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# Topic: Group delay

###### In the News (Wed 19 Jun 19)

 Group Delay - Microwave Encyclopedia - Microwaves101.com Group delay in microwave filters is another great topic, you can find more info here (thanks, Cheryl!) Filters end up contributing a lot of delay to microwave circuits, even though they are often physically very compact. Group delay consistency (unit-to-unit, over temperature, over frequency, over attenuation state) is extremely important in receivers such as monopulse, where amplitude and phase tracking is required to achieve good null depths. Group delay flatness can be an issue in waveguide, especially near the lower cutoff frequency. www.microwaves101.com /encyclopedia/groupdelay.cfm   (572 words)

 Group delay The rate of change of the total phase shift with respect to angular frequency, d θ/d ω, through a device or transmission medium, where θ is the total phase shift, and ω is the angular frequency equal to 2πf, where f is the frequency. Note: For optical fiber dispersion measurement purposes, the quantity of interest is group delay per unit length, which is the reciprocal of the group velocity of a particular mode. The measured group delay of a signal through an optical fiber exhibits a wavelength dependence due to the various dispersion mechanisms present in the fiber. www.ebroadcast.com.au /lookup/encyclopedia/gr/Group_delay.html   (131 words)

 diyAudio Forums - educated me on phase plot and group delay Group delay means the time in milliseconds (usually) the signal at that frequency is delayed versus the rest of the frequency spectrum. Group Delay is derived from the slope of the phase response in the frequency domain. He “normalizes” Group Delay into cycles of delay calculated by dividing the group delay by the period of the frequency at each point (or the frequency times the number of seconds of delay); he feels that this may be a more accurate comparator. www.diyaudio.com /forums/showthread.php?postid=814359   (733 words)

 Group Delay Measurements - Microwave Encyclopedia - Microwaves101.com Group delay is the negative-slope of the transmission phase angle with respect to frequency. One interesting plot is the S21 phase angle, after it is "unwound." The slope of this plot is the group delay. You can generally see were the group delay will not be flat, by any regions of non-linearity on the plot. www.microwaves101.com /encyclopedia/groupdelaymeasurements.cfm   (604 words)

 Prosecutors Focus on Group DeLay Created DeLay's own political action committee, Americans for a Republican Majority, was one of three officers authorized to make decisions about expenditures and contributions by Texans for a Republican Majority, state records show. DeLay's daughter was also paid by the committee to set up events, other records show. DeLay who worked for the committee and, records show, was paid with money from corporate donations. www.yuricareport.com /Corruption/TomDeLayUnderInvestigation.html   (1382 words)

 USATODAY.com - DeLay, Blunt swapped money between secretive groups   (Site not responding. Last check: 2007-09-17) When it all ended, DeLay's private charity, along with the consulting firm that employed DeLay's wife and the Missouri campaign of Blunt's son, Matt, who now is the state's governor, all ended up with a piece of the pie, according to campaign documents reviewed by The Associated Press. None of the hundreds of thousands of dollars in donations DeLay collected for the 2000 convention were ever disclosed to federal regulators because the type of group DeLay used wasn't governed by federal law at the time. DeLay worked at the firm when he made the payments, and that she had nothing to do with Blunt's group. www.usatoday.com /news/washington/2005-10-06-delay-blunt_x.htm?csp=34   (1592 words)

 PSW Sound Reinforcement Forums: LAB Subwoofer => Subs and minimal Group Delay, Decay time Sealed Boxes significantly less group delay, but If you use a Parametric eq, some sort of Linkwitz Transform, or Dual integrator EQ you add more group delay which can be the same or worse than a vented box. Group delay has two meanings, in communications it can mean the way different groups of frequencies are delayed with respect to each other AND it can define the rate of change of a systems delay, the latter view being used in audio. Group Delay is not the same as Time Delay, Group Delay is the derivative of phase thus shows the rate of change in phase, that is it shows the rate the Time Delay is changing. srforums.prosoundweb.com /index.php/m/162274/0   (3540 words)

 diyAudio Forums - Group Delay Question Group delay is nothing more than the phase characteristic corrected to frequency. Group delay is really only problem for the lowest frequencies, which one of the reasons why I much prefer sealed with a LT. Group delay is a problem over the entire spectrum, crossovers also have group delay. www.diyaudio.com /forums/showthread.php?postid=756442   (547 words)

 washingtonpost.com: S. Korean Group Sponsored DeLay Trip DeLay; his wife, Christine; and two other Republican lawmakers departed on a trip financed by the group on Aug. 25 of that year. An aide to DeLay who asked not to be named said DeLay staff members had general discussions about the trip with the ethics committee before leaving and received verbal approval. DeLay said on the report, filed Sept. 26, 2001, that his expenses for the trip were \$13,000 for transportation, \$330 for lodging, \$150 for meals and \$20 for "other." An identical accounting of expenses was provided for his wife. www.washingtonpost.com /ac2/wp-dyn/A22067-2005Mar9?language=printer   (1051 words)

