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Diffstat (limited to 'electronics/cw2')
| -rw-r--r-- | electronics/cw2/writeup.tex | 59 |
1 files changed, 49 insertions, 10 deletions
diff --git a/electronics/cw2/writeup.tex b/electronics/cw2/writeup.tex index 39ea1e2..902402a 100644 --- a/electronics/cw2/writeup.tex +++ b/electronics/cw2/writeup.tex @@ -80,11 +80,10 @@ To build my project, I will split it into manageable subsections, that can each \item[The demodulation system:] \hfill \\ This will take the incoming wave, that will be encoded as an AM signal (not FM), and convert it to the audio wave I wish to detect. This can be made with a low pass filter with a diode, the low pass filter can act as a peek finder (envelope filter) when paired with the diode. - \item[The volume control amplifier:] \hfill \\ - This will be another amplifier that controls the volume of the signal, before it reaches the audio system. This can be made with an op amp a resistor and a potentiometer, it will have a variable gain, allowing it to decrease (less than 1 gain) or increase (greater than 1 gain) the volume of the output. + \item[The volume boost amplifier:] \hfill \\ + This will be another amplifier that controls the volume of the signal, before it reaches the audio system. This can be made with an op amp and two resistors. It will have a gain of around 3, to put the volume to a comfortable listening audio. - - \item[The audio normalisation filter and dividing amplifier:] \hfill \\ + \item[The audio normalisation filter:] \hfill \\ This subsystem will consist of a low pass filter, and a amplifier, this will do two things for the next subsystem. It will divide the amplitude of the audio by 3, making the peak value 5V, this is because the micro controller can't process values above 5V. The low pass filter will find the peaks of the incoming signal, this is because the audio input is at too high a frequency for the micro controller to properly poll, this will lower the input to something it can process. \item[The audio intensity meter:] \hfill \\ @@ -100,19 +99,59 @@ To build my project, I will split it into manageable subsections, that can each % put diagrams and detailed explanations here % 3 of these need to show alternatives \subsubsection{The receiver} +This system will receive data from from the radio waves from an antenna, here is its circuit diagram: + +PUT SYSTEM HERE + +To test this system, I can use a signal generator to create an AM wave, then put the output into a large wire, and finally I can compare the outputs of the signal generator, and the output from the inductor and capacitor, and check if they are the same. + \subsubsection{The initial amplifier} +This amplifier's job is to increase the voltage of the input, as the revive will only output at ~1V-3V, which is not enough to trigger my other components, it should have a gain of around 5. Here is its circuit diagram: + +PUT SYSTEM HERE + +I have used inverting amplifiers throughout this build as they are generally less noisy than non-inverting amplifiers and I can control the input impedance. + +To test this system I will put a voltage of around ~1-3V and test if it multiplies the voltage by the desired gain. + \subsubsection{The demodulation system} % can probably show an alternative to this -\subsubsection{The volume control amplifier} % perhaps show an alternative for here -\subsubsection{The audio normalisation filter and dividing amplifier} +This system will convert the AM wave to a unmodulated regular wave, it will also use a decoupling capacitor to remove any DC offset that is caused by the previous components. Here is its circuit diagram: + +PUT SYSTEM HERE + +To test this I will put in a modulated sine wave into it and confirm that I receive the original wave as an output. + +\subsubsection{The volume boost amplifier} % perhaps show an alternative for here +This is just another op amp, but with different resistor values. Here is its circuit diagram: + +PUT SYSTEM HERE + +Like the previous amplifier it can be tested by putting into a wave into it and checking it was multiplied by the correct gain. + +\subsubsection{The audio normalisation filter} +This is a filter that will only show the peaks of the output from the previous systems, this will allow the micro controller to properly poll the input for the next subsystem. Here is its circuit diagram: + +PUT SYSTEM HERE + +To test this, I can put a sine wave in as input, and then I will check if I see a sine-like wave with smaller troths. \subsubsection{The audio intensity meter} -This system will consist of a micro controller and a bar graph, it will use the output of the volume control amplifier as an input and will display the amplitude of the output on 4 bits of a bar graph +This system will consist of a micro controller and a bar graph, it will use the output of the volume boost amplifier as an input and will display the amplitude of the output on 4 bits of a bar graph. Here is its circuit diagram: + +PUT SYSTEM HERE The code can be seen here: \lstinputlisting[language=C, caption=\textit{using C syntax highlighting to add some colour to the world}]{./final.asm} The way this code works is in the main loop, the ADC is used to read in an analogue input, then it is processed using the convert label. The convert label will move the execution to the \textit{volow, vomid, vohigh, vovhigh} labels, that each move a corresponding value into PORTB to act as an output. The convert label works by anding the input with specific bits, and then subtracting, to see if the input is high enough to trigger a raise in the volume. + +To test this system, I can check which amplitude of signals makes the graph output a higher output on the graph. + \subsubsection{The push pull power amplifier} % can definitely show an alternative for this -\subsubsection{The speaker} +This system will massively boost the current of the input, which will make it audible on a speaker. To make the audio sound better, I will use an op amp to remove crossover distortion. Here is its circuit diagram: + +PUT SYSTEM HERE + +To test this system, I can measure the current in and the current out, and see how the compare. \subsection{Full block diagram} % put a full block diagram here @@ -124,7 +163,7 @@ The way this code works is in the main loop, the ADC is used to read in an analo \subsubsection{The receiver} \subsubsection{The initial amplifier} \subsubsection{The demodulation system} -\subsubsection{The volume control amplifier} +\subsubsection{The volume boost amplifier} \subsubsection{The audio normalisation filter and dividing amplifier} \subsubsection{The audio intensity meter} \subsubsection{The push pull power amplifier} @@ -134,7 +173,7 @@ The way this code works is in the main loop, the ADC is used to read in an analo \subsubsection{The receiver} % might be able to cut this, or make it very short \subsubsection{The initial amplifier} \subsubsection{The demodulation system} -\subsubsection{The volume control amplifier} +\subsubsection{The volume boost amplifier} \subsubsection{The audio normalisation filter and dividing amplifier} \subsubsection{The audio intensity meter} \subsubsection{The push pull power amplifier} |