前言
    目前国内外市场上的静态GPS接收机技术已经趋于成熟，集成度也很高，外业操作十分简单易学，但是相对而言，静态GPS数据的内业处理要求一定的专业知识和专业技巧，通过几年的GPS产品开发，长时间的仪器测试使用，和多次与用户面对面的交流，将在静态GPS数据后处理中最常见的一些问题的解算技巧做了一些总结，下面将以我公司的后处理软件为例讲解说明。

                           正文
  在进行GPS静态数据后处理之前要先导入数据文件，
  目前市场上常见的几种数据格式主要有CMC(*.CMC)、Rinex(*.??0)、JAVAD(*.JPS)、Novate(*.OBS)几种，其中Rinex是通用的标准数据格式，一般的后处理软件都可以将自己公司专用的数据格式转换为标准格式，有时如果用源文件解算结果不理想，可试着先将源文件转换为标准数据格式后再重新进行解算，比对解算结果，查找问题所在。
另外，如果解算中发现有的基线解算结果较差，可以将该条基线的两个测点的Rinex数据文件打开查看一下原始记录数据是否存在误差，Rinex数据文件格式如下图所示：
 上图所示的数据采样间隔为5秒，从左到右，分别是：
6 4 28  8  14  19.999999  0  10  5  21  29  14  18  26  15  9  22  30
年 月日 小时分  秒     间隔符               卫星编号ID
注：日期时间是美国时区。
各个GPS接收机厂家所采用的采样间隔不相同，但两条数据之间的时间间隔应该一致，否则说明原始记录数据有误。采样间隔一般不会大于60秒，如果发现数据采样间隔过大，一是用户在设置参数时有误，二则是原始数据记录出错。
导入数据后开始基线解算，也就是数据预处理。
（1）一般情况下会有少数几条基线解算不成功。基线信息如下图所示：检验或是查看基线解算是否成功的重要标志有两个：RATIO和RMS，如果RATIO>2 ,RMS<0.02 我们认为基线解算成功； RATIO<2且RMS>0.02 我们认为基线解算失败，
注：基线解算是否成功依靠上面的标准不一定可靠，还要通过闭合差检核来确定基线解算是否成功。无论成功状态还是失败状态的基线都参加网平差计算。对于基线解算失败的基线可以重新进行基线解算；解算不好的基线可以考虑把它删除，否则将影响定位精度
（2）对于解算不成功的基线可以修改解算时的一些系统参数，重新解算，如下图所示：
 在外业测量时，测站点距离一般较大，测量人员在实施测量时会约定好每个测点的测量时间，但在实际操作的搬站中，每个时段的起始时间总会有些误差，有时积累到后来时间误差已经相当大，这样的话，同一时段的数据匹配度就较差，此时可以通过调整起始历元和结束历元来提高数据匹配度，在如上图所示的数据历元为0～85，可以将起始历元调高或是结束历元调低后重新解算基线，查看结果。基线解算时屏幕右边同时显示出卫星残差周跳图及基线向量名（*.RES）、RATIO、RMS、距离等。其中横坐标代表历元数；不同颜色的线条代表不同的卫星。代表某一颗卫星的线条越平稳表明数据越可靠，如果发现在起始或是结束的某段历元卫星数据普遍跳跃较大，可以通过调整起始历元和结束历元的值剔除某段时段的数据，不再参与解算以提高解算精度。

采样率如果取值为1，表示每个历元都作为有效数据参加解算；如果取值为2，表示每隔一个历元的数据为有效数据。取值数越大，读入有效数据数目越少，解算速度越快。缺省值为3，可以改变解算时的数据采样率，上图中的解算数据间隔为3，可以调高为5或是调低为1后，重新解算基线，有时同一时段的卫星数据在不用的采样率下匹配程度不一，则会导致解算结果不同，提高或降低精度。

截止角缺省值一般为15度，低于卫星高度截止角的数据不参加解算。如果基线解算达不到要求，可以适当调高截止角的值，但截止角并非越高越好，建议不要超过25度，截止角过高会引起电离层折射误差的加大。

上面说过在屏幕右边同时显示出卫星残差周跳图及基线向量名（*.RES）、RATIO、RMS、距离等。其中横坐标代表历元数；不同颜色的线条代表不同的卫星。代表某一颗卫星的线条越平稳表明卫星数据越可靠。明显可以看出，品红颜色线条代表的12号卫星有两次较大的跳跃，如果此时基线解算精度不够，可以考虑通过卫星删除功能剔除12号卫星数据，不再参与解算。取值为 3 ，表示 3 号卫星所有数据被删除。最多只能删除2颗卫星。尽量不要删除卫星数据。