 Sprint Applied Research Group - Delay Analysis Delay Distribution This graph shows the percentage of packets that experience a given network delay. delays across one routers), the distribution may present multiple spikes that, in general, are related to the size of the packets. Otherwise, minimum delay changing abruptly in the middle of the trace is a clear indication of traffic being re-routed because of a topology change. ipmon.sprint.com /delaystat   (379 words)

 Group delay - Wikipedia, the free encyclopedia It is often desirable for the group delay to be constant across all frequencies; otherwise there is temporal smearing of the signal. The degree of nonlinearity of the phase indicates the deviation of the group delay from a constant. It is therefore important to know the threshold of audibility of group delay with respect to frequency, especially if the audio chain is supposed to provide a high fidelity reproduction. en.wikipedia.org /wiki/Group_delay   (371 words)

 Fractional Delay, and Dispersion The string or bore length is related to the frequency by the velocity of the medium; in contrast, the delay line length is related to the frequency by the sampling period. A fractional delay filter is one which implements a delay that is not an integer multiple of the sampling period. The phase and group delays are equally valid means of specifying the phase response of a system--as good as the typical specification of phase versus frequency. www.owlnet.rice.edu /~elec431/projects97/Phhh/431paper.html   (1923 words)

 AlterNet: DeLay's Dirty Dozen DeLay has tried to distance himself from the group, but documents show DeLay "personally forwarded at least one large check" to the group and was "in direct contact with lobbyists for some of the nation's largest companies" on TRMPAC's behalf. Delay Pays for Golf Tournaments with Cash Meant for Kids: DeLay used a children's charity, Celebrations for Children Inc., as cover for collecting soft money from anonymous interest groups, some of which was used for "dinners, a golf tournament, a rock concert, Broadway tickets and other fundraising events" at the Republican convention in New York. DeLay that is the focus of the criminal inquiry." In December, DeLay was forced to return funds from registered lobbyists because those contributions violated House ethics rules. www.alternet.org /story/21509   (1152 words)

 Group Delay And Amplitude Characteristics from Filtronetics, Inc. The group delay of the Bessel is flat in the passband; whereas the Gaussian group delay is “bullet” shaped. The group delays of the Butterworth and Chebychev have more variation and have a somewhat inverse shape in the Passband relative to the Gaussian. The Bessel and Gaussian filters are also more sensitive to load variations which may seriously affect the good group delay or phase shift response of these filters. www.filtro.net /center/encyclopedia/delay_amp.htm   (229 words)

 Group - Wikipedia, the free encyclopedia Group (mathematics), a set together with a binary operation satisfying certain algebraic conditions in group theory. Group of galaxies, a small number of galaxies near each other; a special case is the Local Group, containing the Milky Way Galaxy. Group (sociology), a sub-set of a culture or of a society. en.wikipedia.org /wiki/Group   (196 words)

 Delay Filters by Nuhertz Technologies The frequency response magnitude of an ideal transport delay filter is unity for all frequencies, and the frequency response group delay is equal to the duration of the transport delay for all frequencies. It is frequently necessary to account for transport delay in controls applications, and it is occasionally useful to delay a signal for timing purposes. With an equiripple period of 2.0, the group delay is designed to be accurate for frequencies up to (N-1) /(T*PI) Hz where N is the order of the filter, and T is the design transport delay. www.filter-solutions.com /delay_filter.html   (220 words)

 USATODAY.com - DeLay, successor Blunt swapped donations   (Site not responding. Last check: 2007-09-17) Both groups — DeLay's and Blunt's — were simultaneously paying Ellis, the longtime DeLay fundraiser who was indicted along with his boss in Texas in the alleged money laundering scheme. The DeLay group began transferring money to Blunt's group in two checks totaling \$150,000 in the spring of 2000, well before Republicans actually met in Philadelphia for the convention. Eight days later, the Blunt group made a \$10,000 donation to DeLay's private charity for children on April 7, 2000, and began the first of several payments totaling \$40,000 to a northern Virginia-based political consulting firm formed by DeLay's former chief of staff, Ed Buckham. usatoday.com /news/washington/2005-10-05-delay-blunt-funds_x.htm?csp=34   (1554 words)

