Obstetric uses of the ultrasonic motion sensor

Experience with an ultrasonic foetal pulse detector.

“…Reports by Callagan et al (1964), Johnson et al (1965), and Bishop (1966) have suggested that an ultrasonic detector, utilizing the Doppler shift phenomenon (the apparent change of frequency of a moving source of sound), may be of practical value when detection of intrauterine life is important.…”

Short History of The Development of Echocardiograpy With Special Reference to That in Japan (2)

“…In the late 1960s and the early 1970s, while the cardiac Doppler was rapidly spread for the early diagnosis of pregnancy [75][76][77], it was not for the heart diagnosis of an adult. People might have been more interested in the cardiac echocardiography than in the cardiac Doppler, because the image was more concrete in the former than in the latter.…”

Preliminary studies for a possible use of Doppier Signals in the analysis of systolic time intervals of fetal heart

“…For more than ten years the foetal heart has been acoustically detectable with an ultrasound probe (DOPPLER effect) [1]. The DOPPLER signals of the foetal heart, transformed into electrical impulses, can be directely transmitted to a normal ink-writing System; this results in groups of irregulär biphasic waves of high frequency.…”