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Topic: Output feedback

	Feedback
		In cybernetics and control theory, feedback is a process whereby some proportion or in general, function, of the output signal of a system is passed (fed back) to the input.
		Feedback is observed or used in various areas dealing with complex systems, such as engineering, economics, and biology.
		Feedback may be negative, which tends to reduce output, or positive, which tends to increase output.
	www.mp3.fm /Feedback.htm (1463 words)

	Wilf Rigter on Schmitt triggers
		Feedback, as the name implies, occurs when a process or interaction is recursively modified by the output or result that it generates.
		The output signal at the PNP collector is non-inverting with respect to the input signal.
		The positive feedback signal at one end of the 3M feedback resistor is alternately Vcc or Gnd depending on the state of the non-inverted output signal at the collector of the PNP transistor.
	www.solarbotics.net /bftgu/tutorials_schmitt.html (2681 words)

	Linear switching regulator - Patent 4292581
		To maintain a constant voltage at the output, the regulator has a network between the input and the output, referred to as the voltage compensation network, and the voltage drop across this network is controlled by the error voltage which is obtained by comparing the output with a reference.
		In general the regulation of the output by voltage feedback is not a good way to balance the two currents, because the inductor current and the output are not in phase, particularly for a high Q low pass filter.
		The output on line 520 is fedback to the negative input of operation amplifier 502 on line 518 via voltage divider composed of resistors 506 and 508 for adjusting the gain of the amplifier system to obtain the proper damping factor k'.
	www.freepatentsonline.com /4292581.html (10384 words)

	Output feedback and under-voltage detection - Patent 6147883
		The feedback signal is used to modulate the duty cycle of the IC regulator or used to allow or disallow cycles in order to control the secondary output.
		The output of the current source 102 is provided to a node 109 which is connected to the drain of a transistor 106.
		One output of the secondary winding of transformer 134 is provided to a Schottky diode 136 which is connected to a capacitor 138.
	www.freepatentsonline.com /6147883.html (4315 words)

	Feedback and fidelity part 1
		Feedback may be as stylish as a ‘63 Dodge Dart, but it’s a dear friend who’s brought beauty and joy to my life.
		The amount of feedback, expressed in decibels (dB), is the ratio of the gains without and with feedback (the open and closed-loop gains): 6dB is a factor of 2 in voltage (4 in power); 20dB is a factor of 10 in voltage (100 in power), etc.
		Feedback is particularly touchy in single-ended circuits because the output transformer cutoff frequency is so close to the top of the audible range.
	www.normankoren.com /Audio/FeedbackFidelity.html (3844 words)

	Some Remarks on Real and Complex Output Feedback
		We exhibit a non-trivial real linear system which is not controllable by real static output feedback and discuss a conjecture from algebraic geometry concerning the existence of real linear systems for which all static feedback laws are real.
		This non-trivial example of a real system which is not controllable by real static output feedback, while presented in the paper (pages 5 and 6 of the manuscript above), is not easy to verify by hand.
		The first vector records the frequency; its (j+1)th component is the number of systems generated with 2j real feedback laws, and the second vector similarly records the percentages.
	www.nd.edu /~rosen/pole/index.html (609 words)

	Feedback Circuits
		The output of a block is the input multiplied by the transmittance written in the block.
		If the output port is driven by a voltage or current, no change occurs at the input port, and the reverse transmittance through the amplifier is zero.
		The transmittances of the general feedback block diagram are found by first finding the equivalent circuits of upper and lower two-port networks shown in the general feedback circuit.
	www.innovatia.com /Design_Center/Feedback_Circuits.htm (2863 words)

	Elements of Feedback Control Chapter 3
		Posi- tion feedback is that type of feedback employed in a system in which the output is either a linear distance or an angular displacement, and a portion of the output is returned or fed back to the input.
		In the case of rate (velocity) feedback, a portion of the output displacement is differentiated and returned so as to restrict the velocity of the output.
		To achieve a relatively rapid response and a minimum of overshoot, the choice of the viscosity of the fluid and the strength of the spring is critical.
	www.fas.org /man/dod-101/navy/docs/fun/part03.htm (2947 words)

