An example of coding a binary signal using rectangular pulse amplitude modulation with polar non-return-to-zero code

An example of Bipolar encoding, or AMI.

An example of Differential Manchester encoding

An example of Biphase mark code

An example of MLT-3 encoding.

In telecommunication, a line code (also called digital baseband modulation) is a code chosen for use within a communications system for transmission purposes. Image File history File links Rectangular pulse amplitude modulation with polar non-return-to-zero coding Derived from Image:Manchester. ... Image File history File links Ami_encoding. ... Image File history File links Ami_encoding. ... Simple example of Manchester encoding, drawn by myself File links The following pages link to this file: Manchester code Categories: BSD images ... Encoding of 11011000100 in Manchester code In telecommunication, Manchester code is a form of data communications line code in which each bit of data is signified by at least one transition. ... Image File history File links Differential_manchester_encoding. ... Image File history File links Differential_manchester_encoding. ... Image File history File links Biphase_Mark_Code. ... Image File history File links Biphase_Mark_Code. ... It has been suggested that this article or section be merged with Differential Manchester encoding. ... Image File history File links MLT3encoding. ... Image File history File links MLT3encoding. ... Image:Ethernet 100-Base-TX Signal. ... Copy of the original phone of Alexander Graham Bell at the Musée des Arts et Métiers in Paris Telecommunication is the assisted transmission of signals over a distance for the purpose of communication. ... In communications, a code is a rule for converting a piece of information (for example, a letter, word, or phrase) into another form or representation, not necessarily of the same type. ... In telecommunication, a communications system is a collection of individual communications networks, transmission systems, relay stations, tributary stations, and data terminal equipment (DTE) usually capable of interconnection and interoperation to form an integrated whole. ... In telecommunications, transmission is the act of transmitting electrical messages (and the associated phenomena of radiant energy that passes through media). ...

For digital data transport line coding is often used. Line coding consists of representing the digital signal to be transported, by an amplitude- and time-discrete signal, that is optimally tuned for the specific properties of the physical channel (and of the receiving equipment). The waveform pattern of voltage or current used to represent the 1s and 0s of a digital signal on a transmission link is called line encoding. The common types of line encoding are unipolar, polar, bipolar and Manchester encoding. The term digital signal is used to refer to more than one concept. ... Waveform quite literally means the shape and form of a signal, such as a wave moving across the surface of water, or the vibration of a plucked string. ... The introduction of this article does not provide enough context for readers unfamiliar with the subject. ... Polar Encoding When the digital encoding is symmetrical--around 0 Volts--it is called a Polar Code. ... In telecommunication, bipolar encoding is a type of line code—a method of encoding digital information to make it resistant to certain forms of signal loss during transmission. ... Encoding of 11011000100 in Manchester code In telecommunication, Manchester code is a form of data communications line code in which each bit of data is signified by at least one transition. ...

For reliable clock recovery at the receiver, one usually imposes a maximum runlength constraint on the generated channel sequence, i.e. the maximum number of consecutive ones or zeros is bounded to a reasonable number. A clock period is recovered by observing transitions in the received sequence, so that a maximum runlength guarantees such clock recovery, while sequences without such a constraint could seriously hamper the detection quality. Some digital data streams, especially high-speed serial data streams (such as the raw stream of data from the magnetic head of a disk drive) are sent without an accompanying clock. ... Run Length Limited codes, or RLL codes are widely used in hard disk drives (and notably digital optical discs, such as CD, DVD and BluRay disc) to prevent long stretches of no transitions, and therefore decoding uncertainty, from creeping in. ...

After line coding, the signal is put through a "physical channel", either a "transmission medium" or "data storage medium". Sometimes the characteristics of 2 very different-seeming channels are similar enough that the same line code is used for them. The most common physical channels are: Channel, in communications (sometimes called communications channel), refers to the medium used to convey information from a sender (or transmitter) to a receiver. ... A transmission medium is any material substance, such as fiber-optic cable, twisted-wire pair, coaxial cable, dielectric-slab waveguide, water, or air, that can be used for the propagation of signals, usually in the form of modulated radio, light, or acoustic waves, from one point to another. ... Many different consumer electronic devices can store data. ...

• the line-coded signal can directly be put on a transmission line, in the form of variations of the voltage or current (often using differential signaling).
• the line-coded signal (the "baseband signal") is further modulated to create the "RF signal" that can be sent through free space.
• the line-coded signal can be used to turn on and off a light in Free Space Optics, most commonly infrared remote control.
• the line-coded signal can be printed on paper to create a barcode.
• the line-coded signal can be converted to a magnetized spots on a hard drive or tape drive.
• the line-coded signal can be converted to a pits on optical disc.

