全球定位系统 毕业论文外文文献翻译

外文资料及译文

1.外文资料

全球定位系统

第一节The principle of GPS

一、GPS

GPS(Navigation Satellite Timing and Ranging /Global Position System )，GPS clock and distance navigation system/global positioning systems, referred to as global

positioning system (GPS), along with

the rapid development of modern

science and technology, and set up a

new generation of satellite navigation

and positioning system precision.

Global positioning system (GPS) is in

1973 by U.S. defense forces began to

organize, and common basic

completion in 1993. This system

consists of space constellation, ground

control and user receiver is composed

of three parts.

（一）Global positioning system 图1-1 GPS Satellite distribution

1.1 Space constellation

GPS space by 24 working part

constellation spare satellite and three satellite. Work in 6 orbit satellite distribution within the surface. Each track surface distribution has 3 ~ 4 satellite, satellite orbits earth's equator Angle relative to the average height of 55, orbit for 20200 kilometers. Satellite operating cycle for 11 hours 45 minutes. Therefore, in the same station daily satellite layout is roughly same, just four minutes every day in advance. Each satellite about 5 hours every day in the horizon, located above the horizon of the satellite number with more time and place, at least 4 November, most. This layout can guarantee on earth at any time, any place can also observed above four satellites.

Satellite signal transmission and reception and the influence, so the GPS is a global, all-weather real-time navigation and positioning for system. After the completion of the global positioning system, its work in the space distribution of satellite 1-1 as shown. GPS satellite zips are installed on the light, microprocessors, message signal emission equipment, storage, and provide power supply by solar cells have little fuel, satellite is used to regulate the satellite orbit and posture, and in the monitor of instruction, start spare satellite.

1.2 The ground monitoring system

GPS ground monitoring system in the world by five sites. One master station, 3 injection station. Five monitor are equipped with automatic acquisition, data center, double-frequency GPS receiver, precision clock, environmental data sensors and computing devices, and to master station provides all kinds of observation data. Master station (in Colorado) for system management and data processing center, its main content is the use of this site and other monitor the observation data of the satellite's star calendar calculation and satellite clock and atmospheric delay correction parameter, provide global positioning system, and the time base station, these parameters to adjust sidetracked into orbit, the satellite to enable spare satellite instead of failure satellite, etc. Injection station master station will be calculated and satellite star calendar, clock, satellite navigation message and other control commands into corresponding satellite etc, and storage system into the correctness of monitoring information. Besides, the master station, GPS ground monitoring system, various unattended highly automated and standardized work.

1.3 User equipment parts

User equipment including GPS receiver host, antenna, power and data processing software component. The host for the microcomputer, quartz oscillators core, and the corresponding input and output interface, and equipment. In the special software under control, the host for homework, satellite data acquisition, processing and storage of the equipment, the system state inspection, alarm and maintenance, the receiving system of automatic management. Antenna, often used for collecting all from each azimuth, arbitrary nonnegative Angle of satellite signal. Due to the satellite antenna pedestal weak signal in a pre-amplifier, amplification, reoccupy coaxial cable input host. Power supply for host and aerial part, can use through rectifier voltage, the mains, also can use the accumulator.

（二）Global positioning system (GPS) signals

GPS satellite launch a coherent wave, the wavelength 1L and frequency respectively 2L ：

f MHZ,

cm f MHZ,cm L L L L 11221575421912276024====..λλ

1L and 2L as a carrier with two modulation signal, a kind of navigation signal, another kind is message signal. Navigation signal S Mb 023.1 is divided again, frequency m A C 293=λ for code rate for the coarse yards (C/A code) and the rate S

Mb 023.1for the essence, the frequency of m p 3.291=λcode (P). Thick yards (C/A code) repeat each signal encoding, can quickly capture signal, according to the design for rough positioning, Pure code (P) yards signal encoding every seven, and repeat each satellite, structure is very complex, not capture, but can be used for accurate positioning. Message signal while the rate s bit 50to the carrier 1L and 2L modulation in, including satellite, the correct star calendar and satellite working state. Through the message signal receiver can choose the best one group of graphics, positioning signals observation data processing.

.第二节 GPS Positioning method

一、 GPS Positioning method classification

（一）、 The static and dynamic positioning

By means of static GPS positioning and can be divided into dynamic positioning.

1、Static positioning

If you stay in the surrounding relatively fixed protection can not perceive motion, or movement is so slowly that require months or years, namely that can be reflected in the earth for fixed-point relative coordinates is fixed, the determination method for the coordinates of static positioning is called. In the mathematics model of the static localization, the position is constant. Due to the rapid solutions of GPS "unknown" technology of the cycle time of operation, static already shortened to a few minutes, so, in addition to the original geodetic measurement and monitoring of the force applied, rapid static orientation has been widely applied to the common measurement and engineering measurement.

2、 Dynamic positioning

Cars, ships, aircraft and aircraft in motion, people often need to know their real-time position. In these sports carrier mounted on GPS receiver, real-time GPS signals measured antenna location, called the GPS kinematic positioning. If the only measure the real-time position, the carrier of sports also determine the speed, time and location, etc, thus guiding

status parameters to reserve the object orientation, called the navigation movement. GPS navigation is virtually dynamic positioning.

(二)、 Absolute positioning and relative location

According to determine the GPS receiver in earth coordinate system in different position, can be divided into a single absolute positioning and the relative positioning, such as machine, 2-1.

1、Absolute positioning

图2-1 Absolute and relative positioning

To determine the absolute positioning is independent coordinate system in the position of the dot. Because single absolute positioning error by satellite reception when the effect, low precision. Mainly used for low precision dynamic positioning, such as ships, aircraft navigation of mineral resources, geological investigation, Marine fishing and determine the relative position of the initial value.

