Editing Digital Signal 1 (section)

==DS1 frame synchronization==
{{see also|Synchronization in telecommunications}}
[[Frame synchronization]] is necessary to identify the [[timeslot]]s within each 24-channel frame. [[Synchronization]] takes place by allocating a framing, or 193rd, bit. This results in 8&nbsp;kbit/s of framing data, for each DS1. Because this 8-kbit/s channel is used by the transmitting equipment as [[Overhead information|overhead]], only 1.536&nbsp;Mbit/s is actually passed on to the user. Two types of framing schemes are [[superframe]] (SF) and [[extended superframe]] (ESF). A superframe consists of twelve consecutive 193-bit frames, whereas an extended superframe consists of twenty-four consecutive 193-bit frames of data. Due to the unique bit sequences exchanged, the framing schemes are not compatible with each other. These two types of framing (SF, and ESF) use their 8&nbsp;kbit/s framing channel in different ways.