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Guided Wave Radar for Precise level Measurement using Time Domain Reflectrometry (TDR) Principle

Ashish Sahare, Amzad Khan, D P Rathod, Raaghu Raichur

In the radar level measurement instruments, the electromagnetic signal travel through air. Once it touches the material under test, it gets reflected back to the input end. The reflection of electromagnetic signal depends on electric and dielectric properties of material. Guided Wave Radar (GWR) meter isbased on the Time Domain Reflectrometry (TDR) principle for precise level measurement. TDR, which is well known measurement technique in telecommunication industries for evaluating electric and dielectric property of various material, used for precise level measurement and fault detection. Despite all advancement made within the last few years, there is still lack of low cost, small TDR meter equipment in market. This paper proposes a designon the development of a new miniaturized lowcost TDR meter capable of sampling a repetitive rectangular waveform, which is used as an excitation signal. The key techniques of pulse generation and time measurement are introduced with the selection of GWR probe for accuracy even when the measurement within a highly unstable environment. The signal generation with fast rising time is accomplished using small electronic circuit and the basic laboratory setup.Generally, there is a need of a high resolution, low power consuming, miniature TDR for dynamic level measurement in petrochemical, oil tank and shipbuilding industries application. Experimental results indicate the feasibility and improved functionality of the system.