MAJOR INNOVATIONS IN SYSTEMS ARE AFFECTING LAW ENFORCEMENT CONTROL, COMMAND, AND COMMUNICATIONS OPERATIONS; COMPUTER AND DIGITAL EQUIPMENT ARE BECOMING AVAILABLE FOR INCREASED COMMUNITY SERVICE AND PERSONNEL SAFETY. THIS MANUAL DESCRIBES THE ADVANTAGES AND DISADVANTAGES OF COMPUTER-AIDED DISPATCH CENTERS, COMPUTER-CONTROLLED COMMUNICATION SYSTEMS AND INFORMATION FILES, PUBLIC-CALLING AND EMERGENCY MEDICAL SERVICE SYSTEMS, DIGITAL SYSTEMS, AUTOMATIC VEHICULAR LOCATION SYSTEMS, VOICE PRIVACY SYSTEMS, REPEATER AND VOTING RECEIVER SYSTEMS, SCANNING RECEIVER SYSTEMS, AND PUBLIC TRANSPORTATION SAFETY CHANNELS. THE PRINCIPAL COMPONENTS OF NEWER COMMUNICATIONS SUBSYSTEMS ARE DESCRIBED. THESE INCLUDE TRANSCEIVERS, ANTENNAS AND COMBINERS, CONTROL CONSOLES, POWER SOURCES, STANDARD AND TELEPHONE INTERFACES, LIGHTING SUPPRESSION, AND TEST EQUIPMENT. EXTENSIVE EARLY PLANNING AND CONTINUAL GOOD MANAGEMENT ARE REQUIRED TO OPERATE EFFECTIVELY ANY OF THESE COMMUNICATION SUBSYSTEMS, AND NEW PUBLIC BUILDINGS AND FACILITIES SHOULD BE PLANNED WITH ADEQUATE CONDUITS TO ALLOW FUTURE DEPLOYMENT OF COMMUNICATIONS SYSTEMS. COST CONSIDERATIONS WILL PLAY AN IMPORTANT ROLE IN CHOOSING EQUIPMENT, SO A LIST OF BUYERS' GUIDES IS INCLUDED FOR GENERAL ELECTRONIC PRODUCTS AND TELECOMMUNICATIONS SYSTEMS.