Abstract: An alarm device having a code verification system is disclosed for registering and transmitting a preselected code to a receiving station. If the preselected code is at the receiving station, no alarm signal will be produced. The code verification system comprises register means under control of an operator for registering a code that is entered therein by the operator. A transmitter is provided which is responsive to a transmit signal for transmitting the contents of the register to the receiving station. A transmitter signal generating means is similarly provided for generating the transmit signal to initiate a transmission. The system further includes a comparator for comparing the code registered in the register with the preselected code and for generating an inhibit signal when the codes are different. Inhibit means is provided which is responsive to the inhibit signal for preventing transmission of the contents of the register.

Abstract: A system for sensing the open or closed position of a closure member such as a window or door includes a first winding having a magnetic core and an audio frequency electromechanical first transducer and electrically interconnected and mounted on the closure member. A second winding having a magnetic core and an audio frequency mechanical electrical second transducer are mounted on a stationary base and the cores are closely coupled as are the transducers when the closure member is in closed position. The second winding is connected to a pulsed ultrasonic alternating current, and the second transducer is connected by way of amplifiers to a multiplex signal transmitting network. The opening of the closure member uncouples the cores and the transducers to produce a signal change at the transmitting network output.

Abstract: A system for registering and transmitting a preselected code to a receiving station which comprises a switch operable between open and closed states. An oscillator is responsive to the operation of the switch to the closed state for producing a pulse train. A control device is provided that has a plurality of states and is movable from state to state in response to an advance signal which is generated by an advance signal generator. The advance signal generator is operable by an energizing signal. A counter is connected to the oscillator for registering the number of pulses in response to one state of the control means. A transmitter is responsive to another state of the control means for connecting the oscillator to a transmission line.