Echo signal processing method of guided wave radar level gauge based on first-order derivative combined with reference curve

Abstract

The invention relates to a guided wave type radar level meter echo signal processing method based on a first-order derivative with the combination of a reference curve. The method includes the steps that firstly, the reference curve is constructed; secondly, echo signals are preprocessed; thirdly, level echo judgment is conducted; fourthly, propagation time is calculated; fifthly, a level value is calculated. Signals which comprise step parts which are not superposed with the level echo need to be stored in advance and serve as the reference curve for the subsequent level echo judgment; 9-point moving and average filtering preprocessing is conducted on the echo signals; first-order derivative calculation is conducted on the filtered echo signals, the echo is detected, multiple parameters are combined with the reference curve to judge the level echo, a level echo positioning point and a reference starting point are determined, and propagating time is calculated; three points are selected in a defined zone at will to be calibrated, and a level-propagating time model is determined; finally, the propagating time is substituted into a function relation between the level and the propagating time, and the level value is obtained.

Description

technical field [0001] The invention belongs to the technical field of material level detection, and in particular relates to a method for processing the echo signal of a guided wave radar level gauge based on a first-order derivative and combined with reference curves, with a single-chip microcomputer as the core. Background technique [0002] The guided wave radar level gauge uses the principle of echo ranging in radar technology to measure the level of the material, and is widely used in the industrial field. The difficulty in the echo signal processing of the guided wave radar level gauge lies in the judgment of the real level echo and the determination of the echo positioning point. Among them, the level echo determines whether the measurement is accurate, and the echo positioning point affects the measurement accuracy. [0003] Aiming at the key issues of signal processing of guided wave radar level gauge, several well-known foreign manufacturers, such as E+H Company,...

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Problems solved by technology

[0005] The problem in this patent is: Butterworth low-pass filtering is a frequency-domain filtering method, which is not effective when applied to the echo signal processing of guided-wave radar level gauges with inconspicuous frequency-domain characteristics; the construction of the reference curve requires first To construct empty tank conditions, when applied to actual production, the material needs to be emptied and updated, otherwise the newly generated interference echo cannot be ruled out; the subtraction of the echo signal from the reference curve may cause the nonlinear movement of the echo positioning point, affecting measurement accuracy

[0007] The problem of the invention patent application is: the limitation of the echo parameter drop ratio may lead to the exclusion of the real echo or the inability to exclude the interference echo, resulting in a wrong judgment; the highest peak point obtained by interpolating the real echo is used as the feature point for calibration and Measurement, its linearity is not the best, that is, the measurement accuracy is not the best; 60-point median average filtering is performed on the measurement results, and the response speed is slow

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