| Level is the important parameter in the industrial production. Numerousinstruments take responsibly of measuring the level. GWR (Guided Wave Radar LevelMeter) as a new type of measurement, achieves a high accuracy in the measurement ofthe level, without the influence of the medium, temperature, pressure, steam, dust andfoam.GWR plays an more and more important role, and thus promises broad marketprospects.GWR is the level measurement instrument transmitting electromagnetic waves,which utilizes the principle of TDR (Time Domain Reflectometry). In essence, it’s therealization of measurement of time difference. After reading lots of domestic andforeign relevant literatures, explain the methods of measurement and the process ofworks in detail, then design main hardware and software function modules.Signal processing have a significant impact on the performance of GWR. Becauseof electromagnetic wave speed very fast, the amount of high-resolution timemeasurement becomes critical of high accuracy. In the part of signal acquisition, use theprinciple of equivalent sampling to complete high-speed sampling, and describe hybridequivalent sampling; In the part of signal preprocessing, represent denoising algorithmusing threshold based on sliding window for the reason of interference of the echosignal; In the part of signal recognition, denote basic principles and criteria of the echosignal recognition to select and screen of the target signal, and manifest the approach oflosing wave signal when the signal does not meet the basic principles and criteria. Inorder to improve the stability of the measurement, and to reduce the instantaneouschange of the conditions and measurement of environmental disturbance caused by thecomplex conditions of the entire measuring range of the signal changes, design thesignal search strategy; In the part of signal location, demonstrate the applicableconditions of different positioning and the use of general engineering experience valuesin view of the characteristic that echo signal is usually the pulse signal, and illustratehow to handle with hump signal when the echo signal composites of the non-singlepulse; In the part of signal damping, explain the impact on settings of measured valuesof the damping time.In addition, it is also pointed out principle of selection and installationrequirements of GWR in the practical application. The measurement value correction methods and improvements are shown after exploring factors that affecting themeasurement error.Finally, introduce the GWR level measurement test of liquid level of atmospherictank in Guangxi Yuchai petrochemical company, and obtain favorable results at last. |
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