Abstract: A wall mounted speaker system which is arranged to alleviate problems of unwanted noise in the production and transmission of audio waves, particularly in the lower wave lengths from 20 to 200 hz. There is a speaker unit having a pair of vertically spaced speakers, and an inertial noise suppressing section positioned between the two speakers. The inertial noise suppressing section has an inertial mass which is moved in a back and forth motion to create an inertial offsetting force into a housing structure of the speaker section. The two speakers also create inertial forces which are also transmitted into the housing of the speaker unit, and these are substantially diminished by the interaction of the inertial forces of the speakers and those of the inertial noise suppressing system.

Abstract: A system for operating a barrier system such as a garage door, gate or fence. A DC motor is connected to and operates a barrier drive. A power amplifier is configured to receive power signals from a power supply and to output modulated DC signals to the DC motor. A controller implements an intelligent closed-loop motion control algorithm to control the power amplifier according to a non-linear motion profile. A feedback sensor provides status signals to the controller to determine position or speed of the barrier.

Abstract: The invention provides a vibration isolation mount for a motorized garage door opener system. The mount includes a substantially planar first mounting plate with apertures configured for mounting to structure inside a garage, and a substantially planar second mounting plate with threaded bolt shafts or other mounting elements configured for mounting to motor mounting structure mounted to a drive motor for use in the system. A vibration isolation material, which may be a natural or synthetic rubber, is disposed between the first and second mounting plates to isolate noise and vibration produced by the motor from the structure mounting the assembly to the interior of the garage.

Abstract: A radio transceiver comprises a reception path, a transmission path, and a frequency generator with a programmable phase lock loop. The reception path, the transmission path, and the frequency generator share a maximum amount of common circuitry to facilitate implementation of the entire radio transceiver on a single integrated circuit. The reception path includes an amplifier and a quadrature mixer for producing low intermediate frequency signals. The transmission path can be controlled by either a modulated voltage controlled transmitter or an in-phase and quadrature modulator transmitter.

Abstract: The mixer circuit is a singled ended input to a double balanced high dynamic range mixer with only two base-emitter junctions across the supply. It provides for the use of bondwires to off chip ground as DC block and DC feed elements. The single ended input and differential output balanced mixer is well suited for the input stage of an integrated radio receiver—off chip circuitry is usually single ended, but on chip circuits are usually differential. No off chip differential RF circuits or baluns are required which reduces off chip component count and improves radio performance. The mixer circuit has lower LO drive requirements because of the DC coupled LO port. This results in better radio performance and a smaller die area because of the DC coupled IF port.

Abstract: A data recovery algorithm for implementation in a radio transmitter or receiver that includes a direct current level setting circuit with a preamble detector which will establish a threshold for a simplified decision simplified equalizer slicer that improves receiver performance in a feedback manner by utilizing an analog comparator, a one symbol long one bit resolution delay line and a summing junction.

Abstract: A superhet receiver with quadrature IF and improved demodulator is configured to recover a modulated signal from a low IF in a radio receiver. A superhet receiver receives a FM radio-frequency signal, converts the input RF signal to an in-phase IF signal and an IF signal in phase quadrature to the in-phase signal, and outputs the IF signals. A plurality of monostables receive the IF signals and each monostable generates a corresponding output pulse. By combining the monostable output pulses, a complex waveform is generated. The complex waveform includes the demodulated signal and a carrier signal at a significantly higher IF. The complex waveform is filtered to recover the desired modulated signal.

Abstract: A method and apparatus for controlling the operation of a garage door opener is disclosed wherein a micro-controller de-energizes a garage door drive motor for a first period when a stop command is received while the garage door drive motor is energized and the garage door is travelling in a first direction. The micro-controller then energizes the drive motor to move the garage door in the opposite direction from the first direction for a second period. The micro-controller then de-energizes the drive motor, placing the door in a static state.

Abstract: A control system for an actuator used to actuate a device. A receiver in the control system receives different transmitter identifiers from multiple transmitters. A central processor coupled to the receiver uses a received transmitter identifier as the address of a memory location. If the control system is set to a write mode when the transmitter identifier is received, a valid bit is set in the addressed memory location to indicate that the transmitter identifier is valid. If the control system is set to read mode when the transmitter identifier is received, the addressed memory location is examined to determine if a valid bit has been set. If the valid bit has been set, the central processor transmits a signal for actuating the device.

Abstract: A drive assembly in a motorized door opener includes a motor that is mounted on a mounting structure. At least one vibration isolator is provided between the motor and the mounting structure. The vibration isolator includes a first mounting fastener configured to be mounted to a mounting fastener on the motor, a second mounting fastener configured to be mounted to the mounting structure to mount the motor on the mounting structure, and an elastomeric material between the first and second mounting fasteners. The elastomeric material lies between the first and second mounting fasteners so that the isolator's two mounting fasteners are not in physical contact.

Abstract: A drive assembly in a motorized door opener includes a motor that is mounted on a mounting structure. At least one vibration isolator is provided between the motor and the mounting structure. The vibration isolator includes a first mounting fastener configured to be mounted to a mounting fastener on the motor, a second mounting fastener configured to be mounted to the mounting structure to mount the motor on the mounting structure, and an elastomeric material between the first and second mounting fasteners. The elastomeric material lies between the first and second mounting fasteners so that the isolator's two mounting fasteners are not in physical contact.

