Decoding RF link using a PC soundcard

[Ray] wanted to use a microcontroller to send signals to some wireless power outlets. Instead of tapping into the buttons on the remote control he is using an RF board to mimic the signals. There are two hurdles to overcome with this method. The first is to make sure your RF module operates on the proper frequency. The second is to get your hands on the codes that are being sent from the remote control unit.

Now you could just hook your oscilloscope up to the transmitter and take a look at the timing of the signals. But most hobbyists don’t have that kind of high-end test equipment in their basement or garage shops. [Ray's] approach uses something we all have available to us: a sound card and some open source software. He connected the data pin from his RF receiver to an audio plug and inserted it in the line-in jack of his computer. Using Audacity he recorded the signal as he pressed buttons on the transmitter.  This method not only captures the data, but the time stamps native to the audio editing program let him easily work out the timing for each signal.

It’s kind of amazing what you can do with this audio analyation technique. Earlier this year we saw it used to measure response time for DSLR cameras.

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