Abstract: A system for monitoring a protected premises from a central station over telephone lines employs different audio tones sent back and forth over the lines. A random succession of audio tones from the central station interrogates the protected premises and is returned as a like succession of different tones to the central station where the latter tones are compared with the first to indicate a normal or a trouble condition at the protected premises or on the lines. When an alarm condition exists at the protected premises, still different tones are sent over the lines to cause an alarm alert at the central station. The entire system can be tested from the protected premises, including operation of the trouble and alarm circuits, without producing a trouble or an alarm alert at the central station.

Abstract: A programmer clock for use with alarm systems in banking and like institutions employs a diode matrix, day and hour stepper switches and a direct current motor driven clock, the positions and controls of all of which are mounted and visible on a single control panel. The condition of the alarm system and the program can be determined at a glance and the program itself can be readily and accurately altered at any time by authorized persons.