Super Frame
Encyclopedia
Super Frame is an older framing standard for T1
s. Also called D4 or D3/D4 framing. In the 1970s it replaced the original T1/D1 framing scheme of the 1960s in which the framing
bit simply alternated.
In order to determine where each channel
is located in the stream of data being received, each set of 24 channels is aligned in a frame. The frame is 192 bit
s long (8 * 24), and is terminated with a 193rd bit, the framing bit, which is used to find the end of the frame.
In order for the framing bit to be located by receiving equipment, a pattern is sent on this bit. Equipment will search for a bit which has the correct pattern, and will align its framing based on that bit. The pattern sent is 12 bits long, so every group of 12 frames is called a Super Frame. The pattern used in the 193rd bit is 1000 1101 1100.
Superframe remained in service in many places through the turn of the century, replaced by the improved Extended Super Frame of the 1980s in applications where its additional features were desired.
Digital Signal 1
Digital signal 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. E1 is used in place of T1 outside North America, Japan, and South Korea...
s. Also called D4 or D3/D4 framing. In the 1970s it replaced the original T1/D1 framing scheme of the 1960s in which the framing
Frame synchronization
While receiving a stream of framed data, frame synchronization is the process by which incoming frame alignment signals, i.e., distinctive bit sequences , are identified, i.e., distinguished from data bits, permitting the data bits within the frame to be extracted for decoding or retransmission...
bit simply alternated.
In order to determine where each channel
Channel (communications)
In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel...
is located in the stream of data being received, each set of 24 channels is aligned in a frame. The frame is 192 bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
s long (8 * 24), and is terminated with a 193rd bit, the framing bit, which is used to find the end of the frame.
In order for the framing bit to be located by receiving equipment, a pattern is sent on this bit. Equipment will search for a bit which has the correct pattern, and will align its framing based on that bit. The pattern sent is 12 bits long, so every group of 12 frames is called a Super Frame. The pattern used in the 193rd bit is 1000 1101 1100.
Superframe remained in service in many places through the turn of the century, replaced by the improved Extended Super Frame of the 1980s in applications where its additional features were desired.