Audio transmission using On Off Keying modulation

Projects General Guidance
1

Hi everyone

I'm working on a Visible Light Communications (VLC) based project where I have to send audio through an LED. I have to modulate the audio using On Off Keying modulation. I did research but found very little information on how to do the modulation.

How can I do On Off Keying modulation using an arduino in order to modulate the audio signal with a LED?

Thanks.

2

Hi Rachel. You might want to ask the forum moderators to move your post to a more suitable part of the forum. Although your project involves an led, there is only one of them and no multiplexing involved. Your question is more related to data protocols than leds. Click "report to moderator" and ask for it to be moved, perhaps to Project Guidance section.

3

On Off keying, as in sending 0, or 1, i.e. digital?
Digitize the audio with the ADC, then pulses at one frequency to indicate a 1 and no pulses to indicate a zero.

Found a lot of hits with Google, this one seems to explain the concept well enough.
https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/RadCom/part19/page1.html

4

PaulRB:
Click "report to moderator" and ask for it to be moved, perhaps to Project Guidance section.

Thank you for the tip.

5

CrossRoads:
On Off keying, as in sending 0, or 1, i.e. digital?
Digitize the audio with the ADC, then pulses at one frequency to indicate a 1 and no pulses to indicate a zero.

Thank you for the link you shared, I've checked it out before but I still have a tough time digitizing my audio. When you mention that I should digitize it using a ADC, i'm not sure how to do that with the arduino.

6

What quality audio do you require? the ADC on an arduino is 10 bits at 10 kHz sampling rate -
that limits you to about 60dB dynamic range and 5kHz max audio frequency - and a pretty serious low pass filter to avoid aliasing. It ain't HIFI.

Could be done - but is it good enough?

regards

Allan

7

Hi Allan.

The audio doesn't need to be flawless. The main aim is to demonstrate audio transmission using visible light and OOK modulation. So a 5kHz audio frequency and a 60db dynamic range is also good enough.

Thanks

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