In one embodiment, a switched amplifier is provided to amplify a data transmission. The switched amplifier may use a control signal that is received via a control signal channel in a transmission cable. Also, the switched amplifier may detect signal power to determine whether the data transmission is received at one of a first port and a second port. Data transmissions via the data transmission channel occur in a first direction and a second direction in a same frequency range in a time division multiplex (TDD) mode. Also, the control signal and data transmission are diverted from the transmission cable that transmits a type of signal different from the control signal and the data transmission. The switched amplifier is controlled based on the control signal or the signal power detected. The amplified signal is diverted in the first direction or the second direction via the data transmission channel back to the transmission cable.

[Problem] To provide a fail-safe function for an operation of grounding a circuit to be grounded and for an operation of ungrounding a circuit to be grounded.

[Solution] The present invention is provided with: a first contact in a first relay connected to a grounded circuit; a resistor which is connected between the first contact and the earth, and which inhibits the flow of electric current to the first contact when the first contact is closed; a second contact in a second relay connected in parallel to the resistor; and an interlocking control means which inhibits opening of the first contact in a closed state when the second contact is opened, and which inhibits closing of the first contact in an open state when the second contact is closed.

Submarine cable branching units with fiber pair switching configured to allow any number of trunk cable fiber pairs to access the optical spectrum any number of branch cable fiber pairs. Access to a particular branch terminal is not limited to predefined subset of the trunk fiber pairs. This approach allows fewer branch cable fiber pairs to be equipped in each branching unit, reducing system cost, simplifies system planning and provides flexible routing of overall trunk cable capacity.

Submarine cable branching units with fiber pair switching configured to allow any number of trunk cable fiber pairs to access the optical spectrum any number of branch cable fiber pairs. Access to a particular branch terminal is not limited to predefined subset of the trunk fiber pairs. This approach allows fewer branch cable fiber pairs to be equipped in each branching unit, reducing system cost, simplifies system planning and provides flexible routing of overall trunk cable capacity.

Provided are: a submarine cable system with which it is possible, with a simple configuration, to acquire the state of each of a plurality of high-voltage relays in a branching device; the branching device; and a state response method therefor. The branching device comprises: a plurality of interlocking relays respectively corresponding to a plurality of high-voltage relays for switching feeding paths; a drive unit which supplies drive electric currents supplied to the plurality of high-voltage relays to the plurality of corresponding interlocking relays, respectively; a state detection unit which detects operation states of the plurality of interlocking relays as the operation states of the plurality of high-voltage relays; and a response unit which, on the basis of the result of detection of the operation states of the plurality of interlocking relays, transmits the operation states of the plurality of high-voltage relays.

Provided are: a submarine cable system with which it is possible, with a simple configuration, to acquire the state of each of a plurality of high-voltage relays in a branching device; the branching device; and a state response method therefor. The branching device comprises: a plurality of interlocking relays respectively corresponding to a plurality of high-voltage relays for switching feeding paths; a drive unit which supplies drive electric currents supplied to the plurality of high-voltage relays to the plurality of corresponding interlocking relays, respectively; a state detection unit which detects operation states of the plurality of interlocking relays as the operation states of the plurality of high-voltage relays; and a response unit which, on the basis of the result of detection of the operation states of the plurality of interlocking relays, transmits the operation states of the plurality of high-voltage relays.

A digital communication system user, via which a first logic signal and a second logic signal are transmitted, includes an activation circuit that includes encompassing a supply unit, a switching unit, a transmission unit, and a communication interface. The supply unit provides an internal supply voltage, the switching unit couples the supply unit to the transmission unit to supply the transmission unit with the internal supply voltage, and the transmission unit outputs a wake-up signal, which includes the first logic signal, to the communication interface in response to being supplied with the internal supply voltage by the supply unit, and subsequently continuously outputs the second logic signal to the communication interface until the switching unit separates the transmission unit from the supply unit by.

A digital communication system user, via which a first logic signal and a second logic signal are transmitted, includes an activation circuit that includes encompassing a supply unit, a switching unit, a transmission unit, and a communication interface. The supply unit provides an internal supply voltage, the switching unit couples the supply unit to the transmission unit to supply the transmission unit with the internal supply voltage, and the transmission unit outputs a wake-up signal, which includes the first logic signal, to the communication interface in response to being supplied with the internal supply voltage by the supply unit, and subsequently continuously outputs the second logic signal to the communication interface until the switching unit separates the transmission unit from the supply unit by.

Systems, methods and devices for a coaxial cable transmission system. A power supply receives a primary power signal from a power source. The power supply generates a switched direct current power signal from the primary power signal. A power gateway receives the switched direct current power signal over a coaxial cable from the power supply. The power gateway generates a secondary power signal from the switched direct current power signal. A load device receives the secondary power signal from the power gateway. In some implementations, the power supply generates the switched direct current power signal at a positive direct current voltage level for a first part of a time period and at a negative direct current voltage level for a second part of the time period.

Systems, methods and devices for a coaxial cable transmission system. A power supply receives a primary power signal from a power source. The power supply generates a switched direct current power signal from the primary power signal. A power gateway receives the switched direct current power signal over a coaxial cable from the power supply. The power gateway generates a secondary power signal from the switched direct current power signal. A load device receives the secondary power signal from the power gateway. In some implementations, the power supply generates the switched direct current power signal at a positive direct current voltage level for a first part of a time period and at a negative direct current voltage level for a second part of the time period.