Mobile emergency unit locating system

摘要: 1,248,066. Radio position-finding. J. P. CHISHOLM. 5 Dec., 1968, No. 57764/68. Heading H4D. Relates to a system in which three fixed and spaced receivers are utilized locate each of several mobile units by determining the relative times arrival pulses from unit. According one aspect invention, unit transmits an assigned time slot at is synchronized with correction signal provided accurate clock. another invention two kinds (e.g. police vehicles other vehicles) first timing means periodically actuates pulse emitter second transmitter actuated transmit higher repetition rate than kind switch renders actuator operative. Coded groups different may be sent units.