Unreferenced date April 2012 Many of the world s radio stations broadcast in a variety of analog and digital formats. This page will list and compare them in chart form. class wikitable sortable border 1 World radio systems Terrestrial style background color rgb 170, 160, 150 System Type Modulation Data rate Sidebands? Channel communications Ch. Bandwidth signal processing Bandwidth KHz Radio spectrum Sound Codec Digital subchannel s Single frequency network SFN Metadata Radio Data System RDS RBDS align center align center AM radio Analog radio Amplitude Modulation N A ? 18 20 kHz 148.5 283.5 kHz Longwave br 530 1610 kHz Europe br 530 1710 kHz USA and Canada N A N A No None align center align center Motorola C QUAM Analog radio AM stereo QAM N A ? 18 20 kHz 530 1610 kHz Europe br 530 1710 kHz USA and Canada N A N A No None align center align center Digital Audio Broadcasting DAB Digital radio OFDM DQPSK around 1000 kbit s 4 channels up to 256 kbit s ? 1500 kHz Band III VHF High 174 240 MHz, br L band 1452 1492 MHz MPEG 1 Audio Layer II MPEG Layer 2 Yes, typically 4 6 stations per channel Yes Yes align center align center Digital Audio Broadcasting DAB.2B and DMB DAB sup sup Digital radio OFDM DQPSK up to 256 kbit s ? 1500 kHz Band III VHF High 174 240 MHz, br L band 1452 1492 MHz HE AAC No Yes Yes align center align center Digital Radio Mondiale Digital radio COFDM QAM up to 72 kbit s ? 4.5 5 kHz hybrid mode , br 9 10 kHz, br Single Channel Simulcast 18 20 kHz Mediumwave 530 1610 kHz Europe , br 530 1710 kHz USA and Canada , br Shortwave SW , Longwave LW MPEG 4 HE AAC CELP HVXC Yes, via In band on channel IBOC No? Yes align center align center FM radio Analog radio Frequency Modulation N A ? 200 kHz 87.5 108 MHz, br 76 90 MHz Japan , br 65.8 74 MHz USSR N A N A None Yes depending on station align center align center HD Radio Hybrid Digital radio COFDM HDC Spectral ban ... more details
systems usually employ multi carrier modulations such as OFDM or Wavelet OFDM to avoid the intersymbol ... line communication power lines , phone lines and ethernet over coax coaxial cables . G.hn uses OFDM ..., G.hn uses different OFDM parameters OFDM symbol duration, Guard Interval duration for each media ... more details
. ref The OFDM PHY is derived from HomePlug AV technology and is deployed in HomePlug based products ... The first option FFT PHY is based on FFT OFDM modulation, with a forward error correction FEC scheme based on Convolutional turbo code CTC . The second option Wavelet PHY is based on Wavelet OFDM modulation ... P1901.2, began taking shape. ref http embedded computing.com overcoming challenges ofdm ieee 1901 2 ixzz1Y8NXDuNz Overcoming smart grid communications challenges with OFDM and IEEE 1901.2 LeClare ... more details
Movement OFDM party to confirm these reports were frustrated by local officials, which led the OFDM ... 31292 OFDM Press Release The Massacre of May, 2008 , Jimma Times 21 June 2008 accessed 9 March ... more details
Politics of Ethiopia The Parliament of Ethiopia consists of two chambers The House of Federation upper chamber Upper Chamber The House of People s Representatives lower chamber Lower Chamber Created with the adoption of the Ethiopian Constitution of 1995 , the Parliament replaced the Shengo as the legislative branch of the Ethiopian government. Many opposition parties are represented in the Ethiopia Parliament where representatives from the Oromia Region hold the most positions and representatives from the Amhara Region hold the second most positions, in correlation with the population order of the corresponding states. ref name ethiopar.net http www.ethiopar.net English hopre hormemb.html 1 Opposition parties and EPRDF in the Ethiopian Parliament ref Various opposition parties including the UEDF , United Ethiopian Democratic Party Medhin Party , Somali People s Democratic Party SPDP , Ethiopian Democratic League EDL , Gambela People s Democratic Movement GPDM , All Ethiopian Unity Organization AEUO , Oromo Federalist Democratic Movement OFDM and the Benishangul Gumuz People s Democratic Unity Front BGPDUF hold many positions in the parliament. ref name ethiopar.net References reflist External links http www.ethiopar.net English hopre hormemb.html 1 Parliament of Ethiopia web site Further reading Dagnachew Befekadu and Habtamu Nini Abino, http www.asgp.info Resources Data Documents GLMVWUTFTXYDHKGJVQUBUKJFFQIUSD.doc Presentation on the Parliamentary System of the Federal Democratic Republic of Ethiopia , Association of secretaries General of Parliament website Africa legislatures Category 1995 establishments Category Government of Ethiopia Category Parliaments by country Ethiopia Category Bicameral legislatures Ethiopia Category National legislatures Ethiopia legislature stub Ethiopia stub be de thiopisches Parlament fr Parlement de l thiopie ka no Etiopias parlament pl Parlament Etiopii ru ... more details
