Multi-channel parallel writing method for photochromic multi-wavelength optical storage
A photochromic, multi-wavelength technology, applied in the direction of optical recording/reproduction/erasing methods, optical recording systems, etc., can solve problems such as interference between sequence codes, and achieve the effect of improving storage capacity and high coding efficiency
Inactive Publication Date: 2006-06-07
TSINGHUA UNIV
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The parameter d controls the highest transmission frequency and thus may cause intersymbol interference when the sequence is transmitted over a band-limited channel
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[0027] The present invention will be further described below in conjunction with the accompanying drawings and a specific example.
[0028] First a brief introduction to the theoretical basis of coding. In optical (magnetic) storage systems, the encoder's task is to convert (binary) user data into a sequence that fits within the constraints of a given channel. On average, m binary user data symbols are converted into n binary channel symbols. The efficiency of the modulation code is measured by the quotient R=m / n of m and n, where R is called the information rate, or code rate for short. For a channel with a given input limit, its maximum code rate is usually called capacity, denoted by C.
[0029] According to the capacity calculation formula of Shannon theory, the capacity formula of the run-length limited (d, k) code can be obtained:
[0030] C(d,k)=log 2 lambda
[0031] where λ is the largest positive real root of the following equation:
[0032] x k+2 -x k+1 -x k...
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A multi-channel parallel writing method for photochromic multi-wavelength optical storage belongs to the technical field of optical storage. This method uses a two-dimensional encoder to convert single-channel one-dimensional user data into multi-channel two-dimensional data, and makes the encoded multi-row two-dimensional data array meet the (d, k) run length limit, wherein the two-dimensional data array Each row of the array satisfies the d constraint, but the logical "or" of the data of the same column on each row of the array satisfies the k constraint; then, the data of each row of the two-dimensional data array is input to a data channel, and each data channel controls a laser writing, realizing data parallel writing of multi-wavelength optical storage. By adopting the multi-channel parallel writing method of the present invention, the data transmission rate of the multi-wavelength optical storage can be doubled compared with that of a single channel. Moreover, since the multi-channel two-dimensional coding method can obtain higher coding efficiency than the traditional single-channel one-dimensional method, the storage capacity of multi-wavelength optical storage can be further improved.
Description
technical field [0001] The invention belongs to the technical field of optical storage, in particular to the technical field of photochromic multi-wavelength optical storage. Background technique [0002] The rapid development of information technology has put forward higher and higher requirements on the capacity and data transmission rate of optical storage systems. The mainstream technology to further increase optical storage capacity is to reduce the size of information symbols, thereby increasing the storage density per unit area. This is achieved by using shorter wavelength lasers and higher numerical aperture objectives. The latest DVR (disc video recording) technology reduces the wavelength of the laser to 405nm, and increases the numerical aperture of the objective lens to 0.85, thereby increasing the capacity to more than 20GB. However, due to the increase of the numerical aperture of the objective lens, the front working distance becomes smaller, so higher requir...
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IPC IPC(8): G11B7/0045
Inventor 徐端颐胡华张启程齐国生
Owner TSINGHUA UNIV