\fBfront\-end\-cal\fR is a calibration tool for some DVB\-T receivers based on the Taiwan's Realtek RTL2832U chipset, sold in form of USB dongles that allow users to watch over\-the\-air DVB\-T European broadcast television on their personal computers, to be used as GNSS front\-ends.
Normally, those devices send partially\-decoded MPEG transport frames over the USB, but exploiting an undocumented mode of operation of the demodulator chip, the user is able to obtain raw I&Q samples, stream them through USB to a personal computer and then use \fBgnss\-sdr\fR, turning the DVB\-T receiver into a GNSS receiver and delivering position in real\-time.
The crystal oscillator that ships with the RTL2832U family devices exhibits limited accuracy to be used as a GNSS receiver front\-end without previous calibration. \fBfront\-end\-cal\fR implements the algorithm proposed in [1], and it requires Internet access since it retrieves Assisted GPS data from SUPL servers.
\fBfront\-end\-cal\fR is able to work with raw data files or, if there is computational power enough, in real time with suitable radio frequency front\-ends. The whole receiver is defined in a single configuration file, and therefore users can define theirs.
\fB\-signal_source=\fR\fI<path\-to\-raw\-signal\-file>\fR If defined, path to the file containing the signal samples (overrides the data file specified in the configuration file).
Example of configuration file available at: ${prefix}/share/gnss\-sdr/conf/front\-end\-cal.conf, where ${prefix}$ uses to be /usr or /usr/local. This will be the configuration file used by default if the \fB\-config_file\fR option is not set.
[1] C. Fernandez\-Prades, J. Arribas, P. Closas, \fITurning a Television into a GNSS Receiver\fR, in Proceedings of ION GNSS+, 15\-16 September 2013, Nashville, Tennessee (USA). A draft copy is freely available at https://www.researchgate.net/publication/257137427_Turning_a_Television_into_a_GNSS_Receiver
This software has been developed at CTTC (Centre Tecnologic de Telecomunicacions de Catalunya, https://www.cttc.cat) with contributions from around the world.