A clear channel assessment attack or Queensland attack is physical layer DoS attack against Wi Fi networks. The attack focuses the need of a wireless network to receive the clear channel assessment which is a function within CSMA CA to determine whether the wireless medium is ready and able to receive data, so that the transmitter may start sending it. The attack makes it appear that the airwaves are busy, which basically puts the entire system on hold. The attack works only on 802.11b , and is not effective on the OFDM based protocols 802.11g and 802.11a . However, some hybrid 802.11b g access points will hinder the 802.11g network when the 802.11b network is attacked. ref cite web url http www98.griffith.edu.au dspace bitstream 10072 12207 1 41331.pdf title Denial of Service Attacks Against 802.11 DCF author Bo Chen, Vallipuram Muthukkumarasamy publisher Griffith University ref Discovery The attack was discovered by researchers at Queensland University of Technology s Information Security Research Center . ref name AusCERT cite web url http www.auscert.org.au render.html?it 4091 title AusCERT Advisory Denial of Service Vulnerability in IEEE 802.11 Wireless Devices publisher AusCERT ref The origin of the Queensland attack name comes thus from its original discoverers. In practice The signal telling the system the airwaves are busy is of course sent through the attacker s NIC , by placing it in continuous transmit mode. The attack can be set up through the use of the Intersil s Prism Test Utility PrismTestUtil322.exe . To execute the attack properly, a high power NIC and external antenna are required. References reflist Category Computer security exploits Category Computer network security ... more details
Orphan date August 2010 Broadcast and Multicast Service BCMCS is an interface for providing broadcast and multicast services in 3GPP2 CDMA CDMA2000 Mobile computing mobile computer network networks . BCMCS can be used to transfer light video and Sound recording and reproduction audio Video clip clips or other data to a large group of mobile subscriber s in an efficient manner. To do so, BCMCS is a so called point to multipoint Service systems architecture service . This means that multiple users receive the same information using the same radio resources . Usage of BCMCS BCMCS can be used for two different kind of services. Broadcast services in which all users within the broadcasting area can receive the information and a multicast Service systems architecture services in which only users that have Subscription subscribed to the service can receive the information Although BCMCS can be used for mobile TV , it has some limitations in the capacity that can be used for this kind of services within the network. Enhanced Broadcast and Multicast Services EBCMCS is an enhanced version of BCMCS. EBCMCS uses a new radio interface based on OFDM to combat problems with Echo phenomenon echoes Multipath propagation multipath in the transmission telecommunications transmission . See also Multimedia Broadcast Multicast Service MBMS , a point to multipoint service defined for 3GPP systems References Citation title Broadcast and Multicast Service in cdma2000 Wireless IP Network, Revision A journal 3GPP2 X.S0022 A date February 16, 2007 url http www.3gpp2.org Public html specs tsgx.cfm . External links http www.telecomabc.com b bcmcs.html Category Broadcasting Category Networks ... more details
0470059761.html ref MBSFN is a transmission mode which exploits LTE s OFDM radio interface ... synchronized for each to arrive at the UE within the OFDM Cyclic prefix Cyclic Prefix CP so as to avoid ... more details
