K.A. Schouhamer Immink

Encoding of dklr-sequences using one weight set

Traditional schemes for encoding and decoding runlength-constrained sequences using the enumeration principle require two sets of weighting coefficients. A new enumeration is presented requiring only one set of coefficients.

Knuth’s balancing of codewords revisited

In 1986, Don Knuth published a very simple algorithm for constructing sets of bipolar codewords with equal numbers of dasia1psilas and dasia-1psilas, called balanced codes. Knuthpsilas algorithm is, since look-up tables are absent, well suited for use with large codewords. The redundancy of Knuthpsilas balanced codes is a factor of two larger than that of a code comprising the full set of balanced codewords. In our paper we will present results of our attempts to improve the performance of Knuthpsilas balanced codes.

Error propagation assessment of enumerative coding schemes

Enumerative coding is an attractive algorithmic procedure for translating long source words into codewords and vice versa. The usage of long codewords makes it possible to approach a code rate which is as close as desired to Shannons noiseless capacity of the constrained channel. Enumerative encoding is prone to massive error propagation as a single bit error could ruin entire decoded words. This contribution evaluates the effects of error propagation of the enumerative coding of runlength-limited sequences.

EFMPlus: The Coding Format of the High-Density Compact Disc

We report on an alternative to Eight- to-Fourteen Modulation (EFM), called EFMPlus, that with regard to the physics and electronics of an optical recorder, has the same characteristics such as runlength parameters Tmin and T,,,, low- frequency content, and clock content. Computer simulations have shown that the low-frequency con- tent of EFMPlus is only slightly larger than its con- ventional EFM counterpart. The rate of EFMPlus is 8/16 which means that a 6-7 % higher informa- tion density can be obtained.We report on an alternative to Eightto-Fourteen Modulation (EFM), called EFMPlus, that with regard to the physics and electronics of an optical recorder, has the same characteristics such as runlength parameters Tmin and T,,,, lowfrequency content, and clock content. Computer simulations have shown that the low-frequency content of EFMPlus is only slightly larger than its conventional EFM counterpart. The rate of EFMPlus is 8/16 which means that a 6-7 % higher information density can be obtained.

Constructions and properties of block codes for partial-response channels

We report on block-coding techniques for partial-response channels with transfer function (1/spl mnplus/D/sup m/), m=1, 2, ... . We consider various constructions of block codes with prescribed minimum Euclidean distance. Upper and lower bounds to the size of a code with minimum squared Euclidean distance greater than unity are furnished. A table is presented of cardinalities of codes of small length with prescribed minimum squared Euclidean distance.

On the design of efficient constrained parity-check codes for optical recording

This paper proposes a general and systematic way to efficiently combine constrained codes with parity-check (PC) codes for optical recording. The proposed constrained PC code includes two component codes: the normal constrained (NC) code and the parity-related constrained (PRC) code. They are designed based on the same finite state machine (FSM). The code rates are only a few tenths below the theoretical maximum. The parity-check constraint is defined by the generator matrix (or generator polynomial) of a linear binary PC code, which can detect any type of dominant error events as well as error event combinations of the system. Two approaches are proposed to design the code in the non-return-to-zero-inverse (NRZI) format and the non-return-to-zero (NRZ) format, respectively. Designing the codes in NRZ format may reduce the number of parity bits required for error detection and simplify post-processing for error correction. Finally, examples of several newly designed codes and their performances are illustrated

An entropy theorem for computing the capacity of weakly (d,k)-constrained sequences

We find an analytic expression for the maximum of the normalized entropy -/spl Sigma//sub i/spl epsiv/T/p/sub i/ln p/sub i///spl Sigma//sub i/spl epsiv/T/ip/sub i/ where the set T is the disjoint union of sets S/sub n/ of positive integers that are assigned probabilities P/sub n/, /spl Sigma//sub n/P/sub n/=1. This result is applied to the computation of the capacity of weakly (d,k)-constrained sequences that are allowed to violate the (d,k)-constraint with small probability.

On the number of encoder states for capacity approaching d = 1 codes

The number of encoder states is a key measure of complexity of a finite-state constrained code. In this paper, we derive analytically the relationship between the number of encoder states and the size of capacity approaching d = 1 codes. By defining the number of encoder states as (generalized) Fibonacci numbers, we obtain the optimum encoder states, which maximize the size of the designed code with minimum number of states, for any desired codeword length

System requirements of a stationary-head multi-track recorder

We report on the design considerations of stationary-head multi-track magnetic recorders. We focus on the particular reasons for adopting the rate 8/10, DC-free recording code, the full-response detection method, and the clock recovery circuitry. Implementation issues of the channel chip, particularly related to cost and power consumption, are addressed. A new multi-track phase-lock loop (PLL) has been developed, in order to improve the recorders robustness against time-base variations. >

The CD System as Standardized by Philips and Sony

It should be stressed that this introduction does not intend to mention and recognize all people within Philips and Sony who contributed to establish the CD digital audio system standard in 1980. This standard is based on the collaborative work of many persons, both from Philips and from Sony, and it would be impossible to properly acknowledge all these individuals in the space of only a few pages. More information on the persons involved can be found in the doctoral thesis (in German) by Jurgen Lang (“Das Compact Disc Digital Audio System”, 1996, RWTH, Aachen, ISBN 3-00-001052-1) introduction only aims at describing some important decisions that were made between the successful demonstration of the CD prototype on March 8, 1979, and the establishment of the Philips-Sony CD standard in June 1980.