Method and apparatus for encoding and precoding digital data within modulation code constraints

An apparatus for encoding information to be transmitted in a digital communication or storage system, the apparatus comprising:

• at least one modulation encoder for encoding the information, the modulation encoder using a modulation code defined by at least one modulation constraint to generate modulation encoded information including a plurality of information bits;
• a parity encoder for parity encoding the modulation encoded information in a manner that adds at least one parity bit to the modulation encoded information;
• and
• a precoder for precoding the parity encoded information,
• wherein the precoder is programmed to satisfy the at least one modulation constraint used by the modulation encoder,
• wherein the precoder processes the first information bit after the at least one parity bit differently than the other information bits and the at least one parity bit.

A method for encoding information to be transmitted in a digital communication or storage system, the method comprising the steps of:

• modulation encoding the information using a modulation code defined by at least one modulation constraint to generate modulation encoded information including a plurality of information bits;
• parity encoding the modulation encoded information in a manner that adds at least one parity bit to the modulation encoded information;
• and
• precoding the parity encoded information in such a way that the precoded encoded information does not violate the at least one modulation constraint,
• wherein the precoding step further comprises precoding the parity encoded information with a precoder, wherein the precoder includes a precoding memory state that affects the manner in which the precoder precodes information, wherein, after the parity encoding step has added the at least one parity bit to the modulation encoded information, the precoding step resets the precoder memory state whenever the precoder reads a parity bit in the parity encoded information, and wherein the precoding step precodes the parity bits and all the information bits other than the first information bit after a parity bit.

An apparatus for encoding information to be transmitted in a digital communication or storage system, the apparatus comprising:

• at least one modulation encoder for encoding the information, the modulation encoder using a modulation code defined by at least one modulation constraint to generate modulation encoded information including a plurality of information bits;
• a parity encoder for parity encoding the modulation encoded information in a manner that adds at least one parity bit to the modulation encoded information;
• and
• a precoder for precoding the parity encoded information, wherein the precoder is programmed to satisfy the at least one modulation constraint used by the modulation encoder,
• wherein the at least one modulation constraint includes a direct current (DC) constraint, and wherein the precoder is programmed to precode the parity encoded information in such a way that the precoded information satisfies the DC constraint,
• wherein the precoder includes a precoding memory state that affects the manner in which the precoder precodes information,
• wherein, after the parity encoder has added the at least one parity bit to the information bits in the modulation encoded information, the precoder resets the precoding memory state whenever the precoder reads a parity bit in the modulation encoded information, and
• wherein the precoder precodes the parity bits and all the information bits other than the first information bit after a parity bit.