基于相关算法的编码超声气体流量计研究
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摘要
超声波流量计作为一种非接触、易于安装维护的仪表在工业领域得到广泛应用。尤其在天然气计量领域,超声波流量计的潜力和优势十分明显。虽然孔板流量计仍是主要测量手段,但超声波流量计具有无可动部件、无压损、测量精确度高等优点,另外随着相关标准的发布和实用领域的探索,超声波流量计将会得到越来越广泛的应用。
本文将伪随机编码信号引入了相关时差法超声流量计的信号处理中。相关时差法是传统时差法与相关算法对结合,兼具二的者优点,并且克服了时差法触发时刻不易确定、时间差难以直接精确测量,相关法被测对象不确定、易受驻波影响等缺点。伪随机编码码信号以其优良的自相关特性,可以实现对微小时间差的精确测量。本文针对巴克序列,m序列以及L序列进行了理论分析及相关试验,比较了各编码方式的特性,并对影响相关结果的重要参数,如:码元宽度,采样频率,序列长度,序列周期个数等,确定了选取标准。
系统硬件电路主要包括超声信号的发射、接收和处理部分。发射部分设计了数字式任意波形发生器,直接产生经过调制的伪随机编码信号。超声信号接收处理电路的作用是从放大滤波后的信号中解调出伪随机编码信号,并将其稳定在一个固定的范围之内。
使用任意波形发生器对本课题选用的SensComp发射/接收型压电陶瓷超声换能器进行了调幅编码特性实验研究,得出参数选择的标准。系统调试成功后,分别用巴克序列、m序列、L序列三种不同编码方式激励超声换能器,比较优劣;并将本设计伪码相关时差法超声波气体流量计在天津大学过程检测与控制实验室的常压气体流量实验装置上进行了试验测试,对测试结果的误差来源进行了详细的分析,并提出了解决和进一步完善设计的方案。
Ultrasonic flowmeter is applied widely in industrial measureing filed, because of its advantages of noncontact installation and maintenance with ease. In the filed of natural gas measuring, ultrasonic flowmeter has evident potential and advantages, such as without mobile component, without pressure loss and high precision in measurement. With relevant standards promulgated and practicality explored, ultrasonic flowmeter must be developed at this filed in the future.
Pseudo Random code is introduced to the correlation time-difference method of ultrasonic flowmeter. Correlation time-difference method combines traditional time-difference method with the correlation method, and inherits their merits. To ensure the sharp figure, the pseudo random code, due to their variety and simplicity, served as the modulation signals in the proposed method. The simulations were carried out to configure the coded waveform parameters including sequence length, code width and code amplitude.
The experimental part of this investigation details how to encode the ultrasonic waveform. Hardware system is composed of the emission, reception and procession of the ultrasonic signal. The emission part is designed of random waveform generator, which can generate Pseudo Random code directly. The reception and procession part is responsible to demodulate Pseudo Random signal from the ultrasonic signal after amplified and filtered, and restricted in the anticipant range.
Using the digital random wave generator, carry through the coding characteristic experiment on the SensComp ultrasonic transceiver piezoelectric transducer. By means of sampling the coded ultrasonic signals and correlating them through mathematic software, compared the results of different coded manners, such as Barker-sequences, m-sequences, and L-sequence. The system finally got verified on the gas flow facility at the Process Detect and Control laboratory in Tianjin University.
