核磁共振找水仪阵列式接收机研制
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摘要
地下水资源是中国重要的供水水源，为了解决西南地区岩溶地下水探测的难题，本文研制核磁共振找水仪阵列式接收机，与原有核磁共振找水仪发射机配合可以进行多点同时采集数据，进而实现二维和三维地下水探测。
本文设计的核磁共振找水仪阵列式接收机，由上位机和阵列式接收单元组成一主多从式通信系统，发射机发出同步信号，触发所有接收单元同时开始采集。根据核磁共振信号的频谱特征，设计了信号调理模块，将信号放大到适合采集范围。信号采集模块采用FPGA+MCU构架，FPGA控制AD快速采样，数据经过在FPGA中编写的信号提取算法处理后保存在FIFO中。最后上位机分别读取阵列式接收单元的数据并显示。
对本文设计的核磁共振找水仪阵列式接收机进行室内测试，并在长春市郊区进行了二维地下水探测实验。实验结果验证了接收机的准确性和稳定性。为下一步使用阵列式接收机进行非层状地下水探测打下了基础。
Groundwater is the important water supply resource in our whole country. Particularly in the northern part, water of life and industrial is ninety percent of groundwater. The groundwater in the northern is mostly layered water, which can be detected directly and effectively by the existing one-dimensional MRS (Magnetic Resonance Sounding) instrument. However in the southwest area, due to karst water is difficult to detect, the exploitation level of groundwater is low. This paper introduces design of array MRS receivers for detecting which can do two-dimensional and three-dimensional groundwater detection by several signals collecting at the same time with the original MRS water detector transmitter.
MRS method is depend on nuclear magnetic resonance of water proton itself so that we can transmit a Larmor frequency current to excitation magnetic which makes the proton go into the higher energy level. Then cut off the transmit current, the hydrogen protons return to its original state, in the process will produce a weak macro alternating magnetic field. The electromotive force generated in loops is called MRS signal. It is a sinusoidal signal with e exponential decay, if we got its initial amplitudes, relaxation time and initial phase then groundwater information would clear by the inversion calculation.
This paper designed the array MRS receiver instrument in the condition of existing transmitter. The communication circuit is the typical serial communication Standard form RS-485bus structure, the computer is host and the receiving units are slaves. The synchronization signal is generated by the COMS uPA1901and the Opto-isolation device6N137, which can reduce the mutual interference between the receiving units, also can extend receiving unit conveniently.
The weak signal extraction circuit is depended on the narrowband spectrum of the MRS signal. The Receiving circuit is composed of the coil and the harmonic capacitor. Then the signal goes through preamp part which can effectively amplify the signal and not introduce noise. The broadband filter will filter out the50Hz frequency interference with a fixed gain. The narrowband filter will filter the signal in the frequency range with the adjusted bandwidth and gain. The programmable gain amplifier can adjust the gain. Therefore the total gain range is from80.6dB to130.1dB and the bandwidth is from110Hz to60Hz.
The signal acquisition board use FPGA+MCU architecture to control the AD7656doing signal acquisition. Because of the work frequency of FPGA is high so we can achieve the sampling frequency to568KSPS. This paper use the4N times sampling algorithm to extract the signal which is implemented in FPGA. The Computer sends the acquisition parameters to MCU, then MCU process the parameters and send them to the FPGA, FPGA do fast sample and arithmetic operation based on the parameters. The calculated data is stored in the FIFO waiting for read by the host computer. The host computer sequentially read and save the data, also calculated the envelope card and graphical display.
The receiver designed in this paper had already did some indoor test, the background noise and input short-circuit noise met the design requirements. We have a good result during the indoor coil simulation experiment too. We also do test in the field where groundwater distribution is known and have confirmed the availability and stability of the instrument.
