wiktionary keyingKeying may refer to Keying, the installation of cryptography cryptographic key material into a device Keying graphics , a technique for compositing two full frame images together Keying telecommunications , a form of modulation where the modulating signal takes one of two or more values at all times Keying vandalism , vandalism by scratching paint with a key Keying official , an official of Ching Dynasty . Keying ship Keying ship , a Chinese junk which sailed to the U.S. and Britain in 1847 1848, named after the official Keying and Marine House , a building named after the official. See also Key disambiguation disambiguation ... more details
Keying is a family of modulation forms where the modulating signal takes one of two or more values at all times. The goal of keying is to transmit a digital signal over an analogue channel. The name derives from the Morse code key used for Telegraphy telegraph signaling. Modulation is the general technique of shaping a signal to convey information. When a digital message has to be represented as an analogue waveform, the technique and term keying or digital modulation is used. Keying is characterized by the fact that the modulating signal will have a limited number of states or values at all times, to represent the corresponding digital states commonly zero and one, although this might depend on the number of symbol data symbols used . This is in contrast to analogue modulation , where an analogue signal is transmitted over an analogue channel, and where the modulated analogue signal will have an infinite number of meaningful states. Furthermore, note that keying or digital modulation applies to transmitting a digital signal over an analogue passband channel . When a digital signal is to be transmitted over an analogue baseband channel , the modulation technique is termed line coding . Several keying techniques exist, including phase shift keying , frequency shift keying and amplitude shift keying . Bluetooth , for example, uses phase shift keying to exchange information between devices. An overview of keying techniques is given on the modulation page. Category Telecommunications terms telecomm term stub ... more details
Treaty of Nanjing , Treaty of the Bogue , Treaty of Wanghia and Treaty of Whampoa Keying ref cite web url http books.google.com.hk books?id jrUOAAAAQAAJ&pg PA521&dq keying hongkong&hl en&sa X&ei coRET7 HKMaUiAealaGaAw&ved 0CGIQ6AEwBw v onepage&q keying 20hongkong&f false title The Indian mail, Issue ... Kong . ref cite web url http books.google.com.hk books?id HFsEAAAAQAAJ&pg PA69&dq keying hongkong visit&hl en&sa X&ei u4VET8aSNM25iAeY7bGxAw&ved 0CEkQ6AEwAA v onepage&q keying 20hongkong 20visit&f false title Visit of High Imperial Commissioner Keying to Hong Kong work Curiosities afterward. Romance ..., Keying was a member of the imperial house of Aisin Gioro and belonged to the Manchu Plain Blue ... official in the Qing court. Role during the Opium Wars In 1842, the Daoguang Emperor entrusted Keying ... 1842. In the following years, Keying also concluded the Treaty of Whampoa with French colonial .... In 1858, the Xianfeng Emperor ordered Keying to negotiate a peace treaty with Britain and France ... Nelson Lay and Thomas Francis Wade sought to expose Keying s duplicity by producing documents the British had captured in Guangzhou , in which Keying expressed his contempt for the British. Humiliated, Keying promptly left the negotiations in Tianjin for Beijing and he was later arrested for having ... Court, but was allowed to commit suicide instead. Commemoration The junk Keying ship Keying , the first Chinese ship to sail to Britain and America, was named after Keying. Keying and Marine House ... more details
Junk Keying Infobox ship career Hide header Ship country Ship flag Ship name Keying Ship ordered ... Keying zh c p q y ng , named after the Manchu official Keying official Keying the English ... States and United Kingdom Britain between 1846 and 1848. Keying had been purchased in August 1846 ... Canton ese . She was commanded by Captain Charles Alfred Kellett , also British. Keying left Hong ... of New York by Samuel Waugh 1814 1885 , depicting the Junk Keying moored in New York harbour in 1847 watercolor on canvas, c. 1853 1855, Museum of the City of New York . The Keying was the first ship ... of Manhattan in July 1847, and was received with great fanfare. The Chinese crew of Keying were understandably ... now Jakarta . Twenty six of them left Keying and returned to Canton on board the