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Topic: QAM

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	Quadrature amplitude modulation - Wikipedia, the free encyclopedia
		As with all modulation schemes, QAM conveys data by changing some aspect of a base signal, the carrier wave, (usually a sinusoid) in response to a data signal.
		Analogue QAM is used in NTSC and PAL television systems, where the I- and Q-signals carry the components of chroma (colour) information.
		Rectangular QAM constellations are, in general, sub-optimal in the sense that they do not maximally space the constellation points for a given energy.
	en.wikipedia.org /wiki/Quadrature_amplitude_modulation (1084 words)

	QAM - a Whatis.com definition - see also: quadrature amplitude modulation (Site not responding. Last check: 2007-10-21)
		QAM (quadrature amplitude modulation) is a method of combining two amplitude-modulated (AM) signals into a single channel, thereby doubling the effective bandwidth.
		QAM is used with pulse amplitude modulation (PAM) in digital systems, especially in wireless applications.
		In a QAM signal, there are two carriers, each having the same frequency but differing in phase by 90 degrees (one quarter of a cycle, from which the term quadrature arises).
	searchnetworking.techtarget.com /sDefinition/0,,sid7_gci541804,00.html (228 words)

	QAM00002.htm (Site not responding. Last check: 2007-10-21)
		QAM utilizes one communication channel to contain two mutually independent orthogonal signals, namely I-channel modulated with a cosine wave and Q-channel modulated with a sine wave.
		In QAM, two components (real and imaginary) of the complex signal is merged into one real signal at the modulator and then transmitted.
		The QAM is standardized in terms of the number of the states determinable by both I- and Q-channel, which is
	homepage.usask.ca /~kut594/QAMDSP02.i2h/QAM00002.htm (438 words)

	United States Patent Application: 0040091060
		The position of the switches 54, 56, 58 and 60 is irrelevant to the 16 QAM mode of operation of the universal modulator.
		The position of the switches 54, 56, 58 and 60 is irrelevant to the 64 QAM or 32 QAM mode of operation of the universal modulator.
		The 32 QAM constellation is a subset of the 64 QAM constellation where the outermost 32 points have been deleted for example, as shown in FIG.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1="20040091060".PGNR.&OS=DN/20040091060&RS=DN/20040091060 (4796 words)

	QAM - Measurement Encyclopedia - National Instruments
		QAM is one of the more interesting forms of modulation.
		In QAM the “dots” representing codes do not reside on a phase-plane circle as depicted in Figure 42.
		The QAM process can be visualized as first digitizing (coding) two quadrature (I and Q) analog signals.
	zone.ni.com /devzone/nidzgloss.nsf/webmain/F8FF7A42C6E88CBC8625686A00794545 (692 words)

	Quadrature Amplitude Modulation (Site not responding. Last check: 2007-10-21)
		Quadrature amplitude modulation (QAM) is a modulation scheme in which two sinusoidal carriers, one exactly 90 degrees out of phase with respect to the other, are used to transmit data over a given physical channel.
		QAM and its derivatives are used in both mobile radio and satellite communication systems.
		Similarly, DPSK requires additional logic at the front end of the QAM modulator to generate the encoded data sequences to the I and Q inputs of the modulator.
	www.altera.com /products/ip/altera/t-alt-qam.html (542 words)

	Learn more about Radio in the online encyclopedia. (Site not responding. Last check: 2007-10-21)
		Microwave dishes on satellites, telephone exchanges and TV stations usually use quadrature amplitude modulation (QAM).
		QAM sends data by changing both the phase and the amplitude of the radio signal.
		Engineers like QAM because it packs the most bits into a radio signal.
	www.onlineencyclopedia.org /r/ra/radio.html (2589 words)

	QAM (Site not responding. Last check: 2007-10-21)
		QAM constellation analysis represents the next generation of digital testing equipment.
		It is a method by which the installation engineer may visually foresee potentially serious problems in the cable network.
		By measuring the QAM signal and displaying it diagrammatically and numerically, the MER (modulation error ratio) can be given a new, visual form capable of displaying a large amount of information.
	www.swires.com /QAM.html (314 words)

