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Topic: Eight-to-Fourteen Modulation

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Eight-to-Fourteen Modulation - Wikipedia, the free encyclopedia EFM belongs to the class of DC -free Run Length Limited (RLL) codes because it ensures that a) the spectrum (power density function) of the encoded sequence vanishes at the low-frequency end and b) both the minimum and maximum number of consective bits of the same kind are within specified bounds. EFM requires 3 merging bits between each 14 bit codewords to ensure that consecutive codewords can be cascaded without violating the specified minimum and maximum runlength constraint. Under EFM rules, the data to be stored is first broken into 8-bit blocks (bytes). en.wikipedia.org /wiki/Eight-to-Fourteen_Modulation

Method and apparatus for performing DSV protection in an EFM/EFM+ encoding same - US Patent 6778104 EFM+ is a state-dependent modulation, and the modulation proceeds according to the state determined by the preceding symbol and the current symbol, which ensures that the adjacent codewords, when connected, can comply with the run length limit (RLL) of 3~11T even without the need for a merging bits mechanism used in EFM modulation. Thus, in the application of EFM+ modulation, the bit values of the bit pattern relevant to the third bit and the fifteenth bit of an EFM+ codeword should be maintained to avoid generating unnecessary decoding errors. In EFM+ modulation, there are certain ambiguous codewords that require the aid of the third bit and the fifteenth bit of the next codeword during decoding. www.patentstorm.us /patents/6778104.html

cdplayer The latter of the two steps is a system known as eight-to-fourteen modulation. The purpose of this modulation is two-fold; disc storage efficiency is increased by reducing the number of 0-to-1 transitions in each data sample, and a rudimentary type of error correction is implemented. The purpose of this modulation is two-fold; disc storage efficiency is increased by reducing the number of pits, and a rudimentary type of error correction is implemented. www.thocp.net /reference/technology/cdplayer.htm

EFM - Eight to Fourteen Modulation, Ethernet First Mile Eight to Fourteen Modulation is used during encoding, because the 8-bit 'magnetic' Byte has to be modulated to a 14-bit 'optical' Byte. Eight-to-Fourteen Modulation used to convert eight data bits to fourteen channel bits prior to recording. Eight to Fourteen Modulation is not the only word formed from EFM. www.auditmypc.com /acronym/EFM.asp

Eight-to-Fourteen-Modulation - Wikipedia Dies stellt eine um 50% erhöhte Datendichte sicher (siehe EFM). Durch diese Doppeltbelegung von Codewörtern werden in allen vier Codiertabellen jeweils wenigstens 87 Codewörter frei, die in vier sogenannten Alternativcodiertabellen aufgenommen werden und damit 87 Bytes noch einmal in allen 4 Status repräsentieren. Das Verfahren ist komplexer als EFM, dafür werden nur 16 statt 17 Zeittakte für 8 Datenbits benötigt, d.h. de.wikipedia.org /wiki/Eight-to-Fourteen-Modulation

Method and apparatus for modulating and demodulating data - US Patent 6697311 However, in the modulation method according to the first embodiment of the present invention, 21 is determined as the total bit number under the condition that the minimum run length of the RLL modulation is 4 and the maximum run length is 10. In addition, the EFM method is too sensitive to jitters during the demodulation of data, so that the EFM method is not adequate for the data modulation method for a high-density recording medium. The EFM method is directed to a modulation method for converting a 8-bit data into a 14-bit code. www.patentstorm.us /patents/6697311.html

Patent 5982816: Digital communication system using packet assembling/disassembling and eight-to-fourteen bit encoding/decoding In the EFM method, an eight-bit data is converted into a set of fourteen channel bits such that the maximum inversion interval is set narrowly and the minimum inversion interval is set widely while a DC component is reduced. modulating/demodulating means for modulating a first carrier wave by the encoded data so as to transmit the forward packet of the outgoing data words in the fourteen-bit form, and for demodulating a second carrier wave to separate therefrom the backward packet of the incoming data received in the fourteen-bit form. Specifically, double phase shift keying (2 PSK) modulation is performed at an RF modulator 2 according to EFIM data, such as, karaoke performance data, which is reproduced from a CD player 1, and the modulated output is transmitted to an RF demodulator 4 via a transmission cable 3. www.freepatentsonline.com /5982816.html

