Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data verification
Reexamination Certificate
1998-04-07
2001-01-30
Kim, W. Chris (Department: 2753)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data verification
Reexamination Certificate
active
06181499
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a method and apparatus for testing in general, and in particular to a method and apparatus for testing digital channel circuitry. Still more particularly, the present invention relates to a method and apparatus for testing digital read channel circuits of data storage devices.
2. Description of the Prior Art
A magnetic recording channel within a magnetic storage device, such as a magnetic tape drive, is designed to accept data for storage and to deliver, without error, the same in response to a subsequent retrieval demand. During data retrieval, self-clocking modulation codes are typically employed to ensure an adequate minimum rate of signal transitions for clock synchronization, without exceeding the maximum transition storage density of the magnetic storage medium during data storage. Such self-clocking modulation codes are preferably run-length-limiting (RLL) codes that represent a one-to-one mapping of binary data into a constrained binary sequence that is then recorded on the magnetic storage medium in the form of a non-return-to-zero (NRZ) waveform.
For an NRZ waveform, the maximum and minimum number of spaces between consecutive transitions correspond to the maximum and minimum run lengths of zeros between two consecutive ones in a corresponding binary sequence, as is well-known in the prior art. Thus, the self-clocking modulation codes within the RLL codes are characterized by parameters (D, K), where D represents the minimum and K represents the maximum number of zeros between two consecutive ones in the code sequence. These codes are the result of the steady evolution of waveform design coupled with improvements in magnetic recording channels, including improved clocking and signal-detection processors.
Generally speaking, a magnetic recording channel includes a write path for writing data to and a read path for reading data from a magnetic storage medium. The write path usually includes a digital write channel and a write driver, and the read path usually includes an analog processor, an analog-to-digital converter, and a digital read channel. The present invention discloses a method and apparatus for testing the integrity of the digital read channel circuit, as well as a formatter/deformatter that is coupled between the digital read channel circuit and the digital write channel circuit.
SUMMARY OF THE INVENTION
In view of the foregoing, it is therefore an object of the present invention to provide an improved method and apparatus for testing.
It is another object of the present invention to provide an improved method and apparatus for testing digital channel circuitry.
It is yet another object of the present invention to provide an improved method and apparatus for testing digital read channel circuits of data storage devices.
In accordance with a method and system of the present invention, a data storage device includes a digital read channel circuit coupled to a simulated impulse response module. A pseudo analog-to-digital waveform is generated by the simulated impulse response module is input into the digital read channel circuit. The digital read channel circuit then decodes the pseudo analog-to-digital waveform to form a set of binary data. After receiving the set of binary data, a formatter/deformatter verifies the correctness of the binary data, such that the integrity of the digital read channel circuit and the formatter/deformatter can be determined.
All objects, features, and advantages of the present invention will become apparent in the following detailed written description.
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Hutchins Robert Allen
Schaffer Scott Jeffrey
Felsman Bradley Vaden Gunter & Dillon, LLP
International Business Machines - Corporation
Kim W. Chris
Sullivan Robert M.
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