| 摘要 |
Vehicles traveling along a predetermined route are equipped with mobile receivers picking up traffic information from a radiating transmission line extending along the route, this information being modulated upon a first carrier F1 for vehicles traveling in one direction and upon a second carrier F2 for vehicles traveling in the opposite direction. Two ancillary short-range transmission stations, located at opposite ends of the line, radiate amplitude-modulated carrier waves directly to vehicles in the vicinity thereof whose receivers are tuned to either of the two carriers F1, F2. The first ancillary station emits the two carriers both modulated with a low-frequency signal f1 whereas the second ancillary station emits the same carriers modulated with a different low-frequency signal f2. A discriminating circuit aboard each vehicle, upon the reception of an amplitude-modulated carrier, tunes the receiver thereof either to the carrier F1 in response to a detected signal f1 or to the carrier F2 in response to a detected signal f2. |
