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OutputCompare carrier frequency modulation


#1

I was going through the Internet of Things book and noticed that the OutputCompare class has a SetBlocked method that takes a frequency parm and modulates a group of pulse widths onto a carrier frequency. The only use for that I’ve seen so far is for IR - but I was just curious, exactly what is the modulation method? If I have a carrier frequency of 32kHz and I encode some pulse widths onto that what exactly is it doing to modulate that onto the output signal? I don’t have any specific application, just curious.


#2

I checked it out on the oscilloscope and if I modulate a 2000Hz, 50% duty signal (250us on and off each period) with a 32kHz carrier, then I see a 16KHz signal that is on for around 250us and off for 250us. So it looks more or less like the signal modulated if you squint your eyes a bit. I’m guessing the reason for it is that makes it easier to rule out background noise (light) for IR stuff.


#3

This was specifically added for IR remotes, which is 38Khz modulated signal.