2、Relative positioning

Relative location is determined simultaneous tracking same GPS signals of several sets of the relative position between the receiver is a kind of method. Since the synchronous observation, the synchronization of many error signal obtained station is identical or similar (such as satellite clock error, error, the signal of the star alex atmospheric transmission error, etc.), can avoid or weaken these errors, obtain high relative position. Relative positioning, signal processing and data than absolute orientation is complex, relative positioning is the synchronization between baseline vector (station), and 3d coordinate need at least a spot for known to the rest of the each point coordinates. The static and dynamic positioning can position by relative positioning,

such as

earth

deformation measurement, ground control aerial photogrammetry, etc.

In the dynamic positioning, often USES "difference", a GPS receiver will be placed on the base coordinate, known as the receiver in sports, all receivers carrier, according to the known synchronous control results, the positioning correct number starting position, in order to improve the real-time to positioning accuracy. This is based on a single point positioning and relative location of positioning mode.

（三)、 Pseudorange method and the carrier phase method

GPS satellite positioning, according to the different signal processing, can divide again pseudorange method and the carrier phase method.

1、Pseudorange method

The positioning principle is simple. When positioning, receiver and the oscillation of

A satellite signal the same group (P yards range yards or C/A code), through delay and receiver receive signals, when two groups compared each other completely coincide (related to signal measured signals, namely for the delay in quantity, satellite signal transmission time with A series of modified times the speed of light, satellites and draw the oblique distance antenna phase center. If the four (or above), i.e. the distance can satellite stations calculate intersection method of location and clock error four unknown. Due to the wavelength m p 3.29λrange yards m A C 293=λ. To one percent of the estimated $yards range resolution, length of to 0.3 meters (P) and 3 meters (C/A code) the ranging accuracy. Therefore, the pseudorange accuracy is relatively low.

2、The carrier phase method

The carrier is a measure of carrier signal, measurements, determine the satellite signal and reference signal receiver, calculate the phase difference observation. Then the same principle and pseudorange method, the position of the station clock error, etc. The wavelength modulated symbol cm L 191=λ,cm L 242=λ, than much shorter wavelength of one percent, to $yards range resolution, estimating length reached 1.9 cm (P) and 2.4 L centimeters (C/A code) the ranging accuracy. In the measurement and precision air triangle measuring, high precision, often USES relative positioning method, the carrier phase to eliminate system error.

The carrier phase method for measuring the complete phase observation data ?from several parts:

????φφ=-=+=++S R R N N I n tF 00~()() (2-1）

Type: s ?for the first phase, the observational S,R ? for the position of the receiver

observation R phase, ~?for the actual phase observations,0N for the whole cycle count,

also called the whole cycle unknown, ()φInt for the actual observation time t the integer part, first observed 0t for the duration of zero, every moment, observation 0t by continuous accumulated through counter counts, called after the cycle count, ()φR F for the actual observation in the integer part, with high precision measurement.

二、GPS positioning operation mode

Mainly includes GPS real-time GPS navigation positioning, afterwards (with) the dynamic positioning and used to measure the static or dynamic) relative orientation accurate.

1 . GPS kinematic positioning

GPS real-time navigation) is required (and observation data in the positioning of the moment, its main purpose is to navigation. AS mentioned above, the absolute positioning (single point positioning) by the us government's "SA" (choose usability) and "AS" (the electronic technology, the influence of deception by civil service standard of GPS level position precision of 100 meters. So many users using differential GPS system (CDGPS and WADGPS) to improve the precision. CDGPS pseudorange method and the users of the station standing range within 100 miles, precision for 5 ~ 10 meters. The carrier phase method CDGPS (also called RTK) standing and users in the station within range, 30 kilometers, the accuracy of cm. And WADGPS big scope is to create multiple known coordinates, standing and vice standing vice standing by data from receiving chain of error sources, after three corrections to users, communication WADGPS pseudorange method for positioning accuracy of about 1 ~ 3 meters, CDGPS superior. And stood and vice standing distance can reach over 1000 kilometers.

2. Dynamic positioning postprocessing

This is a kind of carrier phase of dynamic positioning technologies. Usually a receiver is placed in the ground, and the other on the known a (or more) receiver in high-speed motion object, jr, afterwards synchronous according to the carrier phase difference between objects in motion relative to determine the location of known. Its characteristic is standing with users need to stand between the transmission of real-time data, the distance between the two is less restricted. But in high-speed motion of the object is how to determine the unknown 0N and the whole week jump problem is the technical difficulties. In recent years, the GPS technology of dynamic initialization OTF (again) greatly improve something comes after the practicability of the dynamic positioning. It can reach the

cm-level positioning accuracy. Mainly applicable and low orbit satellite cm-level precision GPS satellite, aerial photogrammetry, airborne gravimetry, magnetic moment of determine the cm-level 3d coordinate of the airborne GPS technology.

https://www.360docs.net/doc/581403323.html,ed to measure the static（and dynamic) relative positioning

Static relative positioning using two sets of (or above), the GPS receiver respectively in each of the baseline endpoints, synchronous observation above four satellites 0.5 ~ 1 hour, baseline length in 20 kilometers. The baseline netted closed graph, constitute the whole event after adjustment, the precision can reach D

5. Applicable to higher

+1

mm?

ppm

accuracy of measurement and control of national land earth deformation monitoring, etc.

