NEW SETS OF TESTING CODES PROVIDING ZERO RANGE SIDELOBES FOR ULTRASONIC PULSE COMPRESSION STRUCTIVE TESTING SYSTEMS

Abstract In conventional ultrasonic pulse compression nondestructive testing systems, complementary codes have been used for modulation of transmit signals in order to obtain zero range sidelobes. In this paper,new sets of testing codes for modulation of transmit signals are shown. The sets are composed of four or more codes and provide zero range sidelobes. In the code lengths less than fifty, the new sets exist at least in twelve different kinds of lengths, for which the conventional complementary codes do not exist. The new sets of testing codes expand the selection range of code lengths providing zero range sidelobes, and thus. arc useful for reduction of dead time in a system using a transducer for both transmission and reception. Sidelobe cancellation using the new sets is demonstrated by experiments.