GB1404783A - Utilization of ultrasonic echo signals - Google Patents

Abstract

1404783 Ultrasonic inspection devices SIEMENS AG 9 Oct 1972 [14 Oct 1971] 46517/72 Heading H4D An ultrasonic Doppler-effect echo system is provided, in which the visual nature of Doppler display marks is varied in accordance with the time of arrival of the associated echo signals. In the embodiment shown body-fluid duct system 5 is scanned by a pulsed transmitreceive system 1 moved in directions x and y. Cathode-ray tube 15 provides either a B-scan or C-scan display according to which of switch pairs 28, 29 and 33, 34 is selected for applying deflection voltages to its plates 31, 32. Doppler signals in a selected frequency band are extracted at 6, 7 and control the display brightness in three selectable modes. Thus if switch 8, 11 or 16 is closed the Doppler signals are applied to respectively a frequency-to-voltage converter 10, a Schmitt trigger 13 or a timer 18. Timer 18 ascertains the interval between transmission of an ultrasonic pulse and occurrence of a Doppler signal, i.e. the pulse echo time. The echo time is converted at 19 to a proportional voltage (which increases or decreases with increasing echo time) for modulating the display brightness. This enhances the spatial impression of the duct system given by the display. For displaying only or emphasizing echo signals from selected depths in duct system 5, an adjustable delay 23 can be switched into circuit so that timer 18 is operative only a given time after the ultrasonic pulse transmission. Instead of brightness modulation in dependence on echo time, the length and/or thickness and/or colour of display marks may be varied according to echo time. An ink jet recorder may be used instead of cathode-ray tube 15.