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@@ -77,47 +77,6 @@ Currently, there seem to be a lack of solutions on detecting crowds or how busy
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For this project the first model is chosen as the IoT stack. This is a more specific for this project.
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-\subsubsection{Characteristics of Sensors}
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- \textbf{{\small Range}}
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- Maximum and minimum value range over which a sensor works well. Sensors may work well outside this range, but require additional calibration. e.g. the output may no longer be linear. \\
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- \textbf{{\small Accuracy}}
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- How well the sensor measures the environment in an absolute sense, i.e. how good the data is when compared with a recognized standard. e.g. a temperature sensor accurate to 0.001oC is expected to agree within 0.001oC with a known temperature standard. This is what you want to compare results with other observations. \\
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- \textbf{{\small Resolution}}
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- The ability of a sensor to see small differences in readings. e.g. a temperature sensor may have a resolution of $\mbox{0.000,01}^{o}\mbox{C}$, but only be accurate to $\mbox{0.001}^{o}\mbox{C}$. Can detect relatively small changes in temperature, smaller than the accuracy of the sensor. Resolution in often controlled by the quantisation in digitising the signal so is not a function of the sensor itself, but of the sampling process. \\
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- \textbf{{\small Repeatability}}
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- This is the ability of a sensor to repeat a measurement when put back in the same environment. It is often directly related to accuracy, but a sensor can be inaccurate, yet be repeatable in making observations. \\
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- \textbf{{\small Drift/Stability}}
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- This is the low frequency change in a sensor with time, i.e., with a given input you always get the same output. It is often associated with electronic aging of components or reference standards in the sensor. \\
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- \textbf{{\small Response time}}
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- A simple estimate of the frequency response of a sensor assuming a change in the measurement. \\
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- \textbf{{\small Output}}
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- What output is given for a change in the parameter being measured. For example, a voltage range e.g. 0 to 5 volts for an input range of 0 to $\mbox{30}^{o}\mbox{C}$. \\
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- \textbf{{\small Power Consumption}}
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- What is needed to power the sensor, quite often specified as the current draw. \\
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- \textbf{{\small Setting Time}}
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- After being switched on, how long before a valid measurement is ready. \\
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- \textbf{{\small Sampling time required}}
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- How often do we need to repeat measurements to get an accurate picture of the phenomenon being measured. \\
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\subsubsection{Communication Protocol for sensor data}
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