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| -rw-r--r-- | paper/safety-reset-paper.tex | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/paper/safety-reset-paper.tex b/paper/safety-reset-paper.tex index c9a54d9..2525b67 100644 --- a/paper/safety-reset-paper.tex +++ b/paper/safety-reset-paper.tex @@ -838,6 +838,13 @@ without triggering them to reset. to the smart meter in the middle through an adapter board. The top left contains a USB hub with debug interfaces to the reset microcontroller. The cables on the bottom left are the debug USB cable and the \SI{3.5}{\milli\meter} audio cable for the simulated mains voltage input.} + \Description{A photo of the safety reset prototype. Visible is a stand made from plywood to which a smart meter is + mounted in the middle. To one side of the smart meter a light switch and a socket are connected. To the other side, + an orange power cable exits towards the back of the stand. The smart meter is connected to a prototype circuit board + with colorful wires. The prototype circuit board is in turn connected to a microcontroller development board. The + development board is connected to a USB hub with both an SWD programming adapter and a USB to serial converter. A + usb cable from the USB hub as well as a 3.5 millimeter audio cable from the prototype circuit board are neatly + coiled up and hang down from the stand.} \label{fig_proto_pic} \end{figure} @@ -864,13 +871,18 @@ the meter's display after boot-up. \centering \includegraphics[width=0.45\textwidth]{prototype_schema} \caption{The signal processing chain of our demonstrator.} - \Description{A photo of the safety reset prototype. Visible is a stand made from plywood to which a smart meter is - mounted in the middle. To one side of the smart meter a light switch and a socket are connected. To the other side, - an orange power cable exits towards the back of the stand. The smart meter is connected to a prototype circuit board - with colorful wires. The prototype circuit board is in turn connected to a microcontroller development board. The - development board is connected to a USB hub with both an SWD programming adapter and a USB to serial converter. A - usb cable from the USB hub as well as a 3.5 millimeter audio cable from the prototype circuit board are neatly - coiled up and hang down from the stand.} + \Description{A diagram showing the signal processing flow. The diagram shows a number of steps going from grid + voltage waveform to trigger decition. The diagram begins with the DMA-assisted ADC capture. At this point, the + signal is a clean analog sine wave. The next step is grid frequency estimation, after which the signal is a + noise-like ragged line. After grid frequency estimation follows DSSS demodulation, which itself is made up of three + steps. The first step of DSSS demodulation is convolution, which produces a small noise signal with a large peak + somewhere in the middle. The peak is roughly ten times the amplitude of the noise and has two prominent negative + sidelobes to the left and right. The following step, CWT peak contrast enhancement, clenas up this signal and + removes the side-lobes leaving only the positive peak sticking out of the background noise. The final step of DSSS + demodulation is maximum likelihood estimation, which produces a vector of n plus k discrete elements. After DSSS + demodulation, this vector is passed through Reed-Solomon error correction, which transforms it into a vector of now + only n discrete elements. This vector is then finally processed in the cryptographic trigger protocol, which + produces the final trigger decision.} \label{fig_demo_sig_schema} \end{figure} |