Patent ID: 7161507
Filing Date: 2007-01-09
Classification: H03M

Abstract:
1. In an enumerative encoder, an index-computation circuit that, for each n-digit sequence of digits b i , i=1, 2, . . . n, of at least a plurality of sequences that belong to a predetermined set of allowed sequences, where b i is a symbol chosen from a respective R i -symbol alphabet, responds to an input signal representing that n-digit sequence by generating as an output a signal that represents an index that identifies that input sequence uniquely among all allowed digit sequences having the same symbol population in accordance with an indexing scheme that assigns indexes to sequences in such a manner that: A) for each i<n, there is associated with each sequence-length-i symbol population a respective single indexing volume V whose value is at least as great as the number of allowed sequences having that symbol population, where, for each sequence-length-i symbol population for which n>i>1: B) the indexing volumes V associated with some symbol populations exceed the number of allowed sequences having those symbol populations; C) some allowed digit sequences whose symbol populations differ are identified by the same index; D) the index assigned to any allowed i-symbol sequence is at least as great as the index assigned to that i-symbol sequence's i−1-symbol prefix; E) with the exception of at most one symbol from the R F) every n-symbol sequence's index is less than r