论文部分内容阅读
水文缆道测流通常是采用无线传输形式,要求在钢丝索和水体大地构成的传输回路中同时传送水面、河底和流速仪三组信号,并要互不干扰易于分辨。所以这些水下讯号源一般多用直流脉冲和交流脉冲混合装置。过去交流脉冲的产生都采用分立元件组装的振荡器,这种装置元件多、可靠性差,加上转换开关及水下电池筒等,显得体积大,对减小偏角不利。用集成门电路来组成脉冲电路,既灵活又方便。同分立元件相比,集成门电路由于元件少,线路简单,便于调试,而且具有功耗低、体积小,开关速度快等优点。因此用与非门电路来组成多谐振荡器脉冲
Hydrological cableway current measurement is usually the form of wireless transmission, requiring cable and water body in the formation of the transmission loop at the same time send water, river bottom and the current meter three sets of signals, and no interference with each other easy to distinguish. Therefore, these underwater signal sources generally use more DC pulse and AC pulse mixing device. In the past, AC pulses were produced using oscillators with discrete components. Such devices have many components with poor reliability, coupled with change-over switches and underwater battery cartridges, which are bulky and detrimental to reducing the declination. Integrated gate circuit to form a pulse circuit, both flexible and convenient. Compared with the discrete components, the integrated gate circuit due to fewer components, simple lines, easy to debug, but also with low power consumption, small size, switching speed and so on. Therefore, NAND gate circuit to form a multivibrator pulse