测绘工程专业英语课文全部翻译

Section 2 The Reliability of a Survey and Errors

测量误差的可靠性

Since every technique of measurement is subject to unavoidable error, surveyors must be aware of all sources and types of error and how they combine. If the accuracy of a measurement is defined as the nearness of that value to its true value (a quantity we can never know) then a surveyor must ensure that the techniques he chooses will produce a result that is sufficiently accurate. He must know, therefore, how accurate he needs to be, how to achieve this accuracy and how to check that the required accuracy has been achieved.

由于每个测量技术是不可避免的误差，测量员必须知道的所有误差的来源和类型，以及它们是如何结合。如果测量的准确性，其真正的值（我们可以永远不知道的数量）的接近程度，该值被定义为，然后测量员必须确保他选择的技术将产生一个结果，是足够精确的。因此，他必须知道他需要的精度如何，如何实现这一目标的准确性和如何检查所要求的精度已经达到。 Accuracy required

When surveying to produce a plan, the accuracy required is defined by the scale of the plot, since there should be no plottable error in the survey data. A good draughtsman can plot a length to within 0.25 mm and so, if a plan of an area is required at a scale of 1/1000, i.e., 1 mm on the plan represents 1 m on the ground, the smallest plottable distance is 0.25 m. Thus, for a survey at 1/1000 scale, all the measurements must be taken such that the relative positions of any point with respect to any other must be determined to 0.25 m or better.

当测量一个平面时,精度通常是根据展图比例决定的，因为在绘图中不能有测量误差。一个好的绘图员可以在大约0.25毫米的范围内画图，假如一个地区的图纸比例尺要求是1/1000，即1毫米图上距离代表1米实地距离，那么最小的测距应该是0.25米。因此，对于1/1000比例尺的测量，所有测量必须保证任意一点与其他任一点的相对位置不得大于0.25米。

The specifications of surveys for other purposes such as engineering works or property boundary definition might well be determined by engineering tolerances or legal standards. 基于测量规范可能被用于其他目的，如工程测量或财产边界的测量将由工程限差和合法的基准决定。 Achieving the specification

To ensure that the specification is achieved the equipment and methods must be chosen such that, not only will they collect the right sort of data, i.e., the correct combination of angles and distances, but that the data will be to the required accuracy. There are several types of error that occur and a knowledge of their importance and characteristics is essential in the understanding of the limitations of the techniques of measurement. The salient features will be stated now but further information is given in later chapters.

为了确保测量符合规范，仪器和数据应按照以下要求进行，并不是只是得到正确的数据，即更正角和边的关系，从而得到的数据满足精度的要求。在测量中有几种类型的误差，掌握它们的重要性和特性对于理解测量技术的限差是必不可少的。本章主要讲解这些误差的主要特征，后面的章节将提供进一步的阐述。 Mistakes 粗差

Blunders or mistakes are often inaccurately referred to as gross errors. Miscounting the number of tape lengths when measuring a long distance or transposing numbers when booking are two very simple, but all too common, examples of mistakes. These types of mistakes can occur at any stage of a survey, when observing, booking, computing or plotting, and they would obviously have a very damaging effect on the results if left uncorrected. However, by following strictly a well-planned observing procedure it is possible to reduce the number that occur and then independent checks at each stage should show up those that have been made. In practice, none should

ever go undetected and uncorrected.

错误经常不准确的理解为粗差。 当测量很长一段距离时，读错尺的读数或记录两个简单的数时颠倒它们的位置，这些都是很常见的错误例子。这些类型的误差可以发生在测量任何阶段，当观测，记录，计算和绘图，如果不纠正这些错误，他们在结果上显然有一个非常有害的影响。但是，通过严格周详的观测过程，可能杜绝这些错误的产生，然后在每个阶段应独立检测可以是这些错误显现出来。在实践中，没有不可发现和不可纠正的粗差。 Systematic errors系统误差

Systematic errors arise from sources which act in a similar manner on observations. The method of measurement, the instruments used and the physical conditions at the time of measurement must all be considered in this respect. Expansion of steel tapes, frequency changes in electromagnetic distance measuring (EDM) instruments and collimation in a level are just a few examples of possible sources of systematic errors.

系统误差的来源于以相同的观测方式。测量时要考虑这些方面，测量的方法、测量仪器和外界环境。钢尺的膨胀，电磁测距仪的频率变化和水准仪的照准情况都是系统误差的可能来源。

These errors are of vital importance in activities which consist of adding together a succession of individual observations (see sections on leveling and traversing). If all the individual measurements contain the same type of systematic error, which by their nature always act in the same direction, then the total effect is the sum of them all.

这些误差在由一系列独立观测（参见水准测量和导线测量部分）累加在一起组成的测量值中极为重要，如果所有的独立测量包含相同类型的系统误差，且这些系统误差总是表现出相同的性质，那么总影响是所有这些的总和。

It must be ensured that measurements are as accurate as required by removing the effects of all factors that, if neglected, would result in a significant error. The errors caused by some factors can be eliminated with the correct observing procedure and others countered by applying corrections. Systematic errors are not revealed by taking the same measurement again with the same instruments. The only way to check adequately for systematic error is to remeasure the quantity by an entirely different method using different instruments.

通过消除所有因素的影响确保精度满足要求。如何忽略这些因素将会导致重大的错误。通过正确的观测程序以及纠正计算可以消除误差。通过同样的仪器用同样的方法测量是检测不出系统误差的。唯一能充分检测系统误差就是重测这些量通过使用完全不同的测量方法和测量仪器。 Random errors

Random errors are really all those discrepancies remaining once the blunders and systematic errors have been removed. Even if a quantity is measured many times with the same instrument in the same way, and if all sources of systematic error have been removed, it is still highly unlikely that all results will be identical. The differences, caused mainly by limitations of instruments and observers, are random errors.

随机误差事实上是除去粗差和系统误差后。即使测定数量很多次以同样的方式与相同的仪器，和已被删除，如果所有系统误差的来源，它仍然是极不可能的，所有的结果将是相同的。的差异，主要仪器和观察员的限制造成的，是随机的误差。

It is found in practice that these errors, although called random, have the following characteristics:

(1) small errors occur more frequently than large ones (2) positive and negative errors are equally likely to occur (3) very large errors seldom occur.

在实践中发现，这些误差，虽然称为随机的，具有以下特点： （1）小误差发生的频率比大

（2）正面和负面的误差发生的可能性相同 （3）非常大的误差很少发生。

These characteristics are typical of errors which are normally distributed and it is assumed that we can use the mathematical theory based on the normal distribution to deal with the errors met with in surveying.

正态分布是这些误差典型的特点是，我们可以用基于正态分布的数学理论来处理这些测量中的误差。

Understanding the errors that limit the accuracy of the measurement techniques is but one step to ensuring specifications are achieved, as will be seen when the methods of survey are described:

了解限定测量方法精度的误差仅仅是确保满足测量规范的一步，按照如下的测量方法进行：

(a) The survey area is always totally covered with the simplest possible framework of high quality

measurements. If the rest of the survey work is carried out within this control the possible damaging accumulation of errors can be contained. This is often termed 'working from the whole to the part',

（a）测区总是由高精度的测量框架所覆盖。如果剩下的测量工作在这个控制网内进行的话，累积误差就可以得到有效地控制。这通常被称为“从整体到的部分的工作，

(b) Observing procedures are designed so that (i) most mistakes that occur are discovered

immediately and (ii) possible sources of systematic errors eliminated. （b）观测程序设计，（ⅰ）大多数误差及时被发现，（ii）系统误差得到有效地控制。

(c) Additional, or redundant, observations are taken so that all data can be checked for the

mistakes, systematic errors and random errors that do occur. For example, the three angles of a triangle would be observed although only two are required to define the shape. The third angle could be deduced but, when measured, acts as a check.

