摘要:
At least one bit of a digital signal including a plurality of bits to be simultaneously recorded on a plurality of tracks of a magnetic tape, is recorded on at least two tracks located at opposite sides with respect to a reference track. The reference track carries a reference signal utilized for producing a synchronous signal with which the plurality of bits are reproduced in synchronization. When reproducing, a.c. signals derived from the two corresponding tracks having the simultaneously recorded bits are added to each other whereby the phase difference of the plurality of bits with respect to the reference signal is compensated while drop out phenomenon is reduced.
摘要:
Source data is organized by a time compression memory (4) into a plurality of successive groups of data words arranged in a pattern of rows and columns with the rows corresponding to respective recording tracks. A plurality of successive groups of parity check words is provided in the same pattern of rows and columns as the data words subsequent to the data word groups. Each parity check word is derived in a parity generator (6) by modulo-2 summations from the data words selected from different data word groups. The data and check words of each row of each respective group are (a) preceded by a synchronization code provided by a sync generator (10) to allow differentiation between data and parity groups, and (b) followed by a cyclic redundancy check, (CRC) code provided by a CRCC generator (9) to allow detection of an error in that data row or check words. The parity check word is used to correct an error specified by the CRC code upon detection of an error.
摘要:
In a magnetic recording and reproducing device having at least one rotating magnetic head for recording and reproducing video signal and digital form audio signal in a contiguous manner along each track which is inclined at an angle relative to the direction of travel of a magnetic tape, a discriminator signal is combined to the digital form audio signal. The discrimination signal has a first section carrying a check code and a second section carrying information. During the reproducing mode, the discrimination signal is detected such that the information carried in the second section is made invalid when the check code has a predetermined code pattern, and the information carried in the second section is made valid when the check code has a code pattern other than the predetermined code pattern. Furthermore, the check code is used to indicate the type of information contained in the second section.
摘要:
A method is disclosed for processing binary data prior to magnetic recording. The binary data is divided into 4-bit data segments which are converted to 8-bit codes according to a predetermined encoding transfer function describing the relationships between the 4-bit data segments and corresponding 8-bit codes, wherein the bit pattern of each 8-bit code has an intra-code run-length of at least two "0" bits and forms an inter-code run-length of from at least two "0" bits to at most nine "0"bits with an adjacent 8-bit code. The method further includes the step of generating a frame synchronization code and interleaving it with 8-bit codes to form a frame of binary digits. The frame sync code has a bit pattern which is unduplicatable by any combination of 8-bit codes that follow.
摘要:
Signal recording method and apparatus for efficiently correcting a bit error due to dropout occurred in recording an analog data into a digital data and reproducing the digital data is disclosed. The digital signal converted from the analog signal is divided into a plurality of groups to each of which a parity check bit is added. Record pattern is recorded on a record medium by a recording apparatus in accordance with a regular coding such as FM (frequency modulation) or MFM (modified frequency modulation) coding such that more than one bits in a group are not simultaneously influenced by the dropout, e.g. individual bits in a group are spaced from each other by several tracks. On reproducing, the coded digital signal is decoded into the original digital signal and the dropout is detected utilizing the nature of the regularity of the coding. The parity is checked for each of the groups. In this a single error in the group can be corrected and a double error is supplemented by holding a previous value, whereby the error due to the dropout is reduced.
摘要:
A method of encoding and decoding binary data, comprising the steps of: dividing the binary data into 2-bit data groups, converting each 2-bit data group into a 5-bit code having a minimum of 4 consecutive bits "0" between a bit "1" and the next bit "1", and converting reversely the encoded 5-bit codes into the original binary data with reference to another 5-bit codes located forwardly of and rearwardly of the 5-bit code. By employing this method, it becomes possible to obtain a density twice higher than that of "MFM" method.
摘要:
In a magnetic recording/reproducing apparatus having a multi-track head for writing a digital signal on a magnetic recording medium, a plurality of head of the multi-track head is electrically divided into a plurality of groups which are respectively driven by writing currents produced in accordance with a plurality of modulated signals indicative of input digital data. The writing currents fed to the heads of the same group are produced in response to a pulse signal such that a plurality of pulse signals having different phases are used for respective groups. The head in the same group are positioned so that they are not adjacent to each other, and therefore, undesirable crosstalk can be reduced because heads corresponding to adjacent tracks are prevented from being driven simultaneously, while the entire writing current power can be reduced. The waveform of each of the writing currents may be controlled in accordance with the period of level inversion of the modulated signals, and therefore, peak shift phenomena due to waveform interference can be reduced.
摘要:
A character recognition unit recognizes a document image to output character candidates; a character correction unit selects a corrected character string which is correct with respect to grammar and vocabulary, from a set of character candidates from the character recognition unit; a keyword extraction unit extracts keywords of a document to be recognized, from the corrected character string; and wherein the character correction unit selects the corrected character string by a use of BUNSETSU evaluation representing correctness with respect to grammar and vocabulary, and an evaluation of the BUNSETSU is increased when the BUNSETSU has the keyword outputted from the keyword extraction unit.
摘要:
A learning and recognition machine has a major classification section for classifying an input pattern into a plurality of category groups and calculating a group belongingness to each category group and a plurality of fine classification sections for calculating a similarity within each category group. The machine causes the plurality of fine classification sections to learn in a coordinated manner by reflecting the group belongingness of the input pattern to update of a weight factor implemented in the fine classification sections, thereby allowing a recognition rate of a pattern situated at the boundary of the category groups to be improved and an effective supplemental learning to be performed.
摘要:
There is disclosed a character recognition machine adapted to recognize Japanese characters such as kanjis and kanas. The machine comprises a character string storage portion, a character extraction portion, a character recognition portion, and a language processing portion. A character string to be recognized is stored as an image in the storage portion. The character extraction portion comprises a network consisting a plurality of interconnected operators each of which has numerous inputs and outputs. An evaluation function which assumes its minimum value when a character extraction produces the best results is calculated by the operators simultaneously so as to minimize the value of the function. The character recognition portion calculates degrees of similarity of a character pattern to various character categories, the character pattern being applied from the character extraction portion. The language processing portion receives these degrees of similarity and selects a character category which seems to provide the most correct combination of characters in terms of vocabulary and grammar.