Rapid static relative position in the central area with a base station, GPS receiver continuous tracking all visible satellites, in order to each other a receiver to the above five starting synchronous satellites, each 1 ~ 2 minutes to benchmark station starting at baseline length within 15 kilometers, with the benchmark stood for radiation center. Afterwards the processing precision can reach D

+1

5, but poor reliability. Applicable to small

mm?

ppm

range of control measure, engineering surveying and cadastration, etc.

Accurate dynamic relative position in the zone, a GPS receiver with benchmark for tracking all visible satellites, another a receiver in starting sites for five first above synchronous satellites for 1-2 minutes and then keep track of all of the satellite, under the situation of continuous flow to the observation of the number of seconds, the observatory was starting to stand at the baseline length benchmark within 15 kilometers. Its characteristic is starting to keep each phase lock. In case of loss locks, must extend

N and the unlocked site observation time after 1 ~ 2 minutes to determine the unknown

0 whole cycle count cycle()φ

Int. Accurate dynamic relative positioning error in baseline can reach 1 ~ 2 cm long, suitable for engineering measurement circuit measurements and topography measurement, etc.

第三节GPS application

一、The GPS in engineering application

In surveying and mapping, GPS satellite positioning technology field has been used to establish the national geodetic measurement accuracy control network, determination of

the earth; the dynamic parameters of the global To establish the land and sea, high-precision measurement datum of land and sea islands; measurement of surveying and mapping al Used for monitoring earth plate motion and the crustal deformation, Used for engineering measure, establish a city and the major means of engineering control network, Used for testing the aerospace photography instant camera position, only a very small ground control or no ground control chart, causing rapid aerial geographic information system, the global environment of remote sensing technology revolution.

In the survey, using GPS technology to develop international league, establish the control of global network, provide high-precision geocentric coordinate, determination and refining geoid. So, for every Chinese department of surveying and mapping work, establish various measurement control network, provides the high plane and elevation 3d benchmarks.

In the engineering survey, the application of static GPS positioning technology, relatively precise control network layont for mining cities, and the subsidence monitoring, oil dam deformation monitoring, high-rise buildings deformation monitoring, tunnel breakthrough measurement precision engineering etc. Encryption, using GPS surveying asbuilts of real-time dynamic positioning technologies (hereinafter referred to as RTK surveying and mapping) of scale topographic map and used in the construction of engineering construction lofting.

In aerial photogrammetry, using GPS surveying workers also aerial technology field control measure, aerial electricity GPS navigation, airborne flying into the figure of the electricity, etc.

On earth, GPS technology used in dynamic monitoring global and regional plate, plate motion of movement monitoring.

The global positioning system (GPS) technology has been used in Marine measurement, underground terrain mapping and, moreover, the military defense, intelligent transportation, post and telecommunications, surveying, coal, oil, building and management of agricultural, meteorology, land, environmental monitoring, finance, public security departments and industry, in aerospace, test, physical detection, etc, also pose measurement are conducted the research and application of GPS technology.

二、The GPS in scientific research applications

The global positioning system (GPS) used in mobile positioning and economical solutions when we directly transferred to customer service center, the mobile phone to check with customer directly short message (GPS positioning, minutes and seconds data format), if the use of electronic map software, general inter-city direct support of its input

GPS data, minutes and seconds, if use the function orientation LingTu days in Beijing, can use the new 5 special software of GPS positioning master manual input coordinates function orientation, this scheme is suitable for low frequency ZhaChe. Enhanced when customers can purchase special satellite positioning management host, it can not only be receiving many car positioning short message, and stored in computer automatic classification, each vehicle is to build a database of clicking a mouse button, finding a car, as long as all the locating records on target data will automatically switch to electronic map shows the location, click on the progress vehicle or the back button on electronic map can demonstrate in the form of automobile, each vehicle can take different names, facilitate management more cars, very convenient, more frequent query for car. Along with the rapid development of urbanization, urban scale expands unceasingly, to provide convenient and fast traffic intelligent transportation information service system, will be the future trend of development, In addition, navigation and positioning system based on mobile phone service, will become the trend for the people to pursue. In the future, all can move, will depend on the GPS. GPS will like mobile phones, Internet, for our life greatly influence. Therefore, the GPS will form the huge industry value chain, significant social and economic benefits.

三、In the emerging field of application of GPS

RTK technology is RTK network a milestone in the development of technology. This technique by several stations composed a network, and has a terminal. Each station by telecommunications network (fiber or DDN) will observation data, the central station to station by reference data and the model through a solution within the pressure-difference method is correct and its through GSM/GPRS public Internet user, users send according to the real-time difference correct information can obtain higher precision. Compared with the traditional RTK technology, network RTK distance between the base can be long, sichuan VRS seismological bureau standing space than average system construction of 60 kilometers, is the longest baseline once more than 90 kilometers. So, same area covered only need less station can be achieved, cost can be greatly reduced. At the same time, the concept of network calculation model makes more reliable. Traditional RTK system if a base, the user can occur in the base area in the implementation of homework, covering technology in network RTK nonexistent this problem, because the center will automatically according to the user's position and the operation condition of choosing base stations operations. With modern communication technology, the computer storage technology and the rapid development of space technology, measuring method and mode has achieved great progress. GPS network in the information revolution is RTK arises in

the new space data acquisition method. It combines modern technology of communication and information technology, computer network distributed storage and processing technology of virtual reference, standing technology (VRS) among, and modern geodetic technology. GPS network is more advanced technology of RTK integration, this system for the country's infrastructure provide conveniences. Also for "digital city provides real-time reliable source.

