| 摘要 |
FIELD: physics. ^ SUBSTANCE: in process of measurement by signal from probe pulse generator piezoelectric transducers alternately radiate ultrasonic wave along with the flow and opposite to it, and transform it into electric sinusoidal signal, which is transformed into sequence of rectangular pulses of single amplitude with the help of comparator. Level-shaping circuit (LSC) sets value of initial level of reference signal below amplitude of the first half-wave of sinusoidal signal. During performance of electric transformation by comparator after the first comparison of forward section of the first half-wave amplitude to value of initial reference signal of comparator, level of reference signal is changed by LSC to zero level, which is set as equal to voltage at information inlet of comparator with absence of electric sinusoidal signal. Time measurement circuit forms digital code from sequence of pulses for measurement of time of ultrasonic waves passage in both directions. ^ EFFECT: increased accuracy of flow measurement by means of elimination of error stipulated by instability of information signal amplitude. ^ 4 cl, 3 dwg |
