Abstract: A terminal transmits via a control channel to another terminal a command demanding header configuration modification. Then the former terminal continues to receive frames with configuration before the modification and at the same time waits for frames with configuration after the modification.

Abstract: This invention relates to a double talk detecting method suited to be used for an echo canceler, and more particularly to a method for correctly detecting whether or not the double talk is present, even in the case where a speech transmitting level difference between a far-end talker and a near-end talker is comparatively large. What is assumed in the present invention is an echo canceler which can be employed in a telephone line network for transmitting a speech of a far-end talker sent through a digital line and a speech of a near-end talker sent through an analog line. A double talk detecting method applicable to the echo canceler here extracts predetermined analyzed parameters respectively from a first speech signal corresponding to the speech of the far-end talker sent from the echo canceler to a hybrid circuit and the speech of the near-end talker input to the echo canceler through the hybrid circuit. The analyzed parameters herein used include, for example, speech pitches, frequency components, etc.

Abstract: A data transmission device comprises a transmitter device and a receiver device. The transmitter device divides a data string to be transmitted into an original data string requiring protection against code error and a data string requiring no protection. The transmitter device then carries out an error detection code adding operation and error correction coding at a redundancy code rate of 1/N on the original data string to generate a coded data string. The transmitter device divides the coded data string by N, and outputs the N divided coded data strings and the data string requiring no protection on a communication line under a time division multiplexing control. The receiver device receives the N coded data strings and the data string requiring no protection.

Abstract: The present invention relates to an echo canceler for training an echo path estimation without providing a hindrance to a speech. The echo canceler of the present invention includes a pseudo noise generator for generating a certain pseudo noise. This pseudo noise is forcibly supplied to a transmission line for transmitting a far-end talker's voice. Here, in the case where the far-end talker's transmitting speech level is faint or the far-end talker is in a speechless condition, a certain correlation is established between the pseudo noise and a signal of the transmission line for transmitting the near-end talker's voice. Based on such a correlation as just mentioned, a coefficient for generating an echo replica is calculated. Therefore, a training for estimating an echo path is performed based on the pseudo noise and without depending on the far-end talker's voice, thereby generating an appropriate echo replica.

Abstract: For the transmission of variable length coded data blocks, a threshold arithmetic calculation circuit (9) obtains a threshold from an average of the bit lengths of the variable length coded data blocks for each group of such block, and the judgment circuit (10) makes a judgment as to whether or not those variable length coded data blocks have bit lengths exceeding the threshold of the block group to which such data blocks belong. Then, a block divider circuit 11 divides the variable length coded data blocks having bit lengths exceeding the threshold into blocks having small bit lengths. Each block thus obtained is fixedly equalized in bit length to an average length level and transmitted in that condition.

Abstract: The present invention relates to an echo canceler for training an echo path estimation without providing a hindrance to a speech. The echo canceler of the present invention includes a pseudo noise generator for generating a certain pseudo noise. This pseudo noise is forcibly supplied to a transmission line for transmitting a far-end talker's voice. Here, in the case where the far-end talker's transmitting speech level is faint or the far-end talker is in a speechless condition, a certain correlation is established between the pseudo noise and a signal of the transmission line for transmitting the near-end talker's voice. Based on such a correlation as just mentioned, a coefficient for generating an echo replica is calculated. Therefore, a training for estimating an echo path is performed based on the pseudo noise and without depending on the far-end talker's voice, thereby enabling to generate an appropriate echo replica.

Abstract: The detection and cancellation of echo in a communications system is enhanced by taking advantage of the accumulated knowledge relating to the echo path delay that an adaptive filter acquires as a result of its adaptation process. Such knowledge improves significantly the ability of an associated Near-End-Speech (NES) detector to detect for the presence of near end speech.