Encoder using an excitation sequence and a residual excitation sequence

A transmitter (2) for transmitting an input signal, the transmitter (2) comprising an encoder (4) with

• I. sequence selection means (46) having
• a. an analysis filter (80) for deriving, from a target signal derived from the input signal, a residual sequence,
• b. an excitation sequence generator (82, 84) for generating a plurality of excitation sequences comprising non zero sample values being separated by a predetermined number of zero sample values, the generator including a phase selector (82) for determining from the residual sequence the position of the non-zero sample values in the plurality of excitation sequences
• c. a second selector (94) for preselecting, from the plurality of excitation sequences, a second plurality of excitation sequences having the largest resemblance with the residual sequence, and
• II. selection means (44) for selecting a selected excitation sequence from the second plurality of excitation sequences, the selected excitation sequence resulting in a minimum error between
• i. a synthetic signal derived from said selected excitation sequence and
• ii. the target signal derived from the input signal,
• the transmitter (2) being arranged for transmitting a signal representing the selected excitation sequence.

An encoder (4) comprising

• I. sequence selection means (46) having
• a. an analysis filter (80) for deriving, from a target signal derived from an input signal, a residual sequence,
• b. an excitation sequence generator (82, 84) for generating a first plurality of excitation sequences comprising non zero sample values being separated by a predetermined number of zero sample values, the generator including a phase selector (82) for determining from the residual sequence the position of the non-zero sample values in the plurality of excitation sequences,
• c. a second selector (94) for preselecting, from the first plurality of excitation sequences, a second plurality of excitation sequences having the largest resemblance with the residual sequence, and
• II. selection means (44) for selecting a selected excitation sequence from the second plurality of excitation sequences, the selected excitation sequence resulting in a minimum error between
• i. a synthetic signal derived from said selected excitation sequences and
• ii. the target signal derived from the input signal,
• the encoder (2) being arranged for outputting a signal representing the selected excitation sequence.

A method for transmitting an input signal, the method comprising

• a. deriving, from a target signal derived from the input signal, a residual sequence according to an analysis filter operation,
• b. generating a first plurality of excitation sequences comprising non zero sample values being separated by a predetermined number of zero sample values, the generating including determining from the residual sequence the position of the non-zero sample values in the plurality of excitation sequences according to a phase selector operation,
• c. selecting, from the first plurality of excitation sequences, a second plurality of excitation sequences having the largest resemblance with the residual sequence,
• d. selecting a selected excitation sequence from the second plurality of excitation sequences, the selected excitation sequence resulting in a minimum error between
• i. a synthetic signal derived from said selected excitation sequence, and
• ii. the target signal derived from the input signal, and
• e. transmitting a signal representing the selected excitation sequence.