261,582 research outputs found
On Implementation and Design of Filter Banks for Subband Adaptive Systems
No full textThis paper introduces a polyphase implementation and design of an oversampled K-channel generalized DFT (GDFT) filter bank, which can be employed for subband adaptive filtering, and therefore is required to have a low aliasing level in the subband signals. A polyphase structure is derived which can be factorized into a real valued polyphase network and a GDFT modulation. For the latter, an FFT realization may be used, yielding a highly efficient polyphase implementation for arbitrary integer decimation ratios N <= K. We also present an analysis underlining the efficiency of complex valued subband processing. The design of the filter bank is completely based on the prototype filter and solved using a fast converging iterative least squares method, for which we give examples. The design specifications closely correspond with performance limits of subband adaptive filtering, which are under-pinned by simulation results
A Generalised Linear and Nonlinear Spline filter
No full textIn this paper, a generalised spline filter, that has a unified description for both the linear spline filter and the nonlinear robust spline filter, is proposed. Based on the M-estimation theory, the general spline filter model can be solved by using an Iterated Reweighted Least Squared method which is also general for both the linear and nonlinear spline filter. The algorithm has been verified to be effective, efficient and fast
Design of Near Perfect Reconstruction Oversampled Filter Banks for Subband Adaptive Filters
No full textIn this brief, a design algorithm for real-valued and complex-valued oversampled filter banks which yield a low level of inband alias and enable simple subband adaptiv structures is presented. The filter banks are either based on complex modulation of a real-valued low-pass prototype or on the direct or modulated setups of real-valued filter banks. If real-valued filter banks are required, then the different channels will have different subsampling ratios so that the bandpass sampling theorem is not violated. This brief also presents design examples of real-valued and complex-valued filter banks
Analogue Filter IP Cores for Design Reuse
No full textThis paper addresses important considerations concerning the design of analogue filters, to ensure their suitability for use in a system on chip environment as intellectual property filter cores. We argue that switched-current is the most suitable circuit design technique and furthermore that the wave filter design methodology is favourable over an integrator approach. To speed up the design process some level of automation is clearly necessary and a system implemented in the SKILL language and within the Cadence Design Framework is particularly attractive given the access to powerful circuit analysis tools. A design flow is presented encompassing all of these attributes
Comparative assessment of grid-spacing-based filter width formulations for Very Large Eddy Simulation
No full textWhen applying hybrid LES/RANS turbulence models the relevant filter width plays a crucial role concerning switching between different operating modes. Presently, the influence of the filter width and the choice of the corresponding criterion within the so-called VLES (Very Large Eddy Simulation) computational framework is investigated. Results obtained by using three eddy-viscosity-based background RANS models in conjunction with different filter-width formulations and two representative wall-bounded flow configurations are presented
Subthreshold FIR Filter Architecture for Ultra Low Power Applications
No full textSubthreshold design has been proposed as an effective technique for designing signal processing circuits needed in wireless sensor nodes powered by sources with limited energy. In this paper we propose a subthreshold FIR architecture which brings the benefits of reduced-leakage energy, reduced minimum energy point, reduced operating voltage and increased operating frequency when compared with recently reported subthreshold designs. We shall demonstrate this through the design of a 9-tap FIR filter operating at 220mV with operational frequency of 126kHz/sample consuming 168.3nW or 1.33pJoules/sample. Furthermore, the area overhead of the proposed method is less than that of the transverse structure often employed in subthreshold filter designs. For example, a 9-tap filter based on transverse structure has 5X higher area than the filter designed using our proposed method
Fast Implementation of Oversampled Modulated Filter Banks
No full textThis paper presents an efficient implementation of oversampled filter banks derived from a prototype filter by modulation. Via a polyphase analysis, redundancies in the filter operations are removed. With some modifications, a very simple and efficient implementation is found, which is briefly compared to existing realisations
On the Design of Oversampled Filter Banks for Channel Coding
No full textOversampled filter banks have been considered for channel coding, because they introduce redundancy into the subband representation of signals and permit more freedom in their design than critically sampled structures. In this paper, based on the knowledge of the channel noise's covariance matrix, we propose a constrained design for the synthesis filter bank in order to minimise the noise power in the decoded signal, subject to admitting perfect reconstruction. For the special case of paraunitary filter banks, a suboptimal iterative design is presented, which highlights the potential benefits of this approach, as demonstrated by a design example
Paraunitary oversampled filter bank design for channel coding
No full textOversampled filter banks (OSFBs) have been considered for channel coding, since their redundancy can be utilised to permit the detection and correction of channel errors. In this paper, we propose an OSFB-based channel coder for a correlated additive Gaussian noise channel, of which the noise covariance matrix is assumed to be known. Based on a suitable factorisation of this matrix, we develop a design for the decoder's synthesis filter bank in order to minimise the noise power in the decoded signal, subject to admitting perfect reconstruction through paraunitarity of the filter bank. We demonstrate that this approach can lead to a significant reduction of the noise interference by exploiting both the correlation of the channel and the redundancy of the filter banks. Simulation results providing some insight into these mechanisms are provided
A hybrid active filter for damping of harmonic resonance in industrial power systems
No full textThis paper proposes a hybrid active filter for damping of harmonic resonance in industrial power systems. The hybrid filter consists of a small-rated active filter and a 5th tuned passive filter. The active filter is characterized by detecting the 5th harmonic current flowing into the passive filter. It is controlled in such a way as to behave as a negative or positive resistor by adjusting a feedback gain from a negative to positive value, and vice versa. The negative resistor presented by the active filter cancels a positive resistor inherent in the passive filter, so that the hybrid filter acts as an ideal passive filter with infinite quality factor. This significantly improves damping the harmonic resonance, compared with the passive filter used alone. Moreover, the active filter acts as a positive resistor to prevent an excessive harmonic current from flowing into the passive filter. Experimental results obtained from a 20 kW laboratory model verify the viability and effectiveness of the hybrid active filter proposed in this paper </p
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