manual.txt

这是国外关于卫星导航方面一书的源代码

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                                USER MANUAL

      last changes (NT update) and translation german to english: 
                          2001-05-01 ... 2002-01-01

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                                  GPS Lab
                                  -------
                   a MatLab5 based toolkit for basics in
                   absolute and relative GPS positioning
                   for educational and testing purposes.

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                           version 12-99/e05-01

             first english version - by iapg/tum 2001 zebhauser      
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contents
========

1. the software package
1.1 (for) what GPSLab is
1.2 objectives of this program development
1.3 the concept; the structure of the program package; adding modules
1.4 system requirements
1.5 hints / tips / recommended
1.6 restrictions
1.7 starting the program
1.8 breaks, exits, program terminations

2. the processing of GPS data - in 10 steps

3. description of the modules / menu items

3.1  File: start RINEX import
3.2  File: view log files 
3.3  File: edit / view header 
3.4  File: time span definition
3.5  File: print graphics
3.6  File: save graphics
3.7  File: save Workspace
3.8  File: Editor
3.9  View: zoom , rotate, reset window
3.10 Visualizing Orbits (Broadcast Ephemeris)
3.11 SPP including DGPS by coordinate differences
3.12 DGPS by double difference pseudoranges
3.13 CDGPS by Ambiguity Mapping Function
3.14 Tools: recent results --> Header
3.15 Tools: coordinate conversion
3.16 Tools: time conversion
3.17 Infos
3.17.1 Infos: Web-Links
3.17.2 Infos: Variables after call of ...  Orbits / SPP / DGPS / CDGPS(amf)
3.18 Exit with / without deleting workspace

4. trial data sets

5. description of all files

5.1 all files in directory
5.2 a short description of all M files
5.3 MAT files
5.4 documentation of results
5.5 data for reference station converted from Rinex
5.6 data for rover station converted from Rinex
5.7 documentation of the data files
5.8 description of all variables after processing of a specified module
5.9 time series files

6. remarks

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1. the software package
=======================

1.1 (for) what GPSLab is
------------------------
GPSLab is a MatLab5 toolkit for visualization and processing
of GPS data. You can read data and ephemeris in RINEX format,
and you can process code as well as carrier phase observations.
The objective is the presentation and full access of data, algorithms
and models, which can be changed or extended in MatLab. 

The program was developed at the Institute for Astronomical and Physical
Geodesy of the Technical University of Munich (iapg). 
(Download: http://www.iapg.bv.tum.de/ftp/contrib/gpslab/gpslab.html )

It is freeware. Please use it in courses and labs.

I ask you for information exchange and help for extending the software.

It is not allowed to distribute only parts of the software package or
changed versions. Extensions and changed files have to be bundled 
seperately and have to be signed as such. 
I want to avoid questions asked to me relating programs I am not the
author of.

It is forbidden to use it for commercial purposes.

There will NOT be given any guarantee for wellfunctioning, correctness
of results, and so on. The author is not responsible for possible
consequences resulting from the use of this program package.
You do use this program on your own responsibility.


1.2 objectives of this program development:
-------------------------------------------
The objective is the visualization of data, effects, parameters and results
as well as the uncovering of the variables, which can be directly accessed 
always. In addition the source code can be modified, improved, changed,
extended or reduced. You can integrate new modules because of the easily 
detectable interfaces and you can expand the menu structure as you want.

The program system is thought for courses and labs relating GPS basics,
for introductory purposes regarding diploma theses and so on ...
If the program modules fulfil your accuracy requirements you can use them
for research purposes. But remember: I do NOT guarantee the correctness
of any module of this program package (see above).

I hope the programs will be used in geodesy, geography, aerospace and land
navigation, telematics, and so on ...


1.3 the concept; the structure of the program package; adding modules
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GPS data processing can be realized in different ways. One distinguishes
between baseline concept and multistation concept, between zero, single and 
double difference concept, ...
This package focuses:
- the processing of one baseline (Reference and Rover)
- the usage of the Broadcast Ephemeris
- the processing of  staticly observed data (partially suitable for 
  kinematic data)
- short baselines, especially regarding carrier phase processing

It will provide you:
- visualization of the results in plots you can save
- text files including important parameters of a solution 
- access to the source code (MatLab M files)
- access to the documented variables after starting data processing 
- format description, simple interfaces
- modularity, that also means the possibility of extensions
- controlling the toolkit via one master window with a menu you can modify
- literature references

Because this is a program package for educational purposes, the algorithms
were strongly simplified for enabling a closer look to the source code.
The complex data stream with its ifs and cases takes the dominant part in 
the source code. This is a problem regarding the ability to understand
what is going on. But GPS data show a broad diversity, although only some
aspects were taken into account: diverse data types as ephemeris,
receiver information, pseudorange and phasen observables in respect to one 
or two frequencies, delays or outages of the second frequency, usual gaps, 
cycle slips, changing number of satellites and the related bookkeeping,
different data quality dependent on time and hardware, free choice of 
registration rate, baseline lengths of some meters as well as of some 
thousands of kilometers, and so on ...

You should have basic knowledge in MatLab5. If you want to modify or
manipulate the program you should be an advanced MatLab5 user.
An installation of MatLab5 is required; start it and type into the
command window: "gpslab". The menu allows you to execute all the modules.
Exceptions: there are erroneous data formats or other problems.
If some eventualities are not handled in the right way you should be able
to recognize that and to solve the problem, supposing you are a GPS, PC 
and MatLab specialist.

