nrzi

• NRZI

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High-Level Data Link Control - Framing

1 When no frames are being transmitted on a simplex or full-duplex synchronous link, a frame

delimiter is continuously transmitted on the link. Using the standard NRZI encoding from bits to line levels (0

bit = transition, 1 bit = no transition), this generates one of two continuous waveforms, depending on

the initial state:https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html

Bit stuffing - Zero-bit insertion

1 SDLC and Low- and full-speed USB data are sent NRZI encoded: a 0 bit

causes a signal transition, whereas a 1 bit causes no change


OpenVMS - Applicable industry standards

1 ISO 1864: Magtape, unrecorded / NRZI and PE


Bit rate - Information rate

1 The net bit rate of the Ethernet 100Base-TX physical layer standard is 100 Mbit/s, while the gross bitrate is 125 Mbit/second, due to the 4B5B (four bit over five bit) encoding. In

this case, the gross bit rate is equal to the symbol rate or pulse rate of 125 Mbaud, due to the NRZI line

code.


USB - Pinouts

1 USB is a serial bus, using four shielded wires for the USB 2.0 variant: two for power

(VBUS and GND), and two for differential data signals (labelled as D+ and D- in pinouts). Non-Return-to-Zero Inverted (NRZI) encoding scheme is used for

transferring data, with a sync field to synchronise the host and receiver clocks. D+ and D- signals are transmitted on a twisted pair, providing half-duplex data

transfers for USB 2.0.https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html

USB - Signaling

1 USB encodes data using the NRZI line coding; a 0 bit is transmitted by toggling the data lines from J to K or

vice-versa, while a 1 bit is transmitted by leaving the data lines

as-is


100BASE-TX

1 Just as in the 100BASE-FX case, the bits are then transferred to the

physical medium attachment layer using NRZI encoding


100BASE-TX - 100BASE-FX

1 100BASE-FX uses the same 4B5B encoding and NRZI line code that 100BASE-TX does


Manchester code - Description

1 The price of these benefits is a doubling of the bandwidth

requirement compared to simpler non-return-to-zero|NRZ coding

schemes (or see also NRZI).


Packet radio - Physical layer: modem and radio channel

1 Due to this simplicity, and just having suitable microchips at hand, the Bell 202

modulation became standard way to send the packet radio data over the radio as two

distinct tones. The tones are 1200Hz for Mark and 2200Hz for space (1000Hz shift). In the case of Bell 103 modulation, a 200Hz shift is used. The data is differentially encoded with

a NRZI pattern, where a data zero bit is encoded by a change in tones and a data one

bit is encoded by no change in tones.


NRZI - Non-return-to-zero inverted

1 'Non return to zero, inverted' ('NRZI') is a method of Map (mathematics)|mapping a Binary numeral system|binary Signalling (telecommunication)|signal to a physical

signal for Transmission (telecommunications)|transmission over some transmission media. The two level

NRZI signal has a transition at a clock boundary if the bit being transmitted is a logical 1, and does not have a transition if

the bit being transmitted is a logical 0.



1 Also, NRZI might take the opposite convention, as in Universal Serial Bus (USB) signalling, when in Mode 1, in

which a transition occurs when signaling zero, and a steady level

when signaling a one.



1 The transition occurs on the leading edge of the clock for the given bit. This distinguishes NRZI from NRZ-

Mark.



1 However, even NRZI can have long series of zeros (or ones if

transitioning on zero), and thus clock recovery can be difficult unless some

form of run length limited (RLL) coding is used in addition to NRZI


Run Length Limited - Need for RLL coding

1 One of the simplest practical codes, Modified Non-Return-to-Zero-Inverted

(NRZI), simply encodes a 1 as a magnetic polarity transition, also

known as a flux reversal, and a zero as no transition


Run Length Limited - Technical overview

1 However, run length limited coding terminology assumes NRZI encoding, so 1 bits indicate changes and 0 bits indicate the absence of change, the above sequence would be expressed as '11000101001000001', and only

runs of zero bits are counted.


Modified Frequency Modulation - Coding

1 As is standard when discussing hard drive encoding schemes, FM and

MFM encodings produce a bit stream which is Non-return-to-zero|NRZI

encoded when written to disk. A 1 bit represents a magnetic transition,

and a 0 bit no transition. Data encoding has to balance two factors:


Virtual Memory System - Applicable industry standards

1 *ISO 1864: Magtape, unrecorded / NRZI

and PE


4B5B

1 When NRZI-encoded, the 1 bits provide necessary clock signal|clock transitions for

the receiver


4B5B

1 On optical fiber, the 4B5B output is NRZI-encoded. FDDI over copper

(CDDI) uses MLT-3 encoding instead, as does 100BASE-TX.