2.译文

全球定位系统

第一节 GPS的原理概述

一、全球定位系统GPS

GPS(Navigation Satellite Timing and Ranging /Global Position System )，授时与测距导航系统/全球定位系统，简称GPS全球定位系统，是随着现代科学技术的迅速发展而建立起来的新一代卫

星导航和精密定位系统。GPS全球定位系

统是由美国国防部于1973年开始组织三军

共同研制，并于1993年基本完成。该系统

由空间星座、地面控制和用户接收机三部

分组成。

（一）全球定位系统组成

1.1 空间星座部分

GPS空间星座部分由24颗工作卫星

和3颗备用卫星组成。工作卫星分布在6

个轨道面内。每个轨道面内分布有3～4颗

卫星，卫星轨道相对于地球赤道面的倾角

为55 ，轨道平均高度为20200公里。卫星

运行周期为11小时58分钟。因此，在同

一测站每天出现的卫星布局大致相同，只图1-1 全球定位系统卫星分布

是每天提前4分钟。每颗卫星每天约有5

个小时在地平线以上，同时位于地平线以

上的卫星数目随时间和地点而异，最少4颗，最多11颗。这样布局可以保证地球上任何时间、任何地点至少可以同时观测到四颗以上的卫星。加之卫星信号的传播和接收不受天气的影响，因此GPS是一个全球性、全天候的连续实时的导航和定位系统。全球定位系统建成后，其工作卫星在空间的分布如图1-1所示。GPS卫星上安装有轻便的原子钟、微处理器、电文存储和信号发射设备，由太阳能电池提供电源，卫星上备有少量燃料，用来调节卫星轨道和姿态，并可在地面监控站的指令下，启动备用卫星。

1.2 地面监控系统

GPS 地面监控系统由分布在全球的五个地面站组成。其中1个主控站，3个注入站。五个监控站均为数据自动采集中心，配有双频GPS 接收机、高精度原子钟、环境数据传感器和计算设备，并为主控站提供各种观测数据。主控站（位于美国科罗拉多）为系统管理和数据处理中心，其主要内容是利用本站和其它监控站的观测数据推算各卫星的星历、卫星钟差和大气延迟修正参数，提供全球定位系统的时间基准，并将这些参数传入注入站，调整偏离轨道的卫星至预定轨道，启用备用卫星代替失效卫星等。注入站将主控站推算和编制的卫星星历、卫星钟差、导航电文和其它控制指令等注入相应卫星的存储系统，并监测注入信息的正确性。除了主控站外，整个GPS 地面监控系统无人值守，各项工作高度自动化和标准化。

1.3 用户设备部分

用户设备包括GPS 接收机主机、天线、电源和数据处理软件所组成。主机的核心为微电脑、石英振荡器，还有相应的输入、输出接口和设备。在专用软件控制下，主机进行作业卫星选择、数据采集、处理和存储，对整个设备的系统状态进行检查、报警和部分非致命故障的排除，承担整个接收系统的自动管理。天线通常采用全方位型的，以便采集来自各个方位的，任意非负高度角的卫星信号。由于卫星信号微弱，在天线基座中有一个前置放大器，将信号放大后，再用同轴电缆输入主机。电源部分为主机和天线供电，可使用经过整流、稳压后的市电，也可以使用蓄电池。

二、GPS 全球定位系统信号

GPS 卫星发射的是一对相干波21L L 和，波长和频率分别为

f MHZ,cm f MHZ,cm L L L L 11221575421912276024====..λλ

21L L 和作为载波载有两种调制信号，一类为导航信号，另一类为电文信号。导航信号又分

为码率为S Mb 023.1，频率为m A

C 293/=λ的粗码（C/A 码）和码率为S Mb 23.10，频率为m P 3.291

=λ的精码（P 码）。粗码（C/A 码）信号编码每1ms 重复一次，可以快速捕捉信号，按设计用于粗略定位；精码（P 码）码信号编码每七天重复一次，且各颗卫星不同，结构十分复杂，不易捕捉，但可以用于精确定位。电文信号同时以50bit S 的速率调制在载波L L 12和上，内容包括卫星星历表、各项改正数和卫星工作状态。通过电文信号，接收机可以选择图形最佳的一组信号进行观测，以利于定位数据处理。

第二节 GPS 定位方法

一、 GPS 定位方法分类

（一) 静态定位和动态定位

按GPS 定位方式可分为静态定位和动态定位。

1 静态定位

如果待定点相对于周围的固定点没有可以察觉的运动，或者运动十分缓慢以至于需要几个月或几年才能反映出来，即认为待定点相对于地球坐标系中是固定不动的，这种待定点的坐标确定方法称为静态定位。在静态定位的数学模型中，待定点的位置是作常数来处理的。由于GPS 的“快速解算整周期未知数”技术的出现，静态作业的时间已缩短至几分钟，因此，除了原先的大地测量及地球动力监测方面的应用外，快速的静态定位已广泛地应用到普通测量和工程测量中。

2动态定位

车、船、飞机和航天器运动中，人们往往需要知道它们的实时位置。在这些运动载体上安装GPS 接收机，实时测得GPS 接收信号天线所在的位置，称为GPS 动态定位。如果不仅测得运动载体的实时位置，还测定其运动速度、时间和方位等状态参数，从而引导该物体向预定方位运动，称为导航。GPS 导航实质上也是动态定位。

