| 摘要 |
The barrier (1) controls the admission e.g. of vehicles to an area under which two inductive loops (4,5) are laid, with the trailing edge of one loop (4) extending partly under the barrier into the protected area. The leading edge of the other loop (5) terminates at the barrier. An output device (3) associated with the first loop issues authorisation in the form of e.g. magnetic cards for raising the barrier. The processing electronic circuitry ensures that the barrier can be passed only in the authorised direction (F). |
