Loose composite constraint codes and their application in DVD

Bane Vasic, Goran Djordjevic, Milorad Tosic

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Constrained coding is used in recording systems to translate an arbitrary sequence of input data to a channel sequence with special properties required by the physics of the medium. Very often, more than one constraint is imposed on a recorded sequence; typically, a run-length constraint is combined with a spectral-null constraint. In this paper, we introduce a low-complexity encoder structure for composite constraints, based on loose multimode codes. The first channel constraint is imposed strictly, and the second constraint is imposed in a probabilistic fashion. Relaxing the second constraint is beneficial because it enables higher code rates and simplifies the encoder. To control the second constraint, a multimode encoder is used. We represent a set of multimode coded sequences by a weighted trellis and propose using a limited trellis search to select optimal output. Using this method, we modify the EFM+ code used in digital versatile disk (DVD). We combine EFM+'s run-length constraint with the first- and second-order spectral-null constraints. The resulting EFM++ code gives more than 10-dB improvement in suppression of low-frequency spectral content in the servo bandwidth over the original EFM+ code with the same complexity.

Original languageEnglish (US)
Pages (from-to)765-773
Number of pages9
JournalIEEE Journal on Selected Areas in Communications
Issue number4
StatePublished - Apr 2001


  • Balanced codes
  • Coding
  • Dc-free codes
  • Modulation coding
  • Optical recording
  • Spectral analysis

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


Dive into the research topics of 'Loose composite constraint codes and their application in DVD'. Together they form a unique fingerprint.

Cite this