| 摘要 |
The recorder employs a number of sensors (111,121), responsive to different types of shock e.g. thermal producing intrinsically distinguishable signals. The signals are filtered and shaped (511,521) and then added (102). When the sum, s(t), exceeds a preset threshold, a trigger circuit (513) switches on a power supply (523) activating the remainder of the recorder. A digitiser (514) operates at a sampling rate, preferably >3 kHz, allowing for the resonance frequency of the accelerometer. The digitised signals are stored in a memory (515) preferably nonvolatile supplied with date and time by a clock circuit (517). On arrival at the destination, the memory can be read by means of a circuit (516) while maintaining the integrity and confidentiality of the contents.
|
