| 摘要 |
PURPOSE:To produce an extremely accurate image free from interference waves on the screen by a device wherein a random number generator is used to change each time a transmission period in irregular manner. CONSTITUTION:While the pulse generator 13 applies a high level output to the switch SW3, the switch SW3 conducts. Interference pulses, if present during this period, are sent to the pulse generator 14 to permit it to start counting and at the same time to enhance the output side to a high level. When the counted number has reached to the number sent from the random number generator 12, the counting stops, the count value is reset, and the output side is changed to a low level. The pulses i and j cause the OR circiut 15 to send out the pulses k. Its trailing edge generates transmission trigger l and ultrasonic wave pulses are transmitted. |