（c）多余的观测是用来检测粗差、系统误差、偶然误差的。例如，一个三角形观测中，只要观测两个角就能决定其形状。但第三角度的观测是用来检核的。

(d) Many quantities are observed several times. These repeated measurements and the observation

of redundant data serve both as checks and to improve on the precision of the final results. （d）许多数据需要多次观测。重复观测是用来检核并提高最终精度的。 Checking the survey

Even with all the checking procedures the surveyor employs, errors can still occur in the finished plan and for this reason final independent checks are required. For simple work this would involve inspecting the final plan in the field and comparing some measurements scaled off the plan with their equivalents on the ground.

虽然测量员按照检核步骤进行检核，但是误差仍然可以出现在最后的平面图中所以最后还需要进行独立检核。对于这项简单的测量工作，需要到野外进行最后的平面图纸的检核和图纸距离放到实地进行比对。

Angle and Direction Measurement角度和方向测量

Horizontaland vertical angles are fundamental measurements in surveying.It is necessary to be familiar withthe meanings of certain basic terms before describing angle and direction measurement. The terms discussed here have reference to the actual figure of the earth.

水平角和竖直角是测量的基本测量工作,在描述角度和方向测量之前，有必要熟悉几个基本术语的含义,这里讨论的这些术语与地球的真实形状有关.

Basic Terms基本术语

A vertical line at any point on the earth’s surface is the line that follows the direction of gravity at that point. It is the direction that a string will assume if a weight is attached at that point and the string is suspended freely at the point. At a given point there is only one vertical line.A horizontal line at a point is any line that is perpendicular to the vertical line at the point. At any point there are an unlimited number of horizontal lines.A horizontal plane at a point is the plane that is perpendicular to the vertical line at the point.There is only one horizontal plane through a given point. A vertical plane at a point is any plane that contains the vertical line at the point. There are an unlimited number of vertical planes at a given point. 地球表面任一点的垂线是指这点上沿着重力的方向的线,如果在这点上用线悬挂一个重物，当线自由静止时，这条线所呈现的方向即重力方向。在给定的一个点上只有一条垂线。一点上的水平线是垂直于过该点的垂线的直线。过任一点的水平线有无数条。过一点的水平面是垂直于过该点的垂线的平面,过给定的一个点只有一个水平面.过一点的竖直面是包含过该点的垂线的任一平面过给定的一点有无数个竖直面. Horizontal Angle and Vertical Angle水平角和竖直角

A horizontal angle is the angle formed in a horizontal plane by two intersecting vertical planes, or a horizontal angle between two lines is the angle between the projections of the lines onto a horizontal plane. For example, observations to different elevation points B and C from A will give the horizontal angle ∠bac which is the angle between the projections of two lines (AB and AC) onto the horizontal plane. It follows that,although the points observed are at different elevations, it is always the horizontal angle and not the space angle that is measured .The horizontal angle is used primarily to obtain relative direction to a survey control point, or topographic detail points, or points to be set out. A vertical angle is an angle measured in a vertical plane which is referenced to a horizontal line by plus (up) or minus (down) angles, or to a vertical line from the zenith direction. Plus and minus vertical angles are sometimes referred to as elevation or depression angles respectively. A vertical angle thus lies between 0° and ±90°.Zenith is the term describing points on a celestial sphere that is a sphere of infinitely large radius with its center at the center of the earth. The zenith is an angle measured in a vertical plane downward from an upward directed vertical line through the instrument. It is thus between 0° and 180°.

水平角是指在一个水平面内由两相交的竖直面形成的角，或者说，两条线之间的水平角是这两条线在水平面上的投影线的夹角.例如，在A点观测不同高度的B和C点，其水平角∠bac是由AB和AC两条线在水平面上的投影构成的.由此得出结论结论，虽然被观测的点在不同的高度上，测出的总是水平角而不是空间角。水平角主要用来由联测控制点获得相对方向，或者地形测量碎部点、或者放样点,竖直角是在一个竖直面内参考于水平线的正（仰）角或负（俯）角，或者相对于一个天顶方向的垂线的角.正负竖直角有时分别被称为仰角或俯角.

Obviously the zenith angle is equal to 90° minus the vertical angles. Vertical angles or zeniths are used in the correction of slope distance to the horizontal or in height determined. For the most part, the instrument used in the measurement of angles is called a transit or theodolite, although angles can be measured with clinometers, sextants (hydrographic surveys), or compasses. The theodolite contains a horizontal and vertical circles of either glass or silver. The horizontal and vertical circles of theodolite can be linked to circular protractors graduated from 0° to 360° in a clockwise manner set in horizontal and vertical plane. The horizontal circle is used when measuring or laying off horizontal angles and the vertical circle is used to measure or lay off vertical angles or zenith angles. Usually the units of angular measurement employed in practice

are degrees, minutes, and seconds, the sexagesimal system.

竖直角位于0～90度之间.天顶方向是一个术语，用来描述在天球上的点，天球是一个半径无限大的球，其中心在地球中心。天顶距是一个在竖直面内从一个过仪器的被定向为向上的竖直方向线向下测量的角。它的范围是从0到180度。显然，天顶距等于90度减去竖直角.竖直角或天顶距用于斜距化平距的改正或者高程的测量.在极大程度上，用来测角的工具被称为经纬仪，虽然角度可以用倾斜仪、六分仪、或罗盘仪来测，经纬仪有一个玻璃的或镀银的水平度盘和竖直度盘.经纬仪的水平度盘和竖直度盘与顺时针刻了0到360度刻划的圆分度器相连。测或拨水平角时用水平度盘，测或拨竖直角或天顶距时用竖直度盘，通常角度测量法使用的单位是六十进制的度、分、秒。 Angle Measurement角度测量

A horizontal angle in surveying has a direction or sense; that is, it is measured or designed to the right or to the left, or it is considered clockwise or counterclockwise. In the above figure, the angle at A from B to C is clockwise and the angle from C to B is counterclockwise. With the theodolite set up, centered, and leveled over at station A, then a simple horizontal angle measurement between surveying point B, A and C would be taken as follows:

在测的水平角有方向，就是说它是向左测还是向右测，或者是说，顺时针测还是逆时针测.如上图所示，在A点由B到C就是顺时针角，而从C到B就是逆时针角，经纬仪在A点安置、对中、整平后，在B、A和C测量点间的简单的水平角测量可以按下列步骤进行：

⑴Commencing on , say, “face left”, the target set at survey point B is carefully bisected and the reading on horizontal scale is 25°.

