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# Topic: Constellation diagram

 Quadrature amplitude modulation - Wikipedia, the free encyclopedia As for many digital modulation schemes, the constellation diagram is a useful representation and is relied upon in this article. Rectangular QAM constellations are, in general, sub-optimal in the sense that they do not maximally space the constellation points for a given energy. The circular 8-QAM constellation is known to be the optimal 8-QAM constellation in the sense of requiring the least mean power for a given minimum Euclidean distance. en.wikipedia.org /wiki/QAM   (1583 words)

 Modulation - Wikipedia, the free encyclopedia In digital modulation, the changes in the signal are chosen from a fixed list (the modulation alphabet) each entry of which conveys a different possible piece of information (a symbol). The alphabet is often conveniently represented on a constellation diagram. In analog modulation, the change is applied continuously in response to the data signal. en.wikipedia.org /wiki/Modulation   (743 words)

 SLM1456 Constellation Diagram=Digital Signal Quality The constellation diagram shows errors in the receiver’s detected level/phase points indicating transmission degradation of the RF signal. A constellation diagram may be used to illustrate the accuracy of the detected amplitude/phase levels contained in the modulated 8 VSB digital signal. The constellation diagram on the Sencore SLM1456 detects noise and interference problems which are impacting the digital TV-RF signal performance. www.sencore.com /newsletter/Nov05/ConstellDiag.htm   (1627 words)

 The Llewellyn Encyclopedia: Magic and Ritual Al Jubana The 14th Mansion of the Moon, corresponding to the constellation Libra. Al Nathrah The sixth Mansion of the Moon, corresponding to the constellation Cancer. This diagram contains ten circles representing the Sephiroth (singular: Sephirah); that is, the "spheres," "numbers," or "emanations." The Sephiroth are the numbers 1 through 10 considered in their archetypal sense. www.llewellynencyclopedia.com /subjects.php?gen_sbj=Magic+and+Ritual   (12163 words)

 QAM Defined and Example Constellation Diagrams of Digital Signal Quality Constellation diagrams are used to graphically represent the quality and distortion of a digital signal. The constellation diagram examples shown are based on 64 QAM modulation and use the following basic settings: maximum possible DVB data transmission rate of 6.92 Msps or 41.73 Mbit/s (64 QAM); Cosine roll-off filtering with roll-off factor r = 0.15 and PRBS (pseudo random binary sequence) data stream, no coding. In the constellation diagram, carrier leakage shows up as a shifting of the signal states corresponding to the DC components of the I and Q components. www.blondertongue.com /QAM-Transmodulator/QAM_defined.php   (660 words)

 WiPAN LVSA Zigbee Analysis Tools Constellation diagrams for an overall indication of signal behavior and clues to the cause of a problem. The constellation diagram example shown is based on OQPSK modulation with half sine pulse-shaping. Eye Diagram reveals the modulation characteristics of the signal and analyze impacts of impairments such as pulse shaping or channel distortions. www.wimax-industry.com /sp/slv/wipanlvsa.htm   (679 words)

 Understanding DTV transmission measurements A constellation diagram is therefore a plot of the tip of the carrier vector sampled at symbol times over a large number of carrier cycles. Figures 4, 5 and 6 are constellation diagrams of off-air signals. The length of this error vector, or its magnitude, is the hypotenuse of the right triangle formed by the I error and the Q error, as shown in Figure 7. broadcastengineering.com /mag/broadcasting_understanding_dtv_transmission   (2189 words)

 LAB303B - Constellation Displays Constellation diagrams are commonly used in analyzing the performance of data communications systems using quadrature signal-generation techniques to phase encode digital data. The constellation diagram is an X-Y display which shows the data states of phase or phase-amplitude encoded data. The constellation diagram requires an oscilloscope with X-Y displays, external sampling clock, and a persistence display, all of which are available in the LeCroy 9300 series oscilloscopes. www.lecroy.com /tm/Library/labs/LAB303b?menuid=2   (727 words)

 Draco Constellation. Mythology - Crystalinks Draco is an extended constellation of the northern hemisphere. The origin of the constellation, Draco, and of most dragon lore as well, was probably the female Chaldean dragon Tiamat, the sea serpent who existed even before the sea and sky had been divided from each other, the dragon of chaos. Theorists predicted that the light from these primordial stars would be "stretched" by the expansion of the universe, so would exist not on the ultraviolet region of the spectrum but in the lower energies of the infrared region. www.crystalinks.com /draco.html   (2393 words)

