hard output  418  increases, the correlation between correlation output  447  and reference output  442  will generally decrease. Ratio Output  457  is compared with a programmable data threshold  465  using a comparator  460 . Where the value of ratio output  457  is less than programmable data threshold  465 , an output of comparator  460  is asserted high. Alternatively, where the value of ratio output  457  is greater than programmable data threshold  465 , comparator output  467  is de-asserted. 
         [0041]    Comparator output  467  is provided to an assertion circuit including a run length monitor  482  and an edge extender  484 . Run length monitor  482  causes an output  483  to assert whenever comparator output  467  is asserted continuously for a predefined number of cycles (i.e., a programmable bit count  480 ). Said another way, whenever comparator output  467  is asserted for a continuous number of cycles equivalent to programmable bit count  480 , output  483  is asserted. This allows the circuit to filter out the occasional misreads or only limited defects regions. Output  483  is provided to an edge extender circuit  484  that operates to extend the assertion period of a media defect output  490 . In particular, media defect output  490  is extended to the left by an amount indicated by a left edge extend input  486  and to the right by a right edge extend input  488 . Extending the right and left edges allows for capture of information from the grey area surrounding a defective media region. The outputs of correlation based defect detection system  400  are similar to those depicted in  FIG. 2   b  above. Again, it should be noted that the timing diagram of  FIG. 2   b  is merely exemplary and that significant changes may occur due to a change in the media data input and the particular implementation of the correlation based media defect detection system. By waiting a period corresponding to programmable bit count  480  before asserting media defect output  490 , false positives are avoided. Further, by making programmable data threshold  465  and programmable bit count  480 , it is possible to adjust the sensitivity of correlation based defect detection system  400 . 
         [0042]    Turning to  FIG. 5 , a storage system  500  including a media defect system is shown in accordance with various embodiments of the present invention. Storage system  500  may be, for example, a hard disk drive. Storage system  500  includes a read channel  510  with an incorporated media defect detector. The incorporated media defect detector may be any media defect detector capable of using a filter based approach to form a determination of a media defect. Thus, for example, the incorporated media defect detector may be, but is not limited to, any of correlation based defect detection systems  100 ,  200 ,  300 ,  400 . In addition, storage system  500  includes an interface controller  520 , a preamp  570 , a hard disk controller  566 , a motor controller  568 , a spindle motor  572 , a disk platter  578 , and a read/write head  576 . Interface controller  520  controls addressing and timing of data to/from disk platter  578 . The data on disk platter  578  consists of groups of magnetic signals that may be detected by read/write head assembly  576  when the assembly is properly positioned over disk platter  578 . In a typical read operation, read/write head assembly  576  is accurately positioned by motor controller  568  over a desired data track on disk platter  578 . Motor controller  568  both positions read/write head assembly  576  in relation to disk platter  578  and drives spindle motor  572  by moving read/write head assembly to the proper data track on disk platter  578  under the direction of hard disk controller  566 . Spindle motor  572  spins disk platter  578  at a determined spin rate (RPMs). 
         [0043]    Once read/write head assembly  578  is positioned adjacent the proper data track, magnetic signals representing data on disk platter  578  are sensed by read/write head assembly  576  as disk platter  578  is rotated by spindle motor  572 . The sensed magnetic signals are provided as a continuous, minute analog signal representative of the magnetic data on disk platter  578 . This minute analog signal is transferred from read/write head assembly  576  to read channel module  564  via preamp  570 . Preamp  570  is operable to amplify the minute analog signals accessed from disk platter  578 . In addition, preamp  570  is operable to amplify data from read channel module  510  that is destined to be written to disk platter  578 . In turn, read channel module  510  decodes (including media defect detection) and digitizes the received analog signal to recreate the information originally written to disk platter  578 . This data is provided as read data  503  to a receiving circuit. A write operation is substantially the opposite of the preceding read operation with write data  501  being provided to read channel module  510 . This data is then encoded and written to disk platter  578 . 
         [0044]    Turning to  FIG. 6 , a communication system  600  including a receiver  620  with a media defect system in accordance with one or more embodiments of the present invention is shown. Communication system  600  includes a transmitter that is operable to transmit encoded information via a transfer medium  630  as is known in the art. The encoded data is received from transfer medium  630  by receiver  620 . Receiver  620  incorporates a media defect detection circuit that is operable to determine whether a “defect” has occurred in transfer medium  630 . Thus, for example, where transfer medium  620  is the Internet, it may determine that no signal is being received. Alternatively, where transfer medium  620  is the atmosphere carrying wireless signals, the media defect detection circuit may indicate a very noisy and unreliable transfer environment. Based on the disclosure provided herein, one of ordinary skill in the art will recognize a variety of mediums that may include defects and that may be utilized in relation to different embodiments of the present invention. The incorporated media defect detector may be any media defect detector capable of using soft information to form a determination of a media defect. Thus, for example, the incorporated media defect detector may be, but is not limited to, any of correlation based defect detection systems  100 ,  200 ,  300 ,  400 . 
         [0045]    In conclusion, the invention provides novel systems, devices, methods and arrangements for detecting media defects. While detailed descriptions of one or more embodiments of the invention have been given above, various alternatives, modifications, and equivalents will be apparent to those skilled in the art without varying from the spirit of the invention. For example, one or more embodiments of the present invention may be applied to various data storage systems and digital communication systems, such as, for example, tape recording systems, optical disk drives, wireless systems, and digital subscribe line systems. Therefore, the above description should not be taken as limiting the scope of the invention, which is defined by the appended claims.

Technology Category: 3