	Linear Feedback Shift Registers
		Output) During a shift, the bit on the far right end of the shift register is moved out of the register.
		By definition, the selected bit values are collected before the register is clocked and the result of the feedback function is inserted into the shift register during the shift, filling the position that is emptied as a result of the shift.
		By convention, the output bit of an LFSR that is n bits long is the nth bit; the input bit of an LFSR is bit 1.
	homepage.mac.com /afj/lfsr.html (1687 words)

	Feedback - a key concept in Economics and Management (Site not responding. Last check: 2007-11-02)
		In this sense, negative feedback loops are (ceteris paribus) auto-regulating.
		It is generally agreed that a decision maker receiving positive feedback tends to be motivated and to continue with the previously chosen course of action only slightly modifying it.
		timing when feedback is given; generally, feedback can be obtained either immediately after the decision making or be delayed (shortly after the decision), or be postponed (delivered much time after the decision making action), or not be delivered at all; for a discussion see this paper.
	www.economicswebinstitute.org /glossary/feedback.htm (1706 words)

	Output - Wikipedia, the free encyclopedia
		Output may also be used as a noun for information transmitted by a source (object).
		In this context, feedback and output are often used interchangeably.
		However, output tends to refer specifically to explicit output, something that is intentionally provided for the user, whereas feedback also encompasses byproducts of operation that happen to contain information (see low-key feedback).
	en.wikipedia.org /wiki/Output (301 words)

	Negative feedback - Wikipedia, the free encyclopedia
		In contrast, positive feedback is a feedback in which the system responds in the same direction as the perturbation, resulting in amplification of the original signal instead of stablizing the signal.
		Both positive and negative feedback requires a feedback loop to operate, as opposed to feedforward, which does not rely on a feedback loop for its control of the system.
		Note that negative feedback is used to "stabilize" the system, not in amplifying the signal, whereas positive feedback is used to amplify the signal itself (which may lead to instability).
	en.wikipedia.org /wiki/Negative_feedback (678 words)

	Positive feedback - Chapter 8: OPERATIONAL AMPLIFIERS - Volume III - Semiconductors (Site not responding. Last check: 2007-11-02)
		The basic principle of negative feedback is that the output tends to drive in a direction that creates a condition of equilibrium (balance).
		Whether the output is directly fed back to the inverting (-) input or coupled through a set of components, the effect is the same: the extremely high differential voltage gain of the op-amp will be "tamed" and the circuit will respond according to the dictates of the feedback "loop" connecting output to inverting input.
		Unlike negative feedback, where the output voltage is "fed back" to the inverting (-) input, with positive feedback the output voltage is somehow routed back to the noninverting (+) input.
	www.allaboutcircuits.com /vol_3/chpt_8/12.html (1143 words)

	Magnetic Coupling \| Magnetic Feedback Ranks High In Military Converters - magnetic coupling
		The advantages of this type of magnetic feedback are that it can be implemented by simply adding an extra winding with little or no physical size increase to the output inductor, and the feedback control voltage is actually the “unified voltage” of all coupled inductors in multiple output converters.
		During the interval when the output voltage is to be sampled, a current source is connected to the output winding of T3 through Q2, causing a voltage to appear at both windings of T3 that increases until CR2 becomes forward biased into the emitter of Q3.
		In practice, the forward sampling magnetic feedback technique has been found to allow somewhat smaller geometry of the feedback magnetics than the flyback technique, although both types of feedback have the advantage of being independent of the load current effect, which tends to limit the load current range of the direct sampling magnetic feedback technique.
	powerelectronics.com /mag/power_magnetic_feedback_ranks/index.html (2252 words)

	Error feedback.
		It can be seen that the input and output of the output stage are again compared, the positive and negative paths being shown by arrows, and with suitable choice of R and gm they can be subtracted and the difference extracted.
		The error feedback method however merely requires an accurate unity gain stage to reduce e to zero and achieve zero distortion, which at least appears to be possible in principle.
		The unity gain differential amplifier in the conventional error feedback circuit has unity gain for both inverting and non-inverting feedback paths, and as shown this is not essential for error cancellation, it is only the positive feedback loop which needs unity gain.
	www.angelfire.com /ab3/mjramp/errorfb.html (2444 words)