⑵The upper plate clamp is released and telescope is turned clockwise to survey point C. The reading on horizontal circle is 75°

⑶The horizontal angle is then the difference of the two directions, i.e. (75°-25°) =50° ⑴说示意，“盘左”，将B点的目标仔细分中，水平度盘读数为25度 ⑵水平度盘制动螺旋松开，顺时针转动望远镜至C点，水平度盘读数75度 ⑶水平角就是两个方向值的差值，即， (75°-25°) =50°

⑷Change face and observe point C on “face right”, and note the reading=255° ⑸Release upper plate and swing counterclockwise to point B and note the reading =205° ⑹The reading or the direction must be subtracted in the same order as 255°-205°=50° ⑺The mean of two values would be accepted if they are in acceptable agreement. ⑷换度盘方向至盘右并照准C点，记下读数为255度 ⑸松开水平度盘，逆时针旋转至B点并记下读数为205度 ⑹读数或者说是方向值按同样的法则相减，255°-205°=50° ⑺如果两个减出来的值的一致性是可接受的，取两个值的平均值。

Modern electronic digital theodolites contain circular encoders that sense the rotations of the spindles and the telescope, convert these rotations into horizontal and vertical (or zenith) angles electronically, and display the value of the angles on liquid crystal displays (LCDs) or light-emitting diode displays (LEDs). These readouts can be recorded in a conventional field book or can be stored in a data collector for future printout or computation. The instrument contains a pendulum compensator or some other provision for indexing the vertical circle readings to an absolute vertical direction.The circle can be set to zero readings by a simple press of a button or initialized to any value on the instrument.

Azimuth is the horizontal angle measured in a clockwise direction from the plane of the meridian, which is a line on the mean surface of the earth joining the north and south poles. Azimuth ranges in magnitude from 0° to 360°, values in excess of 360°, which are sometimes encountered in

computations, are simply reduced by 360° before final listing. Bearing is the traditional way of stating the orientation of the line. It is actually the angle measured from the north or south.The bearing, which can be measured clockwise or counterclockwise from the north or south end of the meridian, is always accompanied by letters that locate the quadrant in which the line falls. For example, bearing N32W indicates a line trending 32° west of the north.It is equal to an azimuth of 328°.

Bearing S12W indicates a line trending 12° west of the south. It is equal to an azimuth of 192°. It is important to state that the bearing and azimuth are respect to true north.

现代的电子数字经纬仪包含编码度盘，能够感知轴和望远镜的旋转，并使之电子地转换为水平角度和竖直角度，并在液晶显示器或发光二极管显示器上显示出来，这些显示可以被一个传统的野外电子手簿或数据收集器记录，以便日后打印或计算。这种仪器具有一个悬挂补偿器或其它装置，使竖盘指标读数指向一个绝对竖直方向，这个度盘可以通过简单的按一个键就将其置零，或初始化成任一值。方位角是从子午面起算按顺时针旋转的角，子午线是在地球平均表面连接北极与南极的线。方位角的取值范围从0度到360度，超过360的值――有时会在计算时遇到，只需减去360度即可。方向角是一种传统的描述直线方向的方法。实际上，它是从南或北方向开始量测的角，方向角可以从子午线，北端或南端以顺时针或逆时针量测，总是伴以字母，用来标明直线所落在的象限。方向角N32W代表一条直线从北方向转向西方向32度，它等于方位角328度，方向角S12W代表一条直线从南方向转向西方向12度，它等于方位角192度。需要重点说明的是，方向角和方位角所用的是真北方向。

Unit 5 Traversing （导线测量）

The purpose of the surveying is to locate the positions of points on or near the surface of the earth.（测量的目的是确定地表或接近地表的点的点位。）

To determine horizontal positions of arbitrary points on the earth’s surface and elevation of points above or below a reference surface are known as a control survey.（确定地表任一【arbitrary任意的】点的平面位置和确定点高于或低于一个参考面的高程的工作被称为控制测量）

The positions and elevations of the points make up a control network.（这些点的平面位置和高程组成了一个控制网）

There are different types of control networks depending on where and why they are established.（依照它们建立的地点和目的不同，有不同的控制网类型）

A control network may have very accurate positions but no elevations (called a Horizontal Control Network) or very accurate elevations but no positions (called a Vertical Control Network).（一个控制网可能有精确的平面位置而没有高程（称为平面控制网），或者有精确的高程而没有平面位置（称为高程控制网））

Some points in a control network have both accurate positions and elevations.（有些控制网的点既有精确的平面位置也有精确的高程）

Control networks range from small, simple and inexpensive to large and complex and very expensive to establish.（控制网的范围从小的、简单的、便宜的网到大的、复杂的、昂贵的网）

A control network may cover a small area by using a “local” coordinate system that allows you to position the features in relation to the control network but doesn’t tell you where the features are on the surface of the earth, or cover a large area by consisting of a few well-placed and precise-established control points, which is sometimes called the primary control.（一个控制网可以是覆盖小范围，使用区域坐标系统，允许你相对于控制网确定地貌特征【feature】，但却不告诉你它们在地表的什么地方；或者覆盖一个广大区域，由少数被适当安置并精确测设的控制点组成，有时被称为基础控制）

The horizontal positions of points in a network can be obtained in a number of different ways.（控制网的点的平面位置可以由许多不同方法来获得）

The generally used methods are triangulation, trilateration, traversing, intersection, resection and GPS.（一般使用的方法有，三角测量、三边测量、导线测量、交会测量、后方交会测量、和GPS测量） The main topic of this text refers to the traversing.（这篇课文主要讲的是导线测量） Triangulation（三角测量）

The method of surveying called triangulation is based on the trigonometric proposition that if one side and three angles of a triangle are known, the remaining sides can be computed by the law of sines.（这种测量方法称为三角测量，基于三角法则，如果三角形的一条边和三个角已知，剩下的边可以用正弦定理计算出）

Furthermore, if the direction of one side is known, the direction of the remaining sides can be determined.（而且，如果一条边的方向已知，余下的边的方向也可以确定）

And then coordinates of unknown points can be computed by application of trigonometry.（那么未知点的坐标就可以使用三角法计算出来）

Trilateration（三边测量）

Since the advent of long-range EDM instrument, a method of surveying called trilateration was adopted to combine with triangulation.（自从远距EDM出现以来，一种叫做三边测量的方法用来和三角测量联合使用。）

The trilateration is based on the trigonometric proposition that if the three sides of a triangle are known, the three angles can be computed by the law of cosines.（三边测量基于三角法则——如果三角形的三条边已知，那么三个角可以由余弦定理计算出）

Trilateration possesses some advantages over triangulation because the measurement of the distances with EDM instrument is so quick, precise and economical while the measurement of the angles needed for triangulation may be more difficult and expensive.（三边测量具有一些相对于三角测量的优势，EDM测距快速、准确、经济，而三角测量所需的角度测量则相对困难和昂贵）

For some precise projects, the combination of triangulation and trilateration which is called triangulateration is applied.（在一些精密工程当中，三角测量和三边测量联合使用，被称为边角测量）

Traversing（导线测量）

A survey traverse is a sequence of lengths and directions of lines between points on the earth, obtained by or from field angle and distance measurements and used in determining positions of the point.（导线是一系列地球上点之间的有长度和方向的直线，由野外角度和距离测量获得，用来确定点位）

The angles are measured using transits, theodolites, or total stations, whereas the distances can be measured using steel tapes or EDM instruments.（角度可以使用经纬仪或全站仪来测，而距离可以使用卷尺或EDM来测）

A survey traverse may determine the relative positions of the points that if connects in series, and if tied to control stations based on some coordinate system, the positions may be referred to that system.（导线可以用来确定互相连接点的相对位置，如果想控制某些坐标系中的站点，其位置应参考该坐标系）

From these computed relative positions, additional data can be measured for layout of new features, such as buildings and roads.（从这些计算出的相对位置，另外的数据可以量出来，用以放样新的地物，如：建筑物和道路。）

Since the advent of EDM equipment, traversing has emerged as the most popular method to establish control networks such as basic area control, mapping, control of hydrographic surveys and construction projects.（自从EDM的出现，导线测量作为最常用的建立控制网的方法显现出来，例如基础区域控制、图根控制、水道测量控制和建筑工程控制）