本文将伪随机编码信号引入了相关时差法超声流量计的信号处理中。相关时差法是传统时差法与相关算法对结合,兼具二的者优点,并且克服了时差法触发时刻不易确定、时间差难以直接精确测量,相关法被测对象不确定、易受驻波影响等缺点。伪随机编码码信号以其优良的自相关特性,可以实现对微小时间差的精确测量。本文针对巴克序列,m序列以及L序列进行了理论分析及相关试验,比较了各编码方式的特性,并对影响相关结果的重要参数,如:码元宽度,采样频率,序列长度,序列周期个数等,确定了选取标准。
系统硬件电路主要包括超声信号的发射、接收和处理部分。发射部分设计了数字式任意波形发生器,直接产生经过调制的伪随机编码信号。超声信号接收处理电路的作用是从放大滤波后的信号中解调出伪随机编码信号,并将其稳定在一个固定的范围之内。
使用任意波形发生器对本课题选用的SensComp发射/接收型压电陶瓷超声换能器进行了调幅编码特性实验研究,得出参数选择的标准。系统调试成功后,分别用巴克序列、m序列、L序列三种不同编码方式激励超声换能器,比较优劣;并将本设计伪码相关时差法超声波气体流量计在天津大学过程检测与控制实验室的常压气体流量实验装置上进行了试验测试,对测试结果的误差来源进行了详细的分析,并提出了解决和进一步完善设计的方案。
Ultrasonic flowmeter is applied widely in industrial measureing filed, because of its advantages of noncontact installation and maintenance with ease. In the filed of natural gas measuring, ultrasonic flowmeter has evident potential and advantages, such as without mobile component, without pressure loss and high precision in measurement. With relevant standards promulgated and practicality explored, ultrasonic flowmeter must be developed at this filed in the future.
Pseudo Random code is introduced to the correlation time-difference method of ultrasonic flowmeter. Correlation time-difference method combines traditional time-difference method with the correlation method, and inherits their merits. To ensure the sharp figure, the pseudo random code, due to their variety and simplicity, served as the modulation signals in the proposed method. The simulations were carried out to configure the coded waveform parameters including sequence length, code width and code amplitude.
The experimental part of this investigation details how to encode the ultrasonic waveform. Hardware system is composed of the emission, reception and procession of the ultrasonic signal. The emission part is designed of random waveform generator, which can generate Pseudo Random code directly. The reception and procession part is responsible to demodulate Pseudo Random signal from the ultrasonic signal after amplified and filtered, and restricted in the anticipant range.
Using the digital random wave generator, carry through the coding characteristic experiment on the SensComp ultrasonic transceiver piezoelectric transducer. By means of sampling the coded ultrasonic signals and correlating them through mathematic software, compared the results of different coded manners, such as Barker-sequences, m-sequences, and L-sequence. The system finally got verified on the gas flow facility at the Process Detect and Control laboratory in Tianjin University.
引文
[1]毛新业,气体超声波流量计.世界仪表与自动化,2001,5(7):50～52
[2]杨建昌,王萍等,气体超声波流量计在天然气计量中的应用,油气储运,2002,21(9):35～37
[3]毛新业,流量仪表的发展趋势及热点,世界仪表与自动化,2006,10(8):59～61
[4]梁国伟,蔡武昌等,流量测量技术及仪表,北京:机械工业出版社,2002
[5]蔡武昌,孙淮清等,流量测量方法和仪表的选用,北京:化学工业出版社,2001
[6]祝海林,邹昊,管道流量非接触测量——方法与技术,北京:气象出版社,1999
[7]J.克劳特克洛默,H.克劳特克洛默,超声检测技术,广州:广东科技出版社,1984
[8]BSI, ISO/TR 12765-1999, Measurement of fluid flow in closed conduits-Methods using transit-time ultrasonic flowmeters, 1999-03-15
[9]SBTS,GB/T 18604-2001,用气体超声流量计测量天然气流量,2001-12-30
[10]郑玉龙,马福军,浅谈气体超声流量计技术现状及应用前景,油气田地面工程,2001,20(5)
[11]毛新业,气体超声波流量计,自动化信息,2004,37(1):21～23
[12]R. Motegi, S. Takeuchi, T. Sato, Widebeam Ultrasonic Flowmeter, Ultrasonics Symposium, 2000, pp.331~336.
