Nec Corporation

Nippon Telegraph and Telephone Corporation

Sakae Okubo

Naoki Mukawa

Toshio Koga

Akihiro Furukawa

Kazumoto Iinuma

Mitsuo Nishiwaki

Tooru Yasuda

Hideo Hashimoto

Tooru Amano

In a predictive encoder for use particularly in a conference television system, a signal processing unit is used in producing a prediction signal and comprises three prediction circuits (22, 23, 31) and a selection circuit (24) coupled to the prediction circuits. The prediction circuits are for producing an inframe, an interframe, and a background prediction signals, respectively. Those signals are produced by processing an original signal at instants which precede a current instant and are different from one another. The selection circuit is for selecting one of the inframe, the interframe, and the background prediction signals. Therefore, it is possible to produce the prediction signal suitably predictive of the original signal. The signal processing circuit serves equally well in a predictive decoder.

Signal processing unit for producing a selected one of signals

In a digital data communication network comprising digital data transmitting and receiving devices (111, 122) and first and second digital communication paths (16, 17) connected to each other and to the transmitting and the receiving devices, respectively, a stuffing circuit (23) is controlled by a control signal producing circuit (24) so as to stuff and not to stuff an input bit sequence when at least one of the first and the second digital communication paths has a restricted transmission characteristic and when both of the communication paths have an unrestricted transmission characteristic. Preferably, necessity and unnecessity of stuffing should be detected for a leading and a trailing part of each block with a shorter interval of time than for other parts of the block. More preferably, some of binary one bits placed at the beginnings of the respective blocks are used as a part of a multiframe synchronization pattern for a signal transmitted through the communication paths.

Digital data transmitting device for communication paths of restricted

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Kanagawa, Japan

Sakae Okubo