（二) 绝对定位和相对定位

根据确定GPS 接收机在地球坐标系位置的不同，可分为单机的绝对定位和多机的相对定位，如图2-1。

1 绝对定位

绝对定位是确定独立待定点在地球坐标系中的位置。由于单点绝对定位受接收卫星信号时误差的影响，精度较低。

主要用于低精度的动态定位，如船舶、飞机的导航，地质矿产资源的调查研究，海洋捕捞等及确定相对定位时的初始值。

2 相对定位

相对定位是确定同步跟踪相同GPS 信号的若干台接收机之间的相对位置的一种方法。由于采用同步观测，各同步站获得信号的许多误差是相同的或大致相同的（如卫星时钟误差、星历误差、信号的大气传播误差等），可以消除或减弱这些误差，获得很高的相对位置。相对定位中，信号观测与数据处理比绝对定位复杂，相对定位获得的是各同步站间的基线向量（三维坐标差），因而至少需要一个观测点为已知点才能求出其余各点的坐标。静态定位和动态定位都可采用相对定位，例如地球变形测量、无地面控制航空摄影测量等。

在动态定位中，常采用“差分”的方法，将一台GPS 接收机置于已知坐标的基准点上，其余接收机安置在运动载体上，所有的接收机同步观测，根据已知控制点的定位结果，将位置改正数实时传给流动站，以提高定位精度。这是一种基于单点定位和相对定位的定位模式。

（三) 伪距法和载波相位法

GPS 卫星定位，根据处理信号的不同，又可以分为伪距法和载波相位法。

1 伪距法

其定位原理简单。定位时，接收机本机振荡产生与卫星发射信号相同的一组测距

图2-1 绝对定位和相对定位

码（P 码或C/A 码），通过延迟器与接收机收到的信号进行比较，当两组信号彼此完全重合（相关）时，测出本机信号延迟量即为卫星信号的传输时间，加上一系列的改正后乘以光速，得出卫星与天线相位中心的斜距。如果同时观测了四颗（或以上）卫星，即可以按距离交会法算出测站的位置和时钟误差四个未知数。由于测距码的波长米3.29=P λ，米293/=A C λ。以百分之一的码元长度估算测距分辩率，只能分别达到0.3米（P 码）和3米（C/A 码）的测距精度。因此，伪距法的精度是比较低的。

2 载波相位法

是把载波作为量测信号，对载波进行量测，确定卫星信号和接收机参考信号的相位差，推算出相位观测值。然后采用和伪距法原理相同，求出测站的位置和时钟误差等。载波的波长厘米191=L λ，厘米242=L λ，比码元波长要短得多，以百分之一的码元长度估算测距分辩率，分别达到1.9厘米（P 码）和2.4L 厘米（C/A 码）的测距精度。在大地测量和精密空中三角测量中，为保证高精度，往往采用载波相位相对定位方法，以消除系统误差。

载波相位法测量完整的相位观测值?由几个部分组成：

????φφ=-=+=++S R R N N Int F 00~()() (2-1）

式中：?S 为卫星首次观测S 处的相位，?R 为接收机观测R 处的位置相位；~?为

实际相位观测值；N 0为整周期数，也称整周期未知数；Int()φ为t 时刻实际观测值的整数部分，对于首次观测t 0时值为零，其余各次观测中由t 0时刻开始，通过计数器连续计数后累计，称为整周期计数；F R ()φ为实际观测值中的不足整数部分，以很高的精度测定。

二 GPS 定位作业方式

GPS 定位主要包括GPS 实时（导航）定位、事后处理的动态定位和用于测量的静态（或准动态）相对定位等几种。

1 GPS 动态定位

GPS 实时（导航）定位是要求观测和处理数据在定位的瞬间完成，其主要目的是导航。如前所述，绝对定位（单点定位）受到美国政府实施的“SA ”（选择可用性）和“AS ”（反电子欺骗）技术的影响，采用民用标准定位服务的GPS 定位水平位置精度为100米左右。因而多数用户采用差分GPS 系统（CDGPS 和WADGPS ）来提高定位精度。伪距法CDGPS 的主站和用户站的作用距离在100公里以内，精度为5～10米。载波相位法CDGPS （也称RTK ）的主站和用户站的作用距离在30公里以内，精度为厘米级。而WADGPS 则是大范围内建立多个已知坐标的主站和副站，主站通过数据链从副站接收各类误差源，计算三项改正后通讯传给用户站，伪距法WADGPS 的定位精度约为1～3米，优于CDGPS 。并且主站与副站的距离可达1000公里以上。

2事后处理的动态定位

这是一种载波相位的动态定位技术。通常一台接收机安置在地面已知点上，而另一台（或多台）接收机置于高速运动的物体上，各站同步观测，事后根据两者间的载波相位差确定运动物体相对于已知点的位置。其特点是主站与用户站之间无须进行实时数据的传输，两者间的距离也少

受限制。但是在高速运动的物体上如何确定整周未知数N

0及整周跳变的问题是其技术难点。近

年来出现的GPS动态初始化技术OTF (On the Fly)大大提高了事后处理的动态定位的实用性。它的定位精度可达厘米级。主要适用与低轨道卫星的厘米级的精密星载GPS定位，航空摄影测量、航空重力测量、磁力测量中的确定测量瞬间的空中三维坐标的厘米级的机载GPS定位技术。

3 用于地面测量的静态（或准动态）相对定位

这是一种载波相位的相对定位技术。一般有三种定位模式：

静态相对定位利用两套（及以上）的GPS接收机，分别安置在每条基线的端点上，同步观测四颗以上的卫星0.5～1小时，基线的长度在20公里以内。各基线构成网状的封闭图形，

事后经过整体平差处理，其精度可达51

mm ppm D

+?。适用于精度要求较高的国家级大地控制

测量、地球形变监测等等。

快速静态相对定位在测区中部选一个基准站，用GPS接收机连续跟踪所有可见卫星，另一台接收机依次到各流动站对5颗以上的卫星同步观测1～2分钟，各流动站到基准站的基线的