. OFDM Modulation the sequence of blocks is modulated according to the Orthogonal frequency division multiplexing OFDM technique, using 1705 or 6817 carriers 2k or 8k mode, respectively ... interval insertion to decrease receiver complexity, every OFDM block is extended, copying in front ... OFDM symbol . On the other hand, continual pilots whose value and position is determined in the standard ... or receiver clock, and so on. Guard interval disposal the cyclic prefix is removed. OFDM demodulation ... frequency division multiplexing OFDM system comparison table OFDM system comparison table Personal ... more details
, if the channel allocation in the latter case is optimized by a good DCA scheme. Especially OFDM ... propagation for wideband channels without complex equalization. OFDM can be extended with OFDMA ... 802.11h standard. OFDM and OFDMA with DCA is often studied as an alternative for 4G wireless systems ... more details
Licenses Wi LAN S Patented W OFDM Technology. & 124 HighBeam Business Arrive Prepared publisher ... , to commercialize their patented W OFDM technology. He founded and co founded a number of hi ... OFDM Wide band Orthogonal Frequency Division Multiplexing he co founded Wi LAN Inc. ref name wi lan1 .... Through Wi LAN s efforts, the Federal Communications Commission FCC has allowed OFDM technology over ... Wi LAN and Philips invited companies to attend a meeting to form an alliance to promote the OFDM ... the OFDM Forum in March 2000. Wi LAN also was a founding member of the WiMAX Forum together with Ensemble ... 1994 2000. ref http www.highbeam.com doc 1G1 63253527.html ref BWS, Libra Product Lines, OFDM modem ... ofdm battle heads into court ref ref www.abheritage.ca abinvents sitemap.htm ref ref www.cellular.co.za ..., Method and apparatus for multiple access between transceivers in wireless communications using OFDM ..., A New Equalization Technique for Wideband OFDM over a Selective Fading Channel, in Advances in Wireless ... more details
on channel FM IBOC HD Radio OFDM modulation over FM and AM band IBOC sideband s FMeXtra FM band IBOC subcarrier s Digital Radio Mondiale extension DRM OFDM modulation over AM band IBOC sideband ... on OFDM modulation Integrated Services Digital Broadcasting ISDB T based on OFDM modulation ATSC Standards ATSC based on 8VSB modulation T DMB Mobile TV reception in handheld devices DVB H based on OFDM modulation MediaFLO based on OFDM modulation DMB based on OFDM modulation Multimedia Broadcast ... DVB SH based on OFDM modulation Satellite TV DVB S for Satellite TV Integrated Services Digital ... more details
IEEE 802.15.4a formally called IEEE 802.15.4a 2007 is an amendment to IEEE 802.15.4 formally called IEEE 802.15.4 2006 specifying that additional physical layers PHYs be added to the original standard. Overview IEEE 802.15.4 2006 specified four different PHYs, three of which utilized direct sequence spread spectrum DSSS , and one which used parallel sequence spread spectrum PSSS . ref IEEE Computer Society, September 8, 2006 . IEEE Standard 802.15.4 2006. New York, NY IEEE. ref IEEE 802.15.4a specifies two additional PHYs using ultra wideband UWB and chirp spread spectrum CSS . The UWB PHY is designated frequencies in three ranges below 1 GHz, between 3 and 5 GHz, and between 6 and 10 GHz. The CSS PHY is designated to the 2450 MHz ISM band . ref IEEE Computer Society, August 31, 2007 . IEEE Standard 802.15.4a 2007. New York, NY IEEE. ref History The IEEE 802.15 Low Rate Alternative PHY Task Group TG4a for wireless personal area network s WPANs , as its name implies, was tasked with amending the 802.15 standard to provide alternate PHY standards that would allow for high aggregate throughput lots of throughput over time communications with a precision ranging capability within 1 meter accuracy and low power usage within the scope of the WPAN. TG4a was one of two groups tasked to standardize UWB the other being TG3a. However, TG3a fell apart because of a deadlock between proponents of two competing UWB technologies Direct Sequence UWB and Multi Band Orthogonal Frequency Division Multiplexing OFDM UWB. Direct Sequence UWB, which was promoted by the ZigBee Alliance , found its home with TG4a, while Multi Band OFDM UWB was adopted by the WiMedia Alliance which published ECMA 368 ECMA is another telecommunications standardization body that is similar to the IEEE . ref http www.podnova.com channel 122071 episode 14 Part 5 Ultra Wideband Update IEEE 802.15.4a and Ecma 368 Podcast ref As was mentioned above, the Direct Sequence UWB PHY was the one that ended up being added i ... more details