Unfortunately, most long-distance communication channels cannot transport a DC component. The DC component is also called the disparity, the bias, the DC coefficient. The simplest possible line code, unipolar, because it has unbounded DC component, gives too many errors on such systems. Most line codes eliminate the DC component -- such codes are called "DC balanced", zero-DC, zero-bias, "DC equalized", etc. There are 2 ways of eliminating the DC component: A transmission line is the material medium or structure that forms all or part of a path from one place to another for directing the transmission of energy, such as electromagnetic waves or acoustic waves, as well as electric power transmission. ... It has been suggested that this article or section be merged into Low voltage differential signaling. ... Baseband is an adjective that describes signals and systems whose range of frequencies is measured from 0 to a maximum bandwidth or highest signal frequency; it is sometimes used as a noun for a band of frequencies starting at 0. ... In telecommunications, modulation is the process of varying a periodic waveform, i. ... Free Space Optics (FSO) is a telecommunication technology that uses light propagating in free space to transmit data between two points. ... For other uses, see Remote control (disambiguation). ... Wikipedia encoded in Code 128 Wikipedia encoded in Code 93 Wikipedia, the free encyclopedia encoded in the DataMatrix 2D barcode For the taxonomic method, see DNA barcoding. ... Typical hard drives of the mid-1990s. ... DDS tape drive. ... “Optical media” redirects here. ... It has been suggested that this article or section be merged with DC offset. ... The introduction of this article does not provide enough context for readers unfamiliar with the subject. ...

• Use a constant-weight code. In other words, design each transmitted code word such that every code word that contains some positive or negative levels also contains enough of the opposite levels, such that the average level over each code word is zero. For example, Manchester code and Interleaved 2 of 5.
• Use a paired disparity code. In other words, design the receiver such that every code word that averages to a negative level is paired with another code word that averages to a positive level. Design the receiver so that either code word of the pair decodes to the same data bits. Design the transmitter to keep track of the running DC buildup, and always pick the code word that pushes the DC level back towards zero. For example, AMI, 8B10B, 4B3T, etc.

Line coding should make it possible for the receiver to synchronize itself to the phase of the received signal. If the synchronization is not ideal, then the signal to be decoded will not have optimal differences (in amplitude) between the various digits or symbols used in the line code. This will increase the error probability in the received data. In coding theory, a constant-weight code is an error detection and correction code where all codewords share the same Hamming weight. ... A Code word may refer any of several concepts: For telecommunications senses, see Code word (telecommunication). ... In telecommunication, Manchester code (also known as Phase Encoding, or PE) is a form of data communications line code in which each bit of data is signified by at least one voltage level transition. ... Interleaved 2 of 5 is a continuous two-width barcode symbology encoding digits. ... In telecommunication, a paired disparity code is a code in which some or all of the characters are represented by two sets of digits of opposite disparity that are used in sequence so as to minimize the total disparity of a longer sequence of digits. ... Alternate Mark Inversion (AMI) is a line encoding technique (line code) for T1s which uses bipolar pulses to represent logical 1 values. ... In telecommunication 8B10B is a line code that maps 8-bit symbols to 10-bit symbols to achieve DC balance and bounded disparity, and yet provide enough state changes to allow reasonable clock recovery. ... Categories: Possible copyright violations ... This article is about a portion of a periodic process. ...

It is also preferred for the line code to have a structure that will enable error detection.

Note that the line-coded signal and a signal produced at a terminal may differ, thus requiring translation. In the context of telecommunications, a terminal is a device which is capable of communicating over a line. ...

A line code will typically reflect technical requirements of the transmission medium, such as optical fiber or shielded twisted pair. These requirements are unique for each medium, because each one has different behavior related to interference, distortion, capacitance and loss of amplitude. A transmission medium is any material substance, such as fiber-optic cable, twisted-wire pair, coaxial cable, dielectric-slab waveguide, water, or air, that can be used for the propagation of signals, usually in the form of modulated radio, light, or acoustic waves, from one point to another. ... Optical fibers An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length. ... A diagram of an STP cable Shielded Twisted Pair, sometimes abbreviated STP, is a kind of copper wiring where a pair of wires are twisted around each other and covered in an insulating tube. ...