	QAM - What's New?
		QAM has acquired a full-size model of a Spitfire Mk I. Added a recent photo of Victa Airtourer VH-CFE with all markings added.
		QAM also commemorated 100 years of controlled, powered flight with the acceptance into the collection of the newly restored Victa Airtourer VH-CFE.
		QAM celebrated 100 years of controlled, powered flight at the Museum in Caloundra on Wednesday 17th December.
	www.qam.com.au /whatsnew.htm (549 words)

	QUADRATURE AMPLITUDE MODULATION FACTS AND INFORMATION (Site not responding. Last check: 2007-10-21)
		However, if the mean energy of the constellation is to remain the same (by way of making a fair comparison), the points must be closer together and are thus more susceptible to noise and other corruption; this results in a higher bit_error_rate and so higher-order QAM can deliver more data less reliably than lower-order QAM.
		valign=topRectangular QAM constellations are, in general, sub-optimal in the sense that they do not maximally space the constellation points for a given energy.
		valign="center" rowspan=2It is the nature of QAM that most orders of constellations can be constructed in many different ways and it is neither possible nor instructive to cover them all here.
	www.witwik.com /quadrature_amplitude_modulation (1197 words)

	ACRO.IT: QAM - Quadrature Amplitude Modulation (Site not responding. Last check: 2007-10-21)
		Operation of QAM is somewhat simple; it operates by modulating a carrier sine wave signal in amplitude and phase.
		In QAM coding scheme each symbol is specific combination of signal amplitude and phase.
		The highest rate [standard V.34] uses the QAM modulation carrier of 1959Hz, and symbol rate of 3429 symbols/sec.
	www.acro.it /Acro-3F504B3D393333.html (323 words)

	Hierarchical QAM: A Spectrally Efficient DC-Free Modulation Scheme
		Note that the spectrum of a typical QAM modulated signal has significant energy at the carrier frequency, or equivalently, the baseband signal spectrum has considerable energy around dc.
		The symbol rate of each sub-QAM system is normalized to 1 (the conventional QAM system has a normalized symbol rate of 2), and the cutoff frequency of the first-order ac-coupling filter is given as a percentage of this normalized symbol rate.
		and ac-coupling with a cutoff frequency of 200 kHz, the SNR degradation from the conventional QAM scheme is approximately 3 dB.
	www.comsoc.org /ci/private/2000/nov/mirabbasi2.html (4363 words)

	Testing 256 QAM transmission of data over HFC (Site not responding. Last check: 2007-10-21)
		The carrier-to-noise ratio for the theoretical coded 256 QAM signal has a 6 dB shift in noise performance as compared to 64 QAM and is therefore less tolerable to noise.
		The QAM signal transmission channels were varied from area to area, with the test channels usually operating at the upper edge of the cable spectrum.
		The 256 QAM average signal power level was adjusted at the headend for operation at 10 dB below the adjacent analog video's peak of sync power.
	www.cedmagazine.com /ced/9612/9612d.htm (2464 words)

	what is 16 QAM,32 QAM - Q&A (Site not responding. Last check: 2007-10-21)
		In 16 QAM 4 different phases and 4 different amplitudes are used for a total of 16 different symbols.
		Qam does stand for quadrature amplitude modulation, it is a technique used to send different signals within one carrier in four different phases.
		Es un tipo de modulacion digital, se modula en amplitud por cuadratura, en 16 QAM existen 4 diferentes fases y 4 diferentes amplitudes para obtener un total de 16 simbolos, de aqui el 16 QAM, esto significa que que un codigo es capaz de transmitirse a una velocidad de 4bps.
	www.faqs.org /qa/qa-4504.html (311 words)

	Quadrature Amplitude Modulation
		I and Q modulation, A.K.A., QAM, is a method for sending two separate (and uniquely different) channels of information.
		As you know, the carrier is shifted to create two carriers: sin and cos versions.
		In the more recent incarnations of the QAM or I and Q modulation techniques, an Analog to Digital Convertor (ADC) is used to first convert the analog input to a serialized digital bit stream and is applied to the QAM modulators; likewise at the receiver.
	www.williamson-labs.com /480_qam.htm (311 words)

