Fujitsu Corporation

Naoji Fujino

Toshiaki Nobumoto

Mitsuru Tsuboi

Kaoru Chujo

Noboru Kobayashi

Naoshi Matsuo

Yoshiyuki Ono

Toshiyuki Ohta

Nobuhide Eguchi

Miki Murakawa

Mitsuru Takahashi

Tomonobu Takashima

Hideaki Kurihara

Koji Okazaki

Kimihide Ono

Takahiro Aramaki

Takao Matsuda

Shoji Tominaga

Yutaka Moriyama

Fumiaki Nishida

Naomi Suga

Norikatsu Tokairin

Ken-ichi Abiru

Naomi Nishiyama

A communication apparatus for processing a fax signal and an audio signal includes an audio compression unit for compressing the audio signal, a fax-termination/switching control unit for terminating the fax signal and for executing control to prevent the fax signal from being compressed by the audio compression unit, a detection unit for detecting a predetermined negotiation signal used in a negotiation procedure for a fax communication from an input signal before compression within a fixed period of time starting at the beginning of the negotiation signal and an exclusion processing unit for carrying out an exclusion process on the negotiation signal upon detection of the negotiation signal.

Communication apparatus and processing method of the same

A communication-status notification apparatus enabling a subscriber to observe various kinds of communication status in a network easily via the subscriber's own terminal in a communication system. The apparatus includes a request analysis section for discriminating whether or not voice data received by gateway equipment from a subscriber terminal contains a request on monitoring/controlling or notifying of a communication status in the network and for analyzing the content of the request when contains, a communication-status monitor/control section for monitoring/controlling the communication status responsive to the content of the request analyzed by the request analysis section based on a processing status of the voice data in the gateway equipment, and a communication-status notification section for notifying the subscriber terminal of the communication status monitored/controlled by the communication-status monitor/control section via the gateway equipment responsive to the content of the request analyzed by the request analysis section. The apparatus is useful when applied to VoIP gateway equipment or the like used for a VoIP communication system.

Communication-status notification apparatus for communication system, communication-status display apparatus, communication-status notification method, medium in which communication-status notification program is recorded and communication apparatus

A multi-channel signal processing apparatus comprises a memory unit, a signal processing unit for single-channel implementing predetermined signal processing using a memory region of the memory unit according to a signal processing program for single-channel, an address generation unit generating a first memory address for single-channel processing, a pointer adding unit adding a pointer value indicating the head of an unused memory region of the memory unit to the first memory address generated by the address generation unit each time the signal processing in the signal processing unit is completed to generate a second memory address, and an address selecting unit selecting either the first memory address or the second memory address as a real address for the memory unit, thereby enabling multi-channel signal processing having a high processing efficiency without adding a large modification to the signal processing program for single-channel.

Memory management apparatus in a multi-channel signal processor

On the basis of tap coefficients which a tap coefficient updating circuit updates in succession, a maximum-tap position detecting unit, a fluctuation width detecting unit and a comparator detect a state where the transmission delay time of an echo path exceeds the echo control time of an echo canceller. In a case where the state has been detected, a changeover controlling unit stops an echo cancelling operation which includes a process for subtracting a pseudo echo signal from a send-in signal.

Echo canceller and method of controlling the same

A coded frame synchronization method for decoding coded information sent every frame includes the steps of: (a) receiving a coded frame having error detection or correction codes, each of which is provided every predetermined number of bits, error detection or correction codes being added to the coded frame in accordance with a predetermined pattern; (b) pulling the coded frame in synchronization by performing an error detection process every predetermined number of bits to be compared with results of the error detection process and thus detecting a phase of the error detection or correction codes; and (c) recognizing a leading end of the coded frame on the basis of the phase of the error detection or correction codes.

Coded frame synchronizing method and circuit

An apparatus synchronizes a voice coder and a voice decoder which are of the vector-coding type in order to prevent a false synchronization even when a signal having the same period as a string of synchronizing bits is inputted. A noise component adding unit adds a noise component to an input voice signal. Therefore, even if the input voice signal has the same period as that of a string of synchronizing bits and is completely periodic, the periodicity of the input voice signal is lost by the added noise component. Based on the input voice signal which is no longer periodic, a vector-coding unit, a quantizing signal vector generating unit, and a code book index transmitting unit generate code book indexes and transmit the generated code book indexes to a voice decoder. Therefore, the voice decoder is prevented from developing a false synchronization.

Apparatus for synchronizing a voice coder and a voice decoder of a

The coder generates code information A.sub.1 -A.sub.N, each representing one of Q quantization points of an input signal, where Q is an integer equal to or less than 2.sup.x and X is a positive number, synthesizes the code information A.sub.1 -A.sub.N into a code H through an operation:

Coding/decoding apparatus and method

The high performance multiplexed transmission system of this invention is configured by a sound coding unit for coding voice input information by separating it into a core information part for assuring the minimum acceptable sound quality and a supplementary information part discardable in stages per the transmission priorities. There is a silent section detecting unit for detecting silent sections of voice input information. In addition, there is a multiplexing unit for multiplexing only the information synchronizing with the correspondent's coder for the voice channels from which no sound is detected, or first the core information part and second the supplementary information part from the ones with the highest priorities in stages in fixed length frames, for discarding the supplementary information parts, which cannot be multiplexed because of a band deficiency.

High performance digitally multiplexed transmission system

The invention provides a synchronism establishing method and apparatus including a plurality of modules having different independent synchronization patterns to be switched wherein the switching transition process having a time length corresponding to the number of protection stages necessary for pull in and protection of synchronism is reduced so small that the presence of such switching transition process can be ignored while assuring similar advantages to those of conventional synchronism establishing apparatus. A master side module delivers a notification of establishment of synchronism thereof to a slave side module. When the slave side module is in a condition wherein synchronism is established, it puts its synchronizing operation into a waiting mode. Even if it thereafter detects a number of abnormal synchronization patterns greater than the number of protection stages, it does not determine a pull out condition and maintains the pulled in phase. If the slave side module detects a false pull out condition from the master side module, the slave side module determines that synchronism is entered therewith and resumes its processing operation.

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Kawasaki, Japan

Naoji Fujino