| 摘要 |
FIELD: physics. ^ SUBSTANCE: invention relates to nondestructive testing objects. The method of forming bell-shaped probing pulses for an electromagnetic acoustic (EMA) transducer involves using a bidirectional counter, a decoder and a functional digital-to-analogue converter to form a quarter of a bell-shaped pulse. A full bell-shaped pulse is formed in four clock cycles, wherein the bidirectional counter is switched into direct and reverse counting mode. The device has a pulse generator, bidirectional counter, decoder, functional digital-to-analogue converter, two scaling circuits, control device, R-S flip flop, counting T flip flop, analogue switch, voltage converter. ^ EFFECT: easier formation of bell-shaped probing pulses with given characteristics. ^ 5 cl, 3 dwg |
