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Frequency response

About: Frequency response is a research topic. Over the lifetime, 25705 publications have been published within this topic receiving 332249 citations.


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Patent
18 Mar 1988
TL;DR: In this paper, a system for calibrating vector corrected electrical measurements to adjust for distortion due to reactance in the measuring circuit, particularly that caused by variable positioning of a circuit element, such as probe or coupling, is presented.
Abstract: A system for calibrating vector corrected electrical measurements to adjust for distortion due to reactance in the measuring circuit, particularly that caused by variable positioning of a circuit element, such as probe or coupling. Initial error factors for directivity, source match, and frequency response, respectively, normally calculated from assumed reflection coefficients of respective primary impedance standards, are adjusted to correct for such reactance. Reflection coefficient measurements (magnitude and phase) of a further impedance standard, different from the primary standards, are obtained at multiple frequencies and corrected by the initial error factors. The corrected magnitude and phase measurements of the further impedance standard are compared with theoretical magnitude and phase values which very linearly with frequency, and the initial error factors are adjusted so as to minimize any deviation of the corrected measurements from the linear values. Thereafter, by positioning the probe or other circuit element relative to a device under test substantially identically to its previous placement relative to the further impedance standard, the adjusted error factors can be used to obtain corrected measurements with minimized magnitude and phase errors due to reactance.

68 citations

Journal ArticleDOI
TL;DR: In this paper, a nonlinear control technique that has one-cycle response, does not need a resetable integrator in the control path, and has nearly constant switching frequency is proposed.
Abstract: This paper proposes a new nonlinear control technique that has one-cycle response, does not need a resetable integrator in the control path, and has nearly constant switching frequency. It obtains one-cycle response by forcing the error between the switched variable and the control reference to zero each cycle, while the on and off pulses of the controller are adjusted each cycle to ensure near constant switching frequency. The small switching frequency variation due to changes in the reference signal and supply voltage and delays in the circuit are quantified. Using double-edge modulation, the switching frequency variation is further reduced, thus, the associated signal distortion is minimized. An experimental 0-20 kHz bandwidth 95 W RMS power audio amplifier using the control method demonstrates the applicability of this control technique for high-fidelity audio applications. The amplifier has a power supply ripple rejection (PSRR) of 63 dB at 120 Hz. Additionally, the total harmonic distortion plus noise (THD+N) is less than 0.07% measured with a power supply ripple of 15%.

68 citations

Journal ArticleDOI
TL;DR: An electromagnetic actuator weighing 2.6 g and operated up to resonant frequencies in excess of 70 Hz is presented with the intended application to flapping-wing MAVs, predicting lift-to-weight ratios well above one for a wide range of the parameter space.
Abstract: An electromagnetic actuator weighing 2.6 g and operated up to resonant frequencies in excess of 70 Hz is presented with the intended application to flapping-wing MAVs. Comprised of a single electromagnetic coil, a permanent magnet rotor, and a “virtual spring” magnet pair, system resonance is achieved using a periodic excitation voltage applied to the coil, resulting in harmonic wing motion. Analytical models describing the electrodynamic interactions of system components and flapping-wing aerodynamic mechanisms are used to develop the equations governing the system's dynamics. Preliminary analysis based on simulation is used to build a working prototype from which further validation is conducted. Wing kinematics and mean lift measurements from the prototype demonstrated a lift-to-weight ratio of over one at 24 V. Based on a simplified equation of motion, approximate solutions for primary resonance mode and peak-to-peak (pk–pk) stroke amplitude were determined using the method of multiple time scales. Validated from frequency response experiments conducted on bioinspired test wings, these approximate solutions are used as a basis for an optimization framework. Finally, the developed framework is used to investigate the performance of the proposed actuator at different scales, predicting lift-to-weight ratios well above one for a wide range of the parameter space.

68 citations

Journal ArticleDOI
TL;DR: In this article, an iterative linear programming approach is presented to design stable IIR digital filters with prescribed magnitude and phase responses, where the complex error of the frequency response is transformed into a linear form by treating the denominator polynomial obtained from the preceding iteration as part of the weighting function, and the poles restricted inside the unit circle by using a set of linear constraints.
Abstract: In this work, an iterative linear programming approach is presented to design stable IIR digital filters with prescribed magnitude and phase responses. At each iteration, the complex error of the frequency response is transformed into a linear form by treating the denominator polynomial obtained from the preceding iteration as a part of the weighting function, and the poles restricted inside the unit circle by using a set of linear constraints. After solving the standard linear programming problem at each iteration, the design algorithm converges to the minimax solution. Design examples demonstrate that our method provides better design results than the conventional linear programming method.

68 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023154
2022389
2021857
20201,105
20191,212
20181,152