本文设计的核磁共振找水仪阵列式接收机，由上位机和阵列式接收单元组成一主多从式通信系统，发射机发出同步信号，触发所有接收单元同时开始采集。根据核磁共振信号的频谱特征，设计了信号调理模块，将信号放大到适合采集范围。信号采集模块采用FPGA+MCU构架，FPGA控制AD快速采样，数据经过在FPGA中编写的信号提取算法处理后保存在FIFO中。最后上位机分别读取阵列式接收单元的数据并显示。
对本文设计的核磁共振找水仪阵列式接收机进行室内测试，并在长春市郊区进行了二维地下水探测实验。实验结果验证了接收机的准确性和稳定性。为下一步使用阵列式接收机进行非层状地下水探测打下了基础。
Groundwater is the important water supply resource in our whole country. Particularly in the northern part, water of life and industrial is ninety percent of groundwater. The groundwater in the northern is mostly layered water, which can be detected directly and effectively by the existing one-dimensional MRS (Magnetic Resonance Sounding) instrument. However in the southwest area, due to karst water is difficult to detect, the exploitation level of groundwater is low. This paper introduces design of array MRS receivers for detecting which can do two-dimensional and three-dimensional groundwater detection by several signals collecting at the same time with the original MRS water detector transmitter.
MRS method is depend on nuclear magnetic resonance of water proton itself so that we can transmit a Larmor frequency current to excitation magnetic which makes the proton go into the higher energy level. Then cut off the transmit current, the hydrogen protons return to its original state, in the process will produce a weak macro alternating magnetic field. The electromotive force generated in loops is called MRS signal. It is a sinusoidal signal with e exponential decay, if we got its initial amplitudes, relaxation time and initial phase then groundwater information would clear by the inversion calculation.
This paper designed the array MRS receiver instrument in the condition of existing transmitter. The communication circuit is the typical serial communication Standard form RS-485bus structure, the computer is host and the receiving units are slaves. The synchronization signal is generated by the COMS uPA1901and the Opto-isolation device6N137, which can reduce the mutual interference between the receiving units, also can extend receiving unit conveniently.
The weak signal extraction circuit is depended on the narrowband spectrum of the MRS signal. The Receiving circuit is composed of the coil and the harmonic capacitor. Then the signal goes through preamp part which can effectively amplify the signal and not introduce noise. The broadband filter will filter out the50Hz frequency interference with a fixed gain. The narrowband filter will filter the signal in the frequency range with the adjusted bandwidth and gain. The programmable gain amplifier can adjust the gain. Therefore the total gain range is from80.6dB to130.1dB and the bandwidth is from110Hz to60Hz.
The signal acquisition board use FPGA+MCU architecture to control the AD7656doing signal acquisition. Because of the work frequency of FPGA is high so we can achieve the sampling frequency to568KSPS. This paper use the4N times sampling algorithm to extract the signal which is implemented in FPGA. The Computer sends the acquisition parameters to MCU, then MCU process the parameters and send them to the FPGA, FPGA do fast sample and arithmetic operation based on the parameters. The calculated data is stored in the FIFO waiting for read by the host computer. The host computer sequentially read and save the data, also calculated the envelope card and graphical display.
The receiver designed in this paper had already did some indoor test, the background noise and input short-circuit noise met the design requirements. We have a good result during the indoor coil simulation experiment too. We also do test in the field where groundwater distribution is known and have confirmed the availability and stability of the instrument.
引文
[1]程娟，孙淑云，聂建平，周林蕻.中国地下水资源的开发利用与保护[A].水利水电技术.2003.05：01-03.
[2]于奭，严毅萍，康彩霞.浅议我国地下水现状及地下水的污染防治[A].资源与环境.2010.01：42-44.
[3]方前发，张宏兵.电法勘探方法在水文和工程地质中的应用[A].大众科技.2006.04：29-31.
[4]陈宇峰.常见地下水探测方法简述[A].中国地球物理报.2011.04:1-16.
[5] M.Lubczynski,J.Roy.Hydrogeological Interpretation and Potential of The NewMagnetic Resonance Sounding(MRS)Mtheod[J].Journal of Hydrology.2003.
[6]林君.核磁共振找水技术的研究现状与发展趋势[A].地球物理学进展.2010.25（2）：681-691.
[7]邹家衡.核磁共振找水方法.铀矿地址[J].1999,第15卷，第1期.
[8] http://www.nercgei.com/keyan/ShowArticle.asp?ArticleID=2.
