【作者】 常莉；

【导师】 沈博；

【作者基本信息】 中国地质大学 ， 检测技术与自动化装置， 2009， 硕士

【摘要】 全球卫星定位导航系统(GPS)是随着现代科学技术的迅速发展而建立起来的以接收导航卫星信号为基础的非自主式导航定位系统,该系统最初只用于军方,向民用开放后快速渗透到各行各业。自上世纪80年代引入我国以来的使用表明,GPS定位技术以观测站间无需通视、测量组人员投入少等优势,给测绘领域带来了一场深刻的技术革命。GPS技术在地球物理勘探中的应用是其一个重要的应用领域。地球物理勘探野外工作,在进行地球物理场测量的同时,须进行点位及其高程测量,GPS技术相对传统测地方法而言具有高精度及高效率的优势,使用更方便。对于地球物理勘探,一般要求水平高程精度都在1米左右,而重力勘探要求高程定位精度在厘米级水平。对于现有单机定位精度为3～5米手持型GPS接收机而言,精度常常不能满足要求;而重力勘探的测地工作中一般需要使用双频差分GPS技术,仪器价格昂贵。而且,市场上还没有专门为满足物探工作需要设计的低成本GPS接收机产品。专业级的差分GPS接收机的测量基线长度一般要求达到数十公里,而工程地球物理勘察及其他相关应用往往并不需要达到如此大的测量范围。本论文以设计低成本、用于短基线测量的较高精度的差分GPS接收机为目标。出于野外工作效率的考虑,提出在测量基线长度不超过3km,观测时间不超过10分钟的前提下,以ARM微处理器为系统控制器,采用快速静态差分技术,获得平面定位及高程测定精度达到厘米级水平设计要求。将ARM嵌入式技术与GPS技术相结合,充分发挥ARM微处理器功耗低、体积小、功能多等特点,利用ARM微处理器配合合适的GPS-OEM模块,开发适用于物探专业需求的GPS接收机具有重要的实用意义。本文正是从这种思想出发,设计开发基于GPS-OEM板的静态测量型GPS接收机。本文首先提出了静态差分测量型GPS接收机的总体设计方案,接下来重点阐述了系统的设计方法,系统设计分为硬件部分和软件部分。硬件部分包括主控单元模块LPC2214、电源电路、复位电路、时钟电路、JTAG电路、系统存储器扩展电路、RS232串行接口电路、128~*64图形点阵液晶显示电路、I~2C与键盘电路、SD卡存储接口电路及GPS接收模块接口电路等部分的设计开发。软件部分主要完成了系统控制程序的开发,主要包括SD卡软件设计,FAT16文件系统的建立,LCD液晶显示,I~2C键盘,GPS数据传输存储等几个细成部分。最后,对GPS接收机进行了系统测试,给出了测试方案并对测试结果进行了解算分析。由于目前只搜集到了一条已知基线资料,没有足够不同长度的已知基线来对样机定位精度随基线长度的变化规律进行分析。因此设计实验测试方案如下:首先,在已知基线上多次重复测量,了解样机的测量精度,确定测量值的误差范围;其次,对不同的基线长度进行多次重复测量,了解随基线长度的增加,系统随机误差的变化趋势;然后,进行流动站点间超短距离的多次重复测量,测量解算结果与钢尺丈量的超短基线数据进行比较,以弥补基线资料不足,了解样机在超短距离差分测量时的误差范围。实验结果表明:接收机工作稳定,定位精度基本不存在系统误差;定位误差随基线长度的增加有所增加,基线长度＜5km,10分钟静态差分定位平距和高差标准差均＜5cm,满足本论文的设计要求。另外,实验中对天气条件影响进行了资料对比和分析。通过系统设计和研究,得到如下主要结论:(1)在GPS-OEM的选择上的尝试是成功的。设计所采用的这一款单频GPS-OEM板的数据手册中给出其差分定位精度为＜0.5m,但在较短基线的差分测量中,该板表现出的定位精度远比其标称值理想。这一特性对用于小范围、较高精度测量的差分GPS接收机的设计,提供了一种降低成本的有效途径,实现了用中低档GPS-OEM板研制高精度GPS接收机的设想。(2)GPS接收机系统的整体设计思路是合理的。用ARM作为系统控制器,发挥了ARM数据处理功能强大,片上资源丰富的优势,简化了系统的外围电路设计,降低了系统开发成本,提高了系统的稳定性;满足了GPS接收机作为野外便携式仪器在功耗、体积等方面的特殊要求。(3)GPS接收机系统精度能满足本论文的设计目标。所设计的接收机样机,在配合使用碟型GPS信号接收天线时进行的差分测量结果表明:在基线长度不超过3km时,10分钟快速静态差分测量获得的测点点位及高程精度均可以达到厘米级水平;随基线长度的增加,接收机定位的点位误差和高程误差均有所增加;气候波动对测量结果的影响有限。系统能满足中大比例尺的地球物理勘探和工程测量中测点工作的需要。最后,指出了本文的主要不足之处并为下一步工作提出了合理的建议。更多还原

