Using Audacity as an Oscilloscope
A good oscilloscope is hard to afford. Spending money on a mediocre one doesn't seem to justify the stiff cost of even low-end scopes. In the meantime, I found a workaround! :-) Why did I need an oscilloscope? I've been wanting to crack my truck's keyless entry transponder code for a while now. I finally got around to it and succeeded with the help of a $5 315 MHz wireless receiver module from sparkfun.com, an old headphone cable, and a free audio editing program named Audacity. Below is a screenshot of the captured code:
|Audacity Sound Editing Software|
With an old broken headphone (2.5 mm) jack, I connected the receiver's output to the input of my laptop.
Note: This could be dangerous! Do not do this unless you know what you're doing. Connecting a high powered circuit to your computer's sound card will probably fry the sound card and your computer!
Once connected, I powered up the receiver from a USB port and hit record while simultaneously hitting the lock button on my truck transponder. Above is a screenshot of the output.
From the captured output, I was able to determine a series of 1's and 0's.
The next step is being able to reproduce the code with microcontroller and send it to a 315 MHz transmitter. The possibilities for this are endless. This also allows me to control multiple vehicles with a single device. More to come soon!