 Zenith: HDTV EVM is often expressed as a ratio, in percent, of the total RMS error normalized to the outer most data level (state) of the ideal constellation, and is just one figure of merit for the signal quality. A constellation diagram is a vector diagram showing the I-channel versus Q-channel channel signal only at symbol clock times, i.e. Constellation diagrams help identify such things as amplitude imbalance, quadrature error, or phase noise. www.zenith.com /sub_hdtv/hdtv_papers_transmission_param.html   (10409 words)

 David Cottingham: Notes on Wireless Technologies   (Site not responding. Last check: 2007-10-12) A constellation diagram is a representation of the Argand plane, with one axis representing the amplitude of the complex component of a wave, and the other the imaginary. Symbols in the transmitter's alphabet can be mapped onto the constellation diagram by means of their real and imaginary components. The greater the separation between the symbols on the Argand diagram, the less likely it is that a received signal will be misinterpreted. www.cl.cam.ac.uk /users/dnc25/wireless.html   (1120 words)

 Digital Terrestrial Television :: PROMAX ELECTRONICS T.+34 932 602 002 With the evolution of technology, advanced measurements such as the COFDM Constellation are required. In an ideal transmission channel free of noise and interfering signals, the symbols are recognised perfectly by the demodulator and appear in the constellation display as clear points located always in the same position as shown in the picture. constellation display is fast, comfortable and clear and is shown in combination with other global important measurements that describe the overall behaviour of the COFDM multiplex such as CSI (Channel Status Information) or MER (Modulation Error Ratio). www.promax.es /ing/noticias/extdnew.asp?text=37   (608 words)

 New Test Approaches for ZIF Transceiver Devices However, the constellation diagram, which must be analyzed to get the EVM value, offers a wealth of information. In the second case, a circular smearing is evident, causing the constellation to appear as though it is rotating in time. As is evident from Figure 4, constellation diagrams and the use of EVM calculations can replace numerous functional block tests and still provide good diagnostic information for the resolution of device maladies. www.evaluationengineering.com /archive/articles/0105/0105new_test.asp   (1810 words)

 Properties of the Stars Computer Exercise   (Site not responding. Last check: 2007-10-12) An HR diagram is a graph of the luminosities and temperatures of stars. If the HR diagram you plotted doesn't go to luminosities that are as low as the one in your textbook, it suggests that your not seeing these low luminosity stars. If your HR diagram you plotted doesn't go to as high a luminosity at the one in your textbook, it suggests that you're not seeing these very high luminosity stars either. info.citruscollege.com /ff/dkary/Starrynight/hrdiagram.html   (1896 words)

 The Impact of Various PLL Parameters The constellation diagram shows the relative phases of the I (in phase) and Q (in quadrature -- 90 degrees phase shift) signals. Each point on the constellation diagram corresponds to a different symbol, which could represent multiple bits. It should also be clear from this constellation diagram interpretation of RMS phase error that higher order modulation schemes are more subject to the RMS phase error of the PLL. www.national.com /nationaledge/feb01/286.html   (1565 words)

 [No title] A constellation diagram graphs the detected amplitude levels contained in the modulated 8 VSB digital signal. Ideal 8VSB constellation diagrams place dots in the center of one of eight quadrants from left to right in the display. A constellation diagram shows degradation of digital signal quality by plotting the RF carrier’s amplitude and phase points on a visual graph. www.sencore.com /newsletter/June05/AchieveGoodHDTV.htm   (1525 words)

 Radio Since the energy of an individual photon of radio frequency is too low to remove an electron from an atom, radio waves are classified as non-ionizing radiation. Electromagnetic radiation travels (propagates) by means of oscillating electromagnetic fields that pass through the air and the vacuum of space equally well, and does not require a medium of transport (such as the aether). Soon, the U.S. Navy experimented with satellite navigation, culminating in the invention and launch of the GPS constellation in 1987. www.brainyencyclopedia.com /encyclopedia/r/ra/radio.html   (4616 words)

 Constellation Plot add in for ModelSim After demodulation, the signal is usually represented as an in-phase and a quadrature component, representing the amplitude of cosine and sine components respectively. It is very helpful to view these signals on a so-called "constellation" diagram, also known as a polar plot or Argand diagram - a 2-dimensional representation with in-phase on the X axis and quadrature on the Y axis. Our constellation plot add-in is an example of how to add custom GUI functionality to ModelSim, providing a display that's not possible in the standard simulator product. www.doulos.com /knowhow/tcltk/examples/constellation   (250 words)

 Columbia Constellation Specifications   (Site not responding. Last check: 2007-10-12) The Constellation has a large fore deck and a raised cabin with two large windows on each side, and two smaller windows in the front. The drawing is too large for me to scan, but here is the modified area. Thus there is a direct path from the Charlie Morgan \ designed C-40 hull to the Constellation and C-38 hulls, which Columbia never attributed to any particular designer. www.columbia-yachts.com /consteln.html   (214 words)

