 digital signal 1 (ds1, sometimes ds-1) is a t-carrier signaling scheme devised by bell labs. ds1 is a widely used standard in telecommunications in north america and japan to transmit voice and data between devices. e-carrier is used in place of t-carrier outside north america, japan, and south korea. ds1 is the logical bit pattern used over a physical t1 line; however, the terms "ds1" and "t1" are often used interchangeably. ==bandwidth== a ds1 circuit is made up of twenty-four 8-bit channels (also known as timeslots or ds0s), each channel being a 64 kbit/s ds0 multiplexed carrier circuit.just circuits â t1 made simple a ds1 is also a full-duplex circuit, which means the circuit transmits and receives 1.544 mbit/s concurrently. a total of 1.536 mbit/s of bandwidth is achieved by sampling each of the twenty-four 8-bit ds0s 8000 times per second. this sampling is referred to as 8-khz sampling (see pulse-code modulation). an additional 8 kbit/s of overhead is obtained from the placement of one framing bit, for a total of 1.544 mbit/s, calculated as follows: : \begin{align} & \left( 8\,\frac{\mathrm{bits}}{\mathrm{channel}} \times 24\,\frac{\mathrm{channels}}{\mathrm{frame}} + 1\,\frac{\mathrm{framing\ bit}}{\mathrm{frame}} \right) \times 8\,000\,\frac{\mathrm{frames}}{\mathrm{second}} \\ = {} & 1\,544\,000\,\frac{\mathrm{bits}}{\mathrm{second}} \\ = {} & 1.544\,\frac{\mathrm{mbit}}{\mathrm{second}} \end{align} ==ds1 frame synchronization==  frame synchronization is necessary to identify the timeslots within each 24-channel frame. synchronization takes place by allocating a framing, or 193rd, bit. this results in 8 kbit/s of framing data, for each ds1. because this 8-kbit/s channel is used by the transmitting equipment as overhead, only 1.536 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 com
Multiplexing Telecommunications_standards