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191 results about "Bandwidth expansion" patented technology

Bandwidth expansion is a technique for widening the bandwidth or the resonances in an LPC filter. This is done by moving all the poles towards the origin by a constant factor γ. The bandwidth-expanded filter Aʼ(z) can be easily derived from the original filter A(z) by: Aʼ(z)=A(z/γ) Let A(z) be expressed as: A(z)=∑ₖ₌₀ᴺaₖz⁻ᵏ The bandwidth-expanded filter can be expressed as: Aʼ(z)=∑ₖ₌₀ᴺaₖγᵏz⁻ᵏ In other words, each coefficient aₖ in the original filter is simply multiplied by γᵏ in the bandwidth-expanded filter.

Base station antenna and dual polarized antenna oscillator thereof

The invention relates to a base station antenna and a dual polarized antenna oscillator thereof. The dual polarized antenna oscillator comprises a radiation piece and a loading branch, wherein the surface of the radiation piece is provided with a hollow part. The dual polarized antenna oscillator has the beneficial effects that: when a feeding network is adopted to feed the radiation piece, a capacitance effect is formed between a tail end of the loading branch and the feeding network, and the capacitance effect is focused on a low frequency end of an operating frequency band; in addition, a capacitance parameter is connected in parallel with an input impedance parameter of the radiation piece, thus the operating frequency band expands towards the lower frequency band; moreover, the hollowpart is beneficial to bandwidth expansion towards a high frequency band, in this way, under the function of the loading branch and the hollow part, the dual polarized antenna oscillator can achieve wide frequency band coverage with one layer of radiation piece, thus the dual polarized antenna oscillator is simple in structure and low in section, and therefore, when the dual polarized antenna oscillator is applied to the base station antenna, miniaturization of the base station antenna can be facilitated.
Owner:COMBA TELECOM TECH (GUANGZHOU) CO LTD

FPGA (field programmable gate array)-based permanent magnet synchronous motor current loop bandwidth expansion device

The invention discloses an FPGA (field programmable gate array)-based permanent magnet synchronous motor current loop bandwidth expansion device. The device comprises a current sampling module, a Clark conversion module, a Park conversion module, a PI (proportional-integral) module, an iPark conversion module, an SVPWM (space vector pulse width modulation) module and a time sequence control module, wherein the current sampling module is used for reading current sampling values ia and ib of a phase A and a phase B; the Clark conversion module is used for converting the ia and the ib into an alpha-beta coordinate system to obtain ialpha and ibeta, the Park conversion module is used for converting the ialpha and the ibeta into a d-q coordinate system to obtain a direct axis current id and a quadrature axis current iq; the PI module is used for comparing a command current with feedback currents id and iq to obtain a current deviation value, and computing to obtain command voltages Vd and Vq in the d-axis and the q-axis; the iPark conversion module is used for converting the Vd and the Vq into an alpha-beta coordinate system to obtain Valpha and Vbeta; the SVPWM module is used for calculating a three-phase PWM duty ratio according to the Valpha and the Vbeta, and generating six paths of PWM waveforms; the time sequence control module is used for starting or closing a corresponding module according to a current control time sequence, and completing the control of the current of a permanent magnet synchronous motor. According to the device, the delay in a current control loop is greatly reduced through the optimization of a control time sequence and the design of an FPGA-based current controller, so that the bandwidth of the current loop is improved.
Owner:HUAZHONG UNIV OF SCI & TECH

Training method of voice bandwidth expansion model and voice bandwidth expansion method

The invention discloses a training method of a voice bandwidth expansion model and a voice bandwidth expansion method, wherein the voice bandwidth expansion method comprises the following steps: acquiring to-be-expanded narrowband voice; calculating an amplitude spectrum and a phase spectrum of the to-be-expanded narrowband voice, and extracting auxiliary characteristics of the to-be-expanded narrowband voice ; processing the amplitude spectrum and the auxiliary characteristics of the to-be-expanded narrowband voice by virtue of the voice bandwidth expansion model which is obtained from training, so that the amplitude spectrum of a reconstructed bandwidth voice high-frequency band can be obtained; conducting mirror image reversing on the phase spectrum of the to-be-expanded narrowband voice in a frequency domain, and determining the phase spectrum of the bandwidth voice high-frequency band; and on the basis of the amplitude spectrum and the phase spectrum of the narrowband voice, and in combination with the amplitude spectrum and the phase spectrum of the reconstructed bandwidth voice high-frequency band, determining a bandwidth voice signal. With the application of the voice bandwidth expansion method provided by the invention, an effect of improving the tone quality and naturalness of the narrowband voice can be achieved.
Owner:INST OF AUTOMATION CHINESE ACAD OF SCI

Active vibration isolation controller and design method thereof

The invention belongs to the field of technologies related with ultra-precision active vibration isolation, and discloses an active vibration isolation controller and a design method thereof. The design method comprises the following steps: (1) designing a feedback controller based on an equivalent model after acoustic emission sensor is extended to determine a bandwidth extension frequency pointof a feedback control error sensor; (2) designing the feedforward controller, and determining a bandwidth extension frequency point of a feedforward reference sensor according to a noise constraint condition, noise performance constraint condition being that the rVPSD of a load caused by noise in a feedback strategy is smaller than or equal to 0.707 times of the rVPSD of the load without the feedback strategy, and the noise constraint condition being that the noise equivalence speed of the feedforward reference sensor noise is smaller than or equal to 0.707 times of the rVPSD of foundation vibration. As low-frequency extension of the sensor and an active vibration isolation controller are unified, the stability is improved, and the control loss caused by insufficient or excessive bandwidthextension of the sensor is avoided.
Owner:HUAZHONG UNIV OF SCI & TECH

