Hướng dẫn bình sai GPS Huace X20 - phần 5

4 CHAPTER IV Manage Your Project
Our GPS data processing applications are all based on the project. Thus, it is
necessary to create a new project or open an existing project before doing either point
positioning, static baseline / Kinematics route processing or network adjustment.
To create a new project, you should:
1. Establish the coordinate system of the surveying area; enter coordinate parameters
in the
Coordinate System Management.
2. Specify which folder the project is to be stored in and download or copy your
observation data into it. Then create a project.
3. Load data into created project.
4.1 Establish Coordinate System and Coordinate System
Management
As shown in the following figure, run
To o ls
>
Coordinate System Management
in the
menu bar when main program is launched.
42. Coordinate System Management
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As shown below, a dialog-box will appear, as shown below, in which a file in the main
program folder called ‘Hit.ini’ will be loaded and all parameters of the coordinate system
in this file will be shown.
There is a Combo box on the top-most-part of the dialog-box, in which the name of the
selected coordinate system is shown (for example, we have selected an ‘Unknown’
system). The Parameters of the coordinate system, such as ellipsoid parameters (A, F),
(
,
,
,
,
,
),
projection parameters
M0
H
B0
L0
N0
E0
and 7 transfer parameters (DX, DY,
DZ, EX, EY, EZ, k) for mutual transferring with WGS-84 system
43. coordinate system parameters
To modify current coordinate system, click ‘Modify’.
To add a coordinate system, click ‘Add’. As shown below, a dialog-box will appear, as
shown below:
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44. Add a coordinate system
Enter ellipsoid parameters, projection parameters and transfer parameters mentioned
above.
Notes:
,
1. If you don’t know the values of these transfer parameters
please enter ‘0’.
Commonly, WGS-84 system will be transferred into selected coordinate system
automatically during post-processing progress.
2. For local coordinate systems with limited survey area that do not obtain the Central
Meridian, enter longitude of the center of the survey area in the
origin longitude.
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4.2 New project
It is ready to create a new project when the coordinate system is properly entered. In a
project, it is highly recommended that a sub-folder should be created first. For example,
there is sub-folder of demo examples under a folder named ‘Example’ in the folder
where the software is installed.
- Select ‘
File
’>’
New project
’. A dialog-box will appear, as shown below:
45. New Project
Now we enter ‘Rinex’ as a new project in the Input-Box on the top and ‘D:\Test\Rinex’
‘New Project Name’ on bottom. A new path will be created automatically if the entered
folder does not exist. To select an existing folder, click its folder in the Tree Window on
the left side. The project name and path will be automatically filled corresponding with
the Input-Box.
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46. Select Folder
Please make sure that you are using a the correct coordinate system when you are
creating a your a new project. It is ‘Unknown’ here.
Working with your project will create some files, they will be stored in the same folder
where your project is stored, or under its sub-directories. As shown in the following
figure, a file ‘Rinex.hit’ and three sub-directories (folders), say, ‘Mov’ stores Kinematics
route results of the processing, ’Res’ stores static baseline results of the processing
and Rinex stores Rinex files transferred from observation files, are generated under
folder ‘Rinex’.
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47. Observation files
It is highly recommended that all observation files should be stored in the folder where
the project is stored or one of its sub-directories. It can ensure that all data and results
of the processing are stored in a consistent folder and easy to save and compress.
4.3 Observation Data
There are two types formats, NMEA and Origin Observation a GPS receivers may
show output. Our GPS data processing application is mainly use for the latter. Most
GPS receiver output shows binary Origin Observation data in various formats.
Besides Huace-self-defined formats, our GPS data processing application can also
process data format output by other typical GPS receiver. In addition, standard RINEX
file is supported as well.
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4.3.1 Observation File
The Main contents of an observation file are original observation data recorded by the
GPS receivers in each epoch. It includes observation time, satellite tracking information,
C/A pseudo-range, P1 pseudo-range, P2 pseudo-range, L1 carrier phase and L2
carrier phase of each channel. In terms of static observation files of this software, there
is a minimum need to include observation time, C/A pseudo-range and L1 carrier phase
in an observation file, while observation time and C/A pseudo-range becomes the
minimum requirement for Kinematics observation.
