浅层地面拖曳式TEM接收系统研究
摘要
瞬变电磁法(Transient Electro-magnetic Methods,TEM)作为一种地球物理探测方法,广泛应用于矿藏勘探、航空和海洋等领域,并取得了不错的效果。近年来,瞬变电磁法应用领域也逐渐拓展到市政工程和煤矿巷道透水等方面。
一般瞬变电磁法仪器包括两部分:发射系统和接收系统。本文研究的是基于PC104的浅层地面拖曳式TEM接收系统。接收系统高速采样,配合具有快速关断、发射电流关断沿记录的发射系统可实现对浅层目标的探测。
首先介绍了瞬变电磁法的基本原理以及国内外同类仪器的发展现状。研究了瞬变电磁拖曳式采集的相关内容,提出了基于PC104的浅层地面拖曳式TEM接收系统的设计方案。然后对高速的同步数据采集系统的硬件电路设计、PC104平台操作系统构建、系统控制软件设计进行了详细阐述。测试部分给出了接收系统性能测试及模型实验结果,验证了系统的可行性。最后对全文做了总结,并对后续设计和研究提出了一些建议。
The near-surface towed TEM(transient electromagnetic methods)receiver system based on PC104 was designed in this thesis.Transient Electromagnetic methods(TEM)can be called as Time Domain Electromagnetic methods(TDEM).TEM utilizes ungrounded loop-line or grounded electric source to send the first field and then measure the induced magnetic field(the second field)created by underground substance during the intermittent periods,and then it can determine the position of underground inhomogeneous substance as well as its scale and electric capability. In recent years,it has developed rapidly both at home and abroad,TEM can resolve a large range of geology problems which almost includes every field of geophysical exploration including air and sea,and achieves remarkable results,so TEM has already become an indispensable method of geophysical exploration.
The transient electromagnetic methods has increasingly applied in engineering and environmental geology problems,which are mostly related to the near-surface detection and evaluation.In the time domain methods,the depth of detection is decided by the time of observation.In order to obtain near-surface, the effective way is using the receiver including the high speed analog-to-digital conversion and the transmitter with the transmitted signal must go to zero very rapidly and can record current falling edge.
The construction method in the field of the traditional ground transient electromagnetic methods detection is to survey point by point,while ground towed TEM system can survey continuously using a transportable insulation device with transmitter,receivers,launch coil, receiver coil on it. Comparing with the traditional transient electromagnetic system , the greatest advantage of the towed transient electromagnetic system is to make a continuous measurement of transient electromagnetic data along the survey line so as to reduce the construction time and costs and manage the rapid measurement of large area.
The receiver system adopts PC104 as a main control unit,FIFO and high-speed AD (ADS8401) as the core unit and the high-speed CPLD as the logic control device.Under the control of the PC104,the High-speed AD makes a digitally intensive sampling on the transient electromagnetic attenuation curve.Signal accumulation and ambipolar acquisition in-phase methods are adopted to reject all kinds of noise.Signal accumulation method aims to reject white noise,and ambipolar acquisition in-phase method to reject the noise with low change,50Hz noise and its harmonic.
The hardware of the receiving system contains a preamplifier circuit,and can take a low-pass filter to the transient electromagnetic signal,which is mainly concentrated in the low-frequency range.The use of high-speed AD convert chip for rapid acquisition can make the sampling rate up to 1.25m at most so as to improve the detection capacity in shallow target.
FIFO (First In First Out) memory is a static memory which is used to cache continuous,instantaneous,high-speed data.It has two ports,the input port and the output port.It storages data temporarily in first in first out order,and turns the intermittent high-speed data transmission into the data transmission with a not high average rate.The storage circuit selected two IDT7204 as the data buffer between the AD chip and the PC104.After the data collecting,AD input the data to FIFO automatically,and during the interval of the data acquisiton,PC104 read the data from the FIFO.
The system selected Altera's CPLD device EPM7128SLC84,using a graphic and text mixed programming.Inside the CPLD,mainly contained the basic logic units such as decoder,frequency divider and some other logic control circults.
