| 摘要 |
<p>A vibration densitometer including a closed loop electromechanical oscillator for vibrating a fluid immersible vane. A digital output directly proportional to density is achieved through a unique digital squarer. The densitometer is an all digital system. In the loop, a tracking filter is provided. Separate search and track automatic gain control feedbacks are provided. A threshold detector controls clamps and a gate to cause the voltage controlled oscillator of a first phase lock loop to search or track the vane resonant frequency. The threshold detector also effects the search feedback. A phase adjustment circuit and a second phase lock loop are employed to impress a sine wave voltage component on the vane driver of a phase which creates maximum efficiency.</p> |
