Fujitsu Corporation

Toshiaki Nobumoto

Naoji Fujino

Mitsuru Tsuboi

Naoshi Matsuo

Noboru Kobayashi

Toshiyuki Ohta

Nobuhide Eguchi

Miki Murakawa

Mitsuru Takahashi

Teruyuki Sato

Kaoru Chujo

Tomonobu Takashima

Hideaki Kurihara

Koji Okazaki

Takahiro Aramaki

Shoji Tominaga

Yutaka Moriyama

Takao Matsuda

Naomi Suga

Ken-ichi Abiru

Naomi Nishiyama

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 information signal detection device and an information signal detection method are disclosed with which it is possible to transmit information by means of a DTMF signal using a channel that is prone to distortion, such as a high-efficiency channel. The information signal detection device comprises a filter bank component and a logic component. The filter bank component receives via a channel an information signal in which are superposed sine waves of two different frequencies selected from a specific number of frequencies sent by the sender, and generates binary information patterns showing in binary information whether the signal components of the various frequencies of this information signal are present. The logic component recognizes the end of the signal region when the binary information pattern generated in the binary information pattern generation step is containing no binary information showing that a signal component is present continuously for a specific period of time. The logic component also integrates the binary information patterns which indicate that at least one type of frequency signal component is contained and which are output from the filter bank component until the end of the signal period is recognized. One the end of the signal period has been recognized, the logic component decides the contents of the DTMF signal sent from the sender based on these integration results.

Information signal detection device and information signal detection

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.

Synchronism establishing method and apparatus

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Fukuoka, Japan

Toshiaki Nobumoto