
	Where results make sense

Topic: Impedance mismatch

Related Topics

Postgres

Impedance match

Impedance

Impedance bridging

Jimmy Lee

Signal reflection

Balancing network

Boat building

Attenuation

	Impedance mismatch - Wikipedia, the free encyclopedia
		Impedance mismatch is a term in systems analysis which describes an inadequate or excessive ability of one system to accommodate input from another.
		On one end of the spectrum, Impedance mismatch labels a common problem in electrical engineering that occurs when two transmission lines or circuits with different impedances are connected.
		The Object-Relational impedance mismatch is a philosophical difference that exists between object-oriented programming and the Relational Model in database technology.
	en.wikipedia.org /wiki/Impedance_mismatch (1171 words)

	Blue Jeans Cable--What is Impedance, Anyway?
		The impedance of the load is expressed in ohms, and the relationship between the current and the voltage in the circuit is controlled by the impedances in the circuit.
		These mismatched impedances redistribute the power in the circuit so that less of it is delivered to the load than the circuit was designed for--because the nature of the circuit is that it can't simply readjust the voltage to deliver the same power regardless of the rate of current flow.
		When we say that the characteristic impedance of a cable is 75 ohms--or 50, 110, 300, or what-have-you--what we mean is that if we attach a load of the specified impedance to the other end of the cable, it will look like a load of that impedance regardless of the length of the cable between.
	www.bluejeanscable.com /articles/impedance.htm (2037 words)

	Diversified Systems, Inc - Controlled Impedance - November 2001
		Discontinuities cause signal noise and impedance mismatch at increasing speeds and switching rates; as a result, the signal degrades or fails.
		In terms of PCB transmission quality, impedance mismatches cause the signal to reflect, disperse, and arrive in fragments and at uneven intervals.
		A stripline conductor with an impedance of 50 ohms could be achieved with a 12 mil trace of 1 oz.
	www.divsys.com /Newsletter/Archives/Articles/ControlledImpedance.asp (864 words)

	Rice Audio® Wired Concepts
		Wherever there is an impedance mismatch a portion of the signal is reflected back into the cable rather than being transmitted to the input (think of a wave motion striking a pool edge or looking a window at an angle).
		Typical high impedance unbalanced signal inputs have an impedance of between 10,000 and 20,000 ohms while typical high impedance outputs are actually either in the mid range or even at a relatively low impedance.
		High impedance unbalanced audio connections are most susceptible to ground fault voltages because the ground or shield is also a part of the signal pair used to carry the signal.
	mywebpages.comcast.net /riceaudio/html/Wired.html (2731 words)

	Automatic system for adjusting the output impedance of fast CMOS drivers - Patent 5095231
		The measuring of the output impedance of the reference drive is indirectly effected by inserting at the reference drive input a clock signal and by periodically measuring the output on the reference transmission line in correspondence with the positive half-period center.
		The output impedance adjustment of the reference driver is carried out by a comparator comparing the maximum voltage of a clock signal supplied by that reference driver at the input of the reference line with a reference voltage equal to half the supply voltage of the output stage of the drivers.
		The output impedance of reference driver DM is measured by measuring the input voltage of line L, which under perfect matching conditions is equal to half the supply voltage of the output stage of the driver, consisting of transistors MA and MB.
	www.freepatentsonline.com /5095231.html (2342 words)

	Understanding Impedance (Site not responding. Last check: 2007-09-17)
		The output voltage from the source is developed across the input impedance of the destination (often called the load impedance, or simply the load), and therefore the signal voltage is passed from source to destination.
		The impedance of a headphone is determined by the design of its voice coils — the length and size of wire used, the number of turns around the former, and so on.
		The use of the transformer is principally to translate the effective load impedance between that required by the valves, and that of a practical loudspeaker — a typical valve output circuit requires a load of between 5k(omega) and 10k(omega), whereas a practical loudspeaker presents a nominal impedance of between 4(omega) and 15(omega).
	www.soundonsound.com /sos/Jan03/articles/impedanceworkshop.asp (5508 words)

	InterSystems Caché - Caché Technology - White Papers - Fighting Impedance Mismatch at the Database Level (Site not responding. Last check: 2007-09-17)
		Impedance mismatch is a term borrowed from electrical engineering, but in the software world it refers to the inherent difference between the relational and object data models.
		Here is one manifestation of impedance mismatch – an object class with a collection having to be translated to the disparate tables of a relational database engine.
		Impedance mismatch – the inherent disconnect between object and relational data models – cannot be avoided, but it can be significantly mitigated by the proper choice of database technology.
	www.intersystems.com /cache/technology/whitepapers/matchwp.html (2194 words)

	InterSystems Caché - Caché Technology - White Papers - The Impedance Mismatch (Site not responding. Last check: 2007-09-17)
		Impedance mismatch is a term commonly used to describe the problem of an object-oriented (OO) application housing its data in legacy relational databases (RDBMS).
		Impedance mismatch arises from the inherent lack of affinity between the object and relational models.
		Given the increasing prevalence of the OO RDBMS impedance mismatch-and its corollary, the mismatch between SQL-based applications and object databases (OODBMS)-an examination of approaches to resolving the resulting problems is both timely and worthwhile.
	www.intersystems.com /cache/technology/whitepapers/impedance.html (2228 words)

