| 摘要 |
The vehicle key (1) carries a calculating unit (9), memory (10) and infra-red emitter (5). On pressing a switch (4) an authorising code is transmitted (5,11), repeatedly, from memory to the on-board calculator (12). Turning the key to ''Start'' powers up (15,16) the on-board circuits. If correspondence with a code held in on-board memory (13) is not established, e.g. due to signal noise, a time-delayed alarm unit (17) re-submits the signal to the calculator (12). The result of the verification process is passed to a holding circuit (18) to confirm the signal voltage exceeds a specific level. When the authenticity of the signal is established, an output unit (14) permits engine starting. Optionally the communication link is by radio. |