	SDM Compared to Combining of QAM Channels into Logical Channels
		The shared wisdom in the industry is that the larger the digital capacity of a channel, the better the statistical multiplexing gains.
		Logical QAM channels, while increasing the size of the channel, do not increase the spectral efficiency of the channel.
		Note that in all cases, SDM outperforms QAM for SD and HD streaming services, as well as for SD and HD movie downloads.
	www.broadbandphysics.com /tech/cable_SvsQ2.html (293 words)

	Drake Digital QQP860 QAM to QAM Processor (Site not responding. Last check: 2007-10-21)
		After error correction, the recovered transport stream is re-encoded with new FEC and QAM modulated.
		A built-in upconverter upconverts to the new QAM output channel.
		High output, 61 dBmV, agile QAM modulator and upconverter are built in.
	www.rldrake.com /digital/qqp860.html (427 words)

	pchdtv.com :: View topic - QAM signal issue, DVB drivers (Site not responding. Last check: 2007-10-21)
		I can tune QAM stations with azap, I get a signal lock and very high signal strength 0xfd00 or more.
		Don't let these previous statements lead you to beleive I can actually make a capture, despite the fact that all the tools seem to work and indicate a lock, when I cat the dvr0 device the resultant data stream doesn't seem to be playable by mplayer.
		If by 160-170, you mean that if you have a digital set-top-box, they appear on channel 160-170, that number has absolutely no bearing on the QAM frequency itself, and is a mapping determined solely by the cable company.
	xmission.com /~pchdtv/forum/viewtopic.php?p=3418&... (891 words)

	Video Equipment - qam technology?
		If I had a cheat sheet from a local QAM expert....
		Quaddrature amplitude modulation, QAM is the method that cable companys have
		QAM is the modulation technique used on digital cable, so it should
	www.totalvideo.org /detail-9846766.html (487 words)

	QAM - OneLook Dictionary Search
		QAM : Dictionary of Computing and Digital Media [home, info]
		QAM : DOD Dictionary of Military Terms: Joint Acronyms and Abbreviations [home, info]
		Phrases that include QAM: 16 qam, 32 qam, 64 qam, 80 qam, 96 qam, more...
	www.onelook.com /cgi-bin/cgiwrap/bware/dofind.cgi?word=QAM (143 words)

	High Def Forum - Your High Definition Community & High Definition Resource - What is QAM
		QAM (quadrature amplitude modulation) is a method of combining two amplitude-modulated (
		QAM is used with pulse amplitude modulation (PAM) in digital systems, especially in
		As I understand the issues, there is more than just QAM involved.
	www.highdefforum.com /showthread.php?t=2929 (272 words)

	Company News On Call
		The specification requires that the receivers implement both QAM and CAP modulation formats.
		Therefore, on a given loop, the downstream can transmit QAM and the upstream can transmit CAP, or vice versa.
		Single tone line codes like CAP and QAM have been used in tens of millions of modems over the last two decades and have proven to be highly robust in the most challenging of communications environments.
	www.prnewswire.com /cgi-bin/stories.pl?ACCT=105&STORY=/www/story/126963 (548 words)

	DSP Trick: Filtering in QAM transmitters and receivers (Site not responding. Last check: 2007-10-21)
		Advantages: The textbook descriptions of QAM receivers sometimes miss practical details.
		These tricks are simply a list of possible reasons for deviating from "normal" QAM filter design.
		In general, there will be filters on the output signals (tx) and the input signals (rx), and also the bit in the middle (the channel).
	www.dspguru.com /comp.dsp/tricks/impl/qam_filt.htm (1065 words)

