A report on Manchester code

An example of Manchester encoding showing both conventions for representation of data

Line code in which the encoding of each data bit is either low then high, or high then low, for equal time.

- Manchester code
An example of Manchester encoding showing both conventions for representation of data

10 related topics with Alpha

Overall
An arbitrary bit pattern in various binary line code formats

Line code

2 links

Pattern of voltage, current, or photons used to represent digital data transmitted down a communication channel or written to a storage medium.

Pattern of voltage, current, or photons used to represent digital data transmitted down a communication channel or written to a storage medium.

An arbitrary bit pattern in various binary line code formats

Common line encodings are unipolar, polar, bipolar, and Manchester code.

The binary signal is encoded using rectangular pulse-amplitude modulation with polar NRZ(L), or polar non-return-to-zero-level code

Non-return-to-zero

2 links

Binary code in which ones are represented by one significant condition, usually a positive voltage, while zeros are represented by some other significant condition, usually a negative voltage, with no other neutral or rest condition.

Binary code in which ones are represented by one significant condition, usually a positive voltage, while zeros are represented by some other significant condition, usually a negative voltage, with no other neutral or rest condition.

The binary signal is encoded using rectangular pulse-amplitude modulation with polar NRZ(L), or polar non-return-to-zero-level code
Unipolar NRZ(L), or unipolar non-return-to-zero level
Non-return-to-zero space
Encoder for NRZS, toggle on zero
An example of the NRZI encoding, transition on 1
The opposite convention, transition on 0
Encoder for NRZI, toggle on one

For a given data signaling rate, i.e., bit rate, the NRZ code requires only half the baseband bandwidth required by the Manchester code (the passband bandwidth is the same).

Group coded recording

1 links

In computer science, group coded recording or group code recording (GCR) refers to several distinct but related encoding methods for representing data on magnetic media.

In computer science, group coded recording or group code recording (GCR) refers to several distinct but related encoding methods for representing data on magnetic media.

Prior to 6,250 bpi tapes, 1,600 bpi tapes satisfied these constraints using a technique called phase encoding (PE), which was only 50% efficient.

An example of Differential Manchester encoding: Gray vertical lines, full and dotted, represent the two clock ticks per bit period. In the shown variant of the encoding, 0 is represented by a transition and 1 is represented by no transition. The two line signals shown differ in their polarity; which one would occur on the line depends on the preceding line state.

Differential Manchester encoding

1 links

Line code in digital frequency modulation in which data and clock signals are combined to form a single two-level self-synchronizing data stream.

Line code in digital frequency modulation in which data and clock signals are combined to form a single two-level self-synchronizing data stream.

An example of Differential Manchester encoding: Gray vertical lines, full and dotted, represent the two clock ticks per bit period. In the shown variant of the encoding, 0 is represented by a transition and 1 is represented by no transition. The two line signals shown differ in their polarity; which one would occur on the line depends on the preceding line state.

An improvement to Manchester coding which is a special case of binary phase-shift keying, it is not necessary to know the initial polarity of the transmitted message signal, because the information is not represented by the absolute voltage levels but by their transitions.

Self-clocking signal

0 links

One that can be decoded without the need for a separate clock signal or other source of synchronization.

One that can be decoded without the need for a separate clock signal or other source of synchronization.

Below is an example signal, in this case using the Manchester code self-clocking signal.

The Manchester Mark 1 was one of the world's first stored-program computers

Manchester Mark 1

0 links

One of the earliest stored-program computers, developed at the Victoria University of Manchester, England from the Manchester Baby .

One of the earliest stored-program computers, developed at the Victoria University of Manchester, England from the Manchester Baby .

The Manchester Mark 1 was one of the world's first stored-program computers
Functional schematic showing the Williams tubes in green. Tube C holds the current instruction and its address; A is the accumulator; M is used to hold the multiplicand and the multiplier for a multiply operation; and B contains the index registers, used to modify instructions.
Section of punched tape showing how one 40-bit word was encoded as eight 5-bit characters.

Data was recorded onto the drum using a phase modulation technique still known today as Manchester coding.

Comparison of twisted pair based ethernet technologies

Ethernet physical layer

0 links

The physical-layer specifications of the Ethernet family of computer network standards are published by the Institute of Electrical and Electronics Engineers (IEEE), which defines the electrical or optical properties and the transfer speed of the physical connection between a device and the network or between network devices.

The physical-layer specifications of the Ethernet family of computer network standards are published by the Institute of Electrical and Electronics Engineers (IEEE), which defines the electrical or optical properties and the transfer speed of the physical connection between a device and the network or between network devices.

Comparison of twisted pair based ethernet technologies

Early Ethernet standards used Manchester coding so that the signal was self-clocking and not adversely affected by high-pass filters.

The Secure Element chip, an NFC chip that contains data such as the Secure Element identifier (SEID) for secure transactions. This chip is commonly found in smartphones and other NFC devices.

Near-field communication

0 links

Set of communication protocols that enables communication between two electronic devices over a distance of 4 cm (11⁄2 in) or less.

Set of communication protocols that enables communication between two electronic devices over a distance of 4 cm (11⁄2 in) or less.

The Secure Element chip, an NFC chip that contains data such as the Secure Element identifier (SEID) for secure transactions. This chip is commonly found in smartphones and other NFC devices.
NFC Protocol stack overview
N-Mark Logo for NFC-enabled devices

In all other cases Manchester coding is used with a modulation ratio of 10%.

Consumer IR

0 links

Class of devices employing the infrared portion of the electromagnetic spectrum for wireless communications.

Class of devices employing the infrared portion of the electromagnetic spectrum for wireless communications.

Modulation schemes: typically 100% amplitude-shift keying (ASK). It may also involve pulse-position modulation, biphase/manchester encoding, etc. of the transmitted pulses (as opposed to the carrier itself). Most remotes use the length of the space between pulses to encode data.

Clock recovery

0 links

Process of extracting timing information from a serial data stream itself, allowing the timing of the data in the stream to be accurately determined without separate clock information.

Process of extracting timing information from a serial data stream itself, allowing the timing of the data in the stream to be accurately determined without separate clock information.

To ensure frequent transitions, some sort of self-clocking signal is used, often a run length limited encoding; 8b/10b encoding is very common, while Manchester encoding serves the same purpose in old revisions of 802.3 local area networks.