9-track

1 Various recording methods were employed during its lifetime as tape speed and data density increased, including 'PE' (Manchester code|

phase encoding), 'GCR' (group code recording) and 'NRZI' (non-return-to-

zero, inverted, sometimes pronounced nur-zee)


9-track - Technical details

1 9-track 800 NRZI and 1600 PE (phase encoding) tapes use a inter-record gap (IRG) between data records to

allow the tape to stop and start between records


9-track - Standards

1 * ANSI INCITS 40-1993 (R2003) Unrecorded Magnetic Tape for

Information Interchange (9-Track, 800 CPI, Non-return-to-zero, inverted|

NRZI; 1600 CPI, Manchester code|PE; and 6250 CPI, Group Code Recording|

GCR)


Dendera zodiac

1 The Mesopotamian traditions], Journal of the British Astronomical Association '108' (1998) 9–28 has been conjectured to represent the

basis on which later astronomy systems were

based.[http://books.google.com/books?

vid=0wPPdxNrZi0_mMbpid=xznqw5EkOCMC Zodiac of Dendera], epitome


Dendera zodiac - History

1 These elicited a controversy as to the age of the zodiac representation,

ranging from tens of thousands to a thousand years to a few hundred,

and whether the zodiac was a planisphere or an astrology|

astrological chart.[http://books.google.com/books

?vid=0wPPdxNrZi0_mMbpid=xznqw5EkOCMC Zodiac of Dendera], epitome


ADAT Lightpipe - Lightpipe Bitstream

1 Instead, NRZI coding is used, where a 0 bit indicates no transition and a 1 bit is a

transition


AES3 - Synchronisation preamble

1 *X (or M) : 11100010 if previous time slot was 0, 00011101 if it was 1. (Equivalently, 10010011 NRZI

encoded.) Marks a word for channel A (left), other than at the start of an

audio block.



1 *Y (or W) : 11100100 if previous time slot was 0, 00011011 if it was 1. (Equivalently, 10010110 NRZI

encoded.) Marks a word for channel B (right).



1 *Z (or B) : 11101000 if previous time slot was 0, 00010111 if it was 1. (Equivalently, 10011100 NRZI

encoded.) Marks a word for channel A (left) at the start of an audio block.


AX.25 - Specification

1 At the datalink level, AX.25 specifies High-Level Data Link Control|HDLC (ISO

3309)ISO/IEC 3309: Information technology. Telecommunications and information

exchange between systems. High-level Data Link Control (HDLC) procedures. Frame

structure (1984). frames transmitted with NRZI encoding. Media access control follows the Carrier sense multiple access approach

with collision recovery (CSMA/CR).


The Den (television) - Christmas

1 Micro Blue Bucket with Removable Arms, a present that Socky desired but which would not be available in

Ireland until the following March.[http://www.youtube.com/watch?

v=wdOnrZi8XnM Dustin - The Den Christmas Special 1998]


Eight-to-fourteen modulation - How it works

1 This is because bits are encoded with Non-return-to-zero, inverted|NRZI

encoding, or modulo-2 integration, so that a binary one is stored on the

disc as a change from a land to a pit or a pit to a land, while a binary zero

is indicated by no change


Conditioned Diphase

1 * Unlike with Manchester encoding, only the presence of a transition is

important, not the polarity. Differential coding schemes will work

exactly the same if the signal is inverted (wires swapped). (Other line

codes with this property include NRZI, bipolar encoding, coded mark

inversion, and MLT-3 encoding).


Prestel - Prestel computer hardware and software

1 In addition twin 9-track NRZI tape drive|tape decks of 800 bytes/inch capacity were provided in order to

support bulk offline updates.


ISO 13239 - Framing

1 When no frames are being transmitted on a simplex or full-duplex synchronous link, a frame

delimiter is continuously transmitted on the link. Using the standard NRZI encoding from bits to line levels (0

bit = transition, 1 bit = no transition), this generates one of two continuous waveforms, depending on

the initial state:https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html

Serial Digital Interface - Electrical interface

1 Data is encoded in NRZI format, and a linear feedback shift register is

used to scrambler|scramble the data to reduce the likelihood that long strings of zeroes or ones will be

present on the interface


Constellation boundaries - Ancient Egyptian star charts and astronomical ceilings

1 The Mesopotamian traditions], Journal of the British Astronomical

Association '108' (1998) 9–28[http://books.google.com/books?vid=0wPPdxNrZi0_mMbpid=xznqw5EkOCMC Zodiac of Dendera], epitome


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