Abstract: Normal hard-wired domestic burglar alarms have cables with six conductors extending between the alarm controller and each remote input/output device (such as an entry keypad). The present alarm system has an alarm controller, a remote input/output device, a cable extending from the alarm controller to the remote input/output device, the cable comprising two conductors only, providing power to the remote input/output device. A signal processor at the controller monitors and processes voltage and current in the conductors to affect functions of the alarm system. A mixer at the remote input/output device processes voltage and current in the conductors to affect functions of the alarm system.

Abstract: Normal hard-wired domestic burglar alarms have cables with six conductors extending between the alarm controller and each remote input/output device (such as an entry keypad). The present alarm system has an alarm controller, a remote input/output device, a cable extending from the alarm controller to the remote input/output device, the cable comprising two conductors only, providing power to the remote input/output device. A signal processor at the controller monitors and processes voltage and current in the conductors to affect functions of the alarm system. A mixer at the remote input/output device processes voltage and current in the conductors to affect functions of the alarm system.