Time code recorded onto an analog audio or video cue track is known as longitudinal time code (LTC). LTC encodes a biphase time code signal onto the analog audio or cue track in the form of a modulated square wave at a bit rate of 2400 bits/second.
Do It Yourself Tutorial: SMPTE Time Code
Download the SMPTE Time Code zip file, which contains the mp3 audio file for this tutorial. Or listen to the file by clicking on the link below.