Improving police command and control with a patrol car emitter-call box sensor car location system

High accuracy is not required for car locator systems used in police operations. Relatively inaccurate patrol car locator devices can greatly improve police operations by significantly reducing response time, by permitting dynamic redeployment of forces, and by providing for better administrative control of forces. The patrol car emitter-call box sensor technique could also be used on passenger buses and taxicabs to summon police assistance. The technique involves equipping patrol cars, buses, or taxicabs with a short-range coded radio frequency (RF) emitter devices and equipping call boxes or other public electrical facilities with a device for sensing the emitter signal of the passing vehicles. Presence and identity of the vehicles can be detected and automatically telemetered over existing telephone or electrical lines to a computer-controlled display board in the dispatching center. Vehicle identification encoding is accomplished by modulating the emitter-transmitter with a selected combination of tones that differs for each vehicle. The system would use a transmitter-receiver combination similar to that used by automatic garage door openers. Vehicle identification encoding would be accomplished by using techniques similar to those of the touch-tone dialing system of the telephone company. By taking advantage of existing call box systems, the implementation of this system would be particularly feasible for cities, such as Washington, D. C., that have an extensive police call box system. How such a system could be installed in Washington, D. C. is described in detail. Features of the system are the following: 1) relatively low installation cost; 2) minimum spectrum space requirements; 3) accuracy of ±¼ mile achievable with existing call box locations in Washington, D. C.; 4) it is possible to selectively increase accuracy by area; 5) spectrum requirements remain constant with increased accuracy or increased geographical area of coverage; 6) simple in- xpensive and proven equipment requirements.