Abstract: Signals from microphones 1, 2 are first stored in memory circuits 4, 6 and then supplied to a cross-correlation arithmetic circuit 7, following which a cross-correlation operation is carried out and cross-correlation function values are calculated for each time difference. An evaluation function circuit 8 carries out addition processing of particular time intervals based on the cross-correlation function values and then searches for the maximum value to calculate time differences. Signals from the microphones 2, 3 are first stored in memory circuits 6, 5 and then supplied to a cross-correlation arithmetic circuit 9, following which a cross-correlation operation is carried out and cross-correlation function values are calculated for each time difference. An evaluation function circuit 10 carries out addition processing of particular time intervals based on the cross-correlation function values and then searches for the maximum value to calculate time differences.

Abstract: Signals from microphones 1, 2 are first stored in memory circuits 4, 6 and then supplied to a cross-correlation arithmetic circuit 7, following which a cross-correlation operation is carried out and cross-correlation function values are calculated for each time difference. An evaluation function circuit 8 carries out addition processing of particular time intervals based on the cross-correlation function values and then searches for the maximum value to calculate time differences. Signals from the microphones 2, 3 are first stored in memory circuits 6, 5 and then supplied to a cross-correlation arithmetic circuit 9, following which a cross-correlation operation is carried out and cross-correlation function values are calculated for each time difference. An evaluation function circuit 10 carries out addition processing of particular time intervals based on the cross-correlation function values and then searches for the maximum value to calculate time differences.

Abstract: In a voice coding section 1, a digital voice signal coded in a voice coder 10, a linear predictive coefficient used as a filter coefficient in a short-term predictive filter 102, a pitch period and a pitch predictive coefficient used, respectively, as a tap coefficient and a filter coefficient in a long-term predictive filter 103, and voice/no-voice status information of an input voice, are multiplexed in a multiplexer 12. Only when the voice/no-voice status information indicate the voice state is a cell assembled and transmitted. In a voice decoding section 2, the received cell is disassembled to provide multiplexed coded data. The voice signal is decoded by a short-term synthesis filter and a long term synthesis filter. The short term synthesis filter uses a linear predictive coefficient as a filter coefficient that is decoded from multiplexed coded data.

Abstract: A pause compressing speech coding/decoding apparatus according to the invention can improve the sound quality of decoded speech in terms of sense of hearing, in which the transmission side includes a speech coder, a speech detector, a hangover time controller for adjusting the duration of a speech interval, and a switch for outputting only coded data in a speech interval to a line, and the reception side includes a speech decoder, a noise generator, an amplifier for controlling the output level of the noise generator, a selector for selecting/outputting one of outputs from the speech decoder and the noise generator, a speech/pause data detector for detecting speech/pause data of data from the line, a gain controller for calculating the gain of the amplifier, a level calculator for calculating the signal level of reproduced speech from the speech decoder, and a memory for storing past level values calculated by the level calculator.

Abstract: An LD-CELP coder 211 codes an input signal supplied through a telephone line based on the low-delay code-excited linear prediction. A speech detector 212 detects voice/no-voice of the input signal. A FAX terminal input detector 213 detects a FAX signal. A multiplexer 214 multiplexes the coded data and the voice/no-voice data through bit steal of one bit per frame from the code. In a CLAD (cell assembling and disassembling) unit 300, a speech data frame is detected, and also the voice/no-voice information that has been multiplexed in the coded data is detected. If the voice/no-voice information indicates voice, the coded data is converted to cell data to be sent out to a transmission line. Concurrently with the operation of the coder, FAX terminal input data is all converted to cell data and sent out to the transmission line independently of the voice/no-voice information.

Abstract: A speech signal coding system including a speech signal encoder for dividing received speech signals into a plurality of frames each having a predetermined time interval and for converting the speech signals into digital speech parameters. The system includes a multiplexer for multiplexing the output digital data from the speech signal encoder into a predetermined frame format; a control frame generator for generating, in response to an inputted facsimile signal, a control frame having speech data frame configuration for identifying a facsimile signal identification data indicating the input signal as the facsimile signal. A facsimile signal demodulator converts the facsimile signal into digital data and a bit-synchronous multiplexer multiplexes the digital data.

Abstract: In a multi-pulse excitation encoder, the number of pulses is controlled in accordance with an updated correlation signal compared to a predetermined value.