The GPS Toolkit (GPSTk) is an open source software project sponsored by the Space and Geophysics Laboratory of Applied Research Laboratories, The University of Texas at Austin. The GPSTk provides processing and analysis tools for GPS data. Clock Tools, a recent addition to the GPSTk, allows for basic clock stability analyses. These Clock Tools are interoperable with other GPSTk programs, allowing clock analyses to be easily run alongside other GPS analyses.

Clock Tools

To Do

• Make outlier removal interval variable
• Label GUI axes
• Incorporate drift into the autocorrelation code
• Properly handle removed data with NaN^? (rmoutlier)

Features to Add

• Proper confidence interval calculation
• Direct rinex processing (in GUI)
• Sharp color contrast (in GUI)

Known Bugs

• The scale/zoom features in allanplot fail when saving the plot

Special Notes

Code Dependencies

• allanplot: matplotlib
• ddevplot.m: octave v. 2.1.57 (does not work on v. 3.0.0)
• Clock GUI: QT 3.3 libraries, OpenGL^?

Outlier Removal

Currently the population standard deviation is used in outlier removal. It may be worthwhile to experiment with using the sample standard deviation to see if results match better with other outlier removal software. (http://en.wikipedia.org/wiki/Standard_deviation)

Clock Tools GUI

Compile

To compile the GUI enter the clockgui directory and type make. An executable named clockgui will be put into the bin directory within the clockgui directory. In order for clockgui to work properly the rest of the clock tools need to have been installed on the machine.

Running

The clockgui executable will be put in the clocktools/bin directory after compilation.

Data

Data must be located in the bin directory along with clockgui to be properly processed. The data file must have a .dat extension.

Development

The Clock GUI was developed using kdevelop version 3.1.1 and QT 3.3. The important files to are

• mainimpl.cpp - brain of the program
• glbox.xpp - graphing routines
• mainbase.ui - The graphics interface file, found under the qmake tab
  • The buttons in this file are linked to the routines in mainimpl.cpp

autoc bias1 & lag1ac

These pieces of code are still untested and need further developement

numGaps

The numGaps variable (which is currently not used) is still present in the deviation calculation code. This variable was used when zeros were placed in data by rmoutlier, and can be adapted for use if zeros are replaced with NaN^? in data w/ outliers removed.

NaN^?

It has been suggested by P. Tavella that outliers should be replaced with NaN^?, and then NaN^? terms dropped from deviation calculations during routines such as dallandev, oallandev, etc.

-- Contributors: TimothyCraddock - 08 Jan 2009

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