[9]陈文升编著.核磁共振地球物理仪器原理[M].地质出版社.1992.
[10]潘玉玲，张昌达等.地面核磁共振找水理论和方法[M].中国地质大学出版社.2000.
[11]M.Hertrich, Imaging of groundwater with nuclear magnetic resonance[J]. Progressin Nuclear Magnetic Resonance Spetroscopy.2008,53(4):227-248.
[12]翁爱华，李舟波，王雪秋.层状导电介质中地面核磁共振响应特征理论研究[J].地球物理学报，2004，47(1)：156-163.
[13]翁爱华，王雪秋，刘国兴等.导电性影响的地面核磁共振反演[J].地球物理学报,2007,50(3):890～896.
[14]Weichman,P.B.,Lavely,E.M.,Ritzwoller,M.H.,Theory of surface nuclear magneticresonance with applications to geophysical imaging problems[J]. Physical ReviewE,2000,62(1, Part B):1290–1312.
[15]Anatoly Legchenko, Pierre Valla, A review of the basic principles for protonmagnetic resonance sounding measurements[J]. Journal of Applied Geophysics,2002,50(1-2):3-19.
[16]M. D. Schirov, A. D. Rojkowski, On the accuracy of parameters determinationfrom SNMR measurements[J]. Journal of Applied Geophysics,2002,50(1-2):207-216.
[17]蒋川东，林君，段清明，田宝凤，郝荟萃.二维阵列线圈核磁共振地下水探测理论研究[J].地球物理学报，2011,54（11）：2973-2983.
[18]段清明，林君，孙淑琴，王应吉，张小华，姜艳秋等.地面核磁共振探测地下水实验样机的设计与实现，发展地学仪器探测地球奥秘，吉林大学出版社.2005:148-156
[19]姜艳秋.地面核磁共振找水仪发射机的研制.[D].吉林.吉林大学.2006.
[20]焦健.核磁共振找水仪电源模块的研制[D].吉林：吉林大学.2008.
[21]刘汉北.基于恒流源的核磁共振地下水探测仪电源设计[D].吉林：吉林大学.2010.
[22]王应吉，林君，荣亮亮，高东旭，贾晓晨.地面核磁共振找水仪放大器设计[A].仪器仪表学报.2008,29（8）：1627-1632.
[23]荣亮亮.核磁共振多匝线圈探测技术研究[D].吉林：吉林大学.2009.
[24]李永敏.检测仪器电子电路[M].西北工业大学出版社1994.
[25]康华光，陈大钦，张林.电子技术基础模拟部分[M].高等教育出版社.1979.
[26]林君，段清明，王应吉等.核磁共振找水仪原理与应用[M].科学出版社.2011.
[27]周润景，图雅，张丽敏.基于QUARTUSⅡ的FPGA/CPLD数字系统设计实例
[M].电子工业出版社.2007.
[28]潘松，黄继业.EDA技术与VHDL[M].清华大学出版社.2005.
[29]高晋占.微弱信号检测[M].清华大学出版社.2004.
[30]林占江，张乃国.电子测量技术[M].电子工业出版社.2003.
[31]何桥，段清明，邱春玲.单片机原理与应用[M].中国铁道出版社.2006.
[32]戴佳，戴卫恒.51单片机C语言应用程序设计实例精讲[M].电子工业出版社.2006.
[33]EDA先锋工作室，王诚，蔡海宁，吴继华，Altera FPGA/CPLD设计（基础篇）[M].人民邮电出版社.2001.
[34]陈杰.MATLAB宝典[M].电子工业出版社.2007.
[35]王永德，王军.随机信号分析基础[M].电子工业出版社.2003.
[2]于奭，严毅萍，康彩霞.浅议我国地下水现状及地下水的污染防治[A].资源与环境.2010.01：42-44.
[3]方前发，张宏兵.电法勘探方法在水文和工程地质中的应用[A].大众科技.2006.04：29-31.
[4]陈宇峰.常见地下水探测方法简述[A].中国地球物理报.2011.04:1-16.
