Design And Implement Of Multi-pulse Transit-time Ultrasonic Flowmeter

During industry manufacture design and science research, flow measurement is necessary. Ultrasonic flowmeter can apply non-contact measure by nipping ultrasonic transducer on the external pipe without intermitting pipe. Due to convenient design and installation and satisfied with the precise measurement of mostly industrial manufacture, it has found wide application recently.Muti-pulse technology which can enhance the anti-interference quality of the system and improve the measurement effect has been applied in this thesis. MSP430F155 is used as the core control of the system, while high-precise time-to-digital converter TDC-GPII and complex programmable logic device ispLSI1032 and so forth have been selected. This thesis has utilized the in-system programmability of the ispLSI1032, designed ultrasonic cancel coupling pulse timer, anti-interference filter, and digital monostable flip-flop circuit and so on. The multi-pulse method transit time measurement has accomplished with the hardware anti-interference improvement, system clock in-phase and electrical level translate.Transmit time is measured precisely by gate circuit transmit time delay inside the chip rather than traditional high-speed digital counter method. The entire system works under the lower frequency and avoid the concerns on more complicated electromagnetic compatibility caused by designing high frequency circuit and whatsoever.Software design is based on the embedded real time operation system Small RTOS 430. Small RTOS 430 which roots in μC/OS-II and Small RTOS 51 can minimize the system requirement code and RAM. The entire software system is composed of several tasks. Each task is independent from each other which has shortened the development period and enhanced the system reliability.Ultrasonic flowmeter applied in the thesis has adopted TDC-GPII to measure transit-time and ensure high-precise measurement and has applied ispLSI1032 to confirm transit-time on multi-pulse condition and accomplish hardware anti-interference circuit like ultrasonic cancel coupling pulse timer, anti- interference filter and so on which can improve the measurement effect of ultrasonic flowmeter.