[13]日本电气测量仪表制造协会,JEMIS032-1987,超声波流量计的流量测量方法,3-12
[14]蒲诚,超声波气体流量计伪码相关技术的研究,天津大学硕士学位论文,2005,12
[15]黄建军,关于改进超声波流量计性能的研究,沈阳工业大学硕士学位论文,2002,3
[16]吕清华,气体超声波流量计的研制,南京信息工程大学硕士学位论文,2005,5
[17]N.Bignell, Ultrasonic Domestic Gas Meters-A Review, FLOMEKO2000
[18]刘存,黄建军,时差法超声波流量计的几点改进,沈阳工业大学学报,2002,24(2):113～115
[19]P.Brassier et al, High-Frequency Transducers and Correlation Method to Enhance Ultrasonic Gas Flow Metering, Flow Measurement and Instrumentation, 2001, 12: 201~211
[20]吴晓庆,李艾华,李芳,基于互相关理论的时差法超声波流量检测系统,仪器仪表学报,2005,12(6):52~54
[21]Mcshane J.L., Ultrasonic Flowmeter Basic, Instrumentation technology, 1971
[22]刘欣荣,流量计,北京:水利水电出版社,1984
[23]J.布利茨,超声技术及其应用,北京:海洋出版社,1992
[24]同济大学声学研究室编,超声工业测量技术,上海:上海人民出版社,1977
[25]费业泰,误差理论与数据处理,北京:机械工业出版社,1988
[26]杨惠连,张涛,误差理论与数据处理,天津:天津大学出版社,1992
[27]徐苓安,相关流量测量技术,天津:天津大学出版社,1988
[28]M. S. Beck, Correlation in instruments: cross correlation flowmeters, J. Phys.E: Sci. Instrum., 1981, Vol. 14, pp.7~19
[29]秦德培,大学物理学第三分册——波动学,重庆:重庆大学出版社,1996
[30]林可祥,汪一飞,伪随机码的原理与应用,北京:人民邮电出版社,1978
[31]李白男,伪随机信号及相关辨识,北京:科学出版社,1987
[32]SensComp, Inc. Application Note-Ultrasonic Ceramic Transducers, 2003
[33]稻叶保(日),振荡电路的设计与应用,北京:科学出版社,2004
[34]程佩青,数字信号处理教程,北京:清华大学出版社,1995
[35]陶亚雄,现代通信原理,北京:电子工业出版社,2003
[36]张会生,现代通信系统原理,北京:高等教育出版社,2004
[37]白居宪,低噪声频率合成,西安:西安交通大学出版社,1995
[38]杨丽,李镇,孙厚军,基于FPGA的多波形信号发生器,无线电工程,2005,35(7):46～48
[39]J.Vankka, Direct Digital Synthesizers Design and Applications, ISBN951-22-5232-5
[40]王建新,张先萌,直接数字频率合成中相位截断误差分析,电子测量与仪器学报,1995,9(1):1～6
[41]H.T.Nicholas, and H.samueli, An Analysis of the Output Spectrum of Direct Digital Frequency Synthesizers in the Presence of Phase-Accumulator Truncation, Proc.41st Annu.Frequency Contr.Symp., 1987, pp.495-502
[42]Soenke Mehrgardt, Noise spectra of Digital sine-Generators Using the Table-Lookup Method, IEEE, T-ASSP, Vol.31, AUGUST 1983 NO.4
[43]Edward M.Mattison and Laurence M.Coyle, Phase Noise in Direct Digital Synthesizers, 42nd Annu.Frequency Contr.Symp., 1988, pp.352-356
[44]王建新,直接数字频率合成中幅度量化误差分析,数据采集与处理,1994,9(2):96～102
[45]H.T.Nicholas, and H.samueli, and B.Kim, The Optimization of Direct DigitalFrequency Synthesizer in the Presence of Finite Word Length Effects Performance, Proc.42nd Anuu.Frequency Contr.Symp., 1988, pp.357-363
[46]ALTERA, ACEX1K Programmable Logic Device Family Data Sheet, 2003