Metropolitan area network planning method

The invention relates to a metropolitan area network planning method. The method comprises the following steps of: collecting metropolitan area network output peak flow, BRAS (Broadband Remote Access Server) peak flow, IPTV (Internet Protocol Television) peak flow and SR peak flow through a network manager of the metropolitan area network, and calculating to obtain metropolitan area network exit proportion of each local area network; calculating the metropolitan area network output peak flow according to the metropolitan area network exit proportion; collecting public broadband user number, government and enterprise dial-in user number, public broadband peak user number and government and enterprise dial-in peak user number of the local area network through the network manager of the metropolitan area network, and calculating a broadband user on-line concentration ratio; calculating on-line average bandwidth used by public broadband and government and enterprise dial-in users; according to the past planning data, reckoning the average bandwidth used by public users in the few next years by using a flow curve extrapolation method. The method can accurately predict the future metropolitan area network flow, saves the network bandwidth of the metropolitan area network to the greatest extent, ensures the development of data service, greatly saves the metropolitan area network bandwidth expansion investment for operators, and has relatively good economic values and social values.
Owner:HUBEI POST TELECOMM PLANNING DESIGN

Monolithic integrated laser chip based on amplification feedback to realize straight-strip bandwidth expansion

ActiveCN104377544ADirect modulation response bandwidth extensionLaser optical resonator constructionLaser output parameters controlGratingActive layer
A monolithic integrated laser chip based on amplification feedback to realize straight-strip bandwidth expansion comprises a lower limiting layer, an active layer, an upper limiting layer, a waveguide layer, a P+electrode layer and an N+electrode layer. The active layer is manufactured on the lower limiting layer, the upper limiting layer is manufactured on the active layer, the waveguide layer is strip-shaped and longitudinally manufactured in the middle of the front of the upper limiting layer, the P+electrode layer is divided into three sections by isolating grooves and manufactured on the waveguide layer, the N+electrode layer is manufactured on the back of the lower limiting layer, the three sections of the P+electrode layer are a DFB (distributed feedback Bragg) laser area, a passive phase adjusting area and an active amplification feedback area respectively, a distribution feedback Bragg grating layer is manufactured on a portion, corresponding to the upper limiting layer, of the DFB laser area, and gain peak between the active layer corresponding to the passive phase adjusting area and the active layer corresponding to the DFB laser area and the active amplification feedback area has 90nm of blue shift. The monolithic integrated laser chip can break through limitation of straight-strip bandwidth of a common laser chip, and laser straight-strip bandwidth expansion can be realized through a method which is ingenious, effective and low in cost.
Owner:INST OF SEMICONDUCTORS - CHINESE ACAD OF SCI

Method for filling opening son (sub) tape using encoding index as well as method for generating encoding index

The present invention provides a blank sub-band filling method, which comprises: receiving a code stream, and obtaining the encoding index for the first reinforcement layer and the encoding index for the second reinforcement layer; determining the decoding information according to the encoding index for the first reinforcement layer, and determining the decoding information according to the encoding index for the second reinforcement layer; filling and smoothing the unquantized sub-band according to the decoding information, filling preliminarily the high-frequency part of the second reinforcement layer that can't be decoded according to the decoding information of the first reinforcement layer, and smoothing the filled sub-band and adjacent sub-bands. A bandwidth expansion parameter encoding method is used for the first reinforcement layer to create the encoding index; for the second reinforcement layer, the low-frequency residual error signal and high-frequency signal are converted to the frequency domain and then quantized, and the vector quantization encoding index is used as the encoding index for the second reinforcement layer. The present invention can effectively reduce the adverse effect of frequency spectrum cavity phenomenon to the decoded signals, and thereby improve the acoustic quality of the decoded signals.
Owner:WUHAN UNIV

Method for reducing peak-to-average power ratio of frequency domain forming OFDM (Orthogonal Frequency Division Multiplexing) without bandwidth expansion

InactiveCN102223341AOvercome the disadvantage of high computational complexityReduce complexityError preventionMulti-frequency code systemsFrequency spectrumEngineering
The invention discloses a method for reducing a peak-to-average power ratio of frequency domain forming OFDM (Orthogonal Frequency Division Multiplexing) without bandwidth expansion and mainly solves the problem that the peak-to-mean ratio performance of an OFDM signal showed in the prior art is too low. The method disclosed by the invention comprises the following steps of: (1) carrying out a serial-to-parallel conversion on input signals by a signal processor and obtaining signal sequences in parallel transmission; (2) multiplying a diagonal matrix and a square matrix, made up of different Chu sequences, to acquire a pre-coding matrix, and weighing the signal sequences by using the pre-coding matrix; (3) constructing a Gaussian-like function as a frequency domain forming function, and weighing the signals; (4) after carrying out a zero insertion operation and a rapid inverse Fourier transform on each data symbol, performing a parallel-to-serial conversion on the signal sequences andacquiring OFDM transmission signals suitable for transmission. The method for reducing the peak-to-average power ratio of frequency domain forming OFDM (Orthogonal Frequency Division Multiplexing) without bandwidth expansion, disclosed by the invention, has the advantages of low complexity and high utilization rate of frequency spectrum; and the peak-to-average ratio of the signals can be reducedremarkably without losing bit error rate of received signals, and the power utilization rate of a transmitter of a communication system is improved.
Owner:XIDIAN UNIV
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