| Ultrasonic Doppler baby's heart instrument are commonly used in fetal diagnosis and can detect the health of the fetus in real time.Its performance directly affects the accuracy of diagnosis.Comprehensive sensitivity is one of the most important indicators to measure the performance of Doppler baby's heart instrument.Domestic pharmaceutical industry standards YY0448-2009 specifies that the comprehensive sensitivity of Doppler baby's heart instrument should not be less than 90 dB.At present,the FS-3 ultrasound Doppler fetal measuring device for measuring the comprehensive sensitivity of the Doppler baby's heart instrument is mainly used to change the sound attenuator continuously to achieve the desired output signal-to-noise ratio,which is complicated and increases the measurement error.In order to make the measurement more convenient,a new measurement method is proposed in this paper: Using an acoustic window with fixed attenuation instead of the acoustic attenuator and an appropriate output signal-to-noise ratio is obtained by changing the vibration speed of the ball target.First of all,it has been confirmed theoretically that there is a fixed equal-conversion relationship between the vibration velocity of the ball target and the attenuation of the acoustic attenuator,and the attenuation compensation relationship between the two is obtained through experimental measurements.Then the overall structure of the fetal heart rate instrument detector based on precise motion control is designed,which lays a foundation for the design of software and hardware in this paper.Secondly,the hardware takes STM32 as the control core and conduct the modular design.Among them,a stepping motor is used to drive the crank slider mechanism to vibrate the ball target up and down.After that,The function of measuring the Doppler baby's heart instrument comprehensive sensitivity and accuracy is implemented through firmware library function programming.Finally,in order to facilitate the management of data,an upper computer system software was designed,which communicates with the fetal heart rate instrument detector through the serial port and realizes the function of data storage and printing.Compared with the FS-3 ultrasound Doppler fetal measuring device,the design of the fetal heart rate instrument detector has the advantages of convenient measurement process and short measurement time,and the measured comprehensive sensitivity error meets the standards of the Chinese pharmaceutical industry. |
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