In order to make TEM receiver and transmitter synchronous in practical work,the line synchronization is adopted in the system.Due to the system of transmitter is force electricity system and the system of receiver is weak electricity system,the synchronization signal into the receiver system need to isolate to avoid interference with the transmitter system.
In order to achieve system control requirement and enhance the performance of the system hardware platform,we use Windows XP Embedded operating system. Windows XP Embedded operating system provides the function of Windows XP operating system based on modular form.In this paper,it elaborated on the reason of choosing Windows XP Embedded operating system for this system and how to develop Windows XP Embedded operating system to fit for the system.
The control software of receiver system is developed in the Visual C++6.0 MFC frame.In the control software we can initialize the parameter of the system,and control the data acquisition.The software can control the transient electromagnetic data acquisition in the Fixed Point mode or in the Tow mode.When work in the tow mode,we stack the data use the setting times.When the system completed to stack the data in the setting times,it will save the data in the CF card of the pc104 and then the system will acquire another transient electromagnetic data in the setting times. Until we complete to survey a line,the system would stop working.
The thesis has given the system test result including standard signal test,system noise test,model experiment in laboratory.The draw-out curves analysis can accurately reflect the location of the abnormal.The results indicate the system has achieved design requirement.
At last,summarize the content of thesis and the work within the two-years master study and give the next research advice.
一般瞬变电磁法仪器包括两部分:发射系统和接收系统。本文研究的是基于PC104的浅层地面拖曳式TEM接收系统。接收系统高速采样,配合具有快速关断、发射电流关断沿记录的发射系统可实现对浅层目标的探测。
首先介绍了瞬变电磁法的基本原理以及国内外同类仪器的发展现状。研究了瞬变电磁拖曳式采集的相关内容,提出了基于PC104的浅层地面拖曳式TEM接收系统的设计方案。然后对高速的同步数据采集系统的硬件电路设计、PC104平台操作系统构建、系统控制软件设计进行了详细阐述。测试部分给出了接收系统性能测试及模型实验结果,验证了系统的可行性。最后对全文做了总结,并对后续设计和研究提出了一些建议。
The near-surface towed TEM(transient electromagnetic methods)receiver system based on PC104 was designed in this thesis.Transient Electromagnetic methods(TEM)can be called as Time Domain Electromagnetic methods(TDEM).TEM utilizes ungrounded loop-line or grounded electric source to send the first field and then measure the induced magnetic field(the second field)created by underground substance during the intermittent periods,and then it can determine the position of underground inhomogeneous substance as well as its scale and electric capability. In recent years,it has developed rapidly both at home and abroad,TEM can resolve a large range of geology problems which almost includes every field of geophysical exploration including air and sea,and achieves remarkable results,so TEM has already become an indispensable method of geophysical exploration.
The transient electromagnetic methods has increasingly applied in engineering and environmental geology problems,which are mostly related to the near-surface detection and evaluation.In the time domain methods,the depth of detection is decided by the time of observation.In order to obtain near-surface, the effective way is using the receiver including the high speed analog-to-digital conversion and the transmitter with the transmitted signal must go to zero very rapidly and can record current falling edge.
The construction method in the field of the traditional ground transient electromagnetic methods detection is to survey point by point,while ground towed TEM system can survey continuously using a transportable insulation device with transmitter,receivers,launch coil, receiver coil on it. Comparing with the traditional transient electromagnetic system , the greatest advantage of the towed transient electromagnetic system is to make a continuous measurement of transient electromagnetic data along the survey line so as to reduce the construction time and costs and manage the rapid measurement of large area.
The receiver system adopts PC104 as a main control unit,FIFO and high-speed AD (ADS8401) as the core unit and the high-speed CPLD as the logic control device.Under the control of the PC104,the High-speed AD makes a digitally intensive sampling on the transient electromagnetic attenuation curve.Signal accumulation and ambipolar acquisition in-phase methods are adopted to reject all kinds of noise.Signal accumulation method aims to reject white noise,and ambipolar acquisition in-phase method to reject the noise with low change,50Hz noise and its harmonic.