A Costas loop is a phase locked loop used for carrier wave carrier phase Carrier recovery recovery from suppressed carrier modulation signals, such as from double sideband suppressed carrier signals. It was invented by John P. Costas engineer John P. Costas at General Electric in the 1950s. Its invention was described as having had a profound effect on modern digital communications . The primary application of Costas loops is in wireless receivers. Its advantage over the PLL based detectors is that at small deviations the Costas loop error voltage is sin 2 sub i sub sub f sub vs sin sub i sub sub f sub . This translates to double the sensitivity and also makes the Costas loop uniquely suited for tracking doppler shifted carriers esp. in OFDM and GPS receiver s ref cite journal url http ieeexplore.ieee.org iel5 5 22249 01037569.pdf?arnumber 1037569 title Introduction to Synchronous Communications , A Classic Paper by John P. Costas engineer John P. Costas author D. Taylor journal Proceedings of the IEEE volume 90 issue 8 pages pp. 1459 1460 year 2002 month August ref Implementation In the usual implementation of a Costas loop, ref cite journal url http rfdesign.com images archive 0102Feigin20.pdf format PDF title Practical Costas loop design author Jeff Feigin date January 1, 2002 journal RF Design pages pp. 20 36 ref a local voltage controlled oscillator provides Quadrature phase quadrature outputs, one to each of two phase detector s, e.g. , Product detector product detectors. The same phase of the input signal information theory signal is also applied to both phase detectors and the output of each phase detector is passed through a low pass filter . The outputs of these low pass filters are inputs to another phase detector, the output of which passes through noise reduction filter before being used to control the voltage controlled oscillator. The overall loop response is controlled by the two individual low pass filters that precede the third phase detect ... more details
unreferenced date February 2008 In telecommunications , a spectral mask , also known as a channel mask or transmission mask, is a math ematically defined set of line mathematics lines applied to the levels of radio or optical transmission telecommunications transmission s. The spectral mask is generally intended to reduce adjacent channel interference by limiting excessive radiation at frequencies beyond the necessary bandwidth signal processing bandwidth . Attenuation of these spurious emission s is usually done with a band pass filter , Tuned filter tuned to allow through the correct center frequency of the carrier wave , as well as all necessary sideband s. The spectral mask is usually one of the things defined in a bandplan for each particular band radio band . It is essential in assuring that a transmission stays within its channel communications channel . An FM broadcasting FM radio station , for example, must attenuate everything beyond 75 kHz from the center frequency by a few decibel s, and anything beyond 100 kHz the channel boundary by much more. Emissions on further adjacent channel s must be reduced to almost zero. FM broadcasting FM broadcast subcarrier s are normally required to stay under 75 kHz and up to 100 kHz if attenuation reduced to comply with the mask. The introduction of in band on channel IBOC digital radio in the United States has been slowed down by issues concerning the subcarriers it uses &ndash and the corresponding increase in the amount of energy in the sidebands &ndash overstepping the bounds of the spectral mask set forth for FM by the National Radio Systems Committee NRSC and enforce d by the Federal Communications Commission FCC . Other types of modulation have different spectral masks for the same purpose. Many digital modulation methods such as OFDM use the electromagnetic spectrum very efficiently, allowing for a very tight spectral mask. This allows placement of broadcast stations or other transmissions on chan ... more details
