GB1425082A - Ultra-sonic pulse echo investigation - Google Patents

Abstract

1425082 Ultrasonic testing SIEMENS AG 20 June 1973 [23 June 1972] 29404/73 Heading H4D In ultrasonic examination equipment, the time interval between ultrasonic pulses applied to the test object is made less than the sum of the time required for the injected and echo pulses to traverse a coupling or preliminary path, and the time for formation of echo images. A transducer 12 emits pulses into the object, e.g. a human body, and echoes are received at transducer 13. The injected and echo pulses have to traverse a coupling 5, e.g. water in a container. The transducer 12 is activated by an ultrasonic generator 14, the pulse repetition frequency being wobbled by generator 15. The time t s between emitted pulses (Fig. 3) is less than the time required for the echo pulses to return i.e. is less than the time for the injected and echo pulses to traverse coupling 5 and to travel in the test object. Thus, the echo pulses E 1 of, e.g. injected pulse S 1 occur after injected pulse S 2 . In this way the pulse repetition frequency is higher and the processing or image forming time is smaller than if t s was sufficient for the echoes of a particular pulse to return. Bi-stable 21 is switched over at each pulse transmission and operates monostables 22, 23 in turn. The monostables 22, 23 each provide a delay corresponding to the travel time t v in coupling 5 and operate a further monostable 24 which produces a voltage U7 (see Fig. 3) for delayed triggering of a sawtooth generator 25 producing a deflection voltage U8 for cathode-ray tube 18. A receiver amplifier 16 provides signals to the tube for indicating the echoes, either by deflecting or bright-up of the electron beam. If the transmitter 12, and receiver 13 scan the object, then the scan drive means operates a sawtooth generator 28 for producing a line scan on screen 19.