Abstract: A garage door drive assembly for moving a linkage arm connected to a garage door, the assembly being adapted for shipping in a partially assembled condition in at least a box for on-site installation, the assembly has a longitudinally-extending rail with laterally extending flanges. The assembly also has a carriage shaped to fit about the flanges. A drive mechanism is movably mounted to the rail. An anchor is coupled to the drive mechanism. The assembly also has a coupler with a selectively releasable connection to the anchor, a connector pivotably connectable to the linkage arm, and a detachable connection enabling the coupler to be fixedly secured to and carried by the carriage. The rail and the carriage may be shipped to the installation site in a box having a smaller cross-sectional profile than would be required to accommodate the carriage and coupling in their connected state.

Abstract: A mounting system for the safety beam units of a garage door opener, the mounting system having two brackets, each bracket having a base with a circular opening and a support, the supports of both brackets being adjustably coupleable together. The mounting system also has a beam unit housing with a cylindrical mounting base fittable through the circular opening in the base of at least one of the brackets. A spring is coupled to the cylindrical mounting base, the spring having at least one end extending beyond a side of the cylindrical mounting base. The beam unit housing being held in position by the at least one spring end extending into contact with the base of least one bracket.

Abstract: A fuse-trimmed tank circuit for an integrated voltage-controlled oscillator (VCO). The tank circuit includes an L-C portion; a cross-coupled pair of transistors, whose collectors are coupled to the L-C portion; a capacitor coupled across the emitters of the cross-coupled pair of transistors; and a pair of resistors, where each resistor is coupled between a corresponding one of the emitters and a ground node. This oscillator circuit provides improved performance over prior oscillator circuits. A technique for trimming the VCO is utilized to adjust its center frequency. Capacitance for the L-C portion of the tank circuit is provided by one or more varactor diodes. When the VCO is operational, the varactors are reverse biased and, thus, act as capacitive elements. One or more of the varactors has an associated fuse coupled in series with the corresponding varactor. To trim the center frequency of the VCO, the capacitance of the L-C portion is adjusted by selectively blowing the fuses.

Abstract: The invention is an improved implementation of an active-RC polyphase band-pass filter with transconductor cross-coupling between filter sections. The polyphase filter has first to fourth inputs, first to fourth outputs, two filter sections, and a block of transconductor pairs. The four input signals to the polyphase filter succeed one another in phase by 90 degrees. The two filter sections have reactances comprised of active balanced operational amplifiers with matched capacitors in their feedback loops. The block of transconductor pairs is coupled between corresponding reactances of each filter. The transconductance of each transconductor pair is set as the product of a desired radian center frequency and the capacitance of the corresponding matched capacitors. In the preferred embodiment, the transconductors are Gm cells and the transconductance of at least one Gm cell is field adjustable.

Abstract: A technique for interfacing transmission media in a local area network (LAN). A first transceiver and a second transceiver, each have a media dependent interface and a media independent interface. Each media dependent interface is coupled to respective transmission media while the media independent interfaces are coupled together. A receive clock output of the first transceiver is coupled to a first input of a first multiplexer. A receive clock output of the second transceiver is coupled to a first input of a second multiplexer. A fixed frequency clock signal is coupled to a second input of the first multiplexer and to a second input of the second multiplexer. An output of the first multiplexer is coupled to a reference clock input of the second transceiver. An output of the second multiplexer is coupled to a reference clock input of the first transceiver. A select input of the first multiplexer is coupled to a status output of the first transceiver.

Abstract: A method and apparatus for modulation of a voltage-controlled oscillator (VCO). The VCO receives a tuning control voltage for adjusting a center frequency of an output periodic signal formed by the VCO. In addition, the VCO receives a modulation control voltage for modulating the output periodic signal by a content-carrying signal according to frequency modulation techniques. A frequency deviation obtained in the output periodic signal in response to changes in the modulation control voltage is linearized by forming the modulation control voltage as the result of a linear correction polynomial. A linear correction circuit forms the modulation control voltage. More particularly, a first amplifier having a gain of K1 receives the tuning control voltage. A first summing block then receives the output of the first amplifier and adds the constant K0. A second amplifier having a gain of m receives the content-carrying signal.

Abstract: A current-limit circuit and a method of limiting current supplied to a load through a power transistor utilize a control transistor that is selectively activated to a conducting state to limit the current conducted through the power transistor in response to a predefined condition. The predefined condition may be a short-circuit condition or an over-current condition. The configuration and operation of the control transistor are such that, when the control transistor is in a conducting state, the current conducted through the power transistor is limited by the structural ratio of the two transistors. However, during normal operating conditions when the control transistor is deactivated to a non-conducting state, the control transistor does not degrade the performance of the power transistor. In a first embodiment, the current-limit circuit is configured to provide protection from a short-circuit condition.

Abstract: An current share controller detects a power converter module having the lowest supply current. That lowest supply current converter module is selected to be the system master. The current share controller is configured such that shared devices within the system can hot-swap capability. An output voltage loop amplifier includes an opto-coupler driver. The voltage loop amplifier compensation is compatible with conventional TL431 shunt regulators. This allows a power supply system to balance supply current between multiple supply modules with an eight pin load balancer configuration.

Abstract: A method and apparatus for controlling the operation of a gas discharge lamp including regulation of power provided to the lamp for maintaining a preselected illumination intensity, automatic lamp shut down for preventing a catastrophic failure of the lamp, and automatic selection of operating frequencies for increasing efficiency and extending useful life of the lamp. An appropriate quality factor Q is achieved by including a low pass filter followed by a high pass filter in the lamp network so as to allow deep dimming of the lamp. Preferably, the arc power delivered to the lamp network is sensed and regulated. By sensing the arc power instead of only the lamp current, the illumination intensity of the lamp is accurately regulated. Further, the lamp ballast is automatically shut down near the end of the lamp's useful life, before operation in partial rectification.