Ultrasonic alarm system
First Claim
1. An ultrasonic alarm system comprising a transmitter, said transmitter comprising an ultrasonic carrier frequency signal generator, modulation means for modulating said carrier signal with a modulation signal, and transmission means for transmitting said modulated ultrasonic carrier signal;
- and at least one receiver, said receiver comprising receiving means for receiving said transmitted modulated ultrasonic carrier signal, demodulating means for demodulating said modulated carrier signal to obtain said modulation signal, and detector means connected to said demodulating means and responsive to a predetermined characteristic of the demodulated signal for producing an alarm actuation signal, said switch means comprising a pushbutton having an enlarged diameter portion and a reduced diameter depending shaft, a button support having a through bore slidingly receiving said shaft for movement of said button from a first position to a second position, said latching means comprises first and second spaced grooves on said shaft connected by a cam surface, and a member on said board normally biased into engagement with one of said grooves when said button is in said first position, said member being operable to ride on said cam surface and into engagement with said second groove when said button is moved to the second position to latch said button in said second position, said switch means further comprising a fixed contact and a movable contact spaced from said fixed contact and abutting said enlarged portion and positioned to be moved into contact with said stationary contact when said button is moved from said first to said second position whereby said switch means is moved from the open to the closed position.
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Accused Products
Abstract
An ultrasonic alarm system comprising a transmitter having an oscillator which produces an ultrasonic carrier frequency signal. An audio signal generator produces a signal which modulates the carrier signal. The modulated signal is applied to a crystal through a tuned circuit. The transmitter is energized by operating a pushbutton which remains latched in operative position and which is unlatched only by the use of special devices. A plurality of receivers are provided and individual receivers are positioned at different locations throughout the premises to be protected. Each receiver includes a demodulator that demodulates the received signal and applies the same to a phase locked loop type phase detector which actuates an alarm when the demodulated signal is present. The alarm indicates the particular receiver that has been activated so that help may be dispatched immediately to the correct location.
10 Citations
10 Claims
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1. An ultrasonic alarm system comprising a transmitter, said transmitter comprising an ultrasonic carrier frequency signal generator, modulation means for modulating said carrier signal with a modulation signal, and transmission means for transmitting said modulated ultrasonic carrier signal;
- and at least one receiver, said receiver comprising receiving means for receiving said transmitted modulated ultrasonic carrier signal, demodulating means for demodulating said modulated carrier signal to obtain said modulation signal, and detector means connected to said demodulating means and responsive to a predetermined characteristic of the demodulated signal for producing an alarm actuation signal, said switch means comprising a pushbutton having an enlarged diameter portion and a reduced diameter depending shaft, a button support having a through bore slidingly receiving said shaft for movement of said button from a first position to a second position, said latching means comprises first and second spaced grooves on said shaft connected by a cam surface, and a member on said board normally biased into engagement with one of said grooves when said button is in said first position, said member being operable to ride on said cam surface and into engagement with said second groove when said button is moved to the second position to latch said button in said second position, said switch means further comprising a fixed contact and a movable contact spaced from said fixed contact and abutting said enlarged portion and positioned to be moved into contact with said stationary contact when said button is moved from said first to said second position whereby said switch means is moved from the open to the closed position.
- View Dependent Claims (2, 3, 4, 5, 6)
- 7. A transmitter for an ultrasonic alarm system comprising a plurality of electrically-operated elements for producing and transmitting an ultrasonic alarm system, a pair of input terminals adapted to be connected to a source of power for energizing said electrically-operated elements, a switch movable from an open to a closed state to connect said pair of input terminals in circuit with said plurality of electrically-operated elements, latching means for latching said switch in said closed state, said switch means comprising a pushbutton having an enlarged diameter portion and a reduced diameter depending shaft, a button support having a through bore slidingly receiving said shaft for movement of said button from a first position to a second position, said latch comprising first and second spaced grooves on said shaft connected by a cam surface, and a member on said board normally biased into engagement with one of said grooves when said button is in said first position, said member being operable to ride on said cam surface and into engagement with said second groove when said button is moved to the second position to latch said button in said second position, said switch further comprising a fixed contact on said board, and a movable contact spaced from said fixed contact and abutting said enlarged portion and positioned to be moved from said first to said second position whereby said switch is moved from the open to the closed state.
Specification