In engineering surveying, it is ideal way to surveys and dimensional control of route-type projects such as highway, railroad, and pipeline construction. （在工程测量当中，导线测量是线型工程测量和立体控制的理想方法，线型工程例如公路、铁路、和管线建筑）

In general, a traverse is always classified as either an open traverse or a closed traverse.（总体上，导线总是分为支导线和闭路导线【按说open traverse是支导线，closed traverse是闭合导线，而connecting traverse是附合导线】）

An open traverse originates either at a point of known horizontal position with respect to a horizontal datum or at an assumed horizontal position, and terminates at a station whose relative position is not previously known.（支导线起始于一个水平位置已知（相对于一个水平基准）或水平位置假定的点，终止于相对位置事先未知的站点。）

The open traverse provides no check against mistakes and large errors for its termination at an unknown horizontal position and lack of geometric closure.（由于其终点位置未知并且缺乏图形闭合，支导线不能提供对错误和较大误差的检核）

This lack of geometric closure means that there is no geometric verification possible with respect to the actual positioning of the traverse stations.（这种图形闭合的缺少意味着没有几何上的检核可能性，对于实际的导线点的确定。）

Thus, the measuring technique must be refined to provide for field verification.（因而，这种测量技术应当提供野外的检核使之精确。）【字面的意思是该技术应当被精确化提供给野外确认】 At a minimum, distances are measured twice and angles are doubled.（至少，距离测两遍，角度测两个测回。）

Open traverses are often used for preliminary survey for a road or railroad.（支导线经常用于道路或铁路的初测）

A closed traverse can be described in any one of the following two ways:（闭路导线可以由下面两种方式的任一种描述：）

⑴A closed loop traverse, as the name implies, forms a continuous loop, enclosing an area. （闭合环路导线，正如名字所示，呈一个连续的环，围绕一个区域）

This type of closed traverse starts at assumed horizontal position or at a known horizontal position with respect to a horizontal datum and ends at the same point.（这种闭路导线起始于一个平面位置假设或相对于一个水平基准已知的点，并终止于该点）

⑵A connecting traverse starts and ends at separate points, whose relative positions have been determined by a survey of equal or higher order accuracy.（附合导线起始和终止于不同的点，它们由等于或高于规定精度的测量测设）

A known horizontal position is defined by its geographic latitude and longitude, or by its X and Y coordinates on a grid system.（一个已知的水平位置是由它的大地经纬度或格网系的X Y坐标表示） Closed traverses, whether they return to the starting point or not, provide checks on the measured angles and distances.（闭合导线，无论它们是否回到起始点，都能提供角度和距离检核。）

In both cases, the angles can be closed geometrically, and the position closure can be determined mathematically.（在两种情况中，角度可以在几何上闭合，位置闭合可以数学的确定【计算出来】） Therefore they are more desirable and used extensively in control, construction, property, and topographic surveys. （因此它们更理想【desirable理想的】，在控制测量、建筑测量、房地产测量和

地形测量使用更广泛）

As we mentioned above, a closed traverse provides checks on the measured angles and distances.（正如我们上面所提到的，闭合导线可以提供角度和距离的检核）

For example, the geometric sum of the interior angles in an n-side closed figure should be (n-2)×180°, but due to systematic and random errors of the measurements, when all the interior angles of a closed traverse are summed, they may or may not total the number of degrees required for geometric closure.（例如，在一个n边闭合图形当中，内角和应该是：(n-2)×180°，但是由于【due to】测量中系统误差和偶然误差的存在，当闭合导线所有的内角加起来后，其角度和【total】可能等于或不等于其几何理论闭合差值）

The difference between the geometric sum and actual field sum of the interior angles is called angular closure.（内角和的理论值和实际值的差值被称为角度闭合差）

The total error of angular closure should be distributed evenly to each angle (if all angles were measured with the same precision) before mathematical analysis of the traverse.（在导线进行数学分析之前，角度闭合差应该平均分配到每个角上（如果所有的角都是相同观测精度））

The important point before doing this is that the overall angular closure can’t be beyond the survey specifications.（重要的一点是，在这样做之前，所有的闭合差都不得超过测量规范）

Closed traverses provide also checks on the measured distances, and the position closure can be determined mathematically, which means that an indication of the consistency of measuring distances as well as angles should be given to a traverse that closes on itself.（闭合导线同时提供测量过的距离的检核，位置的闭合差可以计算得到，这就意味着测量的距离同测角一样，应当予以闭合

Theoretically this position closure from the origin back to itself should be zero.（理论上，从起点闭合到它自己，位置的闭合差应该是0）

But the Errors in the measured distances and angles of the traverses, however, will tend to alter the shape of the traverse, therefore we should compute the algebraic sum of the latitudes and algebraic sum of the departures, and compare them with the fixed latitude and departure of a straight line from the origin to the closing point.（但是距离和角度的测量误差，会改变【alter】导线的形状，因此我们应当分别计算纵距与横距的代数和，然后与从起点到终点的连线的确定的纵距与横距相比较）

By definition, latitude here is the north/south rectangular component of a line and departure is the east/west rectangular component of a line.（精确的说，这里的纵距就是指一条直线的直角坐标的南北分量，横距就是指一条直线的直角坐标的东西分量）

To differentiate direction, north is considered plus, whereas south is considered minus. （对于不同的方向来说，北方向为正，南方向为负）

Similarly, east is considered plus, whereas west is considered minus.（同样的，东为正，西为负） Then the discrepancy should be adjusted by apportioning the closure both in latitudes and in departures on a reasonable basis.（然后差值应以合理的原则进行调整分配闭合差到纵距和横距上去） The adjusted position of each traverse point is determined with respect to some origin.（ This position is defined by its Y coordinates and its X coordinates with respect to a plane rectangular coordinate system in which the Y axis is assumed north-south whereas the X axis east-west.（其位置由平面直角坐标系的Y坐标和X坐标来定义，Y轴代表南北方向，而【whereas反之】X轴代表东西方向）

Unit 6 Methods of Elevation Determination（高程测量方法）

An elevation is a vertical distance above or below a reference datum.（高程是高于或低于一个参考基准的一个垂直距离。）

Although vertical distance can be referenced to any datum, in surveying, the reference datum that is universally employed is that of mean sea level (MSL).（虽然垂直距离可以参考任何一个基准，但是在测量上，这个参考基准一般使用的是平均海平面（MSL））

MSL is assigned a vertical value (elevation) of 0.000 ft or 0.000 m.（MSL被赋予一个0.000英尺或0.000米的高程）

All other points on the earth can be described by the elevations above or below zero.（地球上所有其它点可以用高于或低于0的高程来描述）

Permanent points whose elevations have been precisely determined (benchmarks) are available in most areas for survey use.（高程精确测出的永久点（水准点）被用于大多数区域的测量工作） In China, 7 years of observations at tidal stations in Qingdao from 1950 to 1956 were reduced and adjusted to provide the Huanghai vertical datum of 1956.（在中国，利用青岛验潮站从1950年到1956年7年的观测数据处理和平差，建立了56黄海高程系统）

In the 1987, this datum was further refined to reflect long periodical ocean tide change to provide a new national vertical datum of 1985, according to the observations at tidal stations from 1952 to 1979.（1987年，在依照了验潮站1952到1979年的观测资料后，这个基准被进一步精确——反映长时期海潮变化的85国家高程基准建立起来。）

