Research Of The Measurement Technique Of Guided Wave Radar Level Meter

Level meter is a kind of measuring meter which plays an important role in industrial circle such as oil industry. Following the rapid development of the technology of signal processing and electronic design, the measuring technique has been improved from mechanical to mechanical-electrical integration, then from mechanical-electrical integration to automated. The introduction of the microprocessor to the measuring system makes revolutionary change in level measurement. The Guided Wave Radar Level Meter is an intelligentized measuring meter which has been widely used along with this development process. It has wide application range, high antijamming capability, low power dissipation and cost. It can work steadily and reliably under extreme circumstances. The measurement accuracy of The Guided Wave Radar Level Meter is not as good as some expensive level meters, so that to develop a Guided Wave Radar Level Meter which has high measurement accuracy is very important.In this thesis, we designed a Guided Wave Radar Level Meter on the basis of the reflection characteristics of the electromagnetic wave in the coaxial line. The level meter uses MSP430F149 as the core, composed of four modules: control and information processing module, signal modulation module, signal send-receive module and signal transport module. This level meter uses TDR(Time Domain Reflectometry) principle as the measuring principle. The function of control and information processing module, signal modulation module and signal send-receive module is to produce transmission pulse and sampling pulse; the function of signal transport module is to be the transmitting medium of the electromagnetic wave.Firstly, this thesis discusses the research background and the research significance of the Guided Wave Radar Level Meter; secondly, analyzes the reflection characteristics of the electromagnetic wave in the coaxial line based on the time domain reflectometry; thirdly, introduces the hardware design of the Guided Wave Radar Level Meter, analyzes the function and the circuit design of every module; fourthly, introduces the software design of the Guided Wave Radar Level Meter, provides the program flow chart; fifthly, tests the Guided Wave Radar Level Meter by test platform.Through experimental test, we know that the polarity and the shown time of the reflected waveform are as same as the results of theoretical derivation, which means that the principle of measurement is reliable. By analyzes the experimental data of the Guided Wave Radar Level Meter, we know that the level meter has high resolution and accuracy, good linearity and repeatability. Its resolution is 0.1mm, the error is less than 3mm, the repeatability is less than 3mm. The measurement accuracy of this level meter could be better after the improvement in the future.