Visualise a bit pattern
Get a usb logic analyzer they can be had for as little as 7$ USD .The bandwidth of the logic analyzer needs to be two times higher than the signal your observing. Logic analyzers set a threshold voltage and tell you if the signal is high or low (useful for digital). 

Oscilloscopes allow you to see many different values (analogue) or a range of voltages, and can be useful for troubleshooting noise issues.