| 摘要 |
The system works on the principle of measuring the damped oscillations of sensors with synchronized excitation. Excitation pulses are generated by the processor (12), which in response to the properties of the connected sensor (2) adjusts their amplitude, number, period and rate. The processor (12) controls also the entire behavior of the system, thus considerably enhancing its flexibility. Based on the measured excitation rate and the level of the induced voltage during tail oscillations of the string the processor (12) sets also the corresponding gain of the differential amplifier (4) and tunes the narrow-band amplifying SC filter (6). This allows the system to efficiently excite and identify vast range of various sensor types. Initial searching of the resonance frequency in the non-synchronized state is based on the frequency analysis performed also by the processor (12) upon recorded pulse response of the sensor (2). The exciter (1) itself is enhanced with the current protection against short circuit. Due to the bridge structure of the exciter (1) it is possible to efficiently excite the sensor (2) and to design the subsequent input amplifier of the induced voltage as a differential amplifier (4), which amplifies the useful induced signal while suppressing the common interference. |