Besides the information mentioned above, an observation file also contains station
information, original coordinates, and ephemeris information that is related to the
observation file.
Following chart shows the structure of an observation file.
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Obs. File
Station Infor
Original Coor.
Ephemeris data/file
Epoch1
Time/Channel Data
Epoch2
Time/Channel Data
… … … … … …
Recorded data in Obs.
… … … … … …
48. Observation File
4.3.2
Observation Data Format
4.3.2.1 HCN observation data of our GPS processing software
Huace-self-defined observation files contain various data format defined by different
version and by the main boards of receiver and corresponding collection of applications.
Below table shows some file versions
.
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Versions currently can be loaded by this software refer to Table 7-1
Format Version Data Description Notes
30.0 Dual-Fre. (C,P1,P2,L1,L2) Javad
40.0 Single-Fre. Static(C,L1)
40.1,40.2 Single-Fre. Dynamic All-Star, SuperStar
*.HCN
50.0 Single/Dual(C,P2,L1,L2) NovAtel RT2
54.0 Dual(P1,P2,L1,L2) NovAtel OEM4
1.0
*.??O
2.0
RINEX /
*.??N
2.10
*.DAT Trimble /
Data Format of Observation File and Version Information
In our software, data format will be determined according to the version of the
observation data during processing to form signal/dual-frequency static baseline and
Kinematics route.
4.3.2.2 RINEX Format
The Receiver Independent Exchange Format (RINEX), to which most China made
receivers can easily transfer their own data format, was initially studied by the
Astronomical Institute of the University of Berne, Switzerland to work with different
receiver types. It has been recommended to be used as a standard input format of
software designing for the international geodetic user community.
Our GPS data processing software supports every version of RINEX 1.0 and RINEX
2.0. Only GPS data will be processed in our software, the GLONASS data in RINEX 2.0
will not be processed.
4.3.2.3 Files in Trimble Data Format
Our software support *.DAT observation file of Trimble.
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Data
Ashtech
The software supports file B and file E of Ashtech, former is the observation file and
latter is the ephemeris file.
4.3.3 Data Preparation
Our software is able to process data in various formats. Following the pre-processing
steps should be made before inputting GPS data into processing software:
Step 1
: Input observation data into the computer from the GPS receivers. For data
X-series receivers, please use ‘
Tool>Transfer data
’ in the Menu bar. For data from other
receivers, use corresponding applications to input GPS data. For more Details about of
these applications, refer to Chapter 15.
Step 2
: Copy data into the folder where your project stored.
Step 3
: Input the data into the project. Refer to next section.
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4.3.4 Input Data
As shown in the following figure, select ‘
File’>’Import
’. A window appears listing all
available formats. Besides for the Huace-self-defined formats (*.HCN, for example) and
standard RINEX format, our software also support Trimble, Ashtech, Leica, Sercel, etc.
49. Menu
:
Input Data
50. Select RINEX for Inputting
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Now, we select
RINEX DATA
as an instance, a dialog-box will appear, as shown below,
as shown in the figure The figure below shows.
The File folder in the Dialog-box will point to the project folder. You can make
multi-selection on more than one file here.
51. Select File
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The default choice is ‘Auto’ of a Combo Box for selecting file types on the bottom of this
Dialog-box, in. The Other two choices are ‘Static Observation File’ and ‘Kinematics
Observation File’
52. File Types
When the default value ‘Auto’ is selected, an application will distinguish the way these
files are collected according to their formats. If they are statically collected, (they would
be put together in orders of colleting sessions to build static baseline) the collected
sessions will be put together in order to build a static baseline, otherwise, they will be
combined with static observation files to form Kinematics route.
Notice that the difference between static and kinematics files is only defined in our
self-defined data formats.
Only files stored in the same folder can be saved all at once. Those are in different
types/formats or stored in different folders must be saved separately.
It is true, in the case of data other than Huace-self-defined format that only the
observation files have been into system, because they possibly contain only the
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observation files. However, for Huace-self-defined data, which combines both
observation and ephemeris data in same file, inputting them is inputting of both
observation and ephemeris files together. Therefore, in the first case, you should store
two data (observation and ephemeris) in the same folder to ensure this software is able
to identify ephemeris data and load them into system automatically. On the other hand,
you can manually input ephemeris data in later stage of processing.