Candace , which sailed 6 October 1847. Keying stayed several months in New York. 4,000 visitors a day paid 25 cents to board the ship and observe its design and crew. P. T. Barnum had a copy of Keying built in Hoboken ... may have included some of the Keying Chinese. However the Brooklyn Eagle described Barnum s crew as as one third white and two thirds negroes or mulattoes , so probably no real Keying crew were present. Keying also moored in Boston on November 18, 1847, by the Charles River Bridge, according to the Boston ... of the Junk Keying in Britain. Keying next sailed to Britain. A storm on 28 February wrecked .... Keying was fast, as was noted by the press The Keying next visited Boston, whence she sailed direct ... packet ship packet ship s. Illustrated London News , 1848 Keying reached Britain in March 1848, and a medal .... Image KeyingFullArticle.jpg thumb 150px Illustrated London News, 1848, full article. Keying was praised ... the visits to the Keying as follows The ROYAL CHINESE JUNK KEYING manned by a Chinese Crew ... in the most approved style of the Celestial Empire. Collection of Chinese Curiosities, &c. The Keying ... only on board, price 6d. The Times also reported Keying s visit There is not a more interesting Exhibition ... more details
Modulation techniques Unreferenced date August 2011 On off keying OOK the simplest form of amplitude shift keying ASK modulation that represents digital data as the presence or absence of a carrier wave . In its simplest form, the presence of a carrier for a specific duration represents a Binary numeral system binary one, while its absence for the same duration represents a binary zero. Some more sophisticated schemes vary these durations to convey additional information. It is analogous to unipolar encoding line code . On off keying is most commonly used to transmit Morse code over Radio frequency radio frequencies referred to as CW continuous wave operation , although in principle any digital encoding scheme may be used. OOK has been used in the ISM band s to transfer data between computer s, for example. OOK is more Spectral efficiency spectrally efficient than FSK, but more sensitive to noise. In addition to RF carrier waves, OOK is also used in optical communication systems e.g. IrDA . In aviation, some possibly unmanned airports have equipment that let pilots key their VHF radio a number of times in order to request an Automatic Terminal Information Service broadcast, or Pilot Controlled Lighting turn on runway lights . See also Unipolar encoding External links http www.maxim ic.com appnotes.cfm an pk 4439 CMP ELK12 Application Note I m OOK. You re OOK? Morse code state uncollapsed Bit encoding state uncollapsed Category Quantized radio modulation modes Category Fiber optic communications Category Amateur radio ar bn ko it On off keying ja ... more details
Orphan date December 2009 In wireless technology, handover keying Hokey refers to maintaining a secure connection seamlessly while migrating from one wireless network to another. External links IETF http www.ietf.org html.charters hokey charter.html Working Group http www.networkworld.com news 2007 073007 ietf qa.html Interview with Russ Housley , chair of the Internet Engineering Task Force Category Wireless networking Wireless stub ... more details
shift keying AFSK is a modulation technique by which digital data is represented by changes in the frequency ... zero. AFSK differs from regular frequency shift keying in performing the modulation at baseband frequencies ... shift keying to send and receive data, up to rates of about 1200 bits per second. The common Bell .... References Reflist See also Amplitude shift keying ASK Continuous phase frequency shift keying ... frequencies Frequency change signaling Multiple frequency shift keying MFSK Orthogonal frequency division multiplexing OFDM Phase shift keying PSK Federal Standard 1037C MIL STD 188 External links http cn.ece.cornell.edu publications papers icc2004 pp.pdf dFSK Distributed Frequency Shift Keying Modulation ... shift keying mk nl Frequentieverschuivingsmodulatie ja pl Frequency Shift Keying pt FSK ru fi FSK zh ... more details
changes continuously and linearly. Gaussian minimum shift keying In digital communication , Gaussian minimum shift keying or GMSK is a continuous phase frequency shift keying modulation modulation scheme . It is similar to standard minimum shift keying MSK however the digital data stream ... Pasupathy, Minimum Shift Keying A Spectrally Efficient Modulation , IEEE Communications Magazine ... & illustrations Aerospace Reflist Category Quantized radio modulation modes de Minimum Shift Keying pl MSK es GMSK fr Gaussian minimum shift keying ja ru fi GMSK zh it Minimum shift Keying ... more details
