| 摘要 |
1438183 Electric selective signalling; roadtraffic signals THOMSON-CSF 24 May 1973 [26 May 1972] 25004/70 Headings G4H and G4Q The invention relates to a system for presenting and utilizing data pertaining to vehicles (e.g. buses) at predetermined transit points along a route defined thereby (e.g. bus stops). At a bus stop, frequency-, phase-, or amplitude-modulated radio signals are received and demodulated 1-3 and passed to series/parallel registers 4 where they are checked for parity. The outputs 5-9 from 4 indicate respectively: message valid, bus identity number, vehicle occupancy, distance Dv from a datum point, e.g. start of route, and direction of travel. Signals 5-7 pass to a storage unit 14, Fig. 3 (not shown), which incorporates appropriate gating circuitry. Signal 8 and a signal Ds (distance of bus stop from start of route) are fed to a subtractor 12 which sends signals 20 (De = Ds - Dv) and 22 (sign of De) to 14. Signal 9 is fed to a comparator 10 to check that it is going in the right direction for the bus stop (output 18). Store 14 is linked via a code converter 15 to a display 16 (luminescent, liquid crystal, &c.) which indicates, inter alia, the distance De of the bus from the bus stop and the number of unoccupied seats thereon. If several routes pass the same bus stop, the system will include separate items 10-16 for each route, the comparators 10 being used to discriminate between the different routes. The system may be adapted to control traffic lights when a bus is within a "zone of action" (distance Da) thereof. At each set of traffic lights, Fig. 5, signals De, Da from subtractor 12 and a store 56 are compared at 55: if De<Da and if De>0, a gate 54 is enabled. This enables a gate 57 which passes the vehicle number 6 to a store 49 if this is empty (determined by logic 48-52) and if the received message is correct in other respects (gate 23 and comparator 50). A signal 53 indicating that 49 is not empty is then used to control the traffic lights. The system may be adapted by suitable duplication of components to deal with several buses within the "zone of action" and/or several routes passing the traffic lights. |