 Introducing SAS/GRAPH Output for the Web : Types of Web Presentations Available A treeview diagram is ideal for displaying such data as organizational charts or the hierarchical relationships of the pages of a Web site. Like the Treeview applet, by default, the Constellation applet zooms in on the portion of the diagram that is in the center of the display, as if you were looking through a fish-eye lens. Critical success factor diagrams display the value of a variable in a SAS data set in relation to a range of values. support.sas.com /91doc/getDoc/graphref.hlp/a002136637.htm   (2030 words)

 Beating Impairments with Cable Modem Tests Figure 1 shows a constellation diagram of an unimpaired cable modem signal. The constellation diagram displays the complex amplitude and phase components of the received cable modem signal on a two-dimensional (X-Y coordinate) display, where each defined point represents multiple bits of user data. This results in the cable modem exhibiting an increased error rate as the information represented by a constellation point is altered during transmission over the HFC network. www.commsdesign.com /printableArticle?articleID=16503089   (2519 words)

 What Exactly is 8-VSB Anyway? The eye diagram is the overlay of many traces of the received RF signal amplitude at the instant of sampling. Since the RF signal must attain one of eight possible levels whenever a sampling time occurs (somewhat like when the music stops in the game of musical chairs), the convergence of the many signal traces forms seven "eyes" that coincide with the occurrence of clock pulses in the receiver. Our signal constellation diagram is therefore a series eight vertical lines that correspond to our eight transmitted amplitude levels. www.broadcast.net /~sbe1/8vsb/8vsb.htm   (4826 words)

 Time [Internet Encyclopedia of Philosophy] Feynman diagrams in particle physics were described by Feynman himself as illustrating how a particle's moving forward in time is actually its antiparticle moving backward in time. A Minkowski spacetime diagram displays only what happens before what, but not which time is present time, or past, or future. What is missing from the diagram, say Chisholm and Prior, is some moving point on the time axis representing the observer's "now" as time flows up the diagram. www.iep.utm.edu /t/time.htm   (16682 words)

 When Test Equipment Talks With Design Tools In the lower left, the blue diagram is the spectrum of the modulated signal being measured. Now we are looking at the spectrum being measured, its constellation, and its demodulated contents all at the same time. The EVM trace is a continuous measurement of the difference between the measured signal and a reference signal generated by the VSA. www.evaluationengineering.com /archive/articles/0803pcbased.htm   (1681 words)

 [No title] Explain what the bandwidth delay product is? When referring to an encoding with QAM, explain what a constellation diagram is and how it relates to data rate. What are the objectives and constraints when designing the constellation diagram for an encoding scheme? Suppose the baud rate is 8Mbaud, and QAM 64 is used with one party bit. www.eecis.udel.edu /~bohacek/Classes/419/HW/HW2.doc   (184 words)

 RTI - Constellation - Diagram   (Site not responding. Last check: 2007-10-12) Signal lines are used to describe the relationship among components within the diagram. The colored ‘ports’ are used to indicate external relationships (i.e., with components outside the diagram). A green port indicates that the data will be sent over the network using NDDS. www.rti.com /products/constellation/c_overview1.html   (43 words)

 User:Splash - Wikipedia, the free encyclopedia Spectrum of baseband signal compared to it RF equivalent. Dual constellation diagram for π/4-QPSK showing both constellations with 45° shift. One second of Rayleigh fading with a maximum Doppler shift of 10Hz. en.wikipedia.org /wiki/User:Splash   (1403 words)

 Digital Broadcast Technologies > Transmission Mechanisms   (Site not responding. Last check: 2007-10-12) Figure 4-10 shows the constellation diagram for QPSK and the symbol mapping for each phase angle and amplitude vector. The effect of interleaving is to distribute the errors due to a noise burst over a period of time so that the errored bits are no longer adjacent, which makes FEC more effective. As noise is introduced into a QAM or VSB signal, it perturbs the points on the constellation diagram so that ultimately they overlap and the decoder sees the wrong symbol. www.ciscopress.com /articles/article.asp?p=106971&seqNum=8   (3524 words)

 QAM CONSTELLATION FOR PROLINK-4 :: PROMAX ELECTRONICS T.+34 932 602 002 The QAM constellation diagram is now available as an option for the most advanced TV & Satellite Analyser in today’s market, the PROLINK-4 The constellation diagram is the result of combining I and Q signals resulting from the QAM digital demodulation. It is very useful to identify some type of problems present in the digital signal which are otherwise difficult to observe. www.promax.es /ing/noticias/extdnew.asp?text=18   (177 words)

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