Digital Signal 1 - Bandwidth

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. 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:

$\left( 8\,\frac{\mathrm{bits}}{\mathrm{channel}} \times 24\,\frac{\mathrm{channels}}{\mathrm{frame}} + 1\,\frac{\mathrm{framing\ bit}}{\mathrm{frame}} \right) \times 8000\,\frac{\mathrm{frames}}{\mathrm{second}}$
$= 1544000\,\frac{\mathrm{bits}}{\mathrm{second}}$
$= 1.544\,\frac{\mathrm{Mbit}}{\mathrm{second}}.$

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