Often vectorizing of a problem was renounced although it slows the program 
and makes it less compact. But so the source code remains more legible and
it is easier to modify or to extend it.

Data, Files:
There exists always a data set for observations of a reference station
as well as of a rover station. These data are resident in the directory
as long as new data are converted from RINEX files.That means that also
after exiting and restarting MatLab or rather the PC no new RINEX import 
is necessary as long as no new baseline shall be processed.
The structure of the data (converted from RINEX) is documented; the 
conversion programs rinex2_n.exe and rinex2_o.exe (16 bit programs, 
compiled with Borland C++ 3.1, also applicable outside of the software
package) produce this data files. Basing on these formats one can 
develop a totally different software.
The Menu Info leads to the format descriptions of the header, 
ephemeris, epoch and observation files including examples.
The program always presumes the existence of a total set of files (see 4.)
including data files. Never delete them (exept for emergency), because 
in that case the program is malfunctioning or crashes.
The data files will be overwritten when new data sets are loaded; 
therefore only one converted data set exists and there is no unnecessary
accumulation of data files. By reducing the time span (see file menu)
the data file are overwritten but before that a security copy is created.
Starting the modules (orbits,SPP,DGPS,CDGPS) whole the MatLab workspace
is deleted and the necessary data files are reloaded. So after a run of
a module, only the variables produced by this module are remaining in the
workspace. Also the solution files, created by the modules (SPP,DGPS,CDGPS),
must always be present in the directory and will be overwritten when a new 
run will be started. If you read these files do look at the creation date
and time in the header of these files (also see below, description of the
modules).

Flag for successful computation and for existence of produced variables:
Before a run of a processing module all variables are deleted, after
every run the variables produced by this module are available and a flag
named ..._is_calc reports to following started modules (for showing the
solution files or for plot generation) the availability of the variables
(generated by: SPPLAB,DGPSLAB,AMFLAB,AMFLANE).

Handling:
Whole the process can be controlled by the 3 windows: MatLab command window, 
GPSLab window, and MatLab editor. 
The first one is used for the call of GPSLab and for self-controlled 
operations, data manipulations, small calculations besides or additional
visualizations.
The second one is an interface and the plot window. You can directly call it
as figure(99).
The third shows you the solution files, text files like the header files,
log files, format descriptions or this manual.
Only when unavoidable dialog boxes are generated e.g. for setting parameters
or for showing error announcements and so on.
For program extensions please consider the concept, that everything is 
performed in the GPSLab window (figure(99), reset to subplot(1,1,1) 
eventually) and no additional windows are generated, because the overall 
view and the handling performance would worsen.

Menu structure:
The menu structure is defined in the M-File GPSLAB.M and can be modified
(simplified, rearranged, expanded) optionally. But in this context please
obey the following 2 items:

1.
The first part defines the menu strings ("labels") and their responding 
menu levels (also see "Infos: menu overview"), the second part defines the 
so called callbacks ("calls") that initiate sets of commands (M-file calls).
The number of labels logically must correspond with the number of calls.
2.
For modifying the menu please DO NOT USE the MatLab5 GUI design tool named
"guide" (GUI development environment). GUIDE generates an additional binary
MAT-File containing parts of the menu structure information that is totally
in ASCII here. So please edit the file GPSLAB.M by hand in the editor.
After saving you can control it immediately, without restarting GPSLab, by 
calling "reset window" in the "View" menu. This call does not delete the
workspace, so that all variables are preserved.

Program steps (SPP, DGPS, CDGPS/amf):
The data processing needs 4 steps:
1. Setting of parameters and flags (in dialog boxes or in GPSLAB.M).
2. Call of the processing module (script file, normally ends with ????lab.m)
3. Generation of solution files (*.txt) by running a script file, that
   normally is named erg????.m
4. Generation of a plot out of several possible by calling the corresponding
   plot module (script file, ending with ????plot.m).

Basically I recommend for modification or extensions to start from the 
existing program modules or to check its structure at least.

Suggestions for program extensions:
 -  Visualization of raw data: zero, single, double and triple differences, 
    linear combinations; for pseudoranges as well as for carrier phases
 -  Visualization of the visability of GPS satellites from almanacs in 
    YUMA format
 -  Processing of carrier phase triple differences by sequential least 
    squares estimation and cycle slip control
 -  classical double difference concept with integer ambiguity search 
    methods; regarding L1,L2,Lw,Ln,Lc; for that we need:
 -  cycle slip search and correction algorithms
 -  Kalman filter for processing kinematic observations 
 -  carrier phase smoothed code phase solution (smoothed DGPS)
 -  additional troposphere models, introducing of meteo observations
 -  Indroduction of precise ephemeris (needs software concept modifications 
    overall)
and so on ...


1.4 system requirements:
------------------------
- Win95/98 (with the possibility to execute DOS/16bit programs)
- MatLab 5.1 or higher version of 5.x, full (not sudent) version recommended
  (tested in a V5.1/Win95 und V5.3/Win98 environment)
- screen resolution at least 1024*786 Pixel for displaying the whole GPSLab
  window including its menus.


1.5 hints / tips / recommended: 
-------------------------------
- while running the program do set your virus scan software to DISABLE or
  exit it, because commands on the operating system level like the call of
  Notepad or of the RINEX converters permanently searches the floppy disc 
  drive and so slows down the program execution unnecessarily (known bug
  in MatLab 5.1 / ??).

- In the program directory there always has to exist a decoded data set,
  at least the delivered trial data set (S1xxxx, S2xxxx).