The author writes: I’m hobbyst in electronics, and I don’t really need a real oscilloscope. I don’t want to spend money on it and I don’t have enough space in my electronics corner for it. So, I took a look what is offering at the Net. I found a great (and free) solution: Winscope.
It’s using the sound card and that’s all you need. The problem with this solution is that you just can’t get the sample rate more than 44kSamples/sec. That’s enough for audio signals(<15kHz), but not for 40kHz ultrasound signals. You need around 10 samples per cycle (or more) of the signal you are measuring to get any decent waveform to actually view.
PC oscilloscope: [Link]