Although, strictly speaking, the national vertical datum may not precisely agree with the MSL at specific points on the earth’s surface, the term MSL is generally used to describe the datum.（虽然，严格说来，国家高程基准在特殊的点上与MSL并不恰好吻合，术语MSL一般还是用来描述它） MSL is assigned a vertical value (elevation) of 0.000 ft or 0.000 m.（MSL高程的赋值为0.000英尺或米）

Difference in elevation may be measured by the following methods:(James M. Anderson and Edward M. Mikhail. 1998)（高程的差异可以由下列方法测得（詹姆斯.安德森和爱德华.？？？））

1. Direct or spirit leveling, by measuring vertical distances directly.（水准测量，直接测得垂直距离）

Direct leveling is most precise method of determining elevations and the one commonly used.（水准测量是高程测量方法中精度最高、使用最普遍的方法）

2. Indirect or trigonometric leveling, by measuring vertical angles and horizontal or slope distances.（三角高程测量，利用测量竖直角和水平或斜距来测高程）

3. Stadia leveling, in which vertical distances are determined by tacheometry using engineer’s transit and level rod; plane-table and alidade and level rod; or self-reducing tacheometer and level rod.（视距高程测量，利用视距测量，使用工程经纬仪和水准尺；平板仪和照准仪和水准尺；或者自处理视距仪和水准尺测得垂直距离）

4. Barometric leveling, by measuring the differences in atmospheric pressure at various stations by means of a barometer.（气压水准测量，通过使用气压计测量不同站点大气压力的差值来测高程） 5. Gravimetric leveling, by measuring the differences in gravity at various stations by means of a gravimeter for geodetic purposes.（重力水准测量，通过使用重力计测量不同站点的重力值差值来测高程，用于大地测量学的目的）

6. Inertial positioning system, in which an inertial platform has tree mutually perpendicular axes, one of which is “up”, so that the system yields elevation as one of the outputs.（惯性定位系统，含有一个惯性平台，具有三个互相垂直轴，其中一个是“向上”的，所以这个系统产生的输

出其中一个就是高程。）

Vertical accuracies from 15 to 50 cm in distances of 60 and 100 km, respectively, have been reported.（各自地，据相关报告，在60和100km的距离上，其精度能达到15到50cm）

The equipment cost is extremely high and applications are restricted to very large projects where terrain, weather, time, and access impose special constraints on traditional methods.（这种装置成本极高，只限于非常大的项目，这些项目地质、气象、授时、以及？？施加特殊限制传统方法上） 7. GPS survey elevations are referenced to the ellipsoid but can be corrected to the datum if a sufficient number of points with datum elevations are located in the region surveyed.（GPS高程测量，它的参考面是地球椭球面，但是如果在测区有充分的高程点，可以修正至高程基准上来） Standard deviations in elevation differences of 0.053 to 0.094 m are possible under these conditions.（在这种情况下，其高差的标准差能够达到0.053到0.094米。） Spirit leveling （水准测量）

The most precise method of determining elevations and most commonly use method is direct leveling or spirit leveling which means measuring the vertical distance directly.（精度最高、使用最普遍的高程测量方法就是直接测垂直距离的水准测量方法）

Differential leveling is used to determine differences in elevation between points that are remote from each other by using a surveyor’s level together with a graduated measuring rod.（微差水准测量是利用测量者的水准仪和有刻度的尺来测定远距离的相隔点的高差）

For example, to determine the elevations of desired point B with respect to a point of known elevation A (see Figure 1), the elevation of which (BM) is known to be above sea level, the level is set up at intermediate point between A and B, and rod readings are taken at both locations as a and b respectively.（例如，确定欲测关于点A的点B的高程，（如图1），A点的高程已知（BM点），在A和B点之间的中点处安置水准尺，分别以a和b代表在这两处水准尺上的读数）

Then the elevation of the line of sight of the instrument (being horizontal) is known to be the line of sight of the instrument HA + a.（那么，仪器（整平后）的视线高程就是：HA + a） The elevation of point B can be determined by equation（B点的高程可以由方程来确定）

HB=HA + a － b

In addition to determining the elevation of point B, the elevations of any other points, lower than the line of sight and visible from the level, can be determined in a similar manner.（除确定B点的高程之外，其它点的高程，低于视线的和水准仪可以看见的点，都可以以相似的方法得到。） But some terms should be mentioned from above.（但是上面的一些术语需要提一下）

a is called Backsight (BS) which is a rod reading taken on a point of known elevation in order to establish the elevation of the instrument line of sight.（a 被称为Backsight，是一个放在已知高程点上的尺的读数，用来求得仪器视线的高程。）

b is called Foresight (FS) which is a rod reading taken on a turning point, benchmark, or temporary benchmark in order to determine its elevation.（b 被称为Foresight，是一个放在转点、水准点、或者是临时水准点之上的尺的读数，用来确定该点的高程）

HA + a refers to the Height of Instrument (HI) which is the elevation of the line of sight through the level.（HA + a 指的是仪器高度（HI），是过水准仪的视线的高程）

Owing to refraction, actually the line of sight is slightly curved, the effects of curvature and refraction for the horizontal distance can be reduced to a negligible amount and no correction for curvature and refraction is necessary if backsight and foresight distances are balanced in practical operation.（由于大气折光的缘故，实际上视线是有些弯曲的，曲率和折光的影响可以被当作

可忽略的值，不必加入球气改正，如果在实际工作中后视距和前视距是相等的。） Trigonometric Leveling三角高程测量

Trigonometric Leveling is used where difficult terrain, such as mountainous areas, precludes the use of conventional differential leveling.

三角高程测量被用于复杂的地形，如山区，排除了传统的微差水准测量

The modern approach is to measure the slope distance and vertical angle to the point in question. Slope distance is measured using electromagnetic distance measures and the vertical (or zenith) angle using a theodolite, or the total station that integrate these two instrument into a single instrument.

这个现代手段是测量测站距离未知点的斜距和垂直角。斜距是通过电子测距仪测量的，垂直角（或天顶距）是通过经纬仪测量的，或者使用全站仪测量，全站仪集测距、测角功能于一身。

Total stations contain built-in microprocessors that calculate and display the horizontal distance from the measured slope distance and vertical height. This latter facility has resulted in trigonometrical leveling being used for a wide variety of heighting procedures, including contouring.

全站仪包含了内置的微处理器，它通过测量所得的斜距和垂直高度计算和呈现水平距离。这个新型的设备使得三角高程测量被广泛应用在各种各样的高程测量中，包括等高线。

The basic concept of trigonometrical leveling can be seen from Figure 2. When measuring the vertical angle α and the horizontal distance S is used, then the difference in elevation hAB between ground points A and B is therefore:

hAB = S*tan α+ i - v

三角高程测量的最基本的概念能够从图2上看出。当测量的垂直角α和水平距离S被使用，然后地面 点A和B的高差如下：

hAB = S*tan α + i - v

where i is the vertical height of the measuring center of the instrument above A and v is the vertical height of the center of the target above B. The vertical angles are positive for angles of elevation and negative for angles of depression. The zenith angles are always positive, but naturally when greater then 90 they will produce a negative result.

i是一起的测量中心距离地面点A的垂直高度，v是目标中心距离地面点B的垂直高度。垂直角的值，仰角为正，俯角为负。天顶角总是为正，但是当然当大于90度的时候也会产生一个负值。

Trigonometrical leveling method of determining difference in elevation is limited to horizontal distance less than 300 m when moderate precision is sufficient, and to proportionately shorter distance as high precision is desired. For the distance beyond 300 m the effects of curvature and refraction correction must be considered and applied.

