Techniques for modulating data using short block encoders

A disk drive controller chipset comprising:

• a short block encoder that maps a first portion of each block of input data to an output sequence;
• means for separating even and odd interleaves from a second portion of each block of input data and from the output sequence of the short block encoder;
• means for applying a first modulation constraint to the even interleaves to generate constrained even interleaves;
• and
• means for applying a second modulation constraint to the odd interleaves to generate constrained odd interleaves.

A method for performing modulation encoding on blocks of data prior to recording the data on a computer readable medium, the method comprising:

• applying a modulation constraint to a first portion of each data block to generate a constrained output;
• separating even and odd interleaves of the constrained output and a second portion of each data block;
• imposing modulation constraints on the even interleaves to generate constrained even interleaves;
• imposing modulation constraints on the odd interleaves to generate constrained odd interleaves;
• and
• interleaving the constrained even interleaves and the constrained odd interleaves.