| 摘要 |
PURPOSE:To make it possible to synchronize again even at the time of getting out of synchronous phase by clamping the control voltage in the fixed range in the current meter demodulating the phase modulating signals of the supersonic waves caused by Karman whirl using the voltage control phase deviation circuit. CONSTITUTION:The supersonic waves phase-modulated by Karman whirl become one input V5 of the phase comparator 6. The voltage control phase deviation circuit 8 generates the signals V4, wherein the phase deviation angle from the oscillation signals V1 is controlled according to the output voltage V8 of the loop filter 7 and the clamp circuit 51 becoming the other input of the comparator 6 and constituting the phase synchronous loop. The deviatable phase shift angle of the circuit 8 is limitted and when the signals V5 is phase shift modulated in a wide-angle above this range becomes out of synchronism. Therefore by clamping the voltage V7 in the fixed range through the circuit 51 the circuit 8 maintains the oscillaion frequency at the time out of phase synchronism while returning to the synchronizable range it quickly restores synchronism to make it possible to perform the operation of normal phase synchronous loop and to measure velocity of flow. |
