Coded security switch
AssigneeAmerican District Telegraph Company
InventorsRobert B. Enemark, Stephen Marchetti
Life of this patent
Estimating the term…
Abstract
For use in an alarm system, a security switch is provided, the transition state of which is detected by an associated circuit and a coded signal transmitted along a communication path indicative of the transition state, this coded signal being received and decoded to provide an output indication of the switch state.
Claims15
For use in an alarm system in which a security switch is monitored to denote the transition state thereof, a circuit comprising:
- first gate means including a timing circuit coupled directly to said switch and operative to provide a start signal in response to each switch transition from an open to a closed state and from a closed to an open state and for a time interval determined by the timing circuit;
- first means coupled directly to said switch and operative to provide a logic level indicative of the open and closed states of said switch;
- transmission means including:
- encoder means operative to provide an output code in response to said logic level of the open and closed states of said switch;
- a transmitter operative in response to said output code and to said start signal to provide a coded signal for transmission along a communications path and representative of the transition states of said switch for each said switch transition.
For use in an alarm system in which a security switch is monitored to denote the transition state thereof, a circuit comprising:
- first gate means including a timing circuit coupled directly to said switch and operative to provide a start signal in response to each switch transition from an open to a closed state and from a closed to an open state and for a time interval determined by the timing circuit;
- first means coupled directly to said switch and operative to provide a logic level indicative of the open and closed states of said switch;
- a programmable encoder operative to receive said start signal from said first gate means and said logic level from said first means and to provide an output code for the duration of the timing interval and representative of the transition state of said switch;
- and
- transmitter means operative in response to said output code and for a time interval determined by said start signal to provide a coded signal of a form for transmission along an intended communications path.
An alarm system in which at least one security switch is monitored to denote the states thereof, comprising:
- first gate means including a timing circuit coupled directly to said switch and operative to provide a start signal in response to each switch transition from an open to a closed state and from a closed to an open state and for a time interval determined by the timing circuit;
- first means coupled directly to said switch and operative to provide a logic level indicative of the open and closed states of said switch;
- transmission means including:
- encoder means operative to provide an output code in response to said logic level of the open and closed states of said switch and for the duration of the timing interval;
- a transmitter operative in response to said output code and to said start signal to provide a coded signal for transmission along a communications path and representative of the transition states of said switch for each said switch transition;
- receiver means operative to receive the coded signal from said transmitter means and to demodulate the received signal;
- a decoder operative to decode the demodulated signal;
- and
- means for indicating alarm status.
Dependencies are inferred from the claim text.