	Essay
		As explained in our primer, negative feedback essentially creates a process which compares the output signal to the input signal, derives a difference signal, inverts it (hence the negative term) and applies that to the input of the device.
		global feedback loops the output stage of the entire amplifier to the input stage of the entire amplifier, so that the correction signal affects the entire chain in between and, likewise, the entire chain affects that correction.
		Because of this, the total error which the feedback loop must address, including the high frequency cutoff phase error, is the sum of all the gain stages of the system, which gets a few designers in trouble for reasons already mentioned.
	www.hometheaterhifi.com /volume_5_4/essaynegativefeedbackoctober98.html (1319 words)

	OASYS PCI Avoiding Feedback Loops
		The OASYS PCI S/PDIF output is connected to the DAT's input, and the DAT's S/PDIF output is connected to the OASYS PCI's input.
		Feedback can conceivably happen whenever a digital or analog audio device is bi-directionally connected to the OASYS PCI.
		Once the inputs are muted and the feedback is stopped, you can track down the actual cause of the feedback loop, and then set up monitoring again as desired.
	www.korg.com /oasys_pci_faq_html/oasys_pci_feedback_loops.htm (416 words)

	FIPS 81 - Des Modes of Operation
		OUTPUT FEEDBACK (OFB) MODE FIGURES (The figures for this document are not available at this time.) Figure 1.
		The resulting output block, which equals the original input block to the DES during encryption, is exclusive-ORed with the IV (must be same as that used during encryption) to produce the first plain text block, i.e., (D1,D2,...,D64)= (O1 IV1,O2 IV2,...,O64 IV64).
		The Output Feedback (OFB) mode is an additive stream cipher in which errors in the cipher text are not extended to cause additional errors in the decrypted plain text.
	www.itl.nist.gov /div897/pubs/fip81.htm (6653 words)

	Output Feedback - AMwiki
		In the last chapter we considered the use of state feedback to modify the dynamics of a system through feedback.
		In this chapter we show how to use output feedback to modify the dynamics of the system, through the use of state estimators (also called "observers").
		A state feedback controller and linear observer can be combined to form a stabilizing controller for a reachable and observable linear system by using the estimate of the state in the feedback control law.
	www.cds.caltech.edu /~murray/books/AM05/wiki/index.php?title=Output_Feedback (437 words)

	[No title]
		New telnet AUTHENTICATION mechanisms may specify alternative methods for determining the keys to be used for this cipher suite in their specification, if the session key negotiated by that authentication mechanism is not a DES key and and where this algorithm may not be safely used.
		Security Considerations Encryption using Output Feedback does not ensure data integrity; an active attacker may be able to substitute text, if he can predict the clear-text that was being transmitted.
		Acknowledgments This document was based on the "Telnet Encryption: DES 64 bit Output Feedback" document originally written by Dave Borman of Cray Research with the assistance of the IETF Telnet Working Group.
	www.ietf.org /rfc/rfc2948.txt (1279 words)

	EDN Access--04.10.97 Handy tool troubleshoots feedback loops
		One of the more difficult aspects of power-supply design is stabilizing the feedback control loop.
		The circuit in (a) illustrates the basic gain-reduction concept; the circuit in (b) includes all the necessary regulator components.
		Attaching a few more components to the output divider of the circuit in Figure 1 reduces open-loop gain by more than 6 dB without affecting the regulated output voltage.
	www.edn.com /archives/1997/041097/08di_06.htm (395 words)