Common line codes

• AMI
• 2B1Q
• 4B5B
• 4B3T
• 6b/8b encoding
• 8b/10b encoding
• 64b/66b encoding
• B3ZS
• B8ZS
• CAP
• CMI
• Conditioned Diphase
• Eight-to-Fourteen Modulation (EFM) used in Compact Disc
• EFMPlus used in DVD
• HDB3
• NRZ - Non-return-to-zero
• NRZI - Non-return-to-zero, inverted
• Manchester code (also variants Differential Manchester & Biphase mark code)
• Miller encoding (also known as Delay encoding, and has variant Modified Miller encoding)
• MLT-3 Encoding
• Modified AMI
• RZ - Return-to-zero
• Hybrid Ternary Codes
• Surround by complement (SBC)
• TC-PAM
• Trellis code

See also: Category:Line codes Alternate Mark Inversion (AMI) is a line encoding technique (line code) for T1s which uses bipolar pulses to represent logical 1 values. ... (Redirected from 2B1Q) The physical layer is level one in the seven level OSI model of computer networking. ... In telecommunication, 4B5B is a form of data communications line code. ... Categories: Possible copyright violations ... In telecommunications, 6B/8B is a line code that maps 6-bit symbols to 8-bit symbols. ... In telecommunications, 8b/10b is a line code that maps 8-bit symbols to 10-bit symbols to achieve DC-balance (see DC coefficient) and bounded disparity, and yet provide enough state changes to allow reasonable clock recovery. ... In data networking and transmission, 64B/66B is a line code that transforms 64-bit data to 66-bit line code to achieve DC-balance and bounded disparity, and yet provide enough state changes to allow reasonable clock recovery. ... B3ZS is an abbreviation for bipolar with three-zero substitution, a T_carrier line code in which bipolar violations are deliberately inserted if the stream of user data contains a string of 3 or more consecutive zeros. ... B8ZS is an abbreviation for Bipolar with 8 Zeros Substitution (or Binary Eight Zero Substitution)- which is a method of line coding used in the T-carrier system which allows full 64 Kbits per second per channel, though it does not allow for Clear Channel Capability (CCC - 64 Kbits/sec. ... Carrierless Amplitude Phase Modulation is a non-standard variation of quadrature amplitude modulation (QAM). ... CMI line coding In telecommunication Coded Mark Inversion (CMI) is a Return-to-zero (RZ) line code, in which zero bit is encoded as zero-to-one transition at the pulses center and one is encoded as constant level for entire pulse time. ... Eight-to-Fourteen Modulation (EFM) is an encoding technique used by CDs and MiniDiscs. ... CD redirects here. ... Eight-to-Fourteen Modulation (EFM) is an encoding technique used by CDs and MiniDiscs. ... DVD (also known as Digital Versatile Disc or Digital Video Disc) is a popular optical disc storage media format. ... HDB3 (High-density bipolar-3 zeros) is a telecommunications line code mainly used in Japan,Europe and Australia (for example, in E-1 lines) and is based on AMI. It is also very similar to the B8ZS encoding used in T-1 lines. ... Contrast with: return-to-zero. ... It has been suggested that this article or section be merged into Non-return-to-zero. ... In telecommunication, Manchester code (also known as Phase Encoding, or PE) is a form of data communications line code in which each bit of data is signified by at least one voltage level transition. ... Differential Manchester encoding (also known as CDP; Conditional DePhase encoding) is a method of encoding data in which data and clock signals are combined to form a single self-synchronizing data stream. ... It has been suggested that this article or section be merged with Differential Manchester encoding. ... In telecommunications, delay encoding is the encoding of binary data to form a two-level signal such that (a) a 0 causes no change of signal level unless it is followed by another 0 in which case a transition to the other level takes place at the end of the... Image:Ethernet 100-Base-TX Signal. ... Categories: Stub ... The hybrid (H-) ternary line code operates on a hybrid principle that combines the binary non-return-to-zero-level (NRZ-L) and the polar return-to-zero (RZ) codes and thus it is called H-ternary. ... TC-PAM is an acronym for Trellis Coded Pulse Amplitude Modulation. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

See also

• channel coding
• source coding
• modulation
• Physical layer
• Self-synchronizing code and bit synchronization

In digital telecommunications, channel coding is a pre-transmission mapping applied to a digital signal or data file, usually designed to make error-correction possible. ... It has been suggested that this article or section be merged with Entropy encoding. ... In telecommunications, modulation is the process of varying a periodic waveform, i. ... This article does not cite any references or sources. ... In telecommunications, a self-synchronizing code is a line code in which the symbol stream formed by a portion of one code word, or by the overlapped portion of any two adjacent code words, is not a valid code word. ...

References

• Federal Standard 1037C
• MIL-STD-188

Federal Standard 1037C, entitled Telecommunications: Glossary of Telecommunication Terms is a United States Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. ... MIL-STD-188 is a series of U.S. military standards relating to telecommunications. ...

External links

• Line Codes Analyzer