Abstract: A positional display system for visually indicating given geographical locations such as the position of motor vehicles such as police cars and/or the location of the occurrence of an incident warranting police attention. The system includes a display board having a row and column matrix of individual lights and a map of the local geographic area of concern overlaying the matrix so that each light represents a unique map section. Whenever a patrol car transmits its position to a central station or a remote alarm indicates the occurrence of a robbery or the like, information indicative of the row and column address of the given location and at least one instructional command for determining the light status are entered. The entered information is converted into binary numbers indicative of the row and column addresses and the converted binary numbers are temporarily stored. The stored numbers are compared with the output of a scanning counter.

Abstract: A security alarm with audio monitoring capability including a remote location to be protected, a central monitoring station and transmission lines coupled therebetween. The remote location includes a circuit for generating a DC transmission signal of a first normal polarity. Sensors are provided for detecting various alarm conditions and a switching apparatus responsive to the detection of an alarm condition by the sensors reverses the polarity of the DC signal to indicate the existence of an alarm condition. A plurality of microphones each having its own amplifier and sensitivity control are strategicaly placed about the remote location to pick up audio sounds originating therein. The AC audio signals from the microphones are superimposed onto the DC transmission signal and transmitted to the central monitoring station.