长度在15公里以内，构成以基准站为中心的放射图形。事后处理后其精度可达51

mm ppm D

+?，

但是可靠性较差。适用于小范围的控制测量、工程测量和地籍测量等等。

准动态相对定位在测区内选一个基准站，用GPS接收机连续跟踪所有可见卫星，另一台接收机首先在起始站点对5颗以上的卫星同步观测1～2分钟，然后保持对所有卫星的连续跟踪的情况下，流动到各观测站观测数秒钟，各流动站到基准站的基线长度在15公里以内。其特点是各流动站必须保持相位锁定。万一出现失锁现象，必须在失锁后站点延长观测时间1～2分

钟，以重新确定整周期未知数N

0和整周期计数

Int()φ。准动态相对定位基线中误差可达1～2

厘米，适合于工程测量、线路测量和地形测量等等。

第三节 GPS定位技术的应用

一 GPS在工程技术中应用

对于测绘领域，GPS卫星定位技术已经用于建立高精度的全国性的大地测量控制网，测定全球性的地球动态参数；用于建立陆地海洋大地测量基准，进行高精度的海岛陆地联测以及海洋测绘；用于监测地球板块运动状态和地壳变形；用于工程测量，成为建立城市与工程控制网的主要手段；用于测定航空航天摄影瞬间的相机位置，实现仅有少量的地面控制或无地面控制的航测快速成图，导致地理信息系统、全球环境遥感监测的技术革命。

在大地测量方面，利用GPS技术开展国际联测，建立全球性的大地控制网，提供高精度的地心坐标，测定和精化大地水准面。这样，就为我国各部门的测绘工作，建立各级测量控制网，提供了高精度的平面和高程三维基准。

在工程测量方面，应用GPS静态相对定位技术，布设精密工程控制网，用于城市和矿区油田的沉降监测、大坝变形监测、高层建筑物变形监测、隧道贯通测量等精密工程。加密测图控制点，应用GPS实时动态定位技术（简称RTK）测绘各种比例尺地形图和用于工程建设中的施工放样。

在航空摄影测量方面，测绘工作者也应用GPS技术进行航测外业控制测量、航摄飞行导航、机载GPS航测等航测成图的各个阶段。

在地球动力学方面，GPS技术用于全球板块运动监测和区域板块的运动监测。

全球定位系统（GPS）技术已经用于海洋测量、地下地形测绘，此外，在军事国防、智能交通、邮电通信，地矿、煤矿、石油、建筑以及农业、气象、土地管理、环境监测、金融、公安等部门和行业，在航空航天、测时授时、物理探测、姿态测定等领域，也都开展了GPS技术的研究和应用。

二 GPS在科学研究中的应用

全球定位系统（GPS）用于可移动定位，经济型方案时我们把服务中心直接转移到客户的手机上，客户直接用手机查看到定位短信息（GPS度、分、秒数据格式），如果使用城际通电子地图软件，它直接支持输入GPS度、分、秒数据定位的功能，如果用北京灵图的天新者5，可以借助GPS定位大师专用软件中的手动输入经纬度功能进行定位，这个方案比较适合低频率查车。增强型方案时客户可以购买专用卫星定位管理主机，它不但可以自动接收多辆汽车定位短消息，而且自动分类保存在电脑内，每台车辆都建立一个数据库，轻点鼠标就能调出某辆车的全部定位记录，只要点击目标数据就能自动切换到电子地图上显示车辆的位置，点击前进或者后退按钮还能在电子地图上演示汽车的形式轨迹，每台车辆都可以取不同的名称，便于管理多辆汽车，非常方便，便于多车频繁查询。随着我国城市化的不断推进，城市规模的不断扩大，能够提供方便、快捷交通线路的智能交通信息综合服务系统，必将成为未来的发展趋势；另外，车载导航定位系统以及基于手机的移动定位服务，必将成为人们追求的潮流。今后，所有会动的东西，都将依赖于GPS。GPS将会像手机、互联网那样，对我们的生活产生极大的影响。因此，GPS必将形成巨大的产业价值链，产生重大的社会经济效益。

三 GPS在新兴领域的应用

网络RTK技术是RTK技术发展的一个里程碑。该技术由若干个基站组成一个网络，同时建有一个中心站。各基站通过电信网络（光纤或DDN专线）将观测数据传给中心站，中心站通过参考站数据及模型通过内差法解算得出改正信息并将其通过GSM/GPRS公众网络发送给用户，用户根据这些实时差分改正信息可获得比较高的定位精度。与传统RTK技术相比，网络RTK基站间距离可以比较长，四川地震局VRS系统平均站间距超过60公里，一期建设最长基线曾一度超过90公里。这样，覆盖同样的区域只需要更少的基站就可以实现，成本可以大大降低。同时，网络的概念使模型解算更加可靠。传统RTK系统中如果某个基站发生问题，则用户无法在该基站覆盖区内实施作业，在网络RTK技术中则不存在这个问题，因为中心站会自动根据用户所处位置及各基站运行情况选择合适的基站进行运算。随着近代通讯技术、计算机存储技术及空间定位技术的高速发展，测量手段和方式有了长足的进步。GPS 网络RTK就是在这场信息变革中应运而生的全新的空间数据采集手段。它结合了现代通讯技术、信息网络分发技术、计算机存储及处理技术、虚拟参考站技术（VRS）、以及现代大地测量技术。GPS网络RTK是多种先进技术的融合体，该系统为国家的基础设施建设提供便利条件。同时也为“数字城市”提供了实时可靠的数据源。

