Infrared protocol analysis with PC soundcard

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Infrared communication is widespread among electronic devices that use remote controls. Because of this, there are more protocols in use and the data (bytes) sent to the device depend on manufacturer. This post will show you how to view the waveform of an infrared signal emitted by a remote control, how to analyze and decode it. Then it will be possible to reproduce it. In this way you can program your universal remote control or your mobile device (smartphone with IR transmitter) with the right code for the best results.

Instead of using an oscilloscope for signal analysis, due to the low frequency of the IR bit stream, an ordinary sound card will be used to view the signal. The signal is amplified, filtered and demodulated by the IR receiver, so only the bit stream is sent to the sound card input. This is sampled at the usual audio rate and displayed in various software tools.