基线解算有几种不同的解算方式：可进行L1单频解、L2单频解、Widelane双频宽项解、 Narrowlane双频窄项解及Ion-free双频去电离层解等。缺省的解算方式是L1单频解，这个功能项在数据预处理中用的不多。

注：采取一些解算技巧并不能对本身存在质量问题的野外观测数据进行绝对的弥补，在对解算不成功的基线数据进行了充分的检核和分析后，仍不能满足工程要求的情况下应进行野外返工观测。

 数据预处理只是对观测数据质量的一种检测，如果要作为可用的坐标成果输出，在基线解算成功和闭合差合格后，还要进行网平差。
（1）GPS数据文件是WGS-84坐标系下的观测结果，可以先进行自由网平差，以检核GPS网的内部符合精度，也就是相对精度，相对精度用户可以根据GPS控制网设计的精度要求自行确定。
        （2）实际应用中，往往要求得各GPS点在国家坐标系中的坐标值，为此还要进行坐标转换，将GPS点的坐标值转换为国家坐标系坐标值。也可以将GPS网与地面网进行联合平差，包括固定地面网点已知坐标、边长、方位角、高程等的约束平差，坐标转换，或将GPS基线网与地面网的观测数据一并联合平差。
平面坐标有两选项：平移、平移+旋转+尺度。只求平移参数时一个已知点即可，而后一选项则需要两个或者两个以上的固定点坐标；高程拟合有五选项：平移、平面拟合、XY二次曲面拟合、XX+YY二次曲面拟合、XX+YY+XY二次曲面拟合。平移只需要一个已知的海拔高，平面拟合需要三个已知的海拔高，而曲面拟合需要四个以上已知的海拔高。
还应注意，在进行约束网平差时，对于使用三个以上固定点的GPS网，应分别输入固定点进行平差计算，以检核约束条件的精度及可靠性，然后选择与GPS网相兼容的固定点进行最终平差计算。
约束网平差后的坐标结果可作为最终结果输出。

在实际应用中情况千变万化，上面所述只是个人的一些浅见，应根据实际的技术要求，具体问题具体解决。
 

 On the market at home and abroad, static GPS receiver technology has become mature, and integration is also very high, field operation is very easy to learn, but relatively speaking, a static GPS data processing requirements within the industry, a certain degree of professional knowledge and professional skills, through the years of GPS product development, a long instrument test use, and repeated communication with customers face to face will be in a static GPS data post-processing some of the most common problem solver technique has made some summarized below, According to my company's post-processing software as an example to explain instructions.

                            Text
 during post-processing GPS static data before the first import the data file,
 currently on the market of several common data formats are mainly CMC (*. CMC), Rinex (*.?? 0), JAVAD (*. JPS), Novate (*. OBS) several of which are common to Rinex standard data formats, the general post-processing software can be its own company-specific data format is converted to a standard format, sometimes with the source file if the solver results are not satisfactory, try the first source file is converted to standard data formats and then re - solver than to the solver results to find the problem.
In addition, if the solver found in some of Baseline Solution poorer outcomes can be measured which of the two points of the baseline data file is open look Rinex data on the existence of original records errors, Rinex data file format as shown below:
  The figure shows the data sampling interval is 5 seconds, from left to right are:
6,428,814 19.999999 0,105,212,914,182,615,922 30
Date hours minutes and seconds interval break Satellite ID ID
Note: The date and time is the U.S. time zone.
GPS receivers used by the various manufacturers of the sampling interval is not the same, but the time interval between the two data should be consistent, otherwise, the data shows the original records is wrong. Sampling interval is generally not more than 60 seconds, if we find the data sample interval is too large, one the user to set parameters in error, two errors of the original data records.
 import the data after the baseline solver, which is data pre-processing.
(1) Under normal circumstances there will be a few rules of Baseline Solution unsuccessful. Baseline information as shown below: test, or view the Baseline Solution is an important indicator of success there are two: RATIO and the RMS, if the RATIO> 2, RMS <0.02 We believe that the success of Baseline Solution; RATIO <2 and the RMS> 0.02 we have that the baseline solver fails,
Note: Baseline Solution to rely on the success of the above criteria may not be reliable, but also through close inspection of nuclear to determine the baseline difference solver was successful. Whether successful or failure of the state of the state have participated in the baseline network adjustment calculation. Baseline Solution for the failure of the baseline can be re-Baseline Solution; Solution of the baseline can be considered bad to delete it, or will affect the positioning accuracy of
(2) For the baseline unsuccessful Solution Solution can be modified to some of the system parameters, re-solver, as shown below:
  Outside the industry, measurement, measuring the site distance is larger, surveyors will make an appointment in the implementation of better measurement for each measuring point of the measurement time, but in the actual operation of the moving station, each time the starting time that some of the error, Sometimes, accumulated to a later time error is already quite large, so the same period of data matching on the poor, this time by adjusting the starting and ending epoch epoch to improve data matching, the data shown in the above calendar RMB 0 ~ 85, you can increase the starting epoch, or lower end of the epoch and re-solver baseline, view the results. Baseline Solution at the same time when the right side of the screen shows the residual cycle slips of satellite maps and baseline vector name (*. RES), RATIO, RMS, distance. Numbers on the abscissa the number of representatives of epoch; different color lines represent different satellites. The lines of a satellite on behalf of a more stable and more reliable data show that, if we find at the start or end of a certain epoch of satellite data generally jump higher, you can adjust the starting and ending epoch epoch value of excluding certain time data, is no longer involved in order to improve the solver solver accuracy.