[47]周巧娣,黄继业,刘敬彪,一种基于FPGA的正弦信号发生器的实验方法,实验室研究与探索,2003,22(4):82～83
[48]薛文,DDS任意波形发生器的设计与实现,南京理工大学硕士学位论文,2004
[49]康华光,电子技术基础——模拟部分(第四版),北京,高等教育出版社,1998
[50]张国雄,金篆芷,测控电路,北京:机械工业出版社,2000
[51]侯剑波,数字AGC电路设计,现代电子技术,2006,29(15):72~73
[52]潘松,黄继业,EDA技术实用技术,北京:科学出版社,2002
[53]王璟,戴娟,利用D/A转换技术实现可编程放大器,电子工程师,2000,26(6):43～44
[54]邓湘,张宝芬,“西气东输”工程中的检测与自动化仪表技术,仪器仪表学报,2003,9(2),12～16
[55]TI, Implementing Fast Fourier Transform Algorithms of Real-Valued Sequences with the TM320DSP Family, SPRA291, 1997
[56]W. Q. Yang, and M. S. Beck, An intelligent cross correlator for pipeline flow velocity measurement, Flow Meas. Instrum., 1997, Vol. 8, No. 2, pp.77~84
[57]杨小牛,楼才义,徐建良,软件无线电原理与应用,电子工业出版社,2001
[58]Hans-Jurgen Zepernick,and Adolf Filger,伪随机信号处理—理论与应用,电子工业出版社,2007
[59]王念旭,DSP基础与应用系统设计,北京:北京航空航天大学出版社,2001
[2]杨建昌,王萍等,气体超声波流量计在天然气计量中的应用,油气储运,2002,21(9):35～37
[3]毛新业,流量仪表的发展趋势及热点,世界仪表与自动化,2006,10(8):59～61
[4]梁国伟,蔡武昌等,流量测量技术及仪表,北京:机械工业出版社,2002
[5]蔡武昌,孙淮清等,流量测量方法和仪表的选用,北京:化学工业出版社,2001
[6]祝海林,邹昊,管道流量非接触测量——方法与技术,北京:气象出版社,1999
[7]J.克劳特克洛默,H.克劳特克洛默,超声检测技术,广州:广东科技出版社,1984
[8]BSI, ISO/TR 12765-1999, Measurement of fluid flow in closed conduits-Methods using transit-time ultrasonic flowmeters, 1999-03-15
[9]SBTS,GB/T 18604-2001,用气体超声流量计测量天然气流量,2001-12-30
[10]郑玉龙,马福军,浅谈气体超声流量计技术现状及应用前景,油气田地面工程,2001,20(5)
[11]毛新业,气体超声波流量计,自动化信息,2004,37(1):21～23
[12]R. Motegi, S. Takeuchi, T. Sato, Widebeam Ultrasonic Flowmeter, Ultrasonics Symposium, 2000, pp.331~336.
[13]日本电气测量仪表制造协会,JEMIS032-1987,超声波流量计的流量测量方法,3-12
[14]蒲诚,超声波气体流量计伪码相关技术的研究,天津大学硕士学位论文,2005,12
[15]黄建军,关于改进超声波流量计性能的研究,沈阳工业大学硕士学位论文,2002,3
[16]吕清华,气体超声波流量计的研制,南京信息工程大学硕士学位论文,2005,5
[17]N.Bignell, Ultrasonic Domestic Gas Meters-A Review, FLOMEKO2000
[18]刘存,黄建军,时差法超声波流量计的几点改进,沈阳工业大学学报,2002,24(2):113～115
[19]P.Brassier et al, High-Frequency Transducers and Correlation Method to Enhance Ultrasonic Gas Flow Metering, Flow Measurement and Instrumentation, 2001, 12: 201~211
[20]吴晓庆,李艾华,李芳,基于互相关理论的时差法超声波流量检测系统,仪器仪表学报,2005,12(6):52~54
[21]Mcshane J.L., Ultrasonic Flowmeter Basic, Instrumentation technology, 1971
[22]刘欣荣,流量计,北京:水利水电出版社,1984
[23]J.布利茨,超声技术及其应用,北京:海洋出版社,1992
[24]同济大学声学研究室编,超声工业测量技术,上海:上海人民出版社,1977
[25]费业泰,误差理论与数据处理,北京:机械工业出版社,1988
[26]杨惠连,张涛,误差理论与数据处理,天津:天津大学出版社,1992
[27]徐苓安,相关流量测量技术,天津:天津大学出版社,1988