三角高程测量方法仅限于水平距离低于300米内的高差测量，当中等精度是足够的，和依比例的、所要求更高精度范围内的更短距离的测量。对于那些距离超过300米的，地球曲率和大气折光的影响必须得考虑和应用。

To eliminate the uncertainty in the curvature and refraction correction, vertical-angle observations are made at both ends of the line as close in point of time as possible. 为了消除地球曲率和大气折光中不确定因素的影响，垂直角观测应该在测站的两端分别观测，越靠近同一时间点越可能。

This pair of observation is termed reciprocal vertical-angle observation. The correct difference in elevation between the two ends of the line is the mean of the two values computed both ways either with or without taking into account curvature and refraction.

这一对观测叫做相反的垂直角观测。测距两端点间的高差改正是两个测量值的平均值，测量值可以考虑或不考虑地球曲率和大气折光。

The important notes should be mentioned here is that surveyors used to working with spirit levels have referenced orthometric heights (H) to the “average” surface of the earth, as depicted by MSL. However, the elevation coordinate (h) given by GPS solutions refers to the height from the surface of the ellipsoid to the ground station.

这个重要的说明应该在这里被提到，测量员进行水准测量时过去常常参考距离平均地球表面的正高（H），这个平均地球表面被描述为大地水准面。然而，GPS提供的高程坐标系引用的是参考椭球距离地面基站的高度。

Topographic Surveying 地形测量

Introduction 序言

Topographic surveys are made to determine configuration (relief) of the earth's surface and to locate nature and cultural features on it .By means of various lines and conventional symbols,topographic maps are produced from survey data. A topographic map is a large-scale representation of a portion of the earth's surface showing culture,relief,hydrography,and perhaps vegetation.Cultural（artificial）features are the products of people,such as roads,trails,buildings,bridges,canals,and boundary lines.Names and legends on maps identify the features.

地形图地形测量用来确定地球表面的形状，定位自然和人文地物。通过各种线条和规定的符号，就可以根据测量数据绘制地形图。地形图是大比例表示部分地球表面的人工建筑，救灾，水文，也许植被。人文建筑是人类的产物，例如道路，小径，建筑，桥梁，运河和边界线。地图上的名称和图例是识别的特征。 Topographic maps are made and used by engineers to determine the most desirable and economical locations of

highways,railroads,canals,pipelines,transmission lines,reservoirs,and other facilities；by geologists to investigate mineral,oil,water,and other resources；by foresters to locate fire-control roads and towers；by architects in housing and landscape design；by agriculturists in soil conservation work；and by archeologists,geographers,and scientists in numerous fields. 地形图是工程技术人员用来确定公路，铁路，管，管道，线路，水库，和其他设施最可取的和经济的位置；地质学家用来研究矿物，油，水，和其他资源；林务员用来定位消防道路和塔；建筑师用来设计住房和景观；农学家用来水土保持工作；考古学家，地理学家，许多领域的科学家也都有运用。

A planimetric map depicts natural and natural features in plan only.A hypsometric map shows relief by conventions such as contours,hachures,shading,and tinting.

一幅平面图仅仅在平面中描绘了人文建筑及其特征。一幅地形图则显示了地形，例如等高线、晕线、阴影和着色。

Methods for Topographic Surveying地形测量方法

Topographic surveys are conducted by either aerial（photogrammetric）or ground （field）methods,and often a combination of both.Refined equipment and procedures available today have made photogrammetry accurate and economical；hence,almost all topographic mapping projects covering large areas now employ this method.

地形测绘是由空中（摄影测量)或地面方法完成的，而且经常是两者的结合。现今精良的设备和程序使得摄影测量很精确、经济，因此，现在几乎所有覆盖大面积地区的地形测图工程都使用这种方法。

Ground surveys are still frequently used,however,especially for preparing large-scale maps of

small areas. Even when photogrammetry is utilized,ground surveys are necessary to establish control and to field-check mapped features for accuracy.This chapter concentrates on ground methods.Several feild procedures for locating topographic features,both horizontally and vertically,will be described.

地面测量仍是经常使用的,然而,尤其是准备对大比例尺地图的小区域测图。即使使用摄影测量,地面测量为测量建立控制和现场检查仍然是必要的,。本章集中于地面的方法。一些行业程序定位地形特征,在水平方向和垂直方向,将被描述。

Control for Topographic Surveys

The first requirement of any topographic survey is good control,whether the survey is done by ground or aerial methods.Control is classified as either horizontal or vertical.

地形测量无论调查是用地面还是空中的方法，第一个要求都是良好的控制,。控制是分为水平或垂直控制。 Horizontal control is provided by two or more points on the ground,precisely fixed in position horizontally by distance and direction.It is the basis for map scale and locating topographic features.Horizontal control is usually established by traversing,triangulation,trilateration,or inertial and satellite methods,and can be filled in photogrammetrically for large areas. 平面控制由地面上的两个或多个点来确定，精度由平面坐标位置的距离和方向来固定。地图比例尺和地形特征是基本的要素。平面控制通常由导线测量，三角测量，三边测量，重力和卫星的方法和大区域的摄影测量来确定。

For small areas, horizontal control for topographic work is generally established by a traverse, although a single line may suffice in some cases. Triangulation and trilateration furnish themost economical basic control for surveys extending over a state or the entire United States. These techniques may, however, give way in the future to inertial systems and Satellite Doppler receivers. Monuments of the state plane coordinate systems are excellent for all types of work ,but unfortunately more are needed in most areas

地形测量中，对于一些小面积的水平控制测量工作，尽管在某些情况下单导线就可以满足精度要求，但是通常还是用导线测量。在一个州甚至整个美国，三角测量和三边测量是最经济的基础控制测量方式。无论怎样，这些方技术给未来重力系统和卫星多普勒接收器提供了方法。州的平面坐标系统的埋石对测量的各种类型是有必要的，但是不幸的是大多数区域的埋石太少。

Specified maximum allowable closure errors for both horizontal and vertical control should be established in advance of field work

在外业之前，为了平面和高程控制的建立要指定最大的允许限差。

Vertical control is provided by bench marks in or near the tract to be surveyed. .It becomes the foundation for correctly portraying relief on a map A vertical control net is established by lines of levels starting form and closing on bench marks. Elevations are ascertained for all traverse hubs, with provision in some cases for marks set nearby and out of the way of construction. A lake surface is a continuous turning point or bench mark and may sometimes be used .Even a gently flowing stream may serve as supplementary control. Trigonometric and barometric leveling can be employed to extend vertical control in rugged terrain, but the latter is less accurate. 高程控制由测区的水准基点提供。在地形图上它成了正确描绘地形的基础。一个高程控制网由起止于水准基点的水准路线构成。导线中心确定了高程，在一些情况下，规定要在建筑物附近或外面做标记。湖的表面是一个连续的转折点或标记，有时会使用。即使轻轻流淌的河水可作为辅助控制。在崎岖的地形三角高程和气压水准可以用来延长高程控制，但后者是不准确的。

Topographic details are usually built upon a framework of traverse hubs whose positions and elevations have been established. Any errors in the hub positions or their elevations are reflected

in the location of topography. It is advisable, therefore, to run, check, and adjust the traverse and level circuits before a topographic detail survey is begun ,rather than carry on both processes simultaneously. This is particularly true in plane table work, where an error in elevation or position of an occupied station will displace the plotted locations of all cultural features and contours

