Browse Prior Art Database

Encoder/Decoder Detection for Optical Recording Systems

IP.com Disclosure Number: IPCOM000112396D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Adler, RL: AUTHOR [+2]

Abstract

A technique is described whereby encoder/decoder detection is provided for optical recording systems, so as to detect holes and transitions.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 83% of the total text.

Encoder/Decoder Detection for Optical Recording Systems

      A technique is described whereby encoder/decoder detection is
provided for optical recording systems, so as to detect holes and
transitions.

      Using (2,7)-(3,7) NRZ and (1,6)-(2,6) NRZI rate 1:2 code, each
encoder consists of an output function and a next-state function.
Output functions and next-state functions depend on an internal state
and one data bit.

      Each decoder consists of a single output function.  The NRZ
decoder depends on eight constrained bits.  One error in constrained
bits results in no more than five user bit errors.  The NRZI decoder
depends on seven constrained bits.  One error in constrained bits
results in no more than four user bit errors.

Certain constrains exist in the detection system:

o   The NRZ system is for a detection system that detects holes
    (designated by zeros) and no holes (designated by ones).

o   The NRZI system is for a detection system that detects
    transitions from holes to no holes and vice versa (a transition
    is designated by a one and a no transition by a zero).

o   The (2,7)-(3,7) NRZ and (1,6)-(2,6) NRZI both describe same
    physical constraints on the medium.

o   The above NRZI sequences are obtained from the NRZ sequences by
    the following sliding block code:

                             00  11  01  00

                             V    V  ...