Low-level modulation EE498 Audio Compact Disk - Writing and Reading the Data Illustrated class lecture notes that cover frame-level data encoding (IEC908/Red Book) including interleaving, Eight-to-Fourteen Modulation (EFM), P and Q parity, subcode blocks, and uses of the p- and q-subcode channels. Wireless Systems Laboratory Studying the theory and implementation of solutions to systems-level problems in communications through the design and analysis of coding, modulation, and equalization schemes for highly bandwidth efficient wireless communication systems. modulation amplitude modulation frequency modulation level level best insulin level level biology course level courses course level format service level level history course reading level level marketing www.serebella.com /encyclopedia/article-Low-level_modulation.html

What is Eight-to-Fourteen Modulation? - A Word Definition From the Webopedia Computer Dictionary Eight-to-Fourteen Modulation, or EFM as it is abbreviated, is an encoding technique used by CDs and provides a way of countering errors by encoding a byte into 2 bytes. Emission Control: Modulation Meters - Offers EMI RFI filters in a broad range of three-phase, single-phase, and feed-through configurations to solve all application problems. EFM maximizes the number of transitions possible with an arbitrary pit and land length which is determined by the wavelength of the laser light used to read the data. www.webopedia.com /TERM/E/Eight_to_Fourteen_Modulation.html

MFDigital CD DVD Information Library: Data Modulation & Error Correction EFM Modulation - The EFM (Eight to Fourteen) modulation scheme encodes each 8-bit symbol as 14 bits plus 3 merging bits. The EFM data is then used to define the pits on the disc. These are CIRC error correction and EFM modulation. www.mfdigital.com /2004/06/data-modulation-error-correction.html

Compact Disk These limitations led to the eight-to-fourteen conversion system which represents 8 user-bit bytes with the (minimally required) 14 channel-bit modulation code. The channel code for CD-DA and CD-ROM is called EFM: "eight-to-fourteen modulation". During the play back, the EFM decoder of the CD-ROM works in the opposite direction converting light modulations on the bits into a binary data stream, which is then cleared of any miscellaneous data by the drive's electronics. www.usbyte.com /common/compact_disk_4.htm

GN - Image Compression - Optical Compact Disc Code Also; data bytes (8 data bit) are converted into 14 channel bit code with EFM (Eight-to-Fourteen-Modulation), and "glued" with 3 Merging Channel bits before written on the disk. This provides an adequate modulation of signal intensity (sufficient density of pit/land edges encountered) so that the laser tracking mechanism works properly. EFM is constructed so that each pit/land change is separated by a minimum of two 0's and a maximum of ten 0's. www.laesieworks.com /digicom/Storage_CD.html

CDR-Info, The Recording Authority EFM (Eight to Fourteen Modulation) is a method of encoding source data for CD formats into a form that is easy to master, replicate and playback reliably. The data stream must undergo CIRC error correction and EFM modulation to reduce the possibilities of creating an error. EFM modulation gives the bit stream specific patterns of 1s and 0s, thus defining the lengths of pits and lands. www.cdrinfo.com /Sections/Articles/Specific.asp?ArticleHeadline=Writing+Quality&index=10

Compact disc - Wikipedia, the free encyclopedia This in turn is decoded by reversing the Eight-to-Fourteen Modulation used in mastering the disc, finally revealing the raw data stored on the disc. Philips also contributed the Eight-to-Fourteen Modulation, EFM, which offers both a large playing time and a high resilience against disc handling damage such as scratches and fingerprints; while Sony contributed the error-correction method, CIRC. Each of the 96 subchannel data bytes can be thought of as being divided into eight bits. en.wikipedia.org /wiki/Compact_disc