地形碎步测量经常建立在导线节点网上，且这些节点的平面坐标和高程已确定。节点的水平和高程误差都反映在地形位置上。因此，在地形碎步测量开始之前对导线环和水准环实施检核和平差是适当的，而不是同时实施这两个工作。这在平面室内工作中也是绝对正确的，在这里实测站的高程和坐标误差会显示在标绘的地物的位置和等高线上。

Field measurement errors are more difficult to eliminate than those in mapping procedures .Even though plotting measurements that have been made to the nearest 0.01ft and 1 sec is not possible ,the data may be used for other purposes .Thus special care is required in taking and recording field date

野外测量误差比绘图过程中的误差更难消除。即使把已测得的数据展绘到0.01英尺和1秒是不可能的，但这些数据还可以用在其他方面。因此获取和记录野外数据时要特别小心。

The kind of control (traverse, triangulation, or trilateration)and method selected to get topographic details govern the speed, cost, and efficiency of a topographic survey. A theodolite-EDMI combination total station instrument with tracking system, data storage accessory, and voice recorder plus a communication system for descriptions simplify the note keepers job and reduce field errors. Sketches still must be made in field books, however. Various equipment combinations can be selected for the location methods discussed in succeeding sections 地形碎步控制测量（导线测量，三角测量，三边测量）的方法的选择决定了测量的进度，花费，和地形测量的效率。经纬仪和电子测距仪的结合，具有跟踪系统，数据存储设备，声音记录器，加上通讯系统的全站仪简化了记录员的工作，减少了野外测量误差，但是仍需要在野外测量簿上画出草图。不同仪器配合使用进行位置测定的方法将在接下来进行讨论。

Methods of locating Topographic Details in the Field 野外地形碎步测定的方法

Objects to be located in a survey can range from single points to meandering streams and complicated geological formations. The process of tying topographic details to the control net is called detailing.

要定位的目标可以从单个点到曲折的小溪和复杂的地形结构。联系碎步测量到控制网的过程称为碎步测量。

Seven methods used to locate a point P in the field are illustrated in Fig11-1. All are based on horizontal control. One line , AB, must be fixed in each of the first four methods, and its length known in methods 1, 2, and 4. Positions of three points must be known or identifiable to apply the seventh method called resection or the three-point problem. Quantities to be measured in the respective diagrams are:

在图11-1中显示了在野外确定p点位置的7中方法。所有方法都以水平控制为基础。在前四种方法中线AB必须测定，在1,2,4方法中需要知道它的长度。第七种方法叫做后方交会或三点问题，其中三个点的坐标必须知道或者可以测定。各个图需测量的数据是： (1):Two distances;两个距离 (2)Two angles两个角

(3)One angle and the adjacent distance一个角和相邻边

(4)One angle and the opposite distance(two possible points P

一个角和对边（两个可能的p点）

(5)One distance and a right-angle offset 一个距离和一个直角抵消 (6)The intersection of string lines from straddle hubs (7)Two angles at the point to be located

Method 3 is used most often, but an experienced party chief employs whichever method is appropriate in a given situation, considering both field and office (computation and map) requirement

但是一个有经验的测量队的负责人，在考虑到外业和内业（计算与绘图）的需要的情况下，能使用适合特定情况下的任何一种方法。

Unit 15 The Global Positioning System Preamble序

The Global Positioning System (GPS) is revolutionizing surveying technology. GPS正在革新着测绘技术Like its predecessor, the TRANSIT Doppler system, 像它的前任仪器，中天仪多普勒系统 GPS shifts the scene of surveying operations from ground-to-ground measurements to ground-to-sky ,GPS在测量操作上正在改变着从地对地观测到地对空观测的测量环境with obvious implications: visibility of marks is no longer a criterion for their location :operations are possible in nearly all kinds of weather and can be performed during day or night ;and the skills required to utilize the technology are different both in filed operations and data processing.有一些明显的结论标志的可见性不在是定位的一个标准在几乎任何天气、不分昼夜操作都是可以进行的使用这项技术所要求的技能在野外测量和数据处理中都是不同的 But GPS is not merely a replacement for TRANSIT .the simultaneous visibility of multiple satellites allows effective cancellation of the major sources of error in satellite observations, with the result that with GPS ,relative positioning accuracies of one part per million ( ppm) or better over distances from one kilometer to thousands of kilometers are possible .This means that GPS Can compete with terrestrial techniques over short distances ,and can achieve more accurate results in less time than TRANSIT observations over longer distances.但GPS不只是代替中天仪。多个卫星同时可视可以有效消除卫星观测中主要误差源，因此，用GPS其相对定位精度从一公里到数百公里范围内有可能达到百万分之一。这就意味着GPS在断距离上可以与地面测量技术相当，在长距离上比中天仪用时更少，并能得到更高的精度。 GPS was designed primarily as a navigation system GPS最主要是用作导航系统, to satisfy both military and civilian needs for read-time 满足军用和民用实时定位的需要positioning is accomplished through the use of coded information ,essentially clever timing signals ,transmitted by the satellites .这种定位方式是通过使用编码信息完成的，这些编码本质上是通过卫星传输性能较好的时间信号Each GPS satellite transmits a unique single on two L-band frequencies: L1 at 1575.42 MHz and L2 at 1227.60MHz (equivalent to wavelengths of approximately 19and 24 cm , respectively). 每个GPS卫星以2个L-波段频率传输1个唯一的信号L-1波段的频率1575.2Mhz，L-2波段的频率1227.60Mhz （他们各自向对应的波长 大约为19—24cm）The satellite singles consist of the l-band carrier waves modulated with a “Standard” or S code (formerly called the C/A code ), a “precise” or P code and a Navigation Message containing ,amongst other things ,the S code which is intended mainly for civilian use ,yields a range measurement precision of about 10 m ,The navigation service provided by this code is referred to as the Standard Positioning Service(SPS). The P code is therefore referred to as the Standard Positioning Service (PPS).Although both codes can be used for surveying, a more accurate method is to measure the carrier signal. For this reason. For this reason, we will not discuss the detailed characteristics of the codes in this monograph. For

details we refer the reader to Janiczek (1980).卫星信号由调制的L-波段载波组成，它是用一个“标准的”或称S的点码（以前称为C/A码，一个“精确的”或称P的点码以一个导航信息调制的，卫星的坐标作为事件—“广播星历”—的函数。S码主要是为民用，它可得到大约10m的距离测量精度，由这个码提高的导航服务为标准定为服务(GPS）,因此P码就是精确定为服务（PP是）。虽然两个码都用于测量，但更精确的方法是测量载波信号的相位。因此，在本文中我们将不详细讨论两个码的特点

There are currently eight usable satellites in orbit.当前可用的在轨卫星有8个 There are the experimental,”block1”satellites, which be progressively replaced as the”block2”, operational satellites are placed into orbit beginning in 1986 block1卫星是实验卫星，他们逐渐被black2卫星取代.这些操作卫星将在1986年底送入预定轨道 By 1989 the system should be complete, with 18 satellites in six orbit planes---at about 20200 km altitude , allowing for simultaneous visibility of at least four satellites at any time of day almost anywhere in the world. 截至1989年，大约在20200km 的6个轨道平面上的18颗卫星的系统将会完成这将会保证在世界上任何地点任何时间至少有4可卫星同时可视The present constellation is configured to provide the most favorable geometry for testing the system over North America.当前覆盖北美地区用于测试这个系统的配备的星座提供了最好的几何信息

