Need to analyze a digital signal? Digital storage scilloscopes with deep enough memory banks can be pricey. So use Audacity and a sound card.
What’s the connection to security? The physical world is getting electronic bits added on to it all over. If you can’t understand something, you can’t secure it. And in order to be able to understand things, we need no-budget solutions like this.
“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.”