[28]M. S. Beck, Correlation in instruments: cross correlation flowmeters, J. Phys.E: Sci. Instrum., 1981, Vol. 14, pp.7~19
[29]秦德培,大学物理学第三分册——波动学,重庆:重庆大学出版社,1996
[30]林可祥,汪一飞,伪随机码的原理与应用,北京:人民邮电出版社,1978
[31]李白男,伪随机信号及相关辨识,北京:科学出版社,1987
[32]SensComp, Inc. Application Note-Ultrasonic Ceramic Transducers, 2003
[33]稻叶保(日),振荡电路的设计与应用,北京:科学出版社,2004
[34]程佩青,数字信号处理教程,北京:清华大学出版社,1995
[35]陶亚雄,现代通信原理,北京:电子工业出版社,2003
[36]张会生,现代通信系统原理,北京:高等教育出版社,2004
[37]白居宪,低噪声频率合成,西安:西安交通大学出版社,1995
[38]杨丽,李镇,孙厚军,基于FPGA的多波形信号发生器,无线电工程,2005,35(7):46～48
[39]J.Vankka, Direct Digital Synthesizers Design and Applications, ISBN951-22-5232-5
[40]王建新,张先萌,直接数字频率合成中相位截断误差分析,电子测量与仪器学报,1995,9(1):1～6
[41]H.T.Nicholas, and H.samueli, An Analysis of the Output Spectrum of Direct Digital Frequency Synthesizers in the Presence of Phase-Accumulator Truncation, Proc.41st Annu.Frequency Contr.Symp., 1987, pp.495-502
[42]Soenke Mehrgardt, Noise spectra of Digital sine-Generators Using the Table-Lookup Method, IEEE, T-ASSP, Vol.31, AUGUST 1983 NO.4
[43]Edward M.Mattison and Laurence M.Coyle, Phase Noise in Direct Digital Synthesizers, 42nd Annu.Frequency Contr.Symp., 1988, pp.352-356
[44]王建新,直接数字频率合成中幅度量化误差分析,数据采集与处理,1994,9(2):96～102
[45]H.T.Nicholas, and H.samueli, and B.Kim, The Optimization of Direct DigitalFrequency Synthesizer in the Presence of Finite Word Length Effects Performance, Proc.42nd Anuu.Frequency Contr.Symp., 1988, pp.357-363
[46]ALTERA, ACEX1K Programmable Logic Device Family Data Sheet, 2003
[47]周巧娣,黄继业,刘敬彪,一种基于FPGA的正弦信号发生器的实验方法,实验室研究与探索,2003,22(4):82～83
[48]薛文,DDS任意波形发生器的设计与实现,南京理工大学硕士学位论文,2004
[49]康华光,电子技术基础——模拟部分(第四版),北京,高等教育出版社,1998
[50]张国雄,金篆芷,测控电路,北京:机械工业出版社,2000
[51]侯剑波,数字AGC电路设计,现代电子技术,2006,29(15):72~73
[52]潘松,黄继业,EDA技术实用技术,北京:科学出版社,2002
[53]王璟,戴娟,利用D/A转换技术实现可编程放大器,电子工程师,2000,26(6):43～44
[54]邓湘,张宝芬,“西气东输”工程中的检测与自动化仪表技术,仪器仪表学报,2003,9(2),12～16
[55]TI, Implementing Fast Fourier Transform Algorithms of Real-Valued Sequences with the TM320DSP Family, SPRA291, 1997
[56]W. Q. Yang, and M. S. Beck, An intelligent cross correlator for pipeline flow velocity measurement, Flow Meas. Instrum., 1997, Vol. 8, No. 2, pp.77~84
[57]杨小牛,楼才义,徐建良,软件无线电原理与应用,电子工业出版社,2001
[58]Hans-Jurgen Zepernick,and Adolf Filger,伪随机信号处理—理论与应用,电子工业出版社,2007
[59]王念旭,DSP基础与应用系统设计,北京:北京航空航天大学出版社,2001