SoftGPS project

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GNSS front-ends and software

A supplementary USB GNSS radio front-end (designed by Dennis Akos) is available. It does not come with the book, but instead can be bought on an online electronics store. Please visit this homepage for more details and the original USB driver:

There are also front-ends from other manufactures, which will work with our SDR, but in some cases the code must by modified.
For example few versions of such frontends are manufactured by Nottingham Scientific Limited. These front-ends are based on a very flexible GNSS front-end chip from Maxim. In addition a hardware data packing is employed which reduces the USB data rate from 16MB/s to 4MB/s.

A much bigger, but also a much more versatile SDR front-end is the USRP universal front-end which is used by the GNU radio project.

Other examples are wideband front-ends for professional applications from Fraunhofer IIS that can be connected through USB or other interfaces.

DGC alternative driver for MS Windows (for the front-end from Dennis Akos)

The Danish GPS Center has developed an alternative driver for this front-end (Windows XP only).
Update! Application code was updated on 04/02/2011 to fix a bug (interal data corruption). Download.

The Danish GPS Center recorder application or driver do not have any record length limitations inbuilt. The longer the signal records are the higher is chance that the PC might not be able to keep up writing data to the hard disk. The recorder application might report this kind of error: "ERROR! Buffer overrun in the GNSS Front-end! Recording stopped.". It means that the PC could not keep up with the incoming data from the front-end. Usually the processor speed is not the crucial factor here. The most important is the speed of the hard disk. Disk speed depends on several factors, but the most important are its file fragmentation, disk technology, speed (notebook disks are usually slow, but not all). Also note that the disk speed is reduced when the disk is nearly full. In addition Windows services can interfere with the recording process by performing their own reading/writing operations which will further reduce the disk writing speed.

How to import USB recorder code into Microsoft Visual Studio

Here are instructions how to import the recording application source code into Microsoft Visual Studio 2005.

1) In Visual Studio select menu item: "File"->"New"->"Project From Existing Code..."
2) In the wizard window set project type to "Visual C++" and click "Next"
3.a) Field "Project file location:" must contain full path to the source code of the application (e.g. the code that is contained in folder "app source code")
3.b) Enter some name for the project
3.c) Click "Next"
4.a) Make sure "Use Visual studio" option is selected
4.b) Change "Project Type:" to "Console application project"
4.c) Make sure that none of the other options are selected
4.d) Click "Finish" (the rest of the options in the wizard do not have to be changed)

After this you should be able to build (compile) the VC project.

Project is developed by the Danish GPS Center