Abstract: A siren detection system controls the lights at an intersection to direct traffic and permit an emergency vehicle to travel through the intersection unimpeded. The system determines the frequency of the sound emanating from a siren carried by the emergency vehicle by counting pulses that indicate the frequency of the sound, by determining the elapsed time necessary to count a selected number of pulses, and by utilizing the elapsed time and number of pulses counted to determine the frequency of sound emitted by the siren.

Abstract: System and method for monitoring occupancy and status of restaurant tables to minimize the time each table is unoccupied. The system includes a processor unit coupled by means of serial data buses to a host unit and a plurality of service units. The host unit includes separate push buttons, or "table buttons", which correspond, respectively, to tables within a particular service area of the restaurant. The processor unit computes and stores the status of each table in the restaurant. The processor periodically computes and transmits display information representative of the updated status of the tables to the host unit and the service units. Such display information for a particular table is utilized at both the host station and the appropriate service station to illuminate or flash the table buttons in such a manner as to indicate the present status of the corresponding tables to restaurant personnel.