The hardware of the receiving system contains a preamplifier circuit,and can take a low-pass filter to the transient electromagnetic signal,which is mainly concentrated in the low-frequency range.The use of high-speed AD convert chip for rapid acquisition can make the sampling rate up to 1.25m at most so as to improve the detection capacity in shallow target.
FIFO (First In First Out) memory is a static memory which is used to cache continuous,instantaneous,high-speed data.It has two ports,the input port and the output port.It storages data temporarily in first in first out order,and turns the intermittent high-speed data transmission into the data transmission with a not high average rate.The storage circuit selected two IDT7204 as the data buffer between the AD chip and the PC104.After the data collecting,AD input the data to FIFO automatically,and during the interval of the data acquisiton,PC104 read the data from the FIFO.
The system selected Altera's CPLD device EPM7128SLC84,using a graphic and text mixed programming.Inside the CPLD,mainly contained the basic logic units such as decoder,frequency divider and some other logic control circults.
In order to make TEM receiver and transmitter synchronous in practical work,the line synchronization is adopted in the system.Due to the system of transmitter is force electricity system and the system of receiver is weak electricity system,the synchronization signal into the receiver system need to isolate to avoid interference with the transmitter system.
In order to achieve system control requirement and enhance the performance of the system hardware platform,we use Windows XP Embedded operating system. Windows XP Embedded operating system provides the function of Windows XP operating system based on modular form.In this paper,it elaborated on the reason of choosing Windows XP Embedded operating system for this system and how to develop Windows XP Embedded operating system to fit for the system.
The control software of receiver system is developed in the Visual C++6.0 MFC frame.In the control software we can initialize the parameter of the system,and control the data acquisition.The software can control the transient electromagnetic data acquisition in the Fixed Point mode or in the Tow mode.When work in the tow mode,we stack the data use the setting times.When the system completed to stack the data in the setting times,it will save the data in the CF card of the pc104 and then the system will acquire another transient electromagnetic data in the setting times. Until we complete to survey a line,the system would stop working.
The thesis has given the system test result including standard signal test,system noise test,model experiment in laboratory.The draw-out curves analysis can accurately reflect the location of the abnormal.The results indicate the system has achieved design requirement.
At last,summarize the content of thesis and the work within the two-years master study and give the next research advice.
引文
[1]蒋邦远.磁源瞬变电磁法勘探[M].北京:地质出版社,1998年12月第一版.
[2]林君.电磁探测技术在工程与环境中的应用现状[J].物探与化探.2000,24(3):167-177
[3]静恩杰,李志聃.瞬变电磁法基本原理[J].中国煤田地质,1995,7(2):83-87
[4]王淑玲.基于浮点放大的瞬变电磁法接收机的研制[D].长春:吉林大学硕士论文.2001
[5]徐立忠.基于ATEM-Ⅱ的改进型电磁法发射系统设计与实现[D].长春:吉林大学硕士论文,2008.6:1-2
[6]嵇艳鞠.浅层高分辨率全程瞬变电磁系统中全程二次场提取技术研究[D].长春:吉林大学博士论文.2004.
[7] M N Nabighian.Electromagnetic Methods in Applied Geophysics[M].Tulsa:Society of Exploration Geo-physicists,1987,402-431
[8]于生宝,王忠,嵇艳鞠,林君.瞬变电磁法浅层探测技术[J].电波科学学报,2006,4,21(2):284-287
[9]刘国栋.瞬变电磁仪-以PROTEM为例[C]第8届中国国际地球电磁学讨论会论文集,2007
[10]林君.甚早期时间域电磁系统—VETEM[J].国外地质勘探技术,vol,12,1997
[11] David Allen.A Review of Geophysical Equipment applied to Groundwater and Soil Investigation[R].2004 ANCID/Sustainable Irrigation Travel Fellowship.
