Abstract: Emergency phone stations distributed at intervals of 1 or 2 km along a highway area and connected to a communications channel with a power line. Each phone station has a set of flash lamps which can be blinked in accordance with differing blinking schedules, and with a storage capacitor which stores flash energy. When a lamp is flashed, the storage capacitor discharges from the power line, the charging time-constant of each station being different due to differing distances from a central station. To impose an order on the network, central clocking is employed, with lamp ignitions occurring at each individual station being referenced to clocking signals common to all stations, so that the blinking schedules at all activated stations have a fixed phase interrelationship. This predetermines the times and sequences at which the storage capacitors will recharge. All storage capacitors are identical and are so selected that t.sub.0 /R.C.sub.ges =0.5 to 3, preferably 1.25, t.sub.

Abstract: A succession of emergency-phone stations distributed along the length of a communications cable laid alongside a highway is powered from a remote central station. The phone stations are provided with lamps to form a blinking-lamp signalling system warning of upcoming traffic hazards. Each phone station's blinking system includes a code-evaluator circuit stage which interprets code signals transmitted along the power-supply circuit of the communications cable, the code signals identifying which stations are to have their lamps blink and in accordance with which blinking schedules. Each station is provided with a bistable activation stage which responds to the first occurrence of a transmitted-voltage boost by disconnecting from power the code-evaluator circuit stage of all flashing stations, and all circuitry of all non-flashing stations, but which reconnects to power upon the second occurrence of such voltage boost.

Abstract: A communication system has at least one supervisory station and a large number of repeater stations spaced along a four-wire two-way transmission line. A number of repeater stations are selected at equal intervals along the line to have a coupling network coupling test signals from the first pair of wires in the transmission line to the second pair of wires which differs from the coupling network of the remainder of the repeater stations. To locate a fault, test signals in the form of pulses are sent from the supervisory station to the repeater stations. At each repeater station, if operative, the received test signals are coupled to the second pair of wires for retransmission back to the supervisory station.

Abstract: A carrier frequency system is provided with a transmission band of up to approximately 200 MHz with a small number of partial bands of identical magnitude and kind. These partial bands are translated and cut connected through and vice versa in their entirety into a frequency spectrum within the transmission band of a 60 MHz carrier frequency system of quinary group construction. The partial bands which are cut connected through into the other system are suitable for working with the translators of the other system in the same way as with its own partial bands. The filters required for the system are simple and uncomplicated.