毕业设计（论文）-超声波明渠流量计的设计.doc

超声波明渠流量计的设计
摘要
本设计介绍了一种基于W77E58单片机的超声波明渠流量计。该流量计以空气中超声波的传播速度为确定条件,利用反射超声波测量待测距离,进而得到流量。本设计概述了超声波明渠流量计的发展及基本原理,介绍超声传感器的原理及特性。并且在介绍超声波测明渠流量系统功能的基础上,提出了系统的总体构成。针对系统的发射、接收、检测、显示部分的总体设计方案进行了论证。发射电路采用555定时器构成多谐振荡回路,驱动超声波换能器,使之发射出40 kHz超声波信号。接收电路采用具有带通滤波的三级放大电路,电压比较,检波后经高速光耦6N137返回单片机进行数据处理。利用温度传感器实时检测环境温度以补偿温度引起的声速变化,保证了检测精度。选用MAX7219驱动LED将测得的流量实时的显示出来。完成了系统软件的设计。该流量计具有测量精度高、运行可靠、价格低廉的特点。
关键字: 超声波;明渠流量计;W77E58;MAX7219;温度补偿
The design of the ultrasonic Open Channel flowmeter
Abstract
This design introduces the ultrasonic Open Channel flowmeter as a core of W77E58. The flowmeter could measure certain distance with the reflected wave on condition in which the speed of transmitting wave is fixed, this paper summarizes the development and fundamental principle of ultrasonic Open Channe flowmeter. Then it presents the theory and characters of ultrasonic sensor. Moreove ultrasonic Open Channe flowmeter , it proposes the whole structure of the system by introducing the function of ultrasonic flowmeter. The transmitting, receiver, detection, display scheme of this ultrasonic Open Channe flowmeter system is brought out. The transmitting circuit uses 555 timer prise oscillator circuit and drives the ultrasonic transducer CSB40T, make it produced 40KHz of ultrasonic. Receiving circuit uses amplifier for three times, the singal through preamplifier, parison, after the high-speed detection, through optical coupler 6N137 to the microprocessor for data processing. In order to fulfill practicability of the system, we use ultrasonic transducer of transmitting and receiving. We use temperature sensor pensate the speed of voice caused by temperature. We can make sure the Inspection of precision. his thesis uses MAX7219 to drive LED, so that it can display the value of the flow. plete the software design of system. This flowmeter has a high detection-precision, credibility and low cost.
keywords: ultrasonic; The Open Channel flowmeter; W77E58;MAX7219; pensation

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