[12]吕国印.瞬变电磁法的现状与发展趋势[J].物探化探计算技术,2007,29(增刊):111-115
[13]李慧.海洋瞬变响应理论计算及浅海底瞬变电磁探测技术研究[D].长春:吉林大学博士论文.2007:18-20
[14]王忠,林君,吴国强.TEM接收机低噪声抗饱和前放电路设计[J].吉林大学学报(信息科学版).2002,20(4):1-4
[15]于英民,于佳.计算机接口技术(第3版)[M].北京:电子工业出版社,2004.
[16] Microsoft Corporation.Windows XP Embedded MSDN.Microsoft Corporation.2006.
[17] Engene Olafsen,Kenn Scribner,K.David White.MFC Visual C++6编程技术内幕.第2版.王建华,陈一飞,张焕生等译.北京:机械工业出版社,2000.37-41
[18]高晋占.微弱信号检测[M].北京:清华大学出版社,2004:199-233
[19] Jens E.Danielsena,Esben Auken,Flemming J?rgensen.The application of the transient electromagnetic method in hydrogeophysical surveys[J].Journal of Applied Geophysics,53 (2003) 181–198
[20]邵晖,舒嵘.光电隔离器6n137的特性和应用[J].电子技术1998,2:38-39
[21]孙金辉.被动毫米波雷达中基于PCI总线的数据采集系统设计[D].青岛:中国海洋大学硕士论文,2008.6:42-44
[22]金明等.FIFO芯片在高速系统中的应用[J].电子技术应用.1998(3):61-62
[23]黄正谨等.CPLD系统设计技术入门与应用[M].北京:航空航天大学出版社,2002.
[24]罗日成,李卫国.基于Windows DLL技术实现监测软件中端口读写方法[J].电力自动化设备,2001,10,21(10):30-32
[25]李将渊,谭超,蔡铎昌.利用DLL技术实现化学虚拟仪器的端口操作[J].西华师范大学学报(自然科学版),2003,9,24(3):352-355
[26]程德福,林君,于生宝.瞬变电磁法弱信号检测技术研究[J].吉林大学学报(信息科学版),2002,6,20(2):1-5
[27]于生宝,林君.瞬变电磁法中发射机关断时间的影响研究[J].石油仪器,1999,13(6),15-17
[28]韩王平.瞬变电磁测深法的原理及计算方法[J].山西建筑,2003,29(2):42-43
[29]许志军,徐光辉.CPLD/FPGA的开发与应用[M].北京:电子工业出版社,2002
[30]潘春岭.基于PC104总线的高速硬币清分机研制[D].南京:南京航空航天大学硕士论文.2007,41-44
[31]王艳.浅海底瞬变电磁法接收系统的研制[D].长春:吉林大学硕士论文. 2005,8-13
[32] Microsoft Corporation.Windows XP Embedded Quick Start User Guide.Microsoft Corporation.2006.
[33]郑莉,董渊,张瑞丰.C++语言程序设计(第3版)[M].北京:清华大学出版社,2003.
[34]杜宏璐.基于VC++的图像火焰检测系统上位机软件设计与实现[D].南昌:南昌大学硕士论文.2007,8-10
[35]姜立东等.VHDL语言程序设计及应用(第2版)[M].北京:北京邮电大学出版社,2007
[2]林君.电磁探测技术在工程与环境中的应用现状[J].物探与化探.2000,24(3):167-177
[3]静恩杰,李志聃.瞬变电磁法基本原理[J].中国煤田地质,1995,7(2):83-87
[4]王淑玲.基于浮点放大的瞬变电磁法接收机的研制[D].长春:吉林大学硕士论文.2001
[5]徐立忠.基于ATEM-Ⅱ的改进型电磁法发射系统设计与实现[D].长春:吉林大学硕士论文,2008.6:1-2
[6]嵇艳鞠.浅层高分辨率全程瞬变电磁系统中全程二次场提取技术研究[D].长春:吉林大学博士论文.2004.
