Voltage-controlled filter

About: Voltage-controlled filter is a research topic. Over the lifetime, 5514 publications have been published within this topic receiving 70872 citations. The topic is also known as: VCF.

Subband acoustic feedback cancellation in hearing aids

Abstract: A new subband feedback cancellation scheme is proposed, capable of providing additional stable gain without introducing audible artifacts. The subband feedback cancellation scheme employs a cascade of two narrow-band filters Ai(Z)and Bi(Z)ng with a fixed delay, instead of a single filter Wi(Z)and a delay to represent the feedback path in each subband. The first filter, Ai(Z), is called the training filter, and models the static portion of the feedback path in ith subband, including microphone, receiver, ear canal resonance, and other relatively static parameters. The training filter can be implemented as a FIR filter or as an IIR filter. The second filter, B?I?(Z), is called a tracking filter and is typically implemented as a FIR filter with fewer taps than the training filter. This second filter tracks the variations of the feedback path in the i?th? subband caused by jaw movement or objects close to the ears of the user.

A Compact UWB Bandpass Filter With Embedded SIR as Band Notch Structure

Abstract: In this letter, an ultrawideband (UWB) bandpass filter with a band notch is proposed. The UWB BPF (3.1-10.6 GHz) is realized by cascading a distributed high-pass filter and an elliptic low-pass filter with an embedded stepped impedance resonator (SIR) to achieve a band notch characteristic. The notch band is obtained at 5.22 GHz. It is shown that the notch frequency can be tuned by changing the impedance ratio of the embedded SIR. A fabricated prototype of the proposed UWB bandpass filter is developed. The inband and out-of-band performance obtained by measurement, EM simulation, and that with an equivalent circuit model are in good agreement.

A novel active power filter for harmonic suppression

Abstract: In this paper, a novel active power filter is proposed and implemented by using a voltage-source power converter with a series connected inductor and capacitor set. The power converter is controlled to generate a compensating voltage that is converted into a compensating current via the series connected inductor and capacitor set. The compensating current flows into the power feeder in order to suppress the harmonic currents generated by nonlinear loads. The salient advantages of the proposed active power filter are lower voltage rating of dc capacitor and power switching devices, smaller filter inductor, smaller dimension, light weight, better filter performance and low electromagnetic interference (EMI). A three-phase 100 kVA active power filter is developed to demonstrate the performance of the proposed method. The results show that the proposed active power filter has the expected performance.

A dual-passband filter of canonical structure for satellite applications

Abstract: Due to the complex arrangement of frequency plans and spatial coverages in modern satellite communication systems, channels that are noncontiguous in frequency may be amplified by a single power amplifier and transmitted to the ground through one beam. In this letter, a dual-mode canonical filter with dual-passband is presented. The filter adopts dual-mode technique for mass and volume reduction. Canonical structure is adopted for maximum zero realization. To validate the design technique, a six-pole dual-mode dual-passband filter of canonical structure for Ka-band (30/20GHz) satellite transponder is realized. The measured frequency response of the filter shows good agreement with the computed one.

Active type noise controller

Abstract: PURPOSE:To suppress the increment of arithmetic load on an arithmetic unit and to attain noise reduction precisely by predicting the divergence of a control sound source based on the update quantity of the filter coefficient of an adaptive filter. CONSTITUTION:The filter coefficient is computed so as to minimize the square e of sound pressure based on a reference signal r1m to which filter processing is applied corresponding to the number of combination of transfer relation between microphones 8a-8h and speakers 7a-7d by a microprocessor 16, and the sum computation of the square e of the sound pressure, and the filter processing is applied to a reference signal from a frequency-voltage conversion circuit 11 by the filter coefficient as updating that of the adaptive filter 13 adaptively, and the speakers 7a-7d can be driven. Therefore, since it is possible to predict the divergence of the control sound source and to operate a divergence regulation means 22, divergence phenomenon can be suppressed even when the mechanical characteristics of the speakers 7a-7d and the microphones 8a-8h are changed due to the lapse of time, or the temperature change of control space occurs, etc. Also, it is possible to suppress the increment of arithmetic load on the arithmetic unit.