Abstract: A DTMF telecommunication receiver in which an additional DTMF receiver circuit is provided tuned to a particular pair of tones. Detection of the particular tones opens a switch in the audio output line and eliminates crosstalk in the hybrid circuit making detection of further DTMF tones less likely to error.

Abstract: A piezoelectric loudspeaker having a bending mode piezoelectric diaphragm mounted on a diaphragm stretched across a frame, the piezoelectric diaphragm being supported at its central portion to a support provided at the frame, so that the central portion of piezoelectric diaphragm is stationary free from vibrations, thereby being higher in a sound pressure level and smaller in acoustic distortion than the conventional loudspeaker.

Abstract: A system for radio-telephone communication between a user at a remote location and the commercial telephone system or between two users at remote locations comprises a fixed terminal that is connected by wire lines or the like to the commercial telephone system and a plurality of portable radio units. The terminal is equipped for duplex operation on a plurality of channels, each of which uses separate frequency bands for transmitting and receiving. Each of the portable units is a simplex transceiver adapted to receive on each of the frequencies of transmission from the terminal and to broadcast on each of the frequencies received by the terminal. The terminal places a channel acquisition tone on an unused channel that is the next to be used. The terminal calls portable unit by shifting channel acquisition tone to another channel and broadcasting an identifier to the portable unit.

Abstract: Acoustic transducer having a piezo-electric element, including a lead section connected to the piezo-electric element, the lead section being in the form of a metallic body having a high specific attenuation.

Abstract: A motor control system utilizes a low cost switched controller for provding operator initiated control signals. The controller has therein a pair of switches which together define four possible modes of operation, depending upon operator manipulation of the controller. These four modes cause the system to either stop the motor, decrease the speed of the motor, maintain the speed of the motor constant, or increase the speed of the motor.

Abstract: Electric circuitry to correct for spurious sound pressure responses of audio transducers is disclosed. In particular, electric circuitry to compensate for "pre-shoot" of an audio transducer system is disclosed. The circuitry includes a delay line electric circuit carrying the bulk of the electric signal energy to the audio transducers and a parallel circuit to feed forward in real time an electric signal replica of diminished amplitude to the audio transducers. The replica thereby cancels or greatly minimizes the "pre-shoot" or prior undesired significant sound pressure responses of the audio transducers. The circuits include, in combination with the feed forward circuit, additional circuitry to counteract subsequent undesired significant sound pressure amplitude responses such as resonance (ringing). The new circuits utilize series resonant circuits in parallel to ground with the audio transducers as the preferred means to counteract the subsequent undesired sound pressure responses.

Abstract: An audio system, characterized in that the audio signal passes through a preamplifier, equalization unit and electronic cross-over and before reaching the power amplifiers, which drive the speakers, is modified by an electronic resonance control correction (ERCC) circuit.

Abstract: An acoustic transducer for producing highly directional characteristics comprises a metalized backplate (130) facing the flat surface (134) of an electrostatically charged electret foil (132). The thickness of the electret foil varies along the length thereof according to a predetermined relationship. The sensitivity of the electret transducer varies directly with the thickness of the electret foil.

Abstract: A telephone call screener discriminates between desired and undesired incoming telephone calls. Desired calls are signaled by use of a two-digit code known only to persons selected by the user. The first digit of the code refers to the number of silence gaps between calling tones or rings that the calling party has to wait before entering a second digit of the code from one of the ten numbers on the touch tone or rotary dial on the telephone used to place the call. An incoming call is first detected and electronically answered, after which the output of a sine wave generator is periodically transmitted over the open telephone line to generate false calling tones simulating the periodic audible ringing sequence of a conventional telephone. An enabling circuit detects the correct code being signaled only during the proper silence gap in the false calling tone sequence.

Abstract: A system and method for the automatic control of electrically operated gates is disclosed which includes a gate position transducer which provides an output signal in the form of pulses representing the incremental motion of the gate. The system also includes electronic circuitry responsive to the output signal of the position transducer for determining when the gate is either fully open or fully closed and also for determining when the gate motion is obstructed. The control system is fully automatic and does not require mechanical adjustments or the use of limit switches. Optional operating modes include an automatic close mode and the simultaneous operation of two gates.

Abstract: An ordinary lightning-accessible surface of an aircraft component consisting of a composite material such as a graphite epoxy composite includes one or more layers of dielectric material applied over the exposed composite surface portion of the aircraft, the outermost layer of dielectric material having a binder on the exposed surface thereof for holding a finely divided metal powder distributed uniformly over the surface of the outermost layer of dielectric material.