[7] M N Nabighian.Electromagnetic Methods in Applied Geophysics[M].Tulsa:Society of Exploration Geo-physicists,1987,402-431
[8]于生宝,王忠,嵇艳鞠,林君.瞬变电磁法浅层探测技术[J].电波科学学报,2006,4,21(2):284-287
[9]刘国栋.瞬变电磁仪-以PROTEM为例[C]第8届中国国际地球电磁学讨论会论文集,2007
[10]林君.甚早期时间域电磁系统—VETEM[J].国外地质勘探技术,vol,12,1997
[11] David Allen.A Review of Geophysical Equipment applied to Groundwater and Soil Investigation[R].2004 ANCID/Sustainable Irrigation Travel Fellowship.
[12]吕国印.瞬变电磁法的现状与发展趋势[J].物探化探计算技术,2007,29(增刊):111-115
[13]李慧.海洋瞬变响应理论计算及浅海底瞬变电磁探测技术研究[D].长春:吉林大学博士论文.2007:18-20
[14]王忠,林君,吴国强.TEM接收机低噪声抗饱和前放电路设计[J].吉林大学学报(信息科学版).2002,20(4):1-4
[15]于英民,于佳.计算机接口技术(第3版)[M].北京:电子工业出版社,2004.
[16] Microsoft Corporation.Windows XP Embedded MSDN.Microsoft Corporation.2006.
[17] Engene Olafsen,Kenn Scribner,K.David White.MFC Visual C++6编程技术内幕.第2版.王建华,陈一飞,张焕生等译.北京:机械工业出版社,2000.37-41
[18]高晋占.微弱信号检测[M].北京:清华大学出版社,2004:199-233
[19] Jens E.Danielsena,Esben Auken,Flemming J?rgensen.The application of the transient electromagnetic method in hydrogeophysical surveys[J].Journal of Applied Geophysics,53 (2003) 181–198
[20]邵晖,舒嵘.光电隔离器6n137的特性和应用[J].电子技术1998,2:38-39
[21]孙金辉.被动毫米波雷达中基于PCI总线的数据采集系统设计[D].青岛:中国海洋大学硕士论文,2008.6:42-44
[22]金明等.FIFO芯片在高速系统中的应用[J].电子技术应用.1998(3):61-62
[23]黄正谨等.CPLD系统设计技术入门与应用[M].北京:航空航天大学出版社,2002.
[24]罗日成,李卫国.基于Windows DLL技术实现监测软件中端口读写方法[J].电力自动化设备,2001,10,21(10):30-32
[25]李将渊,谭超,蔡铎昌.利用DLL技术实现化学虚拟仪器的端口操作[J].西华师范大学学报(自然科学版),2003,9,24(3):352-355
[26]程德福,林君,于生宝.瞬变电磁法弱信号检测技术研究[J].吉林大学学报(信息科学版),2002,6,20(2):1-5
[27]于生宝,林君.瞬变电磁法中发射机关断时间的影响研究[J].石油仪器,1999,13(6),15-17
[28]韩王平.瞬变电磁测深法的原理及计算方法[J].山西建筑,2003,29(2):42-43
[29]许志军,徐光辉.CPLD/FPGA的开发与应用[M].北京:电子工业出版社,2002
[30]潘春岭.基于PC104总线的高速硬币清分机研制[D].南京:南京航空航天大学硕士论文.2007,41-44
[31]王艳.浅海底瞬变电磁法接收系统的研制[D].长春:吉林大学硕士论文. 2005,8-13
[32] Microsoft Corporation.Windows XP Embedded Quick Start User Guide.Microsoft Corporation.2006.
[33]郑莉,董渊,张瑞丰.C++语言程序设计(第3版)[M].北京:清华大学出版社,2003.
[34]杜宏璐.基于VC++的图像火焰检测系统上位机软件设计与实现[D].南昌:南昌大学硕士论文.2007,8-10
[35]姜立东等.VHDL语言程序设计及应用(第2版)[M].北京:北京邮电大学出版社,2007