Design Of The Indirect Metering Terminal Of Diaphragm Gas Meter Based On Weak Periodic Signal Detection

Diaphragm gas meter is the meter for measuring the volume of gas by using flexible thin-walled chambers.It is widely used in the measurement of gas consumption in urban households.However,there is no reliable and complete solution to the problem of the existing large number of mechanical diaphragm gas meters'reading.The manual meter reading method has problems such as waste of human resources,lags in data update,failure to real-time monitoring of household gas information,and failure to realize gas temperature and pressure correction in operating conditions.For this reason,this paper designs a Diaphragm gas meter consumption indirect metering terminal,which can complete the digital transformation of the mechanical membrane gas meter and realize its use by adding an additional device without modifying the meter body.And realize state detection and consumption measurement during its use,thus replacing the traditional method of manual meter reading.In order to realize the indirect measurement of mechanical Diaphragm gas meter's consumption,this paper has analyzed the numerical relationship between the periodic operation of the internal mechanism of the Diaphragm gas meter and the pressure cycle fluctuation of the outlet pressure,then proposed a consumption calculation method based on periodic signal detection.According to the physical parameters required for measurement,the valve body of the metering device suitable for home installation has been designed.Inside the valve,a DPS 310 sensor has been installed for detecting the temperature and pressure of the gas.In order to calibrate the gas flow rate in the gas pipeline,a heat-source-type gas flow detection sensor was designed.Because of the gas flow,part of the heat will be transferred from the upstream of the pipeline to the downstream,The temperature difference between the two thermistors upstream and downstream of the pipe can be generated,and the signal can be amplified and output as the gas flow rate parameters.In addition,according to the gas meter outlet pressure fluctuations and the output signal of the flow detection sensor,a gas using state detection method was designed to enable real-time detection of operations such as firing,shutting off,and fire adjustment in the gas process.In order to accurately extract the pressure cycle signal of the outlet of the diaphragm gas meter,this paper proposes an STH-AMDF signal cycle extraction method based on morphological self-complementary Top-Hat filtering and average amplitude difference function,and sets the adaptive threshold to the STH-AMDF sequence to extract its Periodic peaks.This method can accurately realize the consumption measurement of a long-term signal segment containing five or more complete periodic waveforms.Due to the instability of gas pipeline pressure,there is baseline drift noise in pipeline static pressure.This paper proposes a baseline drift removal method based on time-domain feature extraction.This method can preserve the characteristic shape of useful signals to the greatest degree and suppress low-frequency baseline noise to improve the signal to noise ratio.For the pressure signal segment that containing only a small number of cycles,the flow rate detection sensor will be used to determine the flow rate range and give an appropriate flow rate value,thereby achieving approximate metering of short-term consumption.For the total consumption during the system operation,using the pipeline static pressure and gas temperature detection values for temperature and pressure correction,than the final calculated consumption value will be uploaded.For hardware circuit design,this article uses TI's DSP TMS320F28335 as the core MCU.According to the functional requirements,the hardware design was completed and the algorithm migration and program development were completed.The functions and software programs of each module were debugged.Finally,a variety of different types of membrane gas meter has been used in different processes for gas consumption measurement,a large number of experimental data analysis proves the reliability and effectiveness of the indirect measurement terminal for diaphragm gas meter consumption based on weak signal cycle detection.The solution solves the problem of digital reconstruction of existing large-scale diaphragm gas meters,thereby replacing the traditional manual meter reading method and realizing real-time monitoring of the status in domestic gas using,and the results have reached the expected goals.