| 摘要 |
<p>An a.c. signal from an oscillator (7) is fed via cables (6) to the primary loop (2) of a loop installation (1) buried in the surface of the roadway. The secondary loop (3) is connected (8) to a detector circuit (9). The detector output is fed to a signal processor which determines data about a vehicle (4) moving over the loop installation (1), e.g. size of vehicle, speed, number of vehicles per time unit, etc. When the vehicle passes, the a.c. in the secondary loop (3) undergoes phase and amplitude variations. These changes are detected by an amplitude or phase demodulator.</p> |
