\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.
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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.
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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 automatizes the algorithm proposed in [1], and it requires Internet access since it retrieves Assisted GPS data from SUPL servers.
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\fBfront-end-cal\fR is able to work with raw data files or, if there is computational power enough, in real time with suitable radiofrequency front-ends. The whole receiver is defined in a single configuration file, and therefore users can define theirs.
.SH OPTIONS
\fBfront-end-cal\fR takes the following options:
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\fB-config_file=\fR\fI<path-to-configuration-file>\fR Set the configuration file.
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\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).
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\fB-log_dir=\fR\fI<path-to-directory>\fR If defined, overrides the default directory where logs are saved.
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\fB-version\fR Print program version and exit.
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\fB-help\fR Print all the available commandline flags and exit.
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 http://www.cttc.es/publication/turning-a-television-into-a-gnss-receiver/
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Check http://gnss-sdr.org for more information.
.SH BUGS
No known bugs.
.SH AUTHOR
Javier Arribas (javier.arribas@cttc.es)
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This software has been developed at CTTC (Centre Tecnologic de Telecomunicacions de Catalunya, http://www.cttc.es) with contributions from around the world.
