Abstract: A TDMA in a CATV center and a CAU in a subscriber home communicate a B-ch idle/busy map indicating the idle/busy state of a B channel in synchronization with each other, so that the allocation of the B channel dedicated to sound and the C channel dedicated to data in a transmission frame can be dynamically changed according to the contents of the B-ch idle/busy map. Consequently, it becomes possible to effectively use a transmission bandwidth up to its maximum.

Abstract: The present invention relates to a time division multiple access communication technique. A center unit for time division multiple access communications with a plurality of subscriber units comprises a channel receiving section for receiving a synchronization establishing signal with a variable receive timing, from each of the subscriber units as a varying channel signal and further for receiving, as a fixed channel signal, a communication signal from the synchronization established subscriber's unit at a constant timing, and a control section for controlling the receive processing in the channel receiving section so that the varying channel signal is receivable within a period for receiving the fixed channel signal.

Abstract: A communication-line-quality measuring system includes transmission and terminal equipment. Transmission equipment has a first frame assembling part transmitting a down-link multiplexed frame signal to a down-link line having a first frequency, and a first frame disassembling part disassembling an up-link multiplexed frame signal transmitted through an up-link line having a second frequency. Terminal equipment has a second frame disassembling part disassembling the down-link multiplexed frame signal, and a second frame assembling part transmitting the up-link multiplexed frame signal obtained by frame-multiplexing an output signal of the subscriber unit with a control signal, to the up-link line. A pattern generation part in the first frame assembling part provides a test signal to an available channel of signal frames in the down-link multiplexed frame signal.

Abstract: A method of an automatic adjustment of a carrier level is used for a system having a center device, a communication line extending from the center device, and at least one communication-terminal device connected to the communication line. The system conducts two-way communication of data signals on the communication line based on a predetermined multiplexing scheme.

Abstract: In a calling signal transmitting apparatus, a ring trip equipment, including a ring trip detecting circuit for detecting a ring trip signal in response to an off-hook operation of the telephone set during a signal state of an intermittent ringing signal and a loop detecting circuit for detecting a loop signal in response to an off-hook operation of the telephone set during a nonsignal state of the intermittent ringing signal. Also included are a logical OR gate circuit, for providing, as a status signal, a logical sum of the ring trip signal and the loop signal, and a supervising circuit for supervising the status signal.

Abstract: A battery feed circuit for a subscriber line includes first and second feed circuit parts, each supplying a constant current to a corresponding subscriber line. The first and second feed circuit parts are provided with at least one of a common mode noise suppressor and a power source noise suppressor. The common mode noise suppressor includes first and second reference voltage output circuits and an intermediate voltage output circuit to produce the voltage between the first and second subscriber lines and superpose the same onto the first and second reference voltages. The power source noise suppressor functions to cancel the power source noise voltage at the output, of the first and second feed circuit parts.