	CDC2000 Output Feedback of Nonlinear Systems (Site not responding. Last check: 2007-11-02)
		We introduce a new output feedback controller for general MIMO nonlinear systems which are only observable on regions of the state and input spaces.
		The nonlinear formulation is used to derive a simple characterization of stabilizing static output feedback control laws for linear systems in terms of the intersection of two convex sets and a (generally) non-convex set.
		This paper is concerned with the output feedback stabilization of a class of nonholonomic systems in port-controlled Hamiltonian formulae via generalized canonical transformations.
	www.mm.anadolu.edu.tr /ieeecss/39cdc/CD00S156.HTM (860 words)

	Boolean logic processor without accumulator output feedback (US4331893)
		A clocked digital Boolean processor which responds to operation code signals and to successive single bit input (operand) signals to drive a single bit accumulator to output the successive answers of chained Boolean operations.
		The drawings and specification of the Parent Case are here incorporated by reference to provide background of or essential material for the invention and to illustrate one environment in which the invention here claimed finds advantageous use.
		A clocked accumulating logic processor without feedback and responsive to a single bit input signal (LB) for converting a single bit logic answer signal (LA) to the result of a "load", "and", "or" or "exclusive or" operation represented by function code signals, said processor comprising, in combination:
	www.delphion.com /details?pn10=US04331893 (510 words)

	CDC2000 Nonlinear Output Feedback Control (Site not responding. Last check: 2007-11-02)
		By means of the forwarding design method, it is shown that a simple feedback on the new coordinate attains the global output regulation through singularities.
		This paper deals with global output regulation of uncertain nonlinear systems affected by disturbances which are generated from a known exosystem.
		The information needed for the control design is that the uncertain system satisfies the geometric conditions for the output feedback form with stable zero-dynamics and the parameterization is linear for unknown constant parameters and the unmeasurable disturbances.
	www.mm.anadolu.edu.tr /ieeecss/39cdc/CD00S125.HTM (479 words)

	Summary Output Viewer - Feedback & Questions.
		I had a chance to try the new Output Viewer program and everything seemed to work fine.
		This is necessary to install the correct DLLs that the Output Viewer program requires.
		Thanks for the feedback on the output viewer program.
	www.bossintl.com /forums/showthread.php?threadid=8072 (502 words)

	New Computational Procedure to the Pole Placement Problem by Static Output Feedback -- from Mathematica Information ...
		The authors report on a study of the pole placement problem via static output feedback for linear time-invariant multivariable systems from a geometric point of view.
		The main tool for this analysis is a novel formulation of the equations characterising the solution.
		This allows an explicit expression of the output feedback gain matrix K. A computational procedure to find the matrix K is given that does not require restrictive assumptions on the open- and closed-loop system.
	library.wolfram.com /infocenter/Articles/2166 (117 words)

	Welcome to S Janardhanan's Homepage (Site not responding. Last check: 2007-11-02)
		In order to shield it against the effects of disturbances, and dampen the oscillations caused due to this inherent flexibility,a controller is needed.
		The aim of this project was to study the feasibility of the design of such a controller using the robust control technique of ‘Fast Output Sampling’.
		The aim of this project is to design such a controller using the robust control technique of ‘Fast Output Sampling’.
	www.sc.iitb.ac.in /~janas (1099 words)

	OFB: Output Feedback (Site not responding. Last check: 2007-11-02)
		In cryptography, output feedback (OFB) is a mode of operation for a block cipher.
		It has some similarities to the ciphertext feedback mode in that it permits encryption of differing block sizes, but has the key difference that the output of the encryption block function is the feedback (instead of the ciphertext).
		The XOR (exclusive OR) value of each plaintext block is created independently of both the plaintext and ciphertext.
	www.javvin.com /networksecurity/OFB.html (79 words)

	Simultaneous output feedback stabilization of time-delay systems -- Mahmoud and Nounou 23 (2): 211 -- IMA Journal of ...
		Simultaneous output feedback stabilization of time-delay systems -- Mahmoud and Nounou 23 (2): 211 -- IMA Journal of Mathematical Control and Information
		IMA Journal of Mathematical Control and Information Advance Access originally published online on November 10, 2005
		feedback stabilization using static output feedback (SOF) control
	imamci.oxfordjournals.org /cgi/content/abstract/23/2/211 (247 words)

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