	Does the Dish 811 decode Cable QAM? - AVS Forum
		The QAM format being installed in P285 is the "Multiplexed" format, not the "Open" format.
		I was promised a blurb on QAM and will post it here when I get it.
		The reason they're including the Open QAM option is to allow MDU operators to insert local feeds (off-air local channels, CCTV cameras, etc) and have the receiver tune them.
	www.avsforum.com /avs-vb/showthread.php?goto=lastpost&t=553931 (570 words)

	MilwaukeeHDTV.org Forums - Wandering HD channels on TWC QAM
		On my set at least, QAM 0-505 (WDJT HD) and 0-512 (WISN DT) have moved to 109-5 (WDJT) and 109-12 (WISN).
		Both cable cards and generic QAM tuners should point to their cable channel display numbers...
		QAM channel numbers, except a 'Favorites' might help in the matter.
	www.milwaukeehdtv.org /forums/showthread.php?t=5480&goto=newpost (273 words)

	Modem Modulation (Site not responding. Last check: 2007-10-21)
		QAM phase modulates the carrier and also modulates the amplitude of the carrier.
		The baud rate used with QAM is 2400 baud half-duplex.
		For example, V.32bis (14.4 kbps) uses a 64 point constellation to transfer 6 bits per baud.
	www.thelinuxreview.com /howto/intro_to_networking/c4095.htm (581 words)

	Three-Dimensional Equalization For The 3-D Qam System With Strength Reduction (ResearchIndex) (Site not responding. Last check: 2007-10-21)
		First, the QAM equivalent for the three-dimensional case is introduced by extending the 2-D complex notation into a 3-D vector notation.
		The definition is a modification of the well known quaternions.
		Second, the 3-D QAM filtering is redefined using algorithmic strength reduction to reduce the overall complexity by about one third...
	citeseer.ist.psu.edu /275059.html (316 words)

	Business Wire: TV/COM's QAM receiver delivers 256 QAM throughp... @ HighBeam Research (Site not responding. Last check: 2007-10-21)
		TV/COM's QAM receiver delivers 256 QAM throughput capability at the same cost as 64 QAM implementation; patented TV/COM technology combines two silicon chips into single chip ASIC allowing for a 30 percent increase in data transmission in DVB compliant cable set-top box.
		The QAM receiver is a circuit board designed to be incorporated into both consumer cable set-top boxes and commercial digital cable decoders.
		TV/COM's QAM cable receiver supports variable bandwidth which provides flexibility in bandwidth allocation and throughput.
	www.highbeam.com /library/doc0.asp?DOCID=1G1:18675986&refid=holomed_1 (581 words)

	Demodulation of Cochannel QAM Signals (Site not responding. Last check: 2007-10-21)
		This paper has presented a method for demodulating a QAM signal in the presence of a second QAM interferor and intersymbol interference based upon joint maximum likelihood estimation of both the desired signal and the interferor.
		A future paper [8] will report on the use of the Viterbi algorithm as an improved method for implementing the joint maximum likelihood estimator, as well as error bounds for simple channels.
		Gooch, “Optimal Demodulation of Cochannel QAM Signals,” in preparation for submission to IEEE Trans on Communications.
	www.appsig.com /papers/l813f/813f_6.html (244 words)

	QAM - Membership
		But with the work of the QAM membership and contributions of many, we will be able to take pride in our new aviation museum.
		General Membership: An Individual membership is $25 per year; and $35 per year for family membership: Student membership is $10 per year; which serve as the basis form of support for the Quonset Air Museum.
		Benefits include unlimited access to the museum during normal operating hours and all QAM events, except fund raising banquets, a special recognition decal, and a 10% discount at the gift shop.
	users.ids.net /~qam/qam/member.htm (436 words)

	Fusion III QAM HDTV Tuner Card Reviewed :: Build Your Own PVR :: Why Tivo When you can Freevo?
		The DVICO site is severly lacking in userful prodcut info on the Fusions III QAM HDTV Tuner and the sites that they list as US distributors doesn't have much more info and is on pre-order.
		Their newest line of chips, is what allows the reception of QAM signals.
		When Dvico released the QAM version of this card, they added a daughter board which can be seen in the third picture below.
	www.byopvr.com /displayarticle117.html (1220 words)

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