	Tincat Group, Inc. - Mewsings, a Software Development and Data Modeling Blog
		Impedance mismatch refers to the difference between the output of one process and input of another, requiring a transformation to connect the processes.
		There is an huge impedance mismatch between the thoughts of a person and the 0's and 1's of a computer, for example.
		An impedance mismatch occurs when there is enough difference in the data model used for the output of one process and the data model employed for the input of another to require a transformer.
	www.tincat-group.com /mewsings/2006/02/dont-suffer-impedance.html (1647 words)

	LtU Classic Archives
		Pseudonym - Re: Impedance mismatch: RDBMS and PLs
		Antony Blakey - Re: Impedance mismatch: RDBMS and PLs
		Marius Amado Alves - Re: Impedance mismatch: RDBMS and PLs
	lambda-the-ultimate.org /classic/message11790.html (4878 words)

	The Object-Relational Impedance Mismatch
		In the early 1990s the differences between the two approaches was labeled the “object-relational impedance mismatch”, or simply “impedance mismatch” for short, labels that are still in common use today.
		Much of the conversation about the impedance mismatch focus on the technical differences between object and relational technologies, and rightfully so because although there are deceptive similarities there are also subtle yet important differences.
		The impedance mismatch becomes apparent when you look at the preferred approach to access: With the object paradigm you traverse objects via their relationships whereas with the relational paradigm you join the data rows of tables.
	www.agiledata.org /essays/impedanceMismatch.html (1373 words)

	The meaning of "Impedance Mismatch".
		The mismatch I refer to is a result of the differences in structure between a normalized relational database and a typical object oriented class hierarchy.
		Impedance is the measure of the amount that some object impedes (or obstructs) the flow of a current.
		Using "impedance mismatch" for the troubles you get when you try to fit a relational DB with an OO application is merely an analogy (while the two phenomenons presented above are actually the _same_ at a basic level).
	haacked.com /archive/2004/06/15/629.aspx (796 words)

	Impedance considerations for amplifiers
		One of the largest losses of power is caused by impedance differences between the output of one circuit and the input of the next circuit.
		The input impedance of circuit number 2 is represented by a resistor in series with the source.
		The input and output impedances of a transistor amplifier depend upon the configuration of the transistor.
	www.tpub.com /neets/book8/30d.htm (943 words)

	Designing controlled-impedance vias :EDNAsia.com: Voice of the electronics engineer (Site not responding. Last check: 2007-09-17)
		Board designers try to eliminate every impedance mismatch along the high-speed signal path, because those discontinuities generate jitter and decrease the data eye opening-not only reducing the maximum possible distance of data transmission, but also minimizing the margin to common jitter specifications, such as SONET (synchronous optical network) or XAUI (10Gbit attachment-unit interface).
		The formulas they derived predict the impedance exceptionally well (?2?), regardless of the board thickness, because the formula for the via impedance is independent of the board thickness.
		The TDR plot shows that the impedance mismatch of the SMA connector is the same in both cases.
	www.ednasia.com /article-339-designingcontrolledimpedancevias-Asia.html (2719 words)

	The Impedance Mismatch Between Conceptual Models and Implementation Environments
		There is a significant impedance mismatch between the underlying concepts of analysis and the concepts of object-oriented programming.
		For each mismatch we describe the issue from the conceptual modeling point of view, then from the implementation environment point of view.
		To resolve the impedance mismatches requires an extensive amount of research over an extended period of time.
	osm7.cs.byu.edu /ER97/workshop4/sw.html (3898 words)

	Antenna feedpoint impedance - Elmers Forum at eHam.net
		I use an MFJ 962C antenna tuner to match my transceiver to the this feed line, yet I would still have a mismatch at the feed point owing to the roughly 50-60 ohms at the feed point of the antenna and the 450 ohm impedance of my ladder line.
		Despite the mismatch of the ladder line to the antenna your losses are low due to using ladder line.
		For a fixed frequency the feed point impedance would be seen by the TX if the ladder line was 1/2 wavelength increment.
	www.eham.net /forums/Elmers/45561 (1158 words)

	The Basics of Signal Integrity, Part I (Site not responding. Last check: 2007-09-17)
		This impedance of the wire is extremely important, as any mismatch within the transmission path will result in a reduction in quality of the signal.
		Impedance mismatch is caused when the output impedance of the source (Z
		When the transceiver buffers are matched to the transmission media, the impedance mismatch problem is solved.
	www.altera.com /technology/signal/fundamentals/basics/sgl-basics.html (634 words)

