| 摘要 |
PURPOSE:To set easily a start point of a gate in a wide range and a range of the gate by combining a saw tooth wave generator and two comparators constituting a window comparator. CONSTITUTION:Each time a trigger signal (a) synchronized with an ultrasonic oscillation pulse is obtained, a saw tooth wave generator 10 generates a saw tooth wave signal (b). This signal (b) is given to the + terminal of a comparator 18 having an open collector output and the - terminal of a similar comparator 20. Meanwhile, variable resistors 14 and 16 are connected in series to a constant current source circuit 12 to generate reference voltages V1 and V2, and they are given to the - terminal of the comparator 18 and the + terminal of the comparator 20. A gate signal (c) is obtained from outputs of comparators 18 and 20. By this constitution, the gate start point is determined by a resistance value r1 of the resistor 14, and the gate range is determined by a resistance value r2 of the resistor 16. Consequently, knobs of resistors 14 and 16 are adjusted to set the start point of the gate in a wide range and the range of the gate easily. |