Can CloneCD improve the EFM-ability of my writer? The EFM (eight to fourteen modulation) allows hardware based copying of weak sectors. The EFM modulation system is used to convert 8-bit encoded signals into 14-bit signals to match digital signals to disc transmission characteristics. www.slysoft.com /en/can-clonecd-improve-the-efm-ability-of-my-writer-faq.20.580.html

Fehlerkorrekturverfahren - Wikipedia Eine bei IEEE 822.11 benutzte Modulation (müßte ich raussuchen) Die Modulation liefert neben dem demodulierten Signal noch Informationen über die Qualität des Signals. EFM (256 von 16384 (oder 131072) Codes gültig) de.wikipedia.org /wiki/Error-correcting_code

GLOSSARY of CD and DVD TECHNOLOGIES Eight to Fourteen Modulation is used during encoding, because the 8-bit 'magnetic' byte has to be modulated or mapped to a 14- bit 'optical' byte or 14 channel bits. The optical bytes, after the eight-to-fourteen modulation, are recorded in channel bits--which are encoded as pits and lands on the data track. EFM Plus Modulation during encoding is not a true 'eight to sixteen' modulation. www.cdrominc.com /info/glotst04.htm

CD EFM, Eight to Fourteen Modulation, is a solution to being unable to store consecutive 1s on disc due to how the laser reads. It converts the 8-bit sequences to 14-bit sequences, avoiding small pits by minimizing the number of 0-1 and 1-0 transitions. The 1st 4 bits of the auxilary data field are use for detection, the final 276 for correction. www.andrew.cmu.edu /user/taon/CD.html

EFM In transferring from magnetic to optical media, the 8-bit byte has to be modulated to a 14-bit byte. In magnetic media, a byte commonly has 8 bits.Optical media such a CD-ROM disc uses a 14-bit byte, a modification necessary because of the way data is stored and read with laser, using the pits (indentations) and lands (spaces between indentations) on the disc. www.hitscreen.com /dictionary/EFM.html

Audio Compact Disk - Writing and Reading the data EFM means Eight to Fourteen Modulation and is an incredibly clever way of reducing errors. Remember that there are lots of EFM words which end in "1" -- as one example, all the eight-bit binary words from 128 to 152 end in "1". The use of EFM coding means that pits come in discrete lengths ranging from 3 bits long (often written 3T) to 11 bits long (11T). www.ee.washington.edu /conselec/CE/kuhn/cdaudio2/95x7.htm

techsacd18 This coding not only allows unique mapping during demodulation, from one EFM+ codeword to one Data Symbol, but also limits error propagation. EFM+ is then applied to these bytes, providing 16 bits for each converted byte, which are finally preceded by a special EFM+ sync pattern of 32 channel bits. All EFM+ codewords are serialised into EFM+ Sync Frames consisting of 91 converted Data Symbols (half a row from a Recording Sector) and a Sync Word of 32 channel bits. www.daisy-laser.com /technology/techsacd/techsacd18.htm

Glossary: E22 - Fulfilment EFM : Eight to Fourteen Modulation used on every CD for modulation and error correction. ETM : Eight to Twelve Modulation, used for HD DVD and Blu-ray discs instead of the 8 to 16 modulation used for DVD. The purpose of EFM is to keep the number of contiguous 0s or 1s to within 3 and 11 for a CD disc. www.disctronics.co.uk /technology/glossary/glossary_e.htm

issue10.txt Pule-width modulation was one of these - it seemed to be a good way of using the fast switching power transistors that were appearing to replace the (relatively) inefficient Class-A output stages in audio amps. Pulse code modulation was discussed, but everyone said it was too complicated to ever catch on - after all you would have to encode to at least 8 or 10 bits and that would take an awful lot of transistors! efm encodes the data in such a way as to be able to be read within what amounts to a 'time window' enforced by the nature of the pickup optics. www.ibiblio.org /emusic-l/back-issues/vol055/issue10.txt

