exjobb/rapport/discussion.tex

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%% Author: Ola Leifler
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\chapter{Discussion}\label{cha:discussion}

\section{Results}
\section{Initial measurement of the performance of the old equipment}

As can be seen in \autoref{tab:initial-measurements} and \autoref{tab:initial-measurements-cna}, some values exceeded the limits (marked in red). Three of these values even exceeds the old standard's limits, thus indicating that the equipment should probably be usable with the new standard after some service or calibration. With this in mind, the course of the project will be targeted towards the design of an automated verification system, as described in \autoref{sec:planning}. With such a verification equipment at hand, the calibration of the generators might be easier to perform as well.

\section{Method}

It was suprisingly difficult to find and choose apropriate components for the dummy load. The resistors had to tolerate extreme surges and the relays had to have high insulation voltages between the contacts. Even finding the encapsulation for the relay box proved to be a challenge, since the filtering options available at the retailers web stores were not always consistent.


\subsection{Dummy Loads}
The results are well within the \SI{1}{\percent} specified by the standard \cite{iso_7637_2}.

\subsection{Attenuators}
\label{discussion_attenuators}
During the project, the attenuation was considered as the voltage attenuation \mbox{$att = 20 log_{10}\left( \frac{V_{in}}{V_{out}} \right)  \si{\deci\bel}$}. However, lots of information and many tools for RF applications, including the calculator used for the attenuators in this project, assume power attenuation \mbox{$att = 10 log_{10}\left( \frac{P_{in}}{P_{out}} \right)  \si{\deci\bel}$}. The result of these two properties coincides when the input and output impedance, as well as the driving and loading impedance, are all the same.

The fact that these two ways of expressing attenuation could be mixed up was not noticed until very late in the project. Thus the values provided by the online attenuator tool did not give the desired results in the simulator, for the \SI{1000}{\ohm} attenuator. This was at the time manually tweaked until the desired attenuation was acquired, but the out impedance was not considered during the tweaking and thereby ended up being a bit mismatched for the next $\Pi$ link.

There are infinitely many constellations to approximate the nominal value, in this project it was tried to use as few resistors as possible. This process was performed manually, since no suitable software for solving the problem was found. Thus the chosen constellations might not be optimal.


\subsection{Desired vs implemented (simulation)}
Parasitic effects. (real life, back to simulation)

\section{The work in a wider context}
Ethical aspects

\section{References}
Source critisism

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