毕业论文写作十二忌

毕业论文,是高校学生根据我国学位条例的有关规定,在毕业之前,结合本人的专业学习和科研方向,在老师的指导下独立完成的学术论文。撰写毕业论文,是高校教学过程的一个必要环节,也是对毕业生综合运用基础知识和专业知识的检验,它可以反映出毕业生对知识的储备情况和研究问题、解决问题的能力以及语言表达等方面的能力。作为科学研究信息的载体,毕业论文也是奉献科研成果并实现其学术价值的重要工具。历年来,许多高校应届毕业生在老师的精心指导下,撰写出了许多高质量的优秀论文。但也有一些论文暴露出了这样或那样的问题,这体现出有些学生还没有真正掌握撰写毕业论文的要领。根据笔者近年来指导撰写毕业论文的工作实践,并联系毕业论文中存在的带普遍性的问题,下面谈谈撰写毕

论文应注意的几个问题。

1、忌选题不当,题目大小不宜

万事开头难,选题是起点。我们所说的选题,是指挑选用来作为毕业论文论证、探讨和解决的问题,也就是研究的中心问题。主攻研究的方向明确了,才能明确从何下手。一般说来,毕业论文论题的选择应遵循以下四点:一是要选主观上有条件、有能力驾驭的论题;即选与自己的专业或工作有关的论题;二要选难易适当的论;三是选有新意的论题,或前人从未研究过、或有人探讨过但不尽透彻、或研究角度不同有待进一步研究的论题。而有的学生在选题时,不是首先考虑论题的价值,而是首先考虑参考资料多不多;或虽然考虑了论题的社会价值,但题目大小难易限制不适中。有的选题太大,太复杂,写起来像“老虎吃天,无从下口”,由于作者把握不住选题的原则,因而写得肤浅,甚至半途而废。有的选题太窄太容易,没法展开也难以深入。因此,论文选题要从自身条件出发,尽量选大小适宜、难易适中

的题目。从自己所熟悉的领域开个口子去作文章,容易写得深刻切实。联系实际,从具体事物着手,分析归纳出一些带规律性的东西,易于增强文章的说服力,也易于解决问题,这种“小题大作”的论文一般效果很好。

2、忌懒于实践,眼高手低

有的学生由于平时读得多、动笔少,一动笔好象非要一鸣惊人不可。看别人的文,初看钦佩有加,久看觉得平庸肤浅,不过如此而已。而自己真正动笔写又写不出来。久而久之,心灰意懒,写作兴趣索然,正所谓眼高手低。写作文是真功夫,不

仅要语言文字功底扎实,而且要思想严谨而有深度。这就需要经常实践,反复实践。对于毕业

论文则可先写出提纲,打出初稿,然后反复思考研究,反复修改,决不能有半点畏难情绪。人的思维能力、研究能力是在科研实践中提高的,写作能力也是在写作实践中提高的。要想写出优秀的毕业论文,一是要对所研究的问题进行认真深入的探索,二是要对思考研究的所得进行归纳整理,理清头绪,写成条理清晰、逻辑严密的文章。

3、忌中心不明,纲目零乱

作者在下笔撰写毕业论文之前,要确定论证体系,即确定毕业论文的中心论点和分论点,并按一定的逻辑顺序排列好。所谓论证体系就是对讨论的问题,必须有中心,有从属,使中心论点和分论点之间形成一种特定的关系(支撑、从属) 。动笔

时,一定要把握重心,扣紧中心论点,使材料蕴含的力量全部能渗透到中心论点,要防止转移中心,防止偏题。而有的学生写的毕业论文没有一个突出的中心,什么都想说,什么都想解决,好象蜻蜓点水,到处涉及,而处处都不深入,结果一个问题也说不清楚,说不透彻,使人读后不知作者到底想阐明什么观点,说明什么问题。

4、忌凭空想象,似是而非

作为应用文体的毕业论文,毕竟不是文艺作品,既不能合理想象,也不能虚构杜撰;既不能渲染夸张,又不能缩小淡化。王充曾经指出,要“疾虚妄”,刘勰要求“事信而不诞”。可见,真实性是论文的生命。论文应观点鲜明、论据确凿,论证要有严密的逻辑性,这样得出的结论才经得起实践和历史的检验。写毕业论文就是进行“写”的研究,同时也是探求科学真理的过程,其材料必须准确无误。从大的事件到具体细节,甚至一句话,一个数据的引证,都不允许有任何虚假。如果论据靠不住,论点就成了空中楼阁,就会削弱文章的逻辑力量,影响文章的表达效果。因此,在立论上,要从实际出发,不带个人好恶,不凭空臆造;在论据上,要详尽地占有资料,对材料的性质、真假进行甄别;在论证上,要有严谨、周密的逻辑力量。这样,才能克服道听途说、以讹传讹、合理想象、似是而非的虚假结论,才

不会把谬误说成真理。

5、忌结构混乱,言之无序

毕业论文的结构,是作者根据自己的写作意图和要求,对大量材料进行创造性思维加工后形成的思想脉络或论文的框架。结构要解决的问题就是文章的脉络层次和发展顺序问题,结构预先设计得好,就可使文章言之有序。如果没有结构或结

构混乱,那么再精辟深刻的思想,再丰富典型的材料,也行不成好文章。笔者近年来从阅读学员的初稿时发现,即使同一个班的学员,论题大致相同,写进论文的材料也相差无几,但结果完全两样:有的观点鲜明,中心突出,条理十分清晰;而有的看不到中心,内容前后衔接不上,显得杂

