| Electronics > Projects, Designs, and Technical Stuff |
| Brainstorming about bachelor thesis project - Data transmission using car lights |
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| damien22:
I work in optics and this is definitely feasible (but not trivial). Can it be a product on the market, perhaps, datalink would be wireless but headlights could send a simple ID to know who's the pair. Definitely a cool project. Modulation: As stated, light are often controlled using PWM. However, things like the frequency can be modulated on a let's say 5% range step without influencing the PWM duty cycle and brightness of the LED. So the light intensity can still be regulated, and information sent. Demodulation: Here you will need some high response time sensors like photodiode and passive electronics to actually isolate the signal you are looking for. If the PWM frequency is on the 20kHZ range +/- modulation you would need to have a specific pass filter / amplifier for this frequency range and then some sort of MCU to define the exact frequency. Camera definitely won't work. Light pollution: The receiver would need to have specific optics to filter the sunlight. A narrow bandpass filter in the 450nm~ or so that white LED usually exhibit will give a good signal VS sunlight. You would also probably want some lenses to focus the light coming from a specific direction. Note that white LEDs have a response time due to the phosphor and that needs to be accounted for. Although if you have bandpass at 450nm that shouldn't be a concern. |
| TheUnnamedNewbie:
--- Quote from: Someone on October 25, 2019, 10:08:56 am --- --- Quote from: TheUnnamedNewbie on October 25, 2019, 08:36:10 am ---I think (but this is just me thinking out loud) that if you do this spatial modulation, people will notice it far less, since you still have an overall constant brightness (esp if you select the symbols in such a way that every symbol has a same average power). --- End quote --- The constraint of a camera (unless its running at something beyond 200Hz, which just doesn't work in automotive space/cost limits) assures it will be noticeable to a human observer. --- End quote --- I am not so certain. I wonder if, when not directly in field of view, and only lightly modulated, say a few percent (and as I mentioned - in such away that the average power of the entire light is constant) people will really notice. It is not like you are hard switching on-and-off a single lightsource in a repetitive way. |
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