Abstract: Improvements to U.S. Pat. No. 5,428,642 including use of a single clock providing a first frequency to drive a power supply and a second frequency, twice the first frequency, to dual channel pulse width modulators and audio amplifiers. The power supply is improved to provide enough output voltage that the amplifier stays below 90% modulation and the first frequency driver eliminates the dead band, thereby improving efficiency. Current limiting, even against shorts in the load, is provided by inductor inputs to the clipper circuits, where the inductors are in the magnetic fields of the output chokes. The audio amplifiers are isolated by optical couplers for the audio signal and by an optical coupler and isolation transformers for the clock. One clock amplifier supplies both amplifier channels. The pulse width modulator uses the optically isolated clock and receives clipped audio directly. Two channels fit in the space of one old channel.

Abstract: Improvements to U.S. Pat. No. 5,428,642 including use of a single clock providing a first frequency to drive a power supply and a second frequency, twice the first frequency, to dual channel pulse width modulators and audio amplifiers. The power supply is improved to provide enough output voltage that the amplifier stays below 90% modulation and the first frequency driver eliminates the dead band, thereby improving efficiency. Current limiting, even against shorts in the load, is provided by inductor inputs to the clipper circuits, where the inductors are in the magnetic fields of the output chokes. The audio amplifiers are isolated by optical couplers for the audio signal and by an optical coupler and isolation transformers for the clock. One clock amplifier supplies both amplifier channels. The pulse width modulator uses the optically isolated clock and receives clipped audio directly. Two channels fit in the space of one old channel.

Abstract: An end-of-branch (EOB) module system for an audio signal distribution system having a wired trunk and a plurality of wired branches extending communicatively from such trunk, the EOB module system including: a plurality of EOB modules including one EOB module electronically coupled at each distal end of each branch and trunk of the audio signal distribution system, where each EOB module of the plurality of EOB modules has a unique address together forming a plurality of unique addresses; a test system able to send a test carrier signal encoded with any one unique address of the plurality of unique addresses at a time onto the trunk; and a switch within each EOB module, responsive to its unique address to place an end-of-line (EOL) load on its respective branch or trunk, and where power for operation of each EOB module is provided by rectification of the test signal.

Abstract: An end-of-branch (EOB) module system for an audio signal distribution system having a wired trunk and a plurality of wired branches extending communicatively from such trunk, the EOB module system including: a plurality of EOB modules including one EOB module electronically coupled at each distal end of each branch and trunk of the audio signal distribution system, where each EOB module of the plurality of EOB modules has a unique address together forming a plurality of unique addresses; a test system able to send a test carrier signal encoded with any one unique address of the plurality of unique addresses at a time onto the trunk; and a switch within each EOB module, responsive to its unique address to place an end-of-line (EOL) load on its respective branch or trunk, and where power for operation of each EOB module is provided by rectification of the test signal.

Abstract: A courtesy announcement system and method for broadcasting messages audially and visually having a central database server connected to operator workstation computers. Announcements stored and maintained in the database server can be accessed, viewed, modified, and replayed by any of a plurality of operators located at the workstation computers. Operators receive and construct announcements to be broadcast using announcement templates and the broadcasts can be multi-lingual even if the operator is not multi-lingual. Announcement templates includes pre-translated variables, and optional announcement delivery settings permit the operator to conduct the destination of the announcements, when the announcement should be broadcast, and start times for broadcast, among other settings.

Abstract: The instant invention provides a system and method of broadcasting audio and visual information to a plurality of audio reproduction devices and visual display devices utilizing a plurality of control computers linked thereto by a communications network. The invention employs a plurality of pre-recorded digital audio files and corresponding visual representation thereof to allow a user to construct message sequences for broadcast with a minimum of system input. Furthermore, a user may specify a plurality of broadcast zones to broadcast audio and visual messages.

Abstract: An end-of-line module provided at the end of the line of an audio circuit provides a load in response to a test signal. The load is detectable by an announcement control system so that a fault indication may be triggered in the event the announcement control system does not sense the end-of-line module as being connected to the audio circuit and detects an interruption in the audio circuit. In addition, the end-of-line module may include an over-temperature sensor or protection device to prevent the audio circuit from exceeding a predetermined limit, for example, a temperature level assigned to insure compliance with fire, safety and other standards or specifications. A fault or other indication may be reported to or sensed by the announcement control system and may be further processed in a manner appropriate for the application and/or facility having the announcement control system.

Abstract: An end-of-line module provided at the end of the line of an audio circuit provides a load in response to a test signal. The load is detectable by an announcement control system so that a fault indication may be triggered in the event the announcement control system does not sense the end-of-line module as being connected to the audio circuit and detects an interruption in the audio circuit. In addition, the end-of-line module may include an over-temperature sensor or protection device to prevent the audio circuit from exceeding a predetermined limit, for example, a temperature level assigned to insure compliance with fire, safety and other standards or specifications. A fault or other indication may be reported to or sensed by the announcement control system and may be further processed in a manner appropriate for the application and/or facility having the announcement control system.

Abstract: The instant invention provides a system and method of broadcasting audio and visual information to a plurality of audio reproduction devices and visual display devices utilizing a plurality of control computers linked thereto by a communications network. The invention employs a plurality of pre-recorded digital audio files and corresponding visual representation thereof to allow a user to construct message sequences for broadcast with a minimum of system input. Furthermore, a user may specify a plurality of broadcast zones to broadcast audio and visual messages.

Abstract: A signal amplifier device providing output power independent of change in output characteristics or common mode interference including a signal input source to provide an input signal, a first power supply and second power supply having a transformer with a secondary coil and a reference power, first differential amplifier powered by the first power supply to receive the input signal and provide first and second complementary output signals, first and second output amplifiers driven by the reference power supply and each having an input to receive one of the first and second signals and amplify same to provide first and second output signals at the respective outputs so that upon imposition of a transient signal at the output of one of the first and second output amplifiers an isolation network prevent the transient signal from appearing as a differential signal on either output.

Abstract: A multiple program input audio system including a plurality of input channels each adapted to provide an output program signal. Each channel comprises an actuator which compares a rectified program signal with a reference signal and generates an actuator output signal when the rectified signal is greater than the reference signal. A zero crossing detector also receives the program signal and generates an initiator pulse when the voltage of the program signal is zero. A master control switch receives the actuator output signal and generates a first master control output signal when pulsed by the initiator pulse and generates a second master control output signal when no signal is received from the actuator. A program switch receives the program signal and in response to the first master control output signal applies the program signal to an audio program buss where the program signals from all the channels are summed and applied to a digital attenuator.

Abstract: A low impedance digital attenuator to selectively attenuate an alternating current composite program signal composed of output program signals from different input channels in accordance with the number of active input signals where each input channel includes an input channel control device to provide an actuating signal when the channel is in selected operating mode and a program output signal. The actuating signals of the channels are summed and converted to a digital signal. The digital signal is supplied to a converter to generate a digital control signal where the relationship between the digital signal and the digital control signal is nonlinear. First and second digital to analog converters are provided to receive the digital control signal and a reference signal. The first digital to analog converter attenuates the composite program signal as a function of the digital control signal and provides an attenuated composite program signal.

Abstract: Multiple input sound amplifying and activation system including at least two microphones where an input channel is provided for each microphone. Each input channel provides a rectified signal to a summing device which sums the signals from the channels to generate a reference signal. Each input channel also includes a comparator to compare the reference signal with the signal received by the channel and provides a first control signal and second control signal in response to ratio between the reference signal and the channel input signal. The control signals operate a program signal amplifier to provide a program signal to an attenuator which attenuates the signal in response to the number of active channels.