Abstract: A dynamic microphone in which vibrations transmitted to the case of the microphone are cancelled over a very wide frequency range. A moving coil type microphone unit sensitive to sound and a moving coil type vibration pickup unit sensitive to vibrations transmitted to the case of the microphone are provided in the case with a common magnetic circuit. The outputs of the moving coil vibration unit are coupled to the outputs of the microphone unit in opposite phase so that noise components corresponding to the vibrations transmitted to the case are cancelled.

Abstract: A system for translating interconnection supervisory signals, such as Touch Tone signals or dial pulses, from a remote telephone set into alphanumeric data. The system is capable of utilizing any one of a plurality of translation schemes, chosen by the user at the telephone set. Synthesized speech feedback is provided to the user after entry of each character. A number of new translation techniques are also disclosed.

Abstract: A device for visually presenting communications information, communicated over the telephone network by a pair of sequential dual-tone-matrix-frequency (DTMF) signals to a hearing-impaired person's location, includes an integrated circuit filter for separating the dual tones into one high-frequency-group tone and one low-frequency-group tones for concurrent presentation to a decoder. The decoder presents a four-bit signal to a microprocessor programmed to recognize the pair of sequentially-decoded DTMF signals as one of a set of alphanumeric symbols and to the parallel-format this character information. the character information is coupled to display drivers and associated displays, to present a plurality of sequential alphanumeric characters upon a visible display, in scrolled fashion, whereby the hearing-impaired person views visible information converted from audible tones.

Abstract: Energy in a received signal is distinguished as being whole band energy or partial band energy by comparing an average value of the received signal to a modified magnitude value of the received signal. A signal representative of the comparison result is supplied to a filter including hysteresis for generating a signal to control representative of whether whole band or partial band energy is present. Hysteresis is provided in generation of the control signal by comparing the output amplitude of the filter to a first threshold value when the control signal is a first state and then comparing the filter output amplitude to a second lower threshold value when the control signal is a second state. When the modified magnitude value exceeds the average value, the received signal includes whole band energy, otherwise the received signal includes only partial band energy.

Abstract: In sound generating systems, it has been ascertained that various factors cause spurious, audible emanations when transducers of reasonable size and cost are driven in complex motions characteristic of typical high fidelity audio reproduction. In a typical system in which different transducers are used for different frequency ranges, the spurious emanations are reduced by change of amplitude or frequency or both, without affecting transducer performance, to levels at which they are substantially inaudible. Means are coupled to each speaker in a multispeaker system for compensating for mass, compliance and damping. Further, crossover means are provided for introducing opposing signal components in a crossover range between two adjacent range speakers such that opposing signal components are acoustically cancelled in the composite output.

Abstract: A loudspeaker arrangement for a vehicle having a magnetic-field-sensitive device, includes a casing, and first and second loudspeakers disposed in the casing. First and second magnets are incorporated in the first and second loudspeakers respectively. The respective magnetic moments of the first and second magnets are arranged to be antiparallel so that the vector sum of magnetic fluxes produced by the first and second magnets will be reduced at the position of the magnetic-field-sensitive device.

Abstract: In a flapper nozzle actuator system a radial outward flow turbine like flapper is used as the flapper. The angular velocity of the turboflapper is used to lift the turboflapper off a backplate towards a nozzle. The amount of lift off the backplate and hence nozzle outlet area is a function of the angular velocity of the turboflapper. An adjustable opposing torque on the turboflapper controls the angular velocity of the turboflapper and thus controls the flow rate.

Abstract: The invention refers to a programmable signal processing device mainly intended for hearing aids and of the kind which include an electronically controlled signal processor. Hearing aids for persons having impaired hearing are normally adjusted for only one frequency response and are adapted to amplify the frequencies which the patient has difficulties to hear. At different sound environments as for example conversations with disturbing background sounds, normal conversation in quiet environments or at lectures, the conditions of listening are different. Up to now this problem has not been solved satisfactorily for hearing aids. With the present invention a number of different signal processes, can easily be selected to suit different sound situations automatically or by the user himself.

Abstract: A conference system for establishing simultaneous interchange of information among a plurality of participants (E.sub.o -E.sub.k) comprises a conference network (CN). Each participant is connected to a terminal (n.sub.o -n.sub.k) which is connected to a hybrid network (CS.sub.o -CS.sub.k). The output (SW.sub.o -SW.sub.k) from the hybrid networks (CS.sub.o -CS.sub.k) are fed to summing amplifiers (SA.sub.o -SA.sub.k) in the conference network CN. The outputs of the summing amplifiers are fed to the participants via the hybrid networks (CS.sub.o -CS.sub.k).The summing amplifiers (SA.sub.o -SA.sub.k) are arranged so that the signals contributed by the participant to which the particular summing amplifier output is connected is multiplied by a factor .beta. while the signals contributed by the other participants are multiplied by a factor .alpha..