Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1999-11-10
2003-04-29
Tu, Christine T. (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C714S819000
Reexamination Certificate
active
06557136
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to transmission and storage systems with certain constraints such as a maximum number of consecutive zeros within a given block that is transmitted or stored.
2. Description of Background Information
Digital magnetic recording systems use run length limited coding to constrain the number of consecutive recorded zeros within given segments of data. A (d,k) code is used; “d” represents the minimum number of consecutive zeros between the 1's, and “k” represents the maximum number of consecutive zeros between the 1's. Conventional recording systems typically use (0,k) constraints, i.e., constraints in which there is no minimum number of zeros between the 1's. The “k” constraint is used for synchronization purposes, e.g., to ensure that the timing of a phase locked loop remains accurate.
FIG. 1
is a block diagram of a digital magnetic recording system
10
. Data is stored on a recording medium
18
for later playback. The illustrated digital magnetic recording system
10
comprises an ECC (error correction code) encoder
12
. ECC encoder
12
has an output coupled to an input of a (d,k) encoder
14
. The output of (d,k) encoder
14
is connected to an input of a precoder
16
, the output of which is coupled to a mechanism for recording data onto a recording medium
18
. Data played back from recording medium
18
is forwarded to an input of a Viterbi decoder
20
, the output of which is connected to an input of a (d,k) decoder
22
. The output of (d,k) decoder
22
is connected to an input of an ECC decoder
24
. In operation, input data
11
is received at an input of ECC encoder
12
, which ECC encodes the input data and forwards the ECC encoded input data to (d,k) encoder
14
. The (d,k) encoder
14
further encodes the data to control the (d,k) constraints of the data. The (d,k) constrained data is then input to precoder
16
, which precodes the data before it is stored on recording medium
18
. When the data is played back from recording medium
18
, it is input to viterbi decoder
20
, which decodes the data and forwards the decoded data to (d,k) decoder
22
, which reverses the encoding performed by (d,k) encoder
14
. The (d,k) decoded data is then input to ECC decoder
24
, which performs an appropriate ECC decoding operation on the data, and outputs the data at its output
25
.
Some digital magnetic recording systems may utilize turbo coding. Such systems split the decoding operation into two steps, and iterate between them.
FIG. 2
is a block diagram of a turbo coding digital magnetic recording system
28
.
An ECC encoder
29
is provided which has one input and two outputs. Input data
27
is received at its input, the first of its outputs is connected to a multiplex puncture mechanism
30
, and a second output is connected to a convolutional encoder
31
. Convolutional encoder
31
comprises an output which is coupled to multiplex puncture mechanism
30
. Multiplex puncture mechanism
30
comprises an output which is connected to a precoder
32
, the output of which is connected to a random permuting operator
34
. The output of random permuting operator
34
is connected to a mechanism for placing the data it outputs onto a recording medium
36
. When data is played back from recording medium
36
, it is forwarded to an input of an APP channel
40
, which forms one element of an iterative decoder
38
. Decoder
38
comprises an output which is connected to an input of an ECC decoder
56
, which outputs output data
57
at its output. As shown in
FIG. 2
, iterative decoder
38
comprises a plurality of elements, including a reverse random permuting operator
44
, a de-multiplex, de-puncture mechanism
46
, an APP convolutional code mechanism
48
, a multiplex puncture mechanism
50
, and a random permuting operator
54
. The illustrated iterative decoder
38
further comprises first and second adders
42
and
52
. APP channel
40
comprises two inputs, one of which receives data played back from recording medium
36
. It also has an output which is connected directly to first adder
42
. The output of first adder
42
is connected to an input of reverse random permuting operator
44
, the output of which connects to an input of de-multiplex de-puncture mechanism
46
. Mechanism
46
comprises one output which is connected to both APP convolutional code mechanism
48
and an input of second adder
52
. APP convolutional code mechanism
48
comprises a first output which is connected to an input of multiplex puncture mechanism
50
, the output of which is connected to a second input of second adder
52
. The output of second adder
52
is connected to the input of random permuting operator
54
. The output of random permuting operator
54
is connected to a second input of first adder
42
and is further connected to the second input of APP channel
40
.
There is a need for alternate/improved methods for limiting the number of consecutive zeros within a block of information to be stored or transmitted in transmission and storage systems, e.g., in a digital magnetic recording system such as that shown in FIG.
1
. Moreover, there is a need for a method or system which will allow (d,k) encoding methods to be applied to turbo coding systems, such as in the system illustrated in FIG.
2
.
SUMMARY OF THE INVENTION
The present invention is presented to bring about one or more advantages, such as those noted below. One object of the present invention is to provide an alternate, improved method and system for encoding and decoding binary data so as to limit the number of consecutive zeros within a given block of such data, as the data is forwarded to a temporary holding media, such as a transmission media or storage media. A further object of the present invention is to provide a (d,k) coding system which is applicable to newer proposed magnetic recording systems using turbo codes. Another object of the present invention is to provide a coding method and system which will use little overhead in its operation.
The present invention, therefore, is directed to a method or system, or one or more components thereof, for encoding binary input data comprising payload data to facilitate the preservation of the payload data destined for a temporary holding media, such as transmission media or storage media. A scrambler receives and scrambles given binary input data to produce given scrambled data. A de-scrambler receives and unscrambles the given scrambled data to produce given output data. The given scrambled data may be written in the form of media data onto storage media, or it may be transmitted in the form of media data over transmission media. The de-scrambler receives and unscrambles the given scramble data from the media data which is recovered from the storage media or the transmission media.
A criteria checker may be provided for determining whether the given scrambled data satisfies desired criteria. The desired criteria may be a k constraint, which represents the maximum number of consecutive zeros allowed within the given scrambled data. In a particular embodiment, the given scrambled data comprises a block of data of a predetermined size. A scramble modifier changes the given scrambled data until it satisfies the desired criteria. The temporary holding media may comprise a storage media, and may more specifically comprise a magnetic recording disk. In a specific embodiment, the magnetic recording disk comprises a turbo coded magnetic recording disk.
The scrambler, in a particular aspect of the present invention, comprises a pseudo-random scrambler. The pseudo-random scrambler may comprise a set of pseudo-random sequences and a mechanism for XORing a given pseudo-random binary sequence from the set with the given binary input data to produce the given scrambled data. The scramble modifier may comprise a mechanism for causing the scrambler to re-scramble the given binary input data using a different pseudo-random sequence from the set of pseudo-random sequences. The de-scra
Maxtor Corporation
Sigmond David M.
Tu Christine T.
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