 Statistical Research & Applications - CanQues To reduce the number of parameters that have to be estimated and to achieve stability in the tails of the delay distributions, an assumption is made that all cancer cases will be reported within 24 years of diagnosis. The delay distributions were modeled as a function of covariates using a discrete-time proportional hazards model. For each cancer site, a delay distribution was calculated for all races combined and a separate delay distribution was calculated for whites and fls. srab.cancer.gov /delay/covariates.html   (557 words)

 Phase Delay and Group Delay Since LTI filter analysis is based on sinusoids without beginning or end, one cannot in principle distinguish between ``true'' phase delay and a phase delay with discarded sinusoidal periods. For linear phase responses, the group delay and the phase delay are identical, and each may be interpreted as time delay. At this point, it is evident that the group delay at the carrier frequency gives the slope of the linear phase of the translated spectrum. www.technick.net /public/code/cp_dpage.php?aiocp_dp=guide_dft_phase_delay_group   (445 words)

 Noncausality and the Group Delay Parameter (Communications Toolbox)   (Site not responding. Last check: 2007-09-17) This delay, known as the filter's group delay, is the time between the filter's initial response and its peak response. This delay is set so that the impulse response before time zero is negligible and can safely be ignored by the function. Comparing filtered with unfiltered data might be easier if you delay the unfiltered signal by the filter's group delay. www.phys.ufl.edu /docs/matlab/toolbox/comm/tutor217.html   (230 words)

 Klipsch Forums - So what is "Group Delay" anyway?   (Site not responding. Last check: 2007-09-17) In a perfect world there would be no group delay and full range,point source would be the summum of perfection.In the real world the engineers have to work to minimize group delay or at least keep it in check,if I may say. One thing I do know is that group delay does amount to some level of "time delay" in the sense that the impulse of the wave arrives later (versus the arrival time of an impulse with less group delay). Generally speaking, it is desirable for the group delay (rate of change of phase) to be constant across all frequencies; otherwise there is temporal smearing of the signal. forums.klipsch.com /forums/thread/804979.aspx   (2115 words)

 Rane Professional Audio Reference (G) groups (aka subgroup or submix) A combination of two or more signal channels gathered together and treated as a set that can be varied in overall level from a single control or set of controls. group delay Same as envelope delay [technically the time interval required for the crest of a group of waves to travel through a 2-port network -IEEE.] The rate of change of phase shift with respect to frequency. Note that pure signal delay causes a phase shift proportional to frequency, and is said to be "linear phase," or "phase linear." In acoustics, such a system is commonly referred to as a "minimum phase" system. www.rane.com /par-g.html   (1803 words)

 Ultrashort pulse propagation at the photonic band edge: Large tunable group delay with minimal distortion and loss We define group delay by d=(n(g) — 1)L, where L is the length of the sample. We obtained experimental verification of the predictions by measuring the group delay as a function of sample orientation relative to the direction of incidence of the ultrashort optical pulse (see Fig. We determined the delay due to the PBG structure by etching off the crystal's superstrate in one region of the sample, measuring the net optical delay for the substrate with the layered structure, and then the delay for the substrate alone. www.uah.edu /LSEG/past3.htm   (2117 words)

 Delay Equalizers by Nuhertz Technologies If the all pass poles and zeros are positioned strategically, the group delay of the pass band can be flattened. The effect on the group delay can be seen in real time if the RTC box on top of the pole/zero plot is checked. The bulge on the group delay is objectionable in many frequency applications. www.filter-solutions.com /delay.html   (619 words)

 Discussion of Group Delay in Loudspeakers As the delay is reduced further there would come a point where the "delay distorted" or "time smeared" version was indistinguishable from the original recording. group delay is a well defined variation on the concept of "time delay". This can be calculated from group delay by dividing the group delay by the period of the frequency at each point. www.trueaudio.com /post_010.htm   (2252 words)

 True Audio: Bass List Page 2, group delay comparisons At the bottom of the page is a screen shot showing comparisons of the frequency response and group delay for three closed boxes which differ only in their low end bandwidth. This delay that changes with frequency is also what can muck up the shape of a square wave as it passes through a filter. Yes, as Dan notes, the group delay that a closed box loudspeaker exhibits at its corner frequency does increase as the corner frequency is lowered. www.trueaudio.com /basslst2.htm   (1195 words)

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