Abstract: A system for transmitting wideband signals, for example speech, over a narrow band is proposed. Lower frequency range signals are directly transmitted and amplitude information of partial upper frequency ranges is transmitted on pilot frequencies. At a receiver, "equivalent" signals from oscillators having frequencies approximately equal to the mid range frequencies of the partial upper frequency ranges are modulated with the amplitude information of the corresponding partial upper frequency ranges to produce "synthetic" signals. The synthetic signals are modulated with narrow band noise to crreate a more pleasing and realistic sound. Means are provided for controlling at the pick-up end the "modulation factor" of the noise modulation at the reproducing end. This is achieved by controlling the level of the third harmonic of a sync signal transmitted from the pick-up end. The level of the third harmonic may be automatically or manually adjusted to conform to the type of sound being transmitted.

Abstract: The invention provides a system for developing sync pulses when PICOR is used on sound film systems. The sprocket holes in the feed track of the film are used in conjunction with a light source and a photocell to develop sync pulses which are required to synchronize a rotating electronic switch with periodic sequential information recorded on the sound track of the film.

Abstract: The invention provides a circuit for an all-pass reverberator with an MOS delay line and feed back amplifier. The circuit compensates for the frequency-dependent attenuation of the delay line. Two amplifiers of the prior art circuit are replaced by resistors and a third one has specific characteristics.

Abstract: A constant output pump delivers a portion of a fluid, the viscosity of which is to be controlled, into a measuring capillary tube to develop a pressure differential across the measuring capillary tube. Means are provided to sense the pressure differential and control the fluid viscosity in response thereto. A second capillary tube is adapted to receive all of the fluid discharged from the measuring capillary tube and an elastic fluid space is interposed between the measuring capillary tube and the second capillary tube. The flow resistance of the second capillary tube and the elasticity of the fluid space functions to make the pressure differential independent of static fluid pressure changes.

Abstract: An underground station is provided with an access cover assembly including a frame extending about an access opening and a cover hingedly attached to said frame. A support member is attached to said frame and extends about the periphery of the access opening. Attaching members are slidably mounted to said support member so that they may be positioned to any desired location about the periphery of the access opening. Fastening means are provided for fixing said attaching members at desired locations about the support member and for fastening station accessories to the attaching member so that the accessories may be mounted in preferred locations in a particular station.

Abstract: A reverberation device is provided with a delay line in series with an amplifier which is designed to compensate for the inherent frequency dependent attenuation of the delay line. The output of the compensating amplifier is fed back directly to the delay line input.

Abstract: A polarizing D.C. voltage is generated at the capacitance of the ultrasonic transducer and then short-circuited by a parallel-arranged electronic switch controlled by the command signal frequency to be radiated. A direct current stored in an inductance during this short-circuit phase is supplied via a decoupling diode to the electrodes of the ultrasonic transducer upon opening of the switch, and after having been transformed into a voltage. The polarizing D.C. voltage is thus re-generated periodically.

Abstract: A pump is provided with a stationary impeller housing having a motor driven diagonal impeller mounted therein. A diffuser is mounted coaxially with the impeller for converting the kinetic energy of the pumped fluid into a pressure head. A hollow body mounted in the diffuser defines a diffuser passage in which curved diffuser blades are mounted. The impeller has a conical hub having a diameter equal to 40-80 percent of the maximum diameter of the impeller blades.

Abstract: The invention provides a circuit for centrally generating the horizontal and vertical sweep frequencies in a TV receiver. A central oscillator provides a frequency which is divided to obtain the horizontal frequency. A periodic counter with adjustable final counting value divides the central oscillator frequency to establish a vertical sweep signal. Phase comparators and gate circuits are used to gate the oscillator signal to the periodic counter to synchronize the vertical sweep with the transmitted vertical sync signal.