division multiplexing Ultra wideband MB OFDM style text align center Orthogonal frequency division multiplexing Ultra wideband MB OFDM style text align center Direct sequence spread spectrum DSSS , Phase ... OFDM style text align center Orthogonal frequency division multiplexing OFDM style text align center ... more details
wiktionary interfere interference Interference may refer to tocright Sciences Interference wave propagation , in physics, the superposition of two or more waves resulting in a new wave pattern Thin film interference Interference optics , patterns which may be observed when two light waves are superposed Interference communication , anything which alters, modifies, or disrupts a message as it travels along a channel Electromagnetic interference EMI Co channel interference CCI , also known as crosstalk Adjacent channel interference ACI , interference caused by extraneous power from a signal in an adjacent channel Intersymbol interference ISI , distortion of a signal in which one symbol interferes with subsequent symbols Inter carrier interference ICI , caused by doppler shift in OFDM modulation Vaccine interference , may occur when two or more vaccines are mixed together in the same formulation Interference fit , two items attempting to occupy the same space Interference engine , an engine whose pistons can strike and damage the piston valves when the engine is cranked while the timing belt is broken Interference theory in psychology Statistical interference , a method of determining when one distribution of values exceeds another Interference genetic , a phenomenon by which a chromosomal crossover in one interval decreases the probability that additional crossovers will occur nearby Linguistics Language interference, a nontechnical term referring to the Language transfer transfer of native language grammar and pronunciation into the learning and use of a second language Narrative interference, such as a Cline linguistics Cline of narrative interference Law Humanitarian interference in law Interference proceeding s of the United States patent law Sports Interference chess , when a piece is sacrificially interposed between attacker and defender Interference ice hockey , the penalty where a player impedes the movement of another player who does not have the puck Interfe ... more details
In the field of wireless communication, Macrodiversity is a kind of space diversity scheme using several receiver antennas and or transmitter antennas for transferring the same signal. The distance between the transmitters is much longer than the wavelength , as opposed to micro diversity where the distance is in the order of or shorter than the wave length. In a cellular network or a wireless LAN , macro diversity implies that the antennas are typically situated in different base station sites or Wireless access point access points . Receiver macro diversity is a form of antenna combining , and requires an infrastructure that mediates the signals from the local antennas or receivers to a central receiver or decoder. Transmitter macro diversity may be a form of simulcasting , where the same signal is sent from several nodes. If the signals are sent over the same physical channel e.g. the channel frequency and spreading sequence , the transmitters are said to form a single frequency network a term used especially in the broadcasting world. The aim is to combat fading and to increase the received signal strength and signal quality in exposed positions in between the base stations or access points. Macro diversity may also facilitate efficient broadcasting and multicasting services, where the same frequency channel can be used for all transmitters sending the same information. The diversity scheme may be based on transmitter downlink macro diversity and or receiver uplink macro diversity. Examples are CDMA soft handoff UMTS softer handoff softer handover . OFDM and frequency domain equalization FDE based Single Frequency Network s SFN are a form of transmitter macrodiversity used in broadcasting networks such as DVB T and digital audio broadcasting DAB Dynamic Single Frequency Networks DSFN , where a scheduling scheme adapts the SFN formations dynamically to traffic conditions and or receiver conditions 802.16e macro diversity handover MDHO 3GPP long term evolution LTE ... more details
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