mergeinto Frequency shift keying date December 2011 Gaussian Frequency Shift Keying GFSK is a type of Frequency Shift Keying modulation that uses a Gaussian filter to smooth positive negative frequency deviations, which represent a binary 1 or 0. It is used by DECT , Bluetooth ref Sweeney, D. An introduction to bluetooth a standard for short range wireless networking Proceedings. 15th Annual IEEE International ASIC SOC Conference, Rochester, NY, USA, 25 28 Sept. 2002 , pp. 474 475. 2002. http ieeexplore.ieee.org xpls abs all.jsp?arnumber 1158106 ref , Cypress WirelessUSB , Nordic Semiconductor ref Nordic Semiconductor. http www.nordicsemi.com files Product data sheet Preliminary Product Specification nRF24LU1P v1 2.pdf nRF24LU1 Preliminary Product Specification v1.2 ref , Texas Instruments LPRF , z wave and Wavenis devices. For basic data rate Bluetooth the minimum deviation is 115 kHz. Generalization In a GFSK modulator, everything is the same as an Frequency shift keying FSK modulator except that before the baseband pulses 1, 1 go into the FSK modulator, it is passed through a gaussian filter to make the pulse smoother so to limit its spectral width. Gaussian filtering is one of the very standard ways for reducing the spectral width, it is called pulse shaping . If we use 1 for math f c f d math and 1 for math f c f d math , once when we jump from 1 to 1 or 1 to 1, the modulated waveform changes rapidly, which introduces large out of band spectrum. If we change the pulse going from 1 to 1 as 1, .98, .93 ..... .96, .99, 1, and we use this smoother pulse to modulate the carrier, the out of band spectrum will be reduced. ref http www.palowireless.com infotooth knowbase radio 109.asp www.palowireless.com GFSK Differences & Advantages over FSK Modulation ref References Reflist telecomm stub wireless stub Category Quantized radio modulation modes de Gaussian Frequency Shift Keying es Modulaci n por desplazamiento de frecuencia gausiana ko pl GFSK ru GFSK ... more details
Refimprove date August 2008 Modulation techniques Amplitude and Phase shift keying or Asymmetric Phase shift keying , APSK , is a digital modulation scheme that conveys Data Uses of data in computing data by changing, or modulating, both the amplitude and the Phase waves phase of a reference Signal information theory signal the carrier wave . In other words, it combines both Amplitude shift keying ASK and Phase shift keying PSK to increase the Symbol data symbol set . It can be considered as a superclass of Quadrature amplitude modulation QAM . The advantage over conventional QAM, for example 16 QAM, is lower number of possible amplitude levels, resulting in fewer problems with non linear amplifiers. Applications The DVB S2 specification permits the use of 16APSK and 32APSK modes, allowing 16 and 32 different symbols respectively and are intended for mainly professional, semi linear applications. They can be also used for broadcasting but they require a higher level of available Carrier to noise ratio C N and an adoption of advanced Predistortion pre distortion methods in the uplink station in order to minimize the effect of transponder non linearity. Image with unknown copyright status removed Image M APSK.PNG Figure Bit mapping into constellations see Ref.2 References http www.ebu.ch en technical trev trev 300 morello.pdf DVB S2 ready for lift off , article in the European Broadcasting Union EBU technical review http public.ccsds.org publications archive 131x2o1.pdf Flexible Serially Concatenated Convolutional Turbo Codes with Near Shannon bound performance for telemtery applications , CCSDS 131.2 O 1. Category Quantized radio modulation modes electronics stub ca Modulaci per despla ament d amplitud i fase de Amplituden und Phasenmodulation es Modulaci n por desplazamiento de amplitud y fase ... more details
