Digital control system for ultrasonic phased array - uses interruptions of clock signal to control intermediates storage via CCD delay lines

摘要

The control system uses CCD delay lines. The transmission or reception signals to be delayed are temporarily stored in CCD delay lines of equal length by interruptions of a common clock frequency. These interruptions are each controlled by the output of a respective counter coupled to a start-stop logic. The interruptions may correspond to the time taken for the counter to count backwards to zero from an initial value. A required scan angle can be obtained by a preset linear increase in the counter states, while a quadratic increase is used to obtain variable or parabolic focussing of the sound beam. The direction of the latter is varied by adjusting the clock frequency. The phased array is used for workpiece flaw detection or analysis or for ultrasonic medical diagnostic appts.