After inputting, the application will read the observation stations from the observation
files and automatically build static baseline and Kinematics route according to their
observation sessions. For more Details, see the following chapters.
4.3.5 Observation File Name
Observation files are distinguished by file names normally formed by an 8-character
name and an extended name. A Compass HCN observation file name, for example, is
‘ABCD1234.HCN’.
It is not allowed to have duplicate file names in the same project. For example, two files
ABCD1234.HCN and ABCD1234.01O files cannot exist in same project at same time.
Actually, an observation file name is formed by station name and observation session.
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The Following is an introduction of each format.
1) HCN P Observation File
In the case of Compass HCN file, an 8-Character file name contains:
•Point Name
‘!!!!’Stands for station name. It could be formed by characters, numbers or Chinese
characters. When observation files has been inputted, the station name will be
distinguished automatically. A station name with less than 4 characters will be extended
by adding ‘_’on the head of it, for
•Session
‘$$$#’ stands for three numbers and a number/ letter to identify sessions.
‘$$$’ represents Julian date, which means the number is the day that the observation is
made, starting from January 1. For more Details about Julian date, refer to Appendix
B. ‘#’stands for observation time sequence of an observation day, shown as one, 2,
3…A, B, C…Z.
All Compass HCN kinematics observation file names are formed in this way, but their
station names do not make any sense in practice.
2) RINEX Observation File
File name of RINEX data is shown in below table
Observation File !!!!$$$#.yyO
Ephemeris File !!!!$$$#.yyN
The name of RINEX file is similar to HCN file. The difference rest is with ‘yy’, which
stands for the observation year. RINEX data have observation station name saved in
Marker Name. An empty Marker Name will lead to reading the observation files with
mentioned HCN method to generate station information and so on.
3) Other Observation Files
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Please refer to relevant materials.
4.3.6 Properties of Observation File
As shown in the figure the figure below:
- Right click on the observation window
- Select Properties,
Properties of Observation File
dialog-box will appear:
Click to
Modify Ephmeris
53. Properties of Observation File
There are five panels on this dialog-box:
general, single positioning and average
coordinate, observation data chart, tracking satellite chart
and
satellite single.
In the
General
tab, there is a list of file name, observation date, file format, ephemeris
file name, file information, station name, and height of antenna and initial value of
observation file, shown as geodetic system. Ephemeris file name, station name, height
of antenna and initial value of observation file can be edited.
1) Modify station name and height of antenna
2) Modify Ephemeris File
To modify ephemeris file name, click the button marked in the figure above. A
dialog-box will appear, as shown below. Refers to the figure the figure below:
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54. Select Ephemeris File
Please choose a properly formatted file marked the same as the session with
observation file among various formats of ephemeris file in the dialog-box above.
Reentering ephemeris file would be required in one of following cases:
•When ephemeris files with higher precision are wanted. For example, when SP3
precise ephemeris format is wanted.
•A lack of relevant ephemeris file.
• Poor quality of the ephemeris file. For example, an ephemeris file does not contain all
ephemeris of the observation satellites.
3) Modify initial Geodetic System
A qualified initial coordinate value is a must in GPS baseline computation.
Initial
values are obtained by collecting software while processing the single positioning, or by
processing the single positioning in certain software during the data loading. Single
positioning, for normal baseline measurement, can meet precision requirement, for
ordinary baseline vectors. However, modification of mentioned initial value is required
in the following cases.
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•A lack of single positioning result.
A typical cause of lack in the single positioning
result is that the software cannot carry out the positioning due to the absence of the
positioning-coordinate records and the existence of problematic ephemeris file. Under
this situation, you can select ephemeris file again and enter the average value of the
single-positioning coordinates, which can be found on the panel
single positioning/
average coordinates value.
