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\section{Usage Scenarios}
\subsection{Experimentation}
\subsubsection{Creation of Non-Realtime Multiplex}
The creation of a ETI file containing two programmes, one DAB and one
\dabplus{} is covered in section \ref{sec-files}.
\subsubsection{Modulation of ETI for Offline Processing}
The ETI file generated before can then be used with ODR-DabMod to generate a
file containing I/Q samples. Here, we must chose between using the command line
or the configuration file. For a very simple example, using the command line
makes sense, but for more advanced features it is preferable to use a
configuration file. For illustration, we will present both.
To modulate the file \texttt{myfirst.eti} into \texttt{myfirst.iq}, with the
default options, the command is simply
\begin{lstlisting}
odr-dabmod myfirst.eti -f myfirst.iq
\end{lstlisting}
This will create a file containing 16-bit interleaved I/Q at $2048000$ samples
per second. The transmission mode is defined by the ETI file.
The equivalent configuration file would be
\begin{lstlisting}
[input]
transport=file
source=myfirst.eti
[output]
output=file
[fileoutput]
filename=myfirst.iq
\end{lstlisting}
This is a very minimal file that defines only the necessary settings equivalent
to the above command line options. The configuration file however supports more
options that the command line, and becomes easier to manager once the set
becomes more complex. It is best to use the example configuration availble in
the \texttt{doc/} folder.
\subsection{Interfacing Hardware Devices}
\subsubsection{Ettus USRP}
ODR-DabMod integrates support for the UHD library that can interface with all
USRP devices from Ettus. The following configuration file illustrates how to
send the \texttt{myfirst.eti} over a USRP B200 on channel 13C:
\begin{lstlisting}
[remotecontrol]
telnet=1
telnetport=2121
[input]
transport=file
source=myfirst.eti
loop=1
[modulator]
gainmode=2
digital_gain=0.8
[firfilter]
enabled=1
filtertapsfile=simple_taps.txt
[output]
output=uhd
[uhdoutput]
master_clock_rate=32768000
type=b200
txgain=40
channel=13C
\end{lstlisting}
This example also shows more options that the example for the file output:
\begin{itemize}
\item \texttt{remotecontrol telnet=1} enables the Telnet server that can be
used to set parameters while the modulator is running.
\item \texttt{loop=1} rewinds the input file when the end is reached. The
same ETI file will be transmitted over and over.
\item \texttt{gainmode=2} sets the GainMode to VAR, which reduces
overshoots in the output.
\item \texttt{digital\_gain=0.8} reduces the output sample deviation, to
reduce compression in the USRP.
\item \texttt{firfilter enabled=1} enables an additional FIR filter to
improve the spectrum mask.
\item \texttt{master\_clock\_rate=32768000} sets the USRP internal clock to
a multiple of $2048000$, which is required if we want to use the native
DAB sample rate.
\item \texttt{txgain=40} Sets the analog transmit gain of the USRP to 40dB,
which is specific to the B200.
\end{itemize}
Some of these options are not necessary for the system to work, but they
improve the performance.
\subsubsection{Other Hardware}
\subsection{Audio sources}
\subsubsection{Using Existing Web-Streams}
\subsubsection{Encoders at Programme Originator Studios}
\subsection{Single-Frequency Networks}
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