[5] M.Lubczynski,J.Roy.Hydrogeological Interpretation and Potential of The NewMagnetic Resonance Sounding(MRS)Mtheod[J].Journal of Hydrology.2003.
[6]林君.核磁共振找水技术的研究现状与发展趋势[A].地球物理学进展.2010.25（2）：681-691.
[7]邹家衡.核磁共振找水方法.铀矿地址[J].1999,第15卷，第1期.
[8] http://www.nercgei.com/keyan/ShowArticle.asp?ArticleID=2.
[9]陈文升编著.核磁共振地球物理仪器原理[M].地质出版社.1992.
[10]潘玉玲，张昌达等.地面核磁共振找水理论和方法[M].中国地质大学出版社.2000.
[11]M.Hertrich, Imaging of groundwater with nuclear magnetic resonance[J]. Progressin Nuclear Magnetic Resonance Spetroscopy.2008,53(4):227-248.
[12]翁爱华，李舟波，王雪秋.层状导电介质中地面核磁共振响应特征理论研究[J].地球物理学报，2004，47(1)：156-163.
[13]翁爱华，王雪秋，刘国兴等.导电性影响的地面核磁共振反演[J].地球物理学报,2007,50(3):890～896.
[14]Weichman,P.B.,Lavely,E.M.,Ritzwoller,M.H.,Theory of surface nuclear magneticresonance with applications to geophysical imaging problems[J]. Physical ReviewE,2000,62(1, Part B):1290–1312.
[15]Anatoly Legchenko, Pierre Valla, A review of the basic principles for protonmagnetic resonance sounding measurements[J]. Journal of Applied Geophysics,2002,50(1-2):3-19.
[16]M. D. Schirov, A. D. Rojkowski, On the accuracy of parameters determinationfrom SNMR measurements[J]. Journal of Applied Geophysics,2002,50(1-2):207-216.
[17]蒋川东，林君，段清明，田宝凤，郝荟萃.二维阵列线圈核磁共振地下水探测理论研究[J].地球物理学报，2011,54（11）：2973-2983.
[18]段清明，林君，孙淑琴，王应吉，张小华，姜艳秋等.地面核磁共振探测地下水实验样机的设计与实现，发展地学仪器探测地球奥秘，吉林大学出版社.2005:148-156
[19]姜艳秋.地面核磁共振找水仪发射机的研制.[D].吉林.吉林大学.2006.
[20]焦健.核磁共振找水仪电源模块的研制[D].吉林：吉林大学.2008.
[21]刘汉北.基于恒流源的核磁共振地下水探测仪电源设计[D].吉林：吉林大学.2010.
[22]王应吉，林君，荣亮亮，高东旭，贾晓晨.地面核磁共振找水仪放大器设计[A].仪器仪表学报.2008,29（8）：1627-1632.
[23]荣亮亮.核磁共振多匝线圈探测技术研究[D].吉林：吉林大学.2009.
[24]李永敏.检测仪器电子电路[M].西北工业大学出版社1994.
[25]康华光，陈大钦，张林.电子技术基础模拟部分[M].高等教育出版社.1979.
[26]林君，段清明，王应吉等.核磁共振找水仪原理与应用[M].科学出版社.2011.
[27]周润景，图雅，张丽敏.基于QUARTUSⅡ的FPGA/CPLD数字系统设计实例
[M].电子工业出版社.2007.
[28]潘松，黄继业.EDA技术与VHDL[M].清华大学出版社.2005.
[29]高晋占.微弱信号检测[M].清华大学出版社.2004.
[30]林占江，张乃国.电子测量技术[M].电子工业出版社.2003.
[31]何桥，段清明，邱春玲.单片机原理与应用[M].中国铁道出版社.2006.
[32]戴佳，戴卫恒.51单片机C语言应用程序设计实例精讲[M].电子工业出版社.2006.
[33]EDA先锋工作室，王诚，蔡海宁，吴继华，Altera FPGA/CPLD设计（基础篇）[M].人民邮电出版社.2001.
[34]陈杰.MATLAB宝典[M].电子工业出版社.2007.
[35]王永德，王军.随机信号分析基础[M].电子工业出版社.2003.