In telecommunication

Telecommunication

Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

, an Extended Super Frame (ESF) is a T1

T-carrier

In telecommunications, T-carrier, sometimes abbreviated as T-CXR, is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America, Japan, and South Korea....

 framing standard

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...

, sometimes called D5 framing because it was first used in the D5 Channel Bank, invented in the 1980s. It is preferred to its predecessor, Super Frame

Super Frame

Super Frame is an older framing standard for T1s. 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....

, because it includes a cyclic redundancy check

Cyclic redundancy check

A cyclic redundancy check is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data...

 (CRC) and 4000 bit/s channel capacity

Channel capacity

In electrical engineering, computer science and information theory, channel capacity is the tightest upper bound on the amount of information that can be reliably transmitted over a communications channel...

 for a data link

Data link

In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving information. It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver and the interconnecting data telecommunication circuit...

 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...

 (used to pass out-of-band

Out-of-band

The term out-of-band has different uses in communications and telecommunication. In case of out-of-band control signaling, signaling bits are sent in special order in a dedicated signaling frame...

 data between equipment.) It requires less frequent synchronization

Synchronization

Synchronization is timekeeping which requires the coordination of events to operate a system in unison. The familiar conductor of an orchestra serves to keep the orchestra in time....

 than the earlier superframe or D-4

D4 framing standard

In telecommunication, a D-4 is a framing standard for traditional time-division multiplexing, which standard describes user channels multiplexed onto a trunk that has been segmented into 24 bytes of 8 bits each....

 format, and provides on-line, real-time testing of circuit

Telecommunication circuit

A telecommunication circuit is any line, conductor, or other conduit by which information is transmitted.A dedicated circuit, private circuit, or leased line is a line that is dedicated to only one use...

 capability and operating condition.

In ESF, a superframe is 24 frames long

Data frame

In computer networking and telecommunication, a frame is a digital data transmission unit or data packet that includes frame synchronization, i.e. a sequence of bits or symbols making it possible for the receiver to detect the beginning and end of the packet in the stream of symbols or bits...

, and the 193rd 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...

 of each frame is used in the following manner:

• Frames 4, 8, 12, 16, 20, and 24 are used to send the framing pattern, 001011

• Frames 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21 and 23 are used for the data link
  Data link
  In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving information. It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver and the interconnecting data telecommunication circuit...
  
   (totalling half of all framing bits, or 4000 bits per second)

• Frames 2, 6, 10, 14, 18, and 22 are used to pass the CRC
  Cyclic redundancy check
  A cyclic redundancy check is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data...
  
  total for each super frame.

Note: Less-frequent synchronization frees overhead bits for use in testing and monitoring.