DVD Demystified Glossary DVD uses 8/16 modulation, where each set of 8 data bits is replaced by 16 channel bits before being written onto the disc. A modulation method used by CD, where eight data bits are represented by 14 channel bits. modulation - Replacing patterns of bits with different (usually larger) patterns designed to control the characteristics of the data signal. www.dvddemystified.com /glossary.html

Patent 5375249: Eight-to-fourteen-modulation circuit for a digital audio disc system The eight-to-fourteen modulation circuit according to claim 4, wherein said digital sum value calculator means comprises: In the EFM procedure, the number of combinations of 8 bit signal is 256, and that of 16 bit signal is 16,384, thus these combinations are not correspond to each other. According to the present invention, a simple and universal EFM modulating circuit capable of selection of merge bit which ensures a stable reproduction and a rapid signal conversion, is provide. www.freepatentsonline.com /5375249.html

Yamaha :: Multimedia In a normal recording, the recording application will supply a CD recorder with raw digital data, to which the recorder's hardware adds header and error correction information, and then converts it to what is known as EFM (Eight-to-Fourteen-Modulation) patterns. EFM patterns for CD-R writing vary from a minimum of 3T (0.83 micrometers at a linear velocity of 1.2 m/s) to a maximum of 11T (3.05 micrometers at a linear velocity of 1.2 m/s). A combination of patterns, from 3T to 11T, is used for writing to CD-R. The result (other than storing your valuable data, of course) is that the burned area looks darker than the unused area. yamahamultimedia.com /yec/tech/discta2_01.asp?...

SafeDisc 2 Technical Info To ensure that this happens, an invention known as EFM (Eight to Fourteen Modulation) was invented. Because some EFM outputs end and/or begin in 1, it is not possible to put two EFM encoded outputs directly next to each other, and still obey the minimum of two and maximum of ten 0's between two one's. So, since the sectors will be scrambled before they reach the EFM encoder, and since any data pattern XOR'd with the same pattern twice will result in the original data pattern, the EFM encoder will have to write the twice scrambled (or in other terms, the unchanged) sectors, which are regular bit patterns. sirdavidguy.coolfreepages.com /SafeDisc_2_Technical_Info.html

Artikel om CD-R formatet fra Interstage A/S, distributør af professionelt audio udstyr og tilbehør Each byte of the subsequent data stream is then converted to a 14-bit word, a process known as EFM (Eight to Fourteen Modulation). The EFM data +3 merging bits are recorded along the spiral track in the form of 'pits' and 'lands':--a transition from pit to land or land to pit being the moment a digital '1' occurs. The EFM process uses a look up table for converting each 8-bit byte to 14-bit word. www.interstage.dk /Sider/Produkter/Presse/Emner/CDR/CDR_PRE.shtml

Almacenamiento de bit y byte Todos estos condicionantes desembocan en el procedimiento EFM, "eight to fourteen modulation", en el que un byte a almacenar se traduce junto con sus ocho bit en 14 channel bit. Los códigos de la tabla EFM están escogidos de manera que se evita tanto la existencia de dos channel 1 consecutivos como la de una cadena de channel 0 seguidos demasiado larga, estando limitada a un máximo de 11 channel 0. Cuando por ejemplo un primer byte con un channel 1 y con ello el cambio de pit a land (o al revés) acaban, el siguiente byte no puede empezar de nuevo con el mismo tipo de cambio puesto que en medio no hay ningún espacio. www.pchardware.org /cdrom/almacenamiento.php

CD Data Coding The EFM (Eight to Fourteen) modulation scheme encodes each 8-bit symbol (after error correction has been added) as 14 bits plus 3 merging bits (17 bits in all). A modulation scheme is also used to ensure that data can be read correctly. The EFM data is then used to define the length and spacing of pits on the disc. www.disctronics.co.uk /technology/cdbasics/cd_frames.htm

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