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.

Electrically tunable bandpass filter

Abstract: A bandpass filter is described for filtering a television signal. The filter has a passband which may be selectively centered for filtering signals in one of two channels of the television receiver. The television channel at which the filter passband is centered is selectable by applying a voltage to a control terminal. The filter frequency response for each channel selected may be independently controlled and a linear phase response is realized for the selected channel minimizing distortion.

Method for generating a spectral noise weighting filter for use in a speech coder

Abstract: Analysis by synthesis calculates a difference by subtracting (130) synthesized speech from input speech. The synthesized speech is formed by exciting long and short term filters (124,126) with excitation vectors from a codebook store (114) which is searched by codebook generation (120). A weighting filter (132) is applied to the difference signal and the weighted difference is used to calculate an energy measure (134) which is used to control the codebook search (140). The weighting filter is an Rth-order filter controlled with calculated coefficients. The method for calculating coefficients models the frequency response of L Pth-order filters by a single Rth-order filter, where the order R ~ LxP. This method increases the control of a speech coder filter without an increase in hardware complexity.

Combined ofdm and wavelet multi-carrier transceiver

Abstract: A multi-carrier transmitter and receiver for performing data transmission. The multicarrier transmitter and receiver comprise a first inverse fast Fourier transformer for performing an Inverse Fast FourierTransf orm (IFFT) on a parallel input data signal, an imaginary component filter for filtering out the imaginary component of an output signal of the first inverse fast Fourier transformer and a real component filter for filtering out the real component of the output signal of the first inverse fast Fourier transformer. The multicarrier transmitter and receiver also comprise a first prototype filter comprising a polyphase filter having real coefficients. The first prototype filter accepts output data from the imaginary component filter. The multicarrier transmitter and receiver also comprise a second prototype filter comprising a polyphase filter having real coefficients which are selected by taking the real coefficients of the first prototype filter and inverting the sign of each odd-numbered real coefficient. The second prototype filter accepts output data from said real component filter. A combined OFDM and wavelet multi-carrier transceiver is proposed sharing an IFFT block.

A new digital filter for phasor computation. II. Evaluation [power system protection]

Abstract: The results of the evaluation of a new type of digital filter are presented in this paper. The filter theory is outlined in Part I of the paper. The new filter results from the application of a special window to the coefficients of the traditional Fourier, Cosine and Sine algorithms. It is compared in the paper with the Fourier, Cosine and Sine filters in terms of steady-state and transient responses. Extensive time-domain simulations are performed to evaluate the filter transient behavior. The new filter is shown to be more accurate than the Fourier filter for window lengths equal or greater than 3 cycles of the fundamental frequency. It retains its accuracy even for window lengths being different from multiples of one cycle. The new filter is suitable for phasor computation for the fault location and measuring functions required in digital distance relays and fault recorders.

Flat group-delay low-pass filter, mounting structure thereof, flat group-delay low-pass filter device, and optical signal receiver

Abstract: A flat group-delay low-pass filter includes a series element connected between an input terminal and an output terminal, and a shunt element with one end thereof grounded. Inductors define the series element, a parallel circuit including a capacitor and a series circuit including a resistor and a capacitor defines the shunt element. The flat group-delay low-pass filter thus eliminates the need for inserting a fixed attenuator to control the effect of reflections due to impedance mismatching between the filter and other components. The resulting flat group-delay low-pass filter and an optical signal receiver including the filter have very low manufacturing costs and component costs.