Complementary Code Keying CCK is a modulation scheme used with wireless network s WLANs that employ the IEEE 802.11b specification. In 1999, CCK was adopted to supplement the Barker code in wireless digital networks to achieve data rate higher than 2 Mbit s at the expense of shorter distance. This is due to the shorter chipping sequence in CCK 8 bits versus 11 bits in Barker code that means less spreading to obtain higher data rate but more susceptible to narrowband interference resulting in shorter radio transmission range. Beside shorter chipping sequence, CCK also has more chipping sequences to encode more bits 4 chipping sequences at 5.5 Mbit s and 64 chipping sequences at 11 Mbit s increasing the data rate even further. The Barker code, however, only has a single chipping sequence. The complementary codes first discussed by Golay were pairs of binary complementary codes and he noted that when the elements of a code of length N were either 1 or 1 it followed immediately from their definition that the sum of their respective autocorrelation sequences was zero at all points except for the zero shift where it is equal to K N. K being the number of code words in the set . CCK is a variation and improvement on M ary Orthogonal Keying and utilises polyphase complementary codes . They were developed by Lucent Technologies and Harris Semiconductor and were adopted by the 802.11 working group in 1998. CCK is the form of modulation utilised when 802.11b operates at either 5.5 or 11 Mbit s. CCK was selected over competing modulation techniques as it utilised approximately the same bandwidth and could utilise the same preamble and header as pre existing 1 and 2 Mbit s wireless networks and thus facilitated interoperability. Polyphase complementary codes, first proposed by Sivaswamy ... Complementary Code Keying Category Quantized radio modulation modes Category Telecommunications terms Category IEEE 802.11 de Complementary Code Keying fr Complementary Code Keying ... more details
Modulation techniques Phase shift keying PSK is a digital modulation scheme that conveys Data Uses of data ... successive phases, it is termed differential phase shift keying DPSK . DPSK can be significantly simpler ... ly represented data Amplitude shift keying ASK Frequency shift keying FSK Phase shift keying PSK ... information &mdash Differential encoding differential schemes, Phase shift keying Differential phase shift keying .28DPSK.29 some of which do not need a reference carrier to a certain extent . A convenient ... and sine waves. Two common examples are binary phase shift keying Phase shift keying Binary phase shift keying BPSK BPSK which uses two phases, and quadrature phase shift keying Phase shift keying Quadrature phase shift keying QPSK QPSK which uses four phases, although any number of phases may ... keying . The higher speed wireless LAN standard, IEEE 802.11g 2003 ref name ref80211 ref name 80211g .... Bluetooth 1 modulates with Minimum shift keying Gaussian minimum shift keying , a binary scheme ... uses 8 PSK modulation. Binary phase shift keying BPSK Image BPSK Gray Coded.svg 200px right thumb Constellation diagram example for BPSK. BPSK also sometimes called PRK, Phase Reversal Keying, or 2PSK is the simplest form of phase shift keying PSK . It uses two phases which are separated by 180 and so ... error rate. Quadrature phase shift keying QPSK Image QPSK Gray Coded.svg 200px right thumb Constellation ... only one bit of the symbol is changed at a time Offset quadrature phase shift keying OQPSK is a variant of phase shift keying modulation using 4 different values of the phase to transmit. It is sometimes called Staggered quadrature phase shift keying SQPSK . Image Oqpsk phase plot.svg thumb ... signal ternary symbols . DPQPSK Dual polarization quadrature phase shift keying DPQPSK or dual ... to the signal constellation. Differential phase shift keying DPSK Differential encoding main differential coding Differential phase shift keying DPSK is a common form of phase modulation that conveys ... more details
Modulation techniques Amplitude shift keying ASK is a form of modulation that represents digital data as variations in the amplitude of a carrier wave . Any digital modulation scheme uses a wiktionary finite finite number of distinct signals to represent digital data. ASK uses a finite number of amplitudes, each assigned a unique pattern of bit binary digit s. Usually, each amplitude encodes an equal number of bits. Each pattern of bits forms the Symbol data symbol that is represented by the particular amplitude. The demodulator , which is designed specifically for the symbol set used by the modulator, determines the amplitude of the received signal and maps it back to the symbol it represents, thus recovering the original data. Frequency and Phase waves phase of the carrier are kept constant. Like Amplitude modulation AM , ASK is also linear and sensitive to atmospheric noise, distortions, propagation conditions on different routes in PSTN , etc. Both ASK modulation and demodulation processes are relatively inexpensive. The ASK technique is also commonly used to transmit digital data over optical fiber. For LED transmitters, binary 1 is represented by a short pulse of light and binary 0 by the absence of light. Laser transmitters normally have a fixed bias current that causes the device to emit a low light level. This low level represents binary 0, while a higher amplitude lightwave ... a binary zero. This type of modulation is called on off keying , and is used at radio frequency ... an eight level scheme can represent three bits and so on. These forms of amplitude shift keying ... interference, i.e. g t is a Nyquist ISI criterion Nyquist function . See also Frequency shift keying Phase shift keying Nyquist ISI criterion Intersymbol interference Unreferenced date November 2010 ... of an Amplitude Shift Keying ASK Receiver DEFAULTSORT Amplitude Shift Keying Category Quantized radio ... por desplazamiento de amplitud ko it Amplitude shift keying kk ... more details
Modulation techniques Multiple frequency shift keying MFSK is a variation of frequency shift keying FSK that uses more than two frequencies. http sharon.esrac.ele.tue.nl mirrors zl1bpu MFSK is a form of M ary orthogonal modulation , where each symbol consists of one element from an alphabet of orthogonal waveforms. M, the size of the alphabet, is usually a power of two so that each symbol represents log sub 2 sub M bits. M is usually between 2 and 64 Error Correction is generally also used MFSK Fundamentals In a M ary signaling system like MFSK, an alphabet of M tones is established and the transmitter selects one tone at a time from the alphabet for transmission. M is usually a power of 2, so each tone transmission from the alphabet represents log sub 2 sub M data bits. MFSK is classed as an M ary orthogonal signaling scheme because each of the M tone detection filters at the receiver responds only to its tone and not at all to the others this independence provides the orthogonality. Like other M ary orthogonal schemes, the required Eb N0 E sub b sub N sub 0 sub ratio for a given probability of error decreases as M increases without the need for multisymbol coherent detection. In fact, as M approaches infinity the required E sub b sub N sub 0 sub ratio decreases asymptotically to the Shannon limit of 1.6 decibel dB . However this decrease is slow with increasing M, and large values are impractical because of the exponential increase in required bandwidth. Typical values in practice range from 4 to 64, and MFSK is combined with another forward error correction scheme to provide additional systematic coding gain. Like any other form of angle modulation that transmits a single ... Shift Keying url http www.signals.taunus.de TABLES MFSK.HTML accessdate 2008 02 21 Samples ... Multiple Frequency Shift Keying Category Quantized radio modulation modes Category Telephony signals it Multiple frequency shift keying pl MFSK ... more details
Character generation may refer to Character creation , the process of creating a character for a role playing game Character generator , a device or software that produces text for keying into a video stream disambig ... more details
In telecommunication , the term facsimile converter has the following meanings 1. In a facsimile receiver , a device that changes the Signalling telecommunication signal modulation from frequency shift keying FSK to amplitude modulation AM . 2. In a facsimile transmitter , a device that changes the signal modulation from amplitude modulation AM to frequency shift keying FSK . References FS1037C MS188 Category Communication circuits telecomm stub ... more details
Frequency exchange signaling is frequency change signaling in which the change from one significant condition to another is accompanied by decay in amplitude of one or more frequencies and by buildup in amplitude of one or more other frequencies. Frequency exchange signaling applies to supervisory signaling and User telecommunications user information transmission telecommunications transmission . Synonym two source frequency keying telecommunications keying . References FS1037C MS188 Category Telecommunications telecomm stub ... more details
Unreferenced date December 2009 Orphan date March 2008 Higher order modulation is a type of digital modulation usually with an order of 4 or higher. Examples quadrature phase shift keying QPSK , m ary quadrature amplitude modulation m QAM , etc. See also phase shift keying modulation order DEFAULTSORT Higher Order Modulation Category Quantized radio modulation modes ... more details
