Data decoding apparatus and method utilizing a single channel maximum likelihood decoder
AssigneeSamsung Electronics Co., Ltd.
InventorsIwamura Soichi, Jin-kyu Jeon
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Abstract
A data decoding apparatus and method are provided for decoding a reproduction signal in a digital magnetic recording/reproducing apparatus. A Viterbi decoder having a single channel is constructed such that the noise level corresponds to that of an EnPR4 system and the aperture ratio of an eye pattern corresponds to that of a PR(+1, −1) system, thereby improving the efficiency of the Viterbi decoder and allowing state detection by the PR(+1, −1) system. Data can be decoded by a system having a PR4 or EnPR4 channel or selectively by other various systems.
Claims25
A data decoding apparatus in a recording/reproducing system having a PR4 channel including a precoder having a 1/(1+D) characteristic, wherein D is a delay period corresponding to one bit of recorded data, the data decoding apparatus comprising:
- a pre-filter having a (1+D) characteristic, for converting a PR(+1, −1) signal received through said PR4 channel into a PR4(+1, 0, −1) signal;
- an inverse pre-filter having a 1/(1+D) characteristic, for converting the PR4(+1,0,−1) signal received through said PR4 channel into a PR(+1,−1) signal again;
- a maximum likelihood decoder having only a single channel, for maximum-likelihood-decoding the PR(+1, −1) signal output from said inverse pre-filter to generate maximum-likelihood-decoded data;
- and
- a channel demodulator having a (1+D) characteristic, which is an inverse characteristic of said precoder, for channel-demodulating said maximum-likelihood-decoded data to generate decoded data.
A data decoding apparatus in a recording/reproducing system having an EnPR4 channel including a precoder having a 1/(1+D)n+1 characteristic, wherein D is a delay period corresponding to one bit of recorded data and n equals the number of D delay periods of the precoder, the data decoding apparatus comprising:
- a first pre-filter having a (1+D) characteristic, for converting a PR(+1, −1) signal received through said EnPR4 channel into a PR4(+1, 0, −1) signal;
- a state detector for detecting positive and negative state values of the PR(+1, −1) signal depending on positive and negative threshold values varying according to the PR(+1, −1) signal;
- a first inverse pre-filter having a 1/(1+D) characteristic, for feed-back receiving the positive and negative state values detected by said state detector and converting the PR4(+1, 0, −1) signal into the PR(+1, −1) signal which is provided to said state detector, said state detector and said first inverse pre-filter being connected in series;
- a Viterbi decoder having a single channel, for receiving and Viterbi-decoding the positive and negative state values detected by said state detector to generate Viterbi-decoded data;
- and
- a channel demodulator having a (1+D)n+1 characteristic, which is an inverse characteristic of said precoder, for channel-demodulating the Viterbi decoded data to generate decoded data.
A data decoding apparatus in a recording/reproducing system having a PR4 channel including a precoder having a 1/(1+D) characteristic, wherein D is a delay period corresponding to one bit of recorded data, the data decoding apparatus comprising:
- a first pre-filter having a (1+D) characteristic, for converting a PR(+1, −1) signal received through said channel into a PR4(+1, 0, −1) signal;
- a state detector for detecting positive and negative state values depending on positive and negative threshold values varying according to the PR(+1, −1) signal;
- a first inverse pre-filter having a 1/(1+D) characteristic, for feed-back receiving the positive and negative state values detected by said state detector, converting again the PR4(+1, 0, −1) signal into the PR(+1, −1) signal and outputting the converted signal to said state detector, said state decoder and said inverse pre-filter being connected in series;
- a Viterbi decoder having a single channel, for receiving and Viterbi-decoding the positive and negative state values detected by said state detector to generate Viterbi-decoded data;
- and
- a first channel demodulator having a (1+D) characteristic which is an inverse characteristic of said precoder, for channel-demodulating the Viterbi-decoded data to output decoded data of a PR4 mode;
- a second channel demodulator having a (1+D)n characteristic, for channel-demodulating the output of said first channel demodulator to output decoded data of an EnPR4 mode;
- and
- a selector for selecting one of the outputs of said first and second channel demodulators according to a PR4/EnPR4 mode signal.
A data decoding apparatus in a recording/reproducing system having an EnPR4 channel including a precoder having a 1/(1+D)n+1 characteristic, wherein D is a delay period corresponding to one bit of recorded data and n equals the number of D delay periods of the precoder, the data decoding apparatus comprising:
- a pre-filter having a (1+D) characteristic, for converting a PR(+1, −1) signal received through said channel into a PR4(+1, 0, −1) signal;
- a state detector for detecting positive and negative state values of the PR(+1, −1) signal depending on positive and negative threshold values varying according to the PR(+1, −1);
- an inverse pre-filter for feed-back receiving the positive and negative state values, converting again the PR4(+1, 0, −1) signal into the PR(+1, −1) signal and outputting the converted signal to said state detector, said state decoder and said inverse pre-filter being connected in series;
- a Viterbi decoder having a single channel, for receiving and Viterbi-decoding the positive and negative state values detected by said state detector to generate Viterbi-decoded data;
- and
- a first channel demodulator having 1/(1+D)n+1 characteristic, which is an inverse characteristic of said precoder, for channel-demodulating the Viterbi-decoded data to output first decoded data;
- a second channel demodulator having a (1+D)p (p=m−n−1) characteristic, for channel-demodulating the output of said first channel demodulator to output second decoded data;
- and
- a selector for selecting the first decoded data or said second decoded data in accordance with a mode signal.