【Abstract】 Global Position System(GPS) is build upon the rapid development of modern science and technology.To receive navigation satellite signal based on the autonomous navigation and positioning system,the system is just use for military at first,after open up for civilian use it is quickly permeated to all walks of life.The use since it was introduced in China in the 1980s indicated that the GPS positioning technology bring a profound technical revolution in the domain of surveying and mapping with the advantage of dispense with visual between observatories,less input in measuring groups and so on.The GPS technology is an important field in the application of geophysical exploration.The fieldwork of geophysical exploration need to measure the point position and elevation while make geophysical filed survey,the GPS technology have the advantage of high accuracy and high efficiency,and more convenient in contrast with traditional geodesic ways.Commonly, the accuracy of level elevation is about one meter,but gravity prospecting requires the accuracy of elevation positioning to centimeters.The accuracy can not meet the requirement to pocket GPS,whose single machine positioning accuracy is only 3 to 5 meters,and we need use the dual-frequency differential GPS technology in geodesic work of gravity prospecting,the experiment is expensive.There have not a low-cost GPS receiver product for geophysics work in the market.The professional-grade difference GPS receiver’s survey baseline length request dozens of kilometers generally,but the engineering geophysics investigation and other applies often do not need to achieve such a large measuring range.The thesis takes the design of a low-cost,using in the short-baseline and high precision difference GPS receiver as a goal.Considering the efficiency of the field work,the thesis proposes that the baseline length in the measurement is no more than 3km and observation time is no more than 10 minutes,taking the ARM microprocessor as the central controller,and using the fast static difference technology,to obtain the centimeter level of the plane positioning and elevation standard precisions. It has important practical significance to combine the ARM embedded technology and GPS technology,take full advantage of the characteristic such as low consume,small capacity,more function of ARM microprocessor,make use of ARM microprocessor with suitably GPS-OEM module,develop the GPS receiver which is suitable for the demands of geophysical professional.First,this article advanced the whole design scheme of static state difference measurement GPS receive,and then make emphases on the design method of the system,the design of the system divided into the hardware and software.The hardware part has mostly done the circuit design of the main control unit module LPC2214,the power circuit,the reset circuit,the clock circuit,the JTAG circuit,the system memorize expander,RS232 serial interface circuit,128*64 graphics dot matrix LCD circuit,I~2C and keyboard circuit,SD card storage interface circuit and GPS receive module interface circuit and so on.The software part is main completed the development of the system control programming,mainly contains several component such as the SD card software design,establishment of FAT16 file system,LCD Display,I~2C keyboard,GPS data transition and storage and so on.At last,system test is made to the GPS receiver,test plan is given and the result of the test is calculated and analyzed.Because only collected a known baseline data at present,the enough different length’s known baseline has not come to the Positioning Accuracy of the prototype to analyze the rule along with the baseline length change.Therefore the designed experiment tests are given as follows.First,the repeated measure on the known baseline is used to understand the measuring accuracy of the prototype,and to determine the scope of measurement error.Secondly, the repeated measurements on the different baseline lengths,is used to understand the system random error’s change tendency along with baseline lengths increase.Then,the repeated measures on ultra-short distances,comparing the results of measurement with ruler baseline data, is used to understand the range of measurement error in the ultra-short distances of the prototype and to make up for the lack of the baseline data.The experimental results indicated:the work of the receiver is stable.The pointing accuracy does not have the system error basically.The position error increases along with the baseline length increases.When the base length is smaller than 5kin,10 minute static differences locate the even distance are smaller than 5cm with the elevation difference standard deviation,satisfy the design requirements of the thesis.Moreover,the experiments on the effects of weather conditions are analyzed.Through the system design and the research,I mainly obtain the following conclusion:(1)The choice attempt of the GPS-OEM is successful.The difference positioning accuracy of the single-frequency GPS-OEM board given in the datasheet is smaller than 0.5m,this board displays the pointing accuracy is far more ideal than its nominal value in the relatively short baseline difference measurements.This feature provided one kind of efficient path to reduce the cost for the GPS receiver design on the small scope,the high precision and differential measurement,achieves the idea of design high-precision GPS receiver with to the low-grade GPS-OEM board.(2)The design concept of the GPS receiver system is reasonable.Taking the central controller with ARM,ARM has displayed a advantage on formidable in the data processing function and rich resources in the chip,simplified system’s peripheral circuit,reduced the system development cost and enhanced system’s stability.And it can satisfy the special requirements in the power,the volume and so on as a field using portable equipment.(3) The accuracy of the GPS receiver system meets the design goals of this thesis.The differential measurement results of the prototype with antennas indicated:when the baseline lengths do not surpass 3km,the 10-minute rapid static differential measurements results of measuring point position and the elevation precision may achieve the centimeter level;Along with the increase of the baselines length,the spot position error which and the vertical error the receiver locates increases;The effects of climate fluctuations were limited.The system can satisfy the needs of measuring points work in the big scale’s geophysical prospecting and the engineering survey.Finally,this thesis points out the major deficiencies and gives the reasonable proposals for the next step works.更多还原