•Initial Coordinate Doesn’t Meet certain Requirement
When a precise WGS-84 system is wanted, the single positioning, of which the
precision is only 15-30 meters cannot achieve, the coordinates with the better
precision can be obtained by the following methods:
-Repeating the single positioning to get an average value using a receiver,
OR,
-Reading a coordinate value from Known-point in the WGS-84 system
4) Check the single positioning and average coordinate
Select
single positioning and average coordinate
panel. The Following panel below will
appear:
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55. Single Positioning Coordinate
This panel displays the average coordinate value of the single positioning results,
condition of the discrete control points and receiver clock offset. The maximum
difference between the single positioning coordinate and the value output by receiver is
marked on the top-left of the
condition of discrete control points
figure, and the
maximum difference between the clock offset and output value, at the top-left of the
receiver clock offset
figure.
Click
Set Average Value as Initial Value
button
,
the Average coordinate value will be
filled into the
General
panel.
If an error message appears, please to check ephemeris data on
tracking satellites
chart
panel.
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5) Check
observation data chart
Tracking data of each of the satellites is on the
observation data chart
panel. As the
following figure shows, dual-frequency data tracking conditions are shown. The break
line on the panel stands for loss lock of the satellite or other conditions.
56. observation data chart
A primary estimation can be made on data quality from this chart.
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6) Check tracking satellite chart
Distribution condition of the satellites is shown on the
tracking satellite chart
panel.
Refers to the following figure:
57. Tracking Satellite Chart
Tracking satellite chart describes the movement of the satellites from the beginning of
the observation to the end of it. The number-end stands for the position of the satellites
at the beginning of the observation.
Tracking the satellite chart is drawn according to the ephemeris data related to the
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observation file. You can check both distribution condition of the satellites and
ephemeris of the observation file on this panel.
4.3.7 Delete Observation Data
To delete a file, you can
•Select ‘Edit>Delete’ on Menu Bar.
OR
•Right-click, select ‘Delete’ from Pop-up menu
To reverse deleting actions please select ‘undo’.
Related data of the baseline, Kinematics route and observation station will be deleted
when a file is deleted.
If you quit the project or load a new data after deleting, deleted objects would not be
reversed.
4.3.8 Transfer observation data to RINEX 2.0 tables
Huace-self-defined files can be transformed to RINEX format.
To do this, please
• Select wanted file in the
Tree Window
on the left
• Right-Click on window on the right,
• Select ‘Transfer to RINEX’ from the Pop-up Menu.
A file will be generated and saved in folder ‘RINEX’ under the corresponding folder.
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58. Convert to RINEX
When a project is built and the observation data is loaded, the software will generate
the observation files. The Static baseline and Kinematics route will be generated
automatically according to the contents of the observation file.
4.4
Observation Station
Click ‘Observation Station’ on the
Tree Window
on the left
,
station lists will appear on
the right. As shown below:
59. Information of Observation Station
Listed item includes: station name, non-computed point/fixed point, initial point (single
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positioning coordinates), free network adjustment, 3-dimensional adjustment,
2-dimensional constrained adjustment, and height-fitting results.
4.4.1 Generate Observation Points
As mentioned in Section 7.3.5, the observation station name is generated by the
observation file. Additionally, only the information recorded by the static observation file
is useful.
As the figure below shows, there are 15 observation files in the example of RINEX and
seven observation station names, Q007
Q009
Q036
Q041
Q048
Q049
Q050,
can be derived from those names.
60. Observation Data
As mentioned before, the software distinguishes different stations by their names.
Therefore, duplication of the station names are not allowed in a project.
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4.4.2 Properties of Observation Station
To view the properties of a station, right-click on the
Properties of Observation Station
Window
to open a Pop-up Menu. As shown below:
61. Original Value
4.4.2.1 Initial Value of the Observation Station
You can modify the initial value of the observation station on this panel, which puts
certain impact on the network adjustment, by changing the station’s properties.
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4.4.2.2 Known Point of Observation Station
You can enter the coordinates of a known point on this panel. As shown below:
62. Known Point
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You can choose one of following five methods for
fixed coordinates of
known point (xy,
xyH, H, BLH, and BL)
:
Fixed Method
Fix Contents xy xyH H BLH BL
North (x)
East (y)
(
)
Latitude
B
(
)
Longitude
L
(Geodetic Height or
Leveled Height) H
Note:
‘constrained’
must be selected when doing both the static network adjustment
and Kinematics route outputting to make the fixed coordinates valid. Otherwise, the
fixed coordinates would be invalid and what the software can do is nothing but to store
the fixed value in the project files.
