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MATLAB software for GPS cycle-
slip processing
User manual
Zhen Dai
Contact: zhen.dai@dlr.de
Last modified: 23.Oct.2011
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1 Installation.......................................................................................................................... 3
2 Run the programs ............................................................................................................... 3
3 Step 1.................................................................................................................................. 4
3.1 Selection of satellites.................................................................................................. 6
3.2 Add synthetic cycle-slips ...........................................................................................7
4 Step 2.................................................................................................................................. 8
5 Step 3.................................................................................................................................. 8
5.1 Procedure for viewing the results............................................................................... 9
5.2 Results from phase differencing............................................................................... 12
5.3 Results using Doppler data....................................................................................... 13
5.4 Results using phase/code combination..................................................................... 14
5.5 Results using phase combination with ionosphere ignored .....................................15
5.6 Results using phase combination with ionosphere check ........................................ 16
6 A short introduction to the embedded functions.............................................................. 18
7 Contacts............................................................................................................................ 18
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1 Installation
Make sure you have MATLAB environment running.
The installation of the programs can be simply done by unzipping all files into a folder.
2 Run the programs
First of all, please load the m-file “GUIMain.m” into MATLAB and run it.
There are three steps for cycle-slip processing:
Step 1:
“GUIMain.m” Choose the input RINEX file and set related parameters
Step 2:
“mainpro.m”According to the specified parameters, selected cycle-slip detection
approaches will be performed
Step 3:
“DispResult.m”The results generated by “mainpro.m” will be depicted in a GUI.
These three m-files can be loaded and run in MATLAB individually. However, the foregoing
functions must have been invoked.
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3 Step 1
An announcement will show up at first. You have to agree with it in order to go further.
The following interface will be shown
Some general information:
It can be seen that some default values are already presented. If you would like to use
them, please keep them as they are. To user other values you could clear the
corresponding text box first and type in the expected number. Please note the unit.
You may ignore all setting and simply click the “start” button at the right-upper
corner. In this case, the program will process the embedded RINEX file with the default
settings.
The interface is divided into several areas with each performing a specific task
Area Options
Functions
RINEX input
Choose a RINEX observation file.
Buttons
(upper right
corner)
Show readme file
User could manually add cycle-slips to raw data in order to
test the algorithms. See section 3.2 for details.
Start cycle-slip processing with parameters set in the GUI.
Please make sure all parameters are set as expected before
clicking it.
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General
Settings
Sampling interval in
[seconds]
Sampling interval of the RINEX observation file. This
allows you to process the data sampled at a lower rate. For
example, you have a 20-Hertz GPS raw data (namely 0.05 s
sampling interval)and want to reduce the sampling interval
to 0.1 s, then you could simple type in 0.1 in this text box.
Number of epochs to
be processed
You may not want to process all the data contained in the
file. This option allows you to process a specific number of
epochs from the beginning of a RINEX file according to the
specified sampling intervals. If you specify a sampling
interval of 1 s and you want to process 100 epochs, then the
program will try to collect the first 100 data sampled on
“integer” seconds.
Raw data
selection
The program allows the processing of GPS L1 and L2
signals. Checking a box means that the associated signal is
to be processed.
Satellite
selection
See section 3.1
Method
…
…
Methods used to process cycle-slips.
Each method needs related measurements. A method will be
invoked only if the corresponding measurements are found
in the raw data. Otherwise, this method is not taken into
account even if you do select it.
Standard deviation of
carrier phase noise in
[cycles]
The standard deviation of carrier phase noise. This value
affects the sensitivity of detection approaches using phase
differencing and phase combination. It is assumed that the
carrier phase on both carrier signals contain the same level
of noise.
Standard deviation of
pseudorange in [mm]
The standard deviation of pseudorange noise. This value
affects the sensitivity of detection approaches using
phase/code combination. It is assumed that the
pseudoranges on both carrier signals contain the same level
of noise.
(method-oriented)
Number of epochs for
differencing
This is related to the cycle-slip detection by high-order
differencing of carrier phase data. In this approach, previous
epochs need to be collected into a queue in order to obtain
the statistics of the differenced phase measurements.
This option specifies the length of the queue. A larger
number yields a better estimation of the mean value.
However, only when the queue is full, can the cycle-slip
detection be carried out.
