Research On Echo Signal Acquisition And Processing Of Guided Wave Radar Level Meter

Modern industry implements information management, precise measurementof level is very important in the industrial production, and the environment of industrialproduction is becoming more and more complex, the requirements of the level meterperformance is increasingly. The signal of Guided Wave Radar level meter transfers inthe wave guiding rod, it loses little energy, and the measurement is not affected by thefixed structure of the container, the media fluctuation, foam, fog, and the changes oftemperature and pressure or other factors, and it can measure mediums with low relativedielectric constant. Guided Wave Radar level meter has high measuring precision,performances stably, and easy to install and debug, it plays a more and more importantrole in the measurement field.This thesis gives a detailed analysis of Time Domain Reflectometry based on thetheory of transmission lines and measuring principle of guided wave radar level meter, andgives the values of the signal parameters and briefly introduces the system scheme andthe working process of each module. By comparing a variety sorts of signal samplingmethods and according to guided wave radar level meter echo signal has a very narrowpulse width,this thesis uses step equivalent time sampling method to sample the echosignal, and has designed echo signal receiving and processing circuit, and focus on theanalysis of the principles of the four tube balance high speed sampling gate circuit andthe step pulse time delay circuit, and gives the design of echo signal receiving circuitwith detailed parameters, and also has simulated and tested all circuits. According to thesimulation waveforms of the circuits, this thesis detailed analyzed and summarized theimportant parameters of the circuits, then analyzed and verified testing results of thecircuits.By analyzing the simulation waveforms of the echo signal sampling and processingcircuits and testing results of the circuit, it shows that, the design of the guided waveradar level meter echo signal acquisition and receiving circuits can effectively broaden thepulse width, and realized the correct capture of echo signal, and has reachedthe basic function requirements.