Unreferenced date June 2009 Keymat keying material is a generic term for any usually Classified information classified material used in the process of loading key cryptography key s into a cryptographic device. Category Key management crypto stub ... more details
In telecommunication , receive after transmit time delay is the time interval between a the instant of keying telecommunications keying off the local transmitter to stop transmitting and b the instant the local receiver output has increased to 90 of its steady state value in response to an rf Signalling telecommunication signal from a distant transmitter. The rf signal from the distant transmitter must exist at the local receiver input prior to, or at the time of, keying off the local transmitter. Receive after transmit time delay applies only to half duplex operation . References FS1037C MS188 Category Telecommunications ... more details
In telecommunication , the term demand load can have the following meanings In general, the total Electric power power required by a Facility telecommunications facility . The demand Electrical load load is the sum of the operational load including any tactical load and nonoperational demand loads. It is determined by applying the proper demand factor to each of the connected loads and a diversity factor to the sum total. At a communications center , the power required by all automatic telephone exchange switching , Synchronization synchronous , and terminal equipment operated simultaneously on line or in standby , control and keying telecommunications keying equipment, plus lighting, ventilation, and air conditioning equipment required to maintain full continuity of communications. The power required for ventilating equipment, shop lighting, and other support items that may be operated simultaneously with the technical load. The sum of the technical demand and nontechnical demand loads of an operating facility. At a receiver facility, the Power physics power required for all receivers and auxiliary equipment that may be operated on prime or spare antennas simultaneously, those in standby condition, multicouplers, control and keying telecommunications keying equipment, plus lighting, ventilation, and air conditioning equipment required for full continuity of information transfer communications . At a transmitter facility, the power required for all transmitters and auxiliary equipment that may be operated on prime or spare antennas or dummy loads simultaneously, those in standby condition, control and keying equipment, plus lighting, ventilation, and air conditioning equipment required for full continuity of communications. References FS1037C MS188 Category Telecommunications terms ... more details
wiktionary ook Ook or OOK may refer to Ook Chung born 1963 , a Korean Canadian writer from Quebec OOK, acronym of on off keying OOK, IATA airport code for Toksook Bay Airport , Alaska Ook language Discworld , one half of the vocabulary of the fictional orangutan Librarian in Terry Pratchett s series Disambig de Ook it OOK ... more details
In telecommunication , the term carrier shift has the following meanings In the transmission telecommunications transmission of binary file binary or teletypewriter signals, keying telecommunications keying in which the Carrier wave carrier frequency is shifted in one direction for marking signals and in the opposite direction for spacing signals. In amplitude modulation , a condition that results from imperfect modulation in which the positive and negative excursions of the modulating envelope are unequal in amplitude. Note 1 The carrier shift results in a change in carrier power . Note 2 The carrier shift may be a shift to a higher or to a lower frequency. FS1037C MS188 Category Radio modulation modes ... more details
APK may refer to APK file format , as in filename.apk , Android Package, a packaging file format for the Android operating system Afrikaanse Protestantse Kerk , the whites only Calvinist church in South Africa Algemene Periodieke Keuring , the Vehicle inspection The Netherlands vehicle inspection in The Netherlands Amplitude shift keying, see Amplitude and phase shift keying Apopka High School, see Apopka High School Arbetarpartiet Kommunisterna , see Communist Party of Sweden 1995 Arbejderpartiet Kommunisterne , see Workers Communist Party Denmark disambig de APK es APK fr APK ko APK it APK nl APK sv APK ... more details
Encyclopedia
top