Sampling rate of 1 if the value that each epoch of data are to participate as an effective solver; if value is 2, that every one epoch of data for valid data. The number of larger value, the number of valid data read into the less solver faster. The default value is 3, you can change the solver when the data sampling rate, the solution of figure above calculation data interval of 3, you can increase or reduce to 1 to 5, after re-solver baseline, and sometimes the same period of the satellite the data do not match the sampling rate varies, it will result in solver results to differ, to raise or lower accuracy.

The default value is generally close angle of 15 degrees, down from a high cut-off angle of satellite data is not to participate in solver. If the baseline solver is mainly the cut-off angle may be appropriately increased value, but the cut-off angle is not as high as possible, we recommend no more than 25 degrees, cut-off angle is too high will cause the increase of ionospheric refraction error.

As mentioned above, the right side of the screen also shows the residual cycle slips of satellite maps and baseline vector name (*. RES), RATIO, RMS, distance. Numbers on the abscissa the number of representatives of epoch; different color lines represent different satellites. The lines of a satellite on behalf of a more stable and more reliable satellite data show. Can be seen clearly, magenta color line on behalf of the 12 satellite, there are two big jump, if the precision of Baseline Solution at this time is not enough, you can consider the adoption of satellite-delete function removed on the 12th of satellite data, no longer involved in solver. Value of 3, indicating 3 satellite all the data is removed. Can only remove the two satellites. Try not to remove the satellite data.

Baseline Solution Solution There are several different ways: to allow L1 single-frequency solution, L2 single-frequency solution, Widelane pairs of bandwidth Xiang Xie, Narrowlane dual-band narrow-Xiang Xie, and Ion-free dual-band solution to the ionosphere and so on. Solution of the default way of L1 single-frequency solution, this feature item in the data pre-processing using very little.

Note: Solution techniques and take some inherent quality problems can not be field observation data to compensate for the absolute, in the right Solution unsuccessful baseline data sufficient vetting and analysis, still can not meet the engineering required in the circumstances field rework observations should be carried out.

 data pre-processing is only a kind of observational data quality testing, if you want to output the results as the coordinates are available in the Baseline Solution success and closed after passing poor, but also to network adjustment.
(1) GPS data file is the WGS-84 coordinates of the observational results, a free network adjustment can be the first to review the internal network, in line with the nuclear GPS accuracy, that is, relative accuracy, relative accuracy of GPS control network users can design accuracy requirements determine for themselves.
         (2) practical applications often require very different GPS points in the national coordinate system of coordinates, for which also the coordinate transformation, the coordinates of GPS points into the national coordinate system coordinates. GPS network can also carry out joint adjustment with ground-based networks, including the fixed ground network of known coordinates, edge length, azimuth, elevation and other constraints adjustment, coordinate transformation, or GPS baseline network and ground network of observational data in conjunction Joint adjustment.
Plane Coordinate There are two options: translation, translation + rotation + scale. Zhiqiu pan parameter can be a known point and then an option you need two or more fixed-point coordinates; elevation fitting there were five options: translation, plane fitting, XY quadric surface fitting, XX + YY quadratic surface fitting, XX + YY + XY quadratic surface fitting. Translation only need a known high elevation, flat fitting requires three known high altitude, while the surface fitting required more than four known high altitude.
Should also note that, when carrying out constraint net adjustment for the use of three or more fixed points of the GPS network should be split between fixed points of input adjustment calculation, in order to check the accuracy of the nuclear constraints and reliability, and then select the GPS network phase is compatible with a final adjustment of the fixed-point calculations.
Constraint net adjustment the coordinates after the results can be output as the final result.

In practice, the situation is constantly changing, some of the above is only my personal humble opinion, should be based on the actual technical requirements, specific solutions to specific problems.