As it happens , the observation geometry is equally favorable in Australia , and it is possible now to obtain surveying accuracies equally to those obtainable when the system is fully configured , but only for about six hours per day.凑巧的是，这些观测的几何信息在澳大利亚同样也是可用的，现在获取的测量数据的准确性与现在这个系统完全配备以后所能达到的精度是相当的，这种可能性是存在的 At the time of writing(November 1985),the period of maximum mutual visibility of the satellites in eastern Australia is between 6 pm and mid-night local time.1985年11月在写作的这个时间在澳大利亚东部卫星相互可视的最大的时间段是从下午6点到当地时间的午夜 This period regresses by 4 minutes per day (or 2hours per month),returning to the same times a year from now 这个时间段将会以每天4分钟（每月2小时）向后延迟，从现在开始1年之后回归到同样的时刻 this period of useful visibility will increase as additional satellites are launched from late 1985. 这个可以利用的可见性的时间段从1985年底随着另外一些卫星的发射将会增加

As with TRANSIT, much higher accuracies are obtained in relative positioning from observations made simultaneously at two observing stations.正如中天仪一样在2个观测站同时进行相对定位观测将会获得更加高的精度 Consequently, unless otherwise indicated, all discussion concerning data acquisition and processing will assume a two-receiver configuration因此，除了额外的的一些指示，所有关于数据获取和数据处理的讨论将会假定由配备的2个接受机. The position differences so determined constitute the baseline vector or simply the baseline between the points occupied by two receivers.由此测定的坐标差组成了基线矢量或者仅仅是2个接受机所在的测点之间的基线All satellite positioning systems provide ground coordinates of a receiver (or the baseline vrctor between a pair o receives)in an earth-centered coordinate system .The orientation of the system is determined by the tabulated coordinates or ephemerides of the GPS satellites. In order to relate coordinates determined by GPS surveying to the local geodetic datum a transformation relationship needs to be established多有卫星定为系统都提供接收机的地心坐标系（或两个接收机之间的基线矢量。系统的定向由坐标表或GPS卫星的星历确定。为了将GPS测量确定的坐标与地方大地基准联系起来，需要建立起转换关系

The following factors influence the final positioning accuracy obtainable with GPS:下列因素影响由GPS获得的最终的定位精度

1:The precision of the measurement and receiver-satellite geometry测量精度和接收机-卫星的几何图形结构

2:The measurement processing technique adopted;所采用的数据处理方法

3:The accuracy with which atmospheric and ionospheric effects can be modeled大气层和电离层模型的影响精度’

4The accuracy of the satellite ephemerides.卫星星历的精度

Each of these factors is discussed briefly in the next three sections紧接着的3个部分将会简单的讨论每个因素.

GPS measurement types :GPS measurements can be made using either the carrier signal or the codes. GPS测量的类型：GPS测量可以采用载波信号或者编码的2种形式Code measurements are called pseudo-ranges and can be based on either the P code or the S code. ;码测量可以称做伪距观测并且是基于P码或者是S码的 性能的指示

Pseudo-ranges are the simplest to visualize geometrically as they are essentially a measurement of distance contaminated by clock errors.由于伪距本质上是受中差影响的距离测量，它在几何可视性上是最简单的 Throughout this monograph , we use the terms clock, frequency standard and oscillator to denote the same thing, namely ,a device for precisely measuring a time interval在这篇论文中我们使用时钟，标准频率和震荡器这些术语描述的是同一个事物，即，用于精确测量时间间隔的设备. When four satellites are observed simultaneously, it is possible to determine the three-dimensional position of the ground receiver and the receiver clock offset at a single epoch .This is simply resection by distance ,in surveying terminology ,with the technique the precision is a function of the geometry of the receiver in relation to the four visible satellites .The best geometry would be when the satellites are in each of the four quadrants and each at an elevation angle of 40-70 above the horizon. However , pseudo-range measurements are not nearly as precise as phase measurements of the carrier wave itself.当同时观测四个卫星时，就可以在单个历元确定地面接收机的三维位置以及接受的钟差。用测量术语来说，这就是简单的后方交会，GPS定位的精度受接收机与四个可视卫星的几何图形的影响。最佳的图形是：四个卫星分布在四个象限，并且每个高度角位于水平线以上的40度到70度之间。单伪距测量的精度远不如载波相位测量的精度 In order to achieve position accuracies of 10 m from P code measurements or 100 m from S code measurements , it was only necessary to design. a code structure which allowed meter level measurement precision .为了从P码测量中获取10m或从S码中获取100m的定位精度（用于导航是足够的），设计一个含有米级测量精度的码结构是必须的Moreover ,the more precise P code will likely be encrypted, and may therefore not be available for non-military use, when the system becomes operational in 1989.此外在1989年这个系统运营的时候，有可能更加精确的P码进行加密，从而使它对非军方是不可用的 An additional impediment to accurate pseudo ranging arises from multipath effects, that in the tendency of some fraction of the satellites signal to reach the receiver antenna via reflection off the ground or other surfaces .另一个妨碍伪距测量精度的因素是多路径效应， 它是卫星信号的某些部分经过地面或其他事物表面的反射进入接收机的天线 The size and signature of multipath effects depend on antenna design and height of the antenna above ground but probably cannot be reduced below a few decimeters with practical configurations.多路径效应的数量和特征取决于天线的设计类型和天线距地面的高度，但是即使拥有实际的一些配置也不可能降低到几分米以下

Carrier phase measurements are more precise than the pseudo-ranges and not as vulnerable to multipath effects. 载波相位测量比伪距测量更加精确并且不收多路径效应的影响The wavelength of the

Knowledge of the properties of each of these types of measurements已下是有关每种测量类型的

stronger of the two L-band carrier signals,L1,is 19 cm, so even rough interpolation of phase gives centimeter level precision .2个较强的L-波段载波信号的波长，L-1 19cm即使相位有粗略的一些改变也会达到厘米级的精度From the technique of Electronic Distance Measurement, we know that phase measurements are ambiguous ,and unless one can determine the absolute range difference at the initial epoch, phase measurements give only the changes in range over the observing period从电子测距技术我们知道相位测量是不确定的，除非能在初始历元测定完全的边长差，相位测量仅仅能过给出观测期间的边长的改变. However, the absolute range difference can often be easily determined. 但是，完全的边长差经常能够很容易的测定

Carrier phase can be determined from the code-modulated signal either by using the code or other techniques .通过使用码或别的技术载波相位可以通过调制的码信号测得The L1 signal ,which has both P code and S code modulation ,can thus be tracked with S or P code receivers or with codeless receivers。拥有P码和S码的调制解调器L-1信号能够通过S或者P码的接收机或者无码的接收机进行追踪The L2 signal, useful for removing ionospheric effects for very precise applications , has no S code modulation ,so that receivers for these applications must either have P code capability or operate without code.对于精密测量，L-2信号对于消除电离层的影响是非常有用的（相对定位精度小于百万分之二）L-2信号没有S码的调制解调器，因此对于这些测量接受机必须有S码的性能或者是没有码也能运行

It is also possible to track the phase of the 10.23 MHz P code transition signal or P code sub-carrier without knowledge of the codes. 追踪10.23MHz的P码转换信号或者是没有码信息的子载波也是可能的The long wavelength of this signal compared with the L-band carrier allows relatively easy resolution of the integer-cycle ambiguity , producing in effect a pseudo-range measurement.相对于L-波段的载波这种信号的长波长（大约30M）对整周模糊度的解决是相对容易的实际上是产生了一个伪距测量 However, the long wavelength makes the measurements more susceptible to multipath effects, roughly to the same degree as pseudo-range measurements.然而长波长使得测量更容易受到多路径效应的影响定位精度跟伪距测量是同等级

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