.\" Manpage for front\-end\-cal.
.\" SPDX-License-Identifier: GPL-3.0-or-later
.\" SPDX-FileCopyrightText: Javier Arribas <javier.arribas(at)cttc.es>
.\" Contact javier.arribas@cttc.es to correct errors or typos.
.TH front\-end\-cal 1 "15 Dec 2014" "0.0.1" "front\-end\-cal man page"
.SH NAME
\fBfront\-end\-cal\fR \- RF front\-end center frequency and sampling rate calibration tool.
.SH SYNOPSIS
\fBfront\-end\-cal \-config_file=\fR\fI<path\-to\-configuration\-file>\fR [OPTION]...
.SH DESCRIPTION
\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.
\.TP
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.
\.TP
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.
\.TP
\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.
.SH OPTIONS
\fBfront\-end\-cal\fR takes the following options:
.TP
\fB\-config_file=\fR\fI<path\-to\-configuration\-file>\fR Set the configuration file.
.TP
\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).
.TP
\fB\-log_dir=\fR\fI<path\-to\-directory>\fR If defined, overrides the default directory where logs are saved.
.TP
\fB\-version\fR Print program version and exit.
.TP
\fB\-help\fR Print all the available commandline flags and exit.
.SH SEE ALSO
.BR gnss\-sdr (1), volk_gnsssdr_profile (1)
\.TP
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.
\.TP
[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
\.TP
Check https://gnss\-sdr.org for more information.
.SH BUGS
No known bugs.
.SH AUTHOR
Javier Arribas (javier.arribas@cttc.es)
\.TP
This software has been developed at CTTC (Centre Tecnologic de Telecomunicacions de Catalunya, https://www.cttc.cat) with contributions from around the world.