4.4.3 Delete Observation Station
You can delete an observation station on the
Observation Station Window
using a
Pop-up Menu. Related data of the baseline, Kinematics route and observation station
will be deleted when a station is deleted.
To reverse deleting process you can
•Select ‘Edit’>‘Undo’ from Menu Bar
The Corresponding deleted baseline, Kinematics route and observation station can all
restored.
If you quit the project or load new data after deleting, deleted objects would not be
restored.
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4.5 Static Baseline
Click ‘Baseline Vecter’ on the
Tree Window
on the left, a list of baseline vectors will
appear on the right. As shown below:
63. Baseline Vectors Window
The Following items are available on the list: name of baseline, observation data used
in computation, value type of result and residual and adjusted value resulted from free
network adjustment.
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4.5.1 Baseline Components
Any two static observation files, which own a matched session, can form a static
baseline. As shown below:
64. Generate a Baseline
According to their sessions, three static observation files (1,2,3) form two baselines (A,
B).
In our software, a static baseline name is formed by the starting station’s name and the
computing station’s name and the name of computing station session.
Initial station name computing station name the name of computing station session.
For example, Q0072053 and Q0362051 form a baseline called Q007 Q036 2051
It is allowed to have duplicated static baseline names in a project.
4.5.2 Pop-up Menu of the Static Baseline
The figure below shows the Pop-up Menu of the Static Baseline
65. Pop-up Menu
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Pop-up Menu offers the following functions: process baseline alone, processing
settings, browse details, delete, start/end reverse, and baseline properties.
4.5.3 Baseline Properties
Static Baseline
dialog-box as Shown in the figure below
66. Baseline Properties Panel
Baseline Properties
The Following properties are listed on
the
panel: start point file,
end file, start point name, end name, session and options of baseline computation
methods.
If you do not want to delete an unqualified baseline computation result, just leave the
‘baseline processing and network adjustment’ unselected.
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You can determine which computation method would be used in the adjustment with
the Combo-Box ‘Computation Method’.
The Panel for the
Computation Method
lists all kinds of computation methods of the
baseline processing. The figure below shows the result of the fixed computation.
67. Result of Fixed Computation
You can analyze the condition of the observation data and their quality in the panel of
the ‘
Obs.Data Chart
’. Moreover, you can reprocess a baseline by editing its sessions
on this chart.
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68.
Baseline Residual Error
chart is another useful tool of for the reprocessing of the
unqualified baselines. As shown in the below, it the deletion of the satellites data in
certain sessions in which the residual error value is larger than +/-0.1m should be
considered.
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69. Baseline Residual Error chart
For Details of how to reprocess a baseline, see Chapter Baseline Process.
4.5.4 Delete Static Baseline
To delete a file, you can
•Select ‘Edit>Delete’ on Menu Bar.
OR
•Right-click, select ‘Delete’ from the Pop-up menu
To reverse the deleting process please select ‘undo’. Beware, you can repeat undo with
limited times!
Deleting static baseline has no impact on any other objects.
If you quit the project or load, new data after deleting, deleted objects would not be
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restored.
4.5.5 Check Detailed Static Baseline Computation
the
When Baseline Computation is finished, you can check the details of
computation.
As the below shows:
70. Computation Result Details
Files of detailed computation are .txt files, their file names are formed by starting the
file’s name and computing file name and an extended name is ISB. Baseline
Q007 Q036 2051, for example, the file is named as Q0072053.Q0362051.isb. The
Data formats of the detailed computation refer to the relevant sections in Chapter 13.
the
Click ‘Baseline Vectors’ in
Tree Window
to access a list of baseline vectors on the
right. As shown below:
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Baseline Name
Obs. Data
Click an
Item
71. Detailed Computation ( Baseline Vectors) Window
The Following items are available on this list: name of baseline, observation data used
in computation, value type of result and residual and adjusted value resulted from free
network adjustment.
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