A data decoding method in a system having a PR4 channel including a precoder having a 1/(1+D) characteristic, said method comprising the steps of:
- (a) delaying a PR(+1, −1) signal received through said PR4 channel to generate delayed data having a (1+D) characteristic, adding the delayed signal to the PR(+1, −1) signal to generate a PR(+1, 0, −1) signal;
- (b) subtracting the PR4(+1, 0, −1) signal from a feed-back signal to generate a PR(+1, −1) signal;
- (c) detecting positive and negative state values of the PR(+1, −1) signal depending on positive and negative threshold values varying according to the PR(+1, −1) signal generated in said (b) step, and outputting the feed-back signal obtained by adding the positive state value to the negative state value;
- (d) receiving the positive and negative state values and Viterbi-decoding the same to output Viterbi-decoded data;
- and
- (e) delaying the Viterbi-decoded data to have a (1+D) characteristic, which is an inverse characteristic of said precoder, and adding the delayed data to the Viterbi-decoded data to generate decoded data.
A data decoding method in a system having an EnPR4 channel including a precoder having a 1/(1+D)n+1 characteristic, wherein D is a delay period corresponding to one bit of recorded data and n equals the number of D delay periods of the precoder, said data decoding method comprising the steps of:
- (a) unit-bit delaying a PR(+1, −1) signal received through said EnPR4 channel to generate a delayed signal having a (1+D) characteristic, and adding the delayed signal to the PR(+1, −1) signal to generate a PR4(+1, 0, −1) signal;
- (b) subtracting the PR4(+1, 0, −1) signal from a feed-back signal to generate a PR(+1, −1) signal;
- (c) detecting positive and negative state values of the PR(+1, −1) signal depending on positive and negative threshold values varying according to the PR(+1, −1) signal generated in said (b) step, and generating the feed-back signal by adding the positive state value to the negative state value;
- (d) repeating said step (a) through step (c) (n+1)-times;
- (e) Viterbi-decoding the PR(+1, −1) signal after performing said (d) step to generate Viterbi decoded data;
- and
- (f) delaying the Viterbi decoded data by (n+1)-bits and adding the delayed Viterbi decoded data to the Viterbi-decoded data to generate decoded data having a (1+D)n+1 characteristic which is an inverse characteristic of said precoder.
A data decoding method in a system having a PR4 channel including a precoder having a 1/(1+D) characteristic, wherein D is a delay period corresponding to one bit of recorded data, said data decoding method comprising the steps of:
- (a) unit-bit delaying a PR(+1, −1) signal received through said PR4 channel to generate a delayed signal having a (1+D) characteristic, and adding the delayed signal to the PR(+1, −1) signal to generate a PR(+1, 0, −1) signal;
- (b) subtracting the PR(+1, 0, −1) signal from a feed-back signal to generate a PR(+1, −1) signal;
- (c) detecting positive and negative state values of the PR(+1, −1) signal depending on positive and negative threshold values varying according to the PR(+1, −1) signal generated in said step (b), and outputting the feed-back signal obtained by adding the positive state value to the negative state value;
- (d) repeating said (a) through (c) steps n+1 times;
- (e) Viterbi decoding the PR(+1, −1) signal after performing said step (d) to generate Viterbi decoded data;
- (f) unit-bit delaying the Viterbi decoded data to have a (1+D) characteristic which is an inverse characteristic of said precoder, and adding the delayed data to the Viterbi decoded data to generate PR4-mode decoded data;
- (g) n-bit delaying the PR4-mode decoded data to have a (1+D)n characteristic, and adding the n-bit delayed data to the PR4-mode decoded data to generate EnPR4-mode decoded data;
- and
- (h) selecting one of the PR4-mode decoded data and the EnPR4-mode decoded data according to a PR4/EnPR4 mode signal.
A data decoding method in a system having an EnPR4 channel including a precoder having a 1/(1+D)n+1 characteristic, wherein D is a delay period corresponding to one bit of recorded data and n equals the number of delay periods D of the precoder, said data decoding method comprising the steps of:
- (a) unit-bit delaying a PR(+1, −1) signal received through said EnPR4 channel to generate a delayed signal having a (1+D) characteristic, and adding the delayed signal to the PR(+1, −1) signal to generate a PR4(+1, 0, −1) signal;
- (b) subtracting the PR4(+1, 0, −1) signal from a feed-back signal to generate a PR(+1, −1) signal;
- (c) detecting positive and negative state values of the PR(+1, −1) signal depending on positive and negative threshold values varying according to the PR(+1, −1) signal converted in said (b) step, and generating the feed-back signal by adding the positive state value to the negative state value;
- (d) repeating said (a) through (c) steps m times, where m is an integer greater than n+1;
- (e) Viterbi decoding the PR(+1, −1) signal after performing said step (d) step to generate Viterbi decoded data;
- (f) n+1 bit delaying the Viterbi decoded data to have a (1+D)n+1 characteristic, which is an inverse characteristic of said precoder, and adding the n+1 bit delayed data to the Viterbi decoded data to generate first decoded data decoded in an EnPR4 mode;
- (g) p bit delaying the first decoded data to have a (1+D)p (p=m−n−1) characteristic, adding the p bit delayed data to the first decoded data to generate a second decoded data;
- and
- (h) selecting one of the first decoded data and the second decoded data according to a mode signal.
Dependencies are inferred from the claim text.