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Signal and image processing algorithms rely upon assumptions about the underlying sampling process. Ideal sampling and non-overlapping finite-aperture sampling have been examined extensively in the literature. This paper examines the ramifications of spatial sampling of an image with overlapping Gaussian-response photodetectors, which models certain insect vision systems
The problem of missing samples is described in the context of a beamforming operation. Tapering a complete, uniformly spaced sequence is shown to suppress beam sidelobes, but the taper fails to suppress sidelobes when uniformity of sample spacing is destroyed by missing samples. A linear mean square estimator (LMSE) is employed to interpolate the missing samples, thereby regaining sidelobe suppression...
An improved dynamic range analog-to-digital converter (ADC) subsystem is proposed that utilizes a passive superconducting microwave dispersive filter and a digital signal processor. The signal to be converted is passed through a superconducting passive filter and the output from the filter is used as the input to a low-temperature superconductor (LTS) ADC. The dispersive filter can be made using either...
A low-temperature superconductor multi-bit implicit-sampling analog-to-digital converter (ADC) architecture is proposed for wide bandwidth RF applications. The architecture selected differs in several respects from both an explicit-sampling Nyquist ADC and an over-sampling ADC. A high-speed axis-crossing detector senses the difference between the input signal and an appropriate reference signal that...
3D mesh parameterization which converts the complicated 3D mesh to the flat and non-overlapped 2D mesh is used for "texture-mapping" in order to make the correspondence between a texture-image and a 3D mesh in 2D space, and "remeshing" in order to convert polygonal meshes to the regular grid meshes equipped with customizability. In this paper, we propose a 3D mesh parameterization...
This paper analyzes the effect of varying the characteristic parameters of the DSP frontend, on the dynamic power consumed. No significant analysis has been carried out in this direction so far. The power reduction has always been a great challenge till date and it has been at the cost of system's performance. An efficient method of sampling and quantization that can bring down the power consumption...
The scenario we address in this paper is high quality interpolation of 'talking head' lecture video. It is often desired to enlarge streaming media of this type with frame size NtimesM to a higher spatial dimension of, let's say, 2Ntimes2M. Simple interpolation methods are sometimes preferred because of complexity constraints in processing. But even in the absence of such constraints, the quality...
Previous work has shown that for super-resolution image reconstruction from low resolution images, image acquisition with a diverse optical system improves reconstructed image quality as measured by the expected and actual mean squared error. However, other measures of image fidelity should also be considered. An alternative performance measure might be based on edge errors, since edges are often...
In this contribution, we present a multiple-input multiple-output (MIMO) system employing single-carrier (SC) transmission with frequency domain preand post-processing to allow a further adaptation of the transmission. The so-called dominant eigenmode transmission (DET), which is based on the singular value decomposition (SVD) algorithm, is deployed as a typical application for such a pre- and post-processed...
This paper analyzes the impact of narrow-band interference (NBI) on the performance of multi-band (MB) OFDM ultra wideband communication systems. A comprehensive study of the effects of NBI on the analog-to-digital converter (ADC) and carrier synchronization algorithm is presented. The overall impact of NBI is demonstrated by quantifying the MB-OFDM receiver system level performance in terms of block...
To avoid significant losses that might be induced by a narrowband interference (NBI) on the performance of a multi-band (MB) OFDM ultra wideband (UWB) receiver, efficient NBI mitigation schemes are required. This paper proposes a novel mixed-mode NBI suppression scheme that relies on the cooperation between a digital NBI detector and an adaptive analog notch filter. Simulation results show that the...
This paper addresses the problem of blind de-convolution and separation of multiple independent signals. A frequency domain approach is taken wherein a criterion for separating instantaneous linear mixtures is applied at each frequency. To eliminate the permutation and scaling ambiguity across frequencies, time-domain impulse response coefficients are updated instead of weights in the frequency domain...
In this contribution we present a new subspace based technique for the separation of convolutive complex mixtures. We show that using the SVD analysis of the delayed covariance mixture matrix, we can construct a subspace projector. The mixture signals when projected in that subspace lose their memory, yielding a set of instantaneous mixtures of the same sources. The instantaneous mixture model has...
An on-line method for estimating the parameters in a stochastic differential equation model for short-term multipath fading channels is described. The differentiation operator is replaced by a difference operator, a linear regression is formed, and the parameters are estimated using recursive least squares. In a numerical study, the parameter estimates converge to the true values and the mean square...
We present a generalized approach to speaker dependent model-based single channel speech separation techniques in which a priori knowledge of the underlying speakers is used to separate speech signals. For this purpose, we add an identification stage by which we first identify the underlying speakers in the mixture and then use the identified speakers' model to separate speech signals. The proposed...
We present a computationally efficient blind equalization technique to mitigate the effects of inter-symbol interference (ISI). Our technique is based entirely on context sorting of received ISI corrupted samples of a communications system. Techniques based on rank sorting and successive rank sorting provide context based analysis of the underlying state transitions of a finite memory source channel...
In this paper we demonstrate the feasibility of blind equalization of 8-PSK sequences that have been sky wave propagated over a distance of 400 miles using the HF band. Results obtained from our measurements suggest that the channel is varying slowly enough to allow a block-based equalizer coefficient update. A comparison between blind and informed, and block-based and adaptive equalization is performed...
This paper presents a turbo receiver for wireless multicarrier code division multiple access (MC-CDMA) communication systems using maximum a posteriori expectation-maximization (MAP-EM) demodulator with a soft low-density parity-check (LDPC) decoder with pilot-aided robust channel tracking and multiuser detection under time-varying narrowband interference (NBI). It was found that the conventional...
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