GB796600A - Ultrasonic impulse apparatus comprising transmitting and receiving components for measuring small impulse travel times - Google Patents

Abstract

796,600. Ultrasonic gauging. SIEMENSREINIGER-WERKE AKT.-GES. April 14. 1955 [April 14, 1954], No. 10816/55. Class 118(2). Ultrasonic impulse apparatus for the measurement of small impulse travel times by the impulse echo technique, particularly for determining the thickness of workpieces smaller than half the spatial length of an impulse, comprises a transmitter, a receiver, a transducer and an indicator with means disposed between the transducer and the indicator for varying the means frequency of the frequency spectrum to be utilized, whereby multiple echo impulses may be separated to appear on a cathode-ray tube as illustrated in Fig. 5 instead of the unseparated trace normally obtained as in Fig. 4. Two embodiments are described. It is stated that if the receiver 3 is equipped with a variable bandpass filter 10 (Fig. 6) the passed frequencies combine to form an oscillation which is effectively the transmitted ultrasonic frequency amplitude-modulated by the sequence frequency of multiple echo pulses and this appears on a cathode-ray tube as in Fig. 5. A synchronizing device 1 controls the relative timing of a transmitter 2, a receiver 3, time base 4 for the sweep of cathode-ray tube 5 and the calibrating mark signal generator 6. Ultrasonic pulses transmitted from transducer 8 into workpiece 9 are reflected and reconverted into electric impulses which are fed to receiver 3 via adjustable band-pass filter 10, and thence to the cathode-ray tube 5. Alternatively the separation of multiple-echo impulses may be obtained by giving the receiver a narrow pass range which may be adjusted to the desired part of the frequency range (Fig. 3, not shown). This may be performed by using a superheterodyne amplifier with a variable-frequency local oscillator (Fig. 7, not shown). Specifications 569,858, [Group XL], 569,872, 569,874, 633,827, [Group XXXVI], and 641,095 are referred to.