乱无章。原因之一就是作者安排结构的本领有高下。有经验的作者写作时不贸然动笔,不临文觅意、想一点写一点,而是先把结构考虑成熟才动手,然后一气呵成。这就像我们建房之前,必须先搞好整体设计、画出蓝图、再按图施工一样,如果预先没有精密的设计图纸,具体施工就无从下手,自然就盖不出结构合理的房子来。

6、忌观点加例子,论不起来

论文的论证,就是用论据去证明论点的过程。“论”,就是讲道理“, 述”,就是摆事实。只提出论点,摆出一堆论据,不等于讲出了令人信服的道理。只有找出论点和论据的关系,并根据一定的逻辑联系组织出恰当的语言,才算是论起来了。论证实际上就是对事例进行分析说理。有的毕业论文,虽然篇幅较长,但没有针对论点的分析,只是论点加例子,堆砌一些材料,没有分析推理就下结论,文章再长,也达不到说服人的目的,起不到证明观点的作用。这其中最关键的原因是缺乏分析说理这个中间环节。学术论文要有理论性,就要会分析,会论理,就要紧扣中心论点,精心选择材料,再从各个不同的角度展开论述,道理说得越充分、越透彻,论文质量就越高。

7、忌空谈理论,言之无物

歌德曾经说过,理论是灰色的,生活之树常青。这里的生活,即是社会实践。理论如果离开了实践,就成了无源之水,无本之木。理论文章就要联系实际,这是理论形成的根据,也是理论发展的需要。因此毕业论文必须回答实践中提出的问题,

充分体现论文的社会价值。作为高等院校毕业生来说,应通过撰写毕业论文,实现由知识向能力的转化。如果不去认真进行调查研究,不深入实践中去考察,写出来的论文就会只有空话、套话,就会空乏无物、枯燥无味。毛泽东同志曾在《反对党八股》一文中,把这种空谈理论、缺乏生命力的文章比作旧上海滩的“瘪三”,这种“瘪三”式的文章是任何写作技巧也无法使它健全存活的。

8、忌外行逞能,不伦不类

前面说过,选题要适中,量力而行。这就包含着一个选择自己所熟悉、所内行、与所学专业相关的问题。我们所处的时代知识更新换代特别快,任何人都不可能全知天下事。每个学生都有自己的专业、爱好和特长,在自己熟悉的领域或所学的

专业内讨论问题,说的就是内行话,研讨专业外的问题,就可能出现外行现象,自然写不出高水平的论文来。而近年来有的学员的论文偏离了专业和所学的主要课程。例如学行政管理专业的写国际金融市场内容的不少;学政法专业的又研究小城镇建设在农村经济建设中的地位和作用,如此等等。正因为离开了自己的专业学习基地,理论根基不深,情况不熟,结果写出来的论文,不合客观事理和逻辑,有的甚至误入歧途,得出荒谬的结论。因此,有的学员在答辩时支支吾

吾,前言不答后语。

9、忌观点偏激,提法不妥

论文的论点,是作者思想、观点、态度和主张的集中体现。论点是论文的灵魂、统帅和纲领,评价毕业论文的首要条件就是观点正确、鲜明。因此不能随心所欲,不能违背党和国家现行的方针、政策和法律法规,更不能自行其是、钻牛角尖或走极端。在毕业论文写作中,由于个别学员学习不努力,未能及时掌握当前的理论动态,因而在论文中出现观点偏激,提法不妥的现象。要克服这一毛病,首先是要加强学习,努力吸取新知识,接受新事物,使文章所反映出的思想、观点、见解,跟上时代的步伐;其次,在动笔之前和成文之后,都要反复推敲斟酌,看确定论点的总的立场观点是否正确,有无问题;要看文中的主要提法是否妥当,是否符合客观事物的发展规律,有没有片面的、武断的、不实事求是的地方。如果发现了问题,要及时予以纠正。

10、忌抄袭代劳,坐享其成

撰写毕业论文,是一种创造性、自主性劳动,论文篇幅有一定的要求,写作时间又有严格的限制,对于平时动笔较少的学员来说,确实有一定的难度。因此有的学员就产生了畏难情绪和依赖心理。他们不是在老师的指导下去思考研究、独立完

成,而是通过东拼西凑,抄袭组织成文。更有甚者,全文抄袭报刊、杂志、网上现成的论文,或干脆请人代写。正由于作者未经过自己的辛勤劳动,对所抄内容不理解,虽论文写得好,但答辩时不堪一问,无言以对。对于一个真正想充实自己本领的人,应该珍惜毕业论文写作的机会,对棘手问题可以请老师或他人指导解决。借鉴别人的文章是可以的,但要在自己理解、体会的基础上,先吸取其中的营养,再用自己的智慧去创造。千万不要抄袭别人的文章或请他人代笔。这不仅是一种自欺欺人的做法,也是一种很不道德的行为。

11、忌弄错文体,不象论文

论文是议事论理,以议论为主要表达方式的理论性文体,它要求通过材料和逻辑推理来证明作者的观点,辩明是非曲直,它必须具备论点、论据、论证三个要素。而有的学员对文体把握不准,未弄清论文和其它文体的区别,因而写出来的论文,

有的像调查报告,有的像经验总结,有的甚至像报告文学。如有一篇关于《企业改革要以人为本》的文章,作者从报刊、杂志和网上搜集了中外企业举贤授能、重视人才、终于走向成功的几十个典型事例,用文学性语言描写叙述,而一点也没有对事例加以分析,没有生发开去论证观点、形成自己的认识。这样的文章,与其说是论文,倒不如说是“故事会”。因此,把握论文的文体特征,弄清论点、论据、论证三个要素之间的关系,是写好毕业论文的基本要求。12、忌语言、标点出错,格式不整