초록 ▼

A message in the form of a sequence of bits is encoded into relatively short, non-binary signals. The message (or vector) is divided into two halves. The encoder first determines an encoding of the message into a vector half the length of the eventual encoded vector. The half-length vector forms the

A message in the form of a sequence of bits is encoded into relatively short, non-binary signals. The message (or vector) is divided into two halves. The encoder first determines an encoding of the message into a vector half the length of the eventual encoded vector. The half-length vector forms the first half of the encoded, and is negated to form the second half of the encoded vector. An identical synchronization signal is added to both halves of the encoded vector. The synchronization signal is used to compensate for the possibility that the received vector (or message) is cyclically rotated from the original vector. During decoding, the decoder first obtains the synchronization signal by adding the two halves of the vector together, canceling the encoded message. The synchronization signal is used to find the original cyclical shift of the vector. The decoder obtains the half-length encoded message vector by taking the difference between the two halves of the aligned full-length encoded vector. After decoding the vector into a bit sequence, the encoder re-encodes that bit sequence and compares the resulting vector with the original vector to determine whether the original vector truly encoded a message or was simply a noise signal.

대표청구항 ▼

[ What is claimed is:] [2.]2. A method of decoding a received vector of two half vectors into a sequence of bits comprising the steps of:a) receiving a received vector of two half vectors, including a first half vector containing a synchronization signal and a first modulation vector, and a second h

[ What is claimed is:] [2.]2. A method of decoding a received vector of two half vectors into a sequence of bits comprising the steps of:a) receiving a received vector of two half vectors, including a first half vector containing a synchronization signal and a first modulation vector, and a second half vector containing the synchronization signal and a second modulation vector which is the negation of the first modulation vector, where the received vector is a signal extracted from media according to a watermark extraction method;b) averaging the first half vector with the second half vector to obtaining a received synchronization vector,c) determining an amount by which the received synchronization vector must be shifted to obtain the best match with a reference synchronization vector;d) shifting the received vector by the determined amount to obtain an aligned received vector; ande) demodulating the aligned received vector to obtain the sequence of bits comprising averaging a first half of the aligned received vector with the negation of a second half of the aligned received vector to obtain a received modulated vector, demodulating the received modulated vector to obtain an extended sequence of bits, including at least one redundant bit, and correcting errors in the extended sequence of bits using the at least one redundant bit in the extended sequence of bits to obtain the sequence of bits.