Abstract: A non-directional transmitting system non-directionally and simultaneously transmits four signals of different but closely spaced frequency. The system comprises four directional antennas, each oriented to face in a different respective direction, each direction being spaced 90.degree. from the next one. Each directional antenna simultaneously transmits one fourth of the power of each one of the four signals, making for an overall non-directional effect. The four signal sources are coupled to the four directional antennas by way of four 3-dB couplers in such a way that substantially all the power of each signal is transmitted equally to the four directional antennas, avoiding the power loss customary when plural signal sources are coupled to a common non-directional antenna using 3-dB couplers.

Abstract: A corrective network for obtaining a desired overall frequency response comprises a plurality of tunable, non-active resonant circuit stages, each connected with a source and operative for modifying the frequency response over a respective portion of the frequency spectrum. Each resonant stage comprises a variable differential capacitor having a rotor plate terminal and two stator plate terminals. Each stage further includes a series circuit branch constituted of a resistor and an inductor which has one end which is connected to the respective rotor terminal of each stage. The network further includes a common terminal at which the other ends of the series circuit branches are all connected. The source may be a transformer having a tap intermediate its end terminals, and an output impedance is located between the common terminal and the tap of the transformer. The stator plate terminals of at least some of the stages are connected to respective ones of the end terminals of the source.

Abstract: A compensating circuit has a frequency response curve into which can be introduced elevations or depressions of selected breadth at selected frequencies. The compensating circuit includes a plurality of tunable circuit stages associated with different frequency ranges. Each tunable circuit stage includes a resistor and an inductor connected in series with each other and to the rotor terminal of a differential capacitor having two stator terminals. The first stator terminals of the differential capacitors are connected to the first winding or windings of one or more differential transformers, while the second stator terminals of the differential capacitors are connected to the second winding or windings of the one or more differential transformers. The voltage induced across the one or more differential transformers is then employed to supplement the voltage which is being transmitted to the output resistor of the compensating circuit by the input transformer of the compensating circuit.

Abstract: A low loss corrective network for obtaining a desired overall frequency response comprises a plurality of tunable resonant circuit stages which are operative for modifying the frequency response over respective portions of the frequency spectrum. Each resonant stage comprises a variable differential capacitor having two stator plate input terminals and a rotor plate output terminal. Each stator plate input terminal is connected to respective end terminals of a source. A single voltage divider common to all of the stages has two end terminals which are connected with the source and which are also commonly connected with all of the respective stator plate input terminals of the individual stages, and a tap point located intermediate the end terminals of the divider which is commonly connected with all of the respective rotor plate output terminals of the individual stages. Moreover, matching resistors and inductors are employed to compensate for the capacitive loading presented by the differential capacitors.

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 circuit for connecting to the output of a constant-current power supply for limiting output voltage in the event of an interruption, such as open circuits, in a feed comprises a first resistor and a first thyristor in series across the output and a second resistor and a second thyristor in series across the output, a capacitor connecting the junction of the first resistor with the first thyristor to the junction of the second resistor with the second thyristor. Triggering of the first resistor connects the first resistor to the output so as to form a dummy load and triggering of the second thyristor turns off the first thyristor.

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.