Abstract: A telephone exchange operating on a volume controller provided with functions for inputting digitized speech data and volume control data, and converting a volume of the inputted speech data. A talker's sound inputted from a first channel has the volume converted and is outputted to a second channel for outputting a listener's sound. A volume of the speech data is converted according to a volume control data and exchanged. An augmenter for a sound level is calculated according to a reference signal sent from a first circuit to a second circuit.

Abstract: A method of deciding whether an extension terminal is called or not is provided. The kind of communication is recognized on the basis of a set-up message received from the ISDN. Whether the extension terminal is called or not is decided on the basis of the result of comparison between the kind of the extension terminal and the kind of the communication recognized. There is also provided a private branch exchange comprising: a detector to detect a reception from an analog external line; a digital interface to connect a terminal corresponding to a procedure for a digital line; and a judging circuit to judge whether the terminal corresponds to a procedure for an analog line or not, wherein when the judging circuit decides that the terminal corresponds to the procedure for the analog line when the reception is detected by the detector, the digital interface transmits the set-up message to the terminal.

Abstract: An image signal coding apparatus includes reference and coding line change point detection circuits, reference line shift registers, a coding line shift register, a symbol detection circuit, coding and reference line ROM tables, and a code determination circuit. The coding line change point detection circuit receives a serial reference line image signal in synchronism with a serial coding line image signal. The reference line shift registers receive serial change point data in the reference line image signal and output parallel reference line change point data. The coding line shift register receives serial change point data in the coding line image signal and outputs parallel coding line change point data. The symbol detection circuit monitors output states of the reference and coding line shift registers. A run length counter counts the number of pixels between the change points in the coding line image signal.

Abstract: A decoder for two-dimensionally encoded image codes such as modified READ or modified READ codes ensures fast decoding operation by outputting reference codes in parallel while serially discriminating input codes and monitoring the relationship of both codes.