ULTRASONIC DOPPLER BLOOD FLOW METER

PURPOSE:To suppress the generation of a beat signal and to surely measure even the blood flow speed of a thin blood vessel by providing a band-pass filter and equalizing a frequency difference between the echo signal from an organism and an orthogonal signal to orthogonally detect it. CONSTITUTION:A...

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Bibliographic Details
Main Authors KAWABUCHI MASAMI, SAKAI IKUO, NAKAMURA TAKAHIRO
Format Patent
LanguageEnglish
Published 02.10.1990
Subjects
DIAGNOSIS
HUMAN NECESSITIES
HYGIENE
IDENTIFICATION
MEDICAL OR VETERINARY SCIENCE
SURGERY
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Summary:PURPOSE:To suppress the generation of a beat signal and to surely measure even the blood flow speed of a thin blood vessel by providing a band-pass filter and equalizing a frequency difference between the echo signal from an organism and an orthogonal signal to orthogonally detect it. CONSTITUTION:An ultrasonic pulse transmitted into the organism by ac ultrasonic transmitting and receiving means 1 is made into the echo signal, received by the ultrasonic transmitting and receiving means 1, made to pass a band-pass filter 11, orthogonally detected by the orthogonal signal from an orthogonal signal generator 5 by means of orthogonal detectors 6a and 6b and integrated in a period in which a sample gate signal is generated by means of integrators 7a and 7b, and a Doppler signal to an integration result is held in sample holds 8a and 8b. A frequency detecting means 12 outputs the frequency of the echo signal with a corresponding voltage, a filter control means 13 controls the frequency band characteristic of the band-pass filter 11 by the voltage, and the frequencies of the echo signal and orthogonal signal are always made equal. Consequently, a frequency step difference is eliminated, the generation of the beat signal in the integration section is suppressed, and a dynamic range can be widely improved.
Bibliography:Application Number: JP19890068214