Digital data transmission system having error detecting and correcting function
First Claim
1. In an information transmission system for coding n-bit information data in the form of an NRZL code into m-bit coded data such that each of said information data corresponds to only one of said coded data which are all different from one another, n being greater than 2 and m being greater than n, NRZI converting said m-bit coded data such that m-bit coded data having a codeword digital sum (CDS) which does not have the same polarity as a digital sum variation (DSV) of previously NRZI converted m-bit coded data is selected as a next NRZI conversion input to limit the DSV of the NRZI converted signal, and transmitting the thus NRZI converted coded data, the combination of:
- first controlling means for generating a control signal to control NRZI conversion of said m-bit coded data and for generating a mode signal;
code generating means for generating identification data having a predetermined data pattern corresponding to said n-bit information data and for outputting said identification data and said m-bit coded data obtained by coding of said n-bit information data in response to said mode signal and a coding control signal;
CDS generating means for generating a CDS corresponding to said identification data and m-bit coded data output by said code generating means in response to said mode signal and the coding control signal;
NRZI converting means responsive to said control signal from said first controlling means for outputting the identification data obtained from said code generating means as they are without NRZI converting the same and for executing NRZI conversion of said m-bit coded data outputted from said code generating means using an initial value determined by a conversion initial value signal;
latching means for latching the last bit of the identification data outputted from said NRZI converting means and providing the latched bit as said conversion initial value signal;
DSV detecting means for detecting a current DSV corresponding to an output signal of said NRZI converting means in response to said conversion initial value signal and a DSV immediately preceding said current DSV; and
second controlling means for generating said coding control signal in response to said control signal from said first controlling means, said identification data and m-bit coded data output from said CDS generating means, said conversion initial value signal and the detected current DSV from said DSV detecting means to limit the DSV of the output signal of said NRZI converting means.
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Accused Products
Abstract
In an information data recording and reproducing device which can record and reproduce input information data accurately, an error correction code of the product sign format is added to the input information data to form coded data. The coded data are then NRZI converted and recorded onto a recording medium together with identification data of a predetermined data pattern. Error detecting and correcting are performed on data reproduced from the recording medium so as to obtain the data recorded on the recording medium. The device comprises an NRZI converting circuit for outputting the identification data as they are, that is, without NRZI conversion, and for NRZI converting the coded data using the last bit of the identification data as an initial value, and a memory controlling circuit for controlling writing and reading of a memory, which is provided to convert the reproduction data from a series of inner codes into another series of outer codes, so that write address information for the memory which is obtained from the reproduction data may be compensated for when it is not obtained properly and outer code error detection and correction may be readily executed.
39 Citations
19 Claims
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1. In an information transmission system for coding n-bit information data in the form of an NRZL code into m-bit coded data such that each of said information data corresponds to only one of said coded data which are all different from one another, n being greater than 2 and m being greater than n, NRZI converting said m-bit coded data such that m-bit coded data having a codeword digital sum (CDS) which does not have the same polarity as a digital sum variation (DSV) of previously NRZI converted m-bit coded data is selected as a next NRZI conversion input to limit the DSV of the NRZI converted signal, and transmitting the thus NRZI converted coded data, the combination of:
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first controlling means for generating a control signal to control NRZI conversion of said m-bit coded data and for generating a mode signal; code generating means for generating identification data having a predetermined data pattern corresponding to said n-bit information data and for outputting said identification data and said m-bit coded data obtained by coding of said n-bit information data in response to said mode signal and a coding control signal; CDS generating means for generating a CDS corresponding to said identification data and m-bit coded data output by said code generating means in response to said mode signal and the coding control signal; NRZI converting means responsive to said control signal from said first controlling means for outputting the identification data obtained from said code generating means as they are without NRZI converting the same and for executing NRZI conversion of said m-bit coded data outputted from said code generating means using an initial value determined by a conversion initial value signal; latching means for latching the last bit of the identification data outputted from said NRZI converting means and providing the latched bit as said conversion initial value signal; DSV detecting means for detecting a current DSV corresponding to an output signal of said NRZI converting means in response to said conversion initial value signal and a DSV immediately preceding said current DSV; and second controlling means for generating said coding control signal in response to said control signal from said first controlling means, said identification data and m-bit coded data output from said CDS generating means, said conversion initial value signal and the detected current DSV from said DSV detecting means to limit the DSV of the output signal of said NRZI converting means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An information transmission system for converting coded data in the form of an NRZL code into an NRZI code and transmitting the NRZI code together with identification data included in a predetermined data pattern, comprising:
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NRZI converting means for NRZI converting said coded data but outputting the identification data without NRZI conversion; and latch means for latching the last bit of said identification data of an output of said NRZI converting means, and said NRZI converting means NRZI converting said coded data using output data of said latch means as an initial value. - View Dependent Claims (10, 11, 12, 13)
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14. An information recording device for converting coded data in the form of an NRZL code into NRZI coded data and recording the NRZI coded data together with identification data included in a predetermined data pattern, comprising:
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NRZI converting means for NRZI converting said coded data while outputting the identification data without NRZI conversion thereof; latch means for latching a last bit of said identification data in an output of said NRZI converting means; said NRZI converting means NRZI converting said coded data using output data of said latch means as an initial value; and means for recording an output signal of said NRZI converting means on a record medium. - View Dependent Claims (15, 16, 17, 18)
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19. An information data recording and reproducing device for adding an error correction code of the product sign format to input information data to form coded data, NRZI converting the coded data, recording the NRZI converted coded data together with predetermined data including identification data on a record medium, and performing error detection and correction of reproduction data obtained from such record medium to reproduce data recorded on the record medium, comprising:
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NRZI converting means for outputting the identification data without NRZI conversion thereof while NRZI converting the coded data, said NRZI converting means further including a latch means for latching the last bit of the identification data outputted from said NRZI converting means said NRZI converting means using output data of said latch means as an initial value in said NRZI converting of said coded data; inner code error detecting and correcting means for detecting an inner code error of said transmission data, correcting the thus detected inner code error and outputting inner code correction data in a predetermined block data unit; memory means for storing said inner code correction data therein; counting means for counting said inner code correction data for each said block of data as a unit; identification data detecting means for detecting identification data of each said block of data of the inner code correction data which is free of error or which has been corrected to eliminate error; offset detecting means for detecting an offset amount between output data of said counting means and output data of said identification data detecting means and providing corresponding offset data; adding means for adding the output data of said identification data detecting means and output data of said offset detecting means and providing an added output which presets said counting means; monitoring means for monitoring continuity of said block data on the basis of output data of said counting means and output data of said identification data detecting means as well as an error flag generated by said inner code error detecting and correcting means, and for judging from said monitoring whether or not the block data are correct block data and providing a corresponding selecting signal; data selecting means for selecting either the output data of said counting means or the output data of said identification data detecting means as an output signal in response to said selecting signal of said monitoring means; address generating means for generating address data identifying addresses at which said inner code correction data are to be written in said memory means in response to the output data from said data selecting means; and outer code error detecting and correcting means for reading out data stored in said memory means in accordance with a series of outer codes in accordance with said offset data from said offset detecting means, detecting an outer code error of the data thus read out and correcting the outer code error thus detected.
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Specification