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42 lines
2.2 KiB
C
42 lines
2.2 KiB
C
/*
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(WORK IN PROGRESS)
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Penguin's Circular Buffer Example -- Turning a noisy bell curve into a less noisy bell curve
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Here's an example of using the circular buffer library for sensor data:
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Let's say I have a sensor that gives me temperature at 1khz (using ideals so it is exactly 1khz)
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If this sensor was only giving me raw analog data, I might want to do some processing on these values
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so that I can make sure the values are as clean as possible. The more samples we have, the closer we are to the actual value.
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The faster we gather samples, the closer we get to representing our data in realtime.
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Using the sample rate, I can decide on a sampling window (in seconds) and an OSR (Oversampling Rate). The larger the buffer size, the more memory I need, so
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it is useful to find a happy medium between a large buffer and clean values.
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A sampling window is the window of time in which we can accept values for an average value. Depending on your application,
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a sampling window may need to be extremely small or maybe not so small. A rocket going extremely fast using
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some sensor for real time controls will want an extremely small sampling window as well as a lot of measurements for
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both clean, near noiseless data and as close to realtime data as possible.
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The sampling windows is usually an engineering requirement given that can match the sampling rate of the sensor with the following:
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sampling window (in seconds) = 1 / frequency
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Here, the OSR is simply 1.
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So at 1khz sample rate, let's say I decide I only need a 0.125 second sample window and I want to clean up some noisy data.
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We can now use this equation:
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OSR = frequency * sample window (in seconds)
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All of these have ignored real world slowdowns like the time it takes to do math on lower end hardware, interrupts slightly delaying the math, etc
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Without wanting to do some hard analysis on whatever hardware we're using, I usually take my frequency and half it to ensure timing requirements are met, like so:
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OSR = frequency / 2 * sample window
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Please note: In applications that require real real-time data, this is not a good way of doing things.
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*/
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#include <stdio.h>
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int main()
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{
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return 0;
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} |