	Zero Autoformers, Impedance Multiplying Transformers [English]
		Impedance matching between amplifiers and speakers is no less important, especially since the ability of an amplifier to control driver movement, the damping factor, is directly related to the ratio of amplifier output impedance and speaker impedance.
		In addition, when considering low impedance loudspeakers, some manufacturers specifically state that their amplifiers should not be used with planar speakers like Magnepans because the speaker impedance may dip below a level considered safe for the amplifier.
		It is easy to understand the benefits of raising the speaker's impedance for an OTL amplifier, but people have a harder time accepting the possible benefits of adding an autoformer in front of solid state amplifiers and tube amplifiers that already have multiple output taps.
	www.tnt-audio.com /accessories/zero_autoformer_e.html (2555 words)

	impedance mismatch xml - RE: What is XML For? (Site not responding. Last check: 2007-09-17)
		Objects and relations have an impedance mismatch because they are solving different problems.
		XML and objects have an impedance mismatch because they are solving different problems.
		Which is to say that in the types of applications XML is designed for, there is _almost always_ an impedance mismatch between the _shared representation_ of the data and the _in-memory_ representation that any particular application uses.
	www.stylusstudio.com /xmldev/200210/post21260.html (1325 words)

	Object-relational impedance mismatch - Wikipedia, the free encyclopedia
		The Object-relational Impedance Mismatch refers to a set of conceptual and technical difficulties which are often encountered when a relational database management system is being used by a program written in an object-oriented programming language or style; particularly when objects and/or class definitions are mapped in a straightforward way to database tables and/or relational schemata.
		Object-relational impedance mismatch is derived from the loosely related electrical engineering term impedance mismatch.
		As a result of the Object-Relational Impedance Mismatch, it is often argued by partisans on both sides of the debate that the other technology ought to be abandoned or reduced in scope.
	en.wikipedia.org /wiki/Object-Relational_impedance_mismatch (1821 words)

	Object Relational Impedance Mismatch
		Second, many of the problems purported to belong to the impedance mismatch are due to a lack of understanding of exactly what the relational model is, and how it is intended to work.
		This mismatch exists only as a result of bad designs, and because of OO people ignoring most fundamental database principles, and on a higher level because of a psychological impedance mismatch.
		"We explained the impedance mismatch problem, and claimed that the solution to that problem was not to bring the database language down to the record-at-a-time level, but rather to raise the programming language to the set-at-a-time level.
	c2.com /cgi/wiki?ObjectRelationalImpedanceMismatch (5046 words)

	Effect of Impedance Mismatch of Coaxial Connectors on System Performance
		It is capable therefore of predicting the effects of using coaxial connectors of different or incorrect Zo in the middle of, or at the end of a transmission line.
		There are two loss components: transmission loss in the connector when incorrectly terminated, and mismatch or reflection loss in the system on the side of the system nearest to the generator.
		Normally, a mismatched connector would not be used at frequencies where length of the connector approaches 1/4-wavelength at its own velocity factor.
	www.smeter.net /feeding/connect.php (537 words)

	BYTE.com
		The problem is called impedance mismatch and refers to the difference between the declarative, set-level operation o f relational-database query languages and the procedural, record-level operation of a typical 3GL (third-generation language).
		One of the most elegant solutions to the impedance mismatch problem is to augment the database's query language with procedural flow-of-control operations (e.g., WHILE loops and IF-ELSE constructs).
		But--and this is no small matter--until the impedance mismatch problem is resolved, inconsistencies will continue to exist between the ways in which the DBMS and the programming language handle data items.
	www.byte.com /art/9404/sec7/art3.htm (2750 words)

	KVR: Impedance mismatch - is this a quick and easy fix?
		There is a mismatch but I don't think it messes with the sound.
		Impedance mismatch issues are pretty much a thing of the (old and transformer-coupled) past.
		Besides, impedance mismatch issues most often present themselves as simply level changes, not as the sudden appearance of noise.
	www.kvraudio.com /forum/viewtopic.php?p=2167395 (1394 words)

	IEC: Design Considerations for Gigabit Backplane Systems
		Additional data was analyzed to ascertain the impedance mismatch’s effect on measured loss.
		The impedance mismatch was calculated by subtracting 100-Ohms (all are differential cases) from the measured impedance of the line.
		To prove this point further, 8-mil lines with varying degrees of impedance mismatch were plotted on the same graph.
	www.iec.org /online/tutorials/design_backplane/topic03.html (698 words)

	What is Impedance?
		As the length of a cable becomes closer to a large fraction of the electrical wavelength of the signal it carries, the cable can resonate at that wavelength or a closely related wavelength, and an impedance mismatch can result in portions of the signal being lost.
		How much of the signal is lost in this way is highly dependent upon frequency and the length of the cable, and this can wreak havoc, because a complex video signal is not just a single frequency, but a whole range of frequencies spread across a large bandwidth.
		The best defense against the problem is, of course, a cable of the right impedance: for digital video or SPDIF digital audio, this means a 75 ohm cable like Belden 1694A or Canare L-5CFB; for AES/EBU balanced digital audio, this means a 110 ohm cable like Belden 1800F.
	forum.ecoustics.com /bbs/messages/34579/131527.html (1879 words)

Try your search on: Qwika (all wikis)