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Vocal signal digital processing. Instrument for analog to digital conversion study  [PDF]
Ovidiu-Andrei Schipor,Felicia-Florentina Giza
Computer Science , 2014,
Abstract: The goal of this article is to present interactive didactic software for analog to digital conversion using PCM method. After a short introduction regarding vocal signal processing we present some method for analog to digital conversion. The didactic software is an applet that can be direct accessed by any interested person.
Analog-to-digital conversion of information in the retina  [PDF]
Andrey N. Volobuev, Eugeny. S. Petrov
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.31007
Abstract: We considered the physiological mechanisms of functioning of the retina’s neural network. It is marked that the primary function of a neural network is an analog-to-digital conversion of the receptor potential of photoreceptor into the pulse-to-digital signal to ganglion cells. We showed the role of different types of neurons in the work of analog-to-digital converter. We gave the equivalent circuit of this converter. We researched the mechanism of the numeric coding of the receptor potential of the photoreceptor.
Analog-to-Digital and Digital-to-Analog Conversion with Memristive Devices  [PDF]
Y. V. Pershin,E. Sazonov,M. Di Ventra
Physics , 2011, DOI: 10.1049/el.2011.3561
Abstract: We suggest a novel methodology to obtain a digital representation of analog signals and to perform its back-conversion using memristive devices. In the proposed converters, the same memristive systems are used for two purposes: as elements performing conversion and elements storing the code. This approach to conversion is particularly relevant for interfacing analog signals with memristive digital logic/computing circuits.
Quantum digital-to-analog conversion algorithm using decoherence  [PDF]
Akira SaiToh
Computer Science , 2014,
Abstract: We consider the problem of mapping digital data encoded on a quantum register to analog amplitudes in parallel. It is shown to be unlikely that a fully unitary polynomial-time quantum algorithm exists for this problem; NP becomes a subset of BQP if it exists. In the practical point of view, we propose a nonunitary linear-time algorithm using quantum decoherence. It tacitly uses an exponentially large physical resource, which is typically a huge number of identical molecules. Quantumness of correlation appearing in the process of the algorithm is also discussed.
Low Power Analog-to-Digital Conversion in Millimeter Wave Systems: Impact of Resolution and Bandwidth on Performance  [PDF]
Oner Orhan,Elza Erkip,Sundeep Rangan
Mathematics , 2015,
Abstract: The wide bandwidth and large number of antennas used in millimeter wave systems put a heavy burden on the power consumption at the receiver. In this paper, using an additive quantization noise model, the effect of analog-digital conversion (ADC) resolution and bandwidth on the achievable rate is investigated for a multi-antenna system under a receiver power constraint. Two receiver architectures, analog and digital combining, are compared in terms of performance. Results demonstrate that: (i) For both analog and digital combining, there is a maximum bandwidth beyond which the achievable rate decreases; (ii) Depending on the operating regime of the system, analog combiner may have higher rate but digital combining uses less bandwidth when only ADC power consumption is considered, (iii) digital combining may have higher rate when power consumption of all the components in the receiver front-end are taken into account.
A Novel Analog-to-digital conversion Technique using nonlinear duty-cycle modulation
Jean Mbihi,Fran?ois Ndjali Beng,Martin Kom,Léandre Nneme Nneme
International Journal of Electronics and Computer Science Engineering , 2012,
Abstract: A new type of analog-to-digital conversion technique is presented in this paper. The interfacing hardware is a very simple nonlinear circuit with 1-bit modulated output. As a implication, behind the hardware simplicity retained is hidden a dreadful nonlinear duty-cycle modulation ratio. However, the overall nonlinear behavior embeds a sufficiently wide linear range, for a rigorous digital reconstitution of the analog input signal using a standard linear filter. Simulation and experimental results obtained using a well tested prototyping system, show the feasibility and good quality of the proposed conversion technique.
Effective Dynamic Range in Measurements with Flash Analog-to-Digital Convertor  [PDF]
Q. Yue
Physics , 2003, DOI: 10.1016/S0168-9002(03)02020-5
Abstract: Flash Analog to Digital Convertor (FADC) is frequently used in nuclear and particle physics experiments, often as the major component in big multi-channel systems. The large data volume makes the optimization of operating parameters necessary. This article reports a study of a method to extend the dynamic range of an 8-bit FADC from the nominal $\rm{2^8}$ value. By comparing the integrated pulse area with that of a reference profile, good energy reconstruction and event identification can be achieved on saturated events from CsI(Tl) crystal scintillators. The effective dynamic range can be extended by at least 4 more bits. The algorithm is generic and is expected to be applicable to other detector systems with FADC readout.
Transceiver Design with Low-Precision Analog-to-Digital Conversion : An Information-Theoretic Perspective  [PDF]
Jaspreet Singh,Onkar Dabeer,Upamanyu Madhow
Mathematics , 2008,
Abstract: Modern communication receiver architectures center around digital signal processing (DSP), with the bulk of the receiver processing being performed on digital signals obtained after analog-to-digital conversion (ADC). In this paper, we explore Shannon-theoretic performance limits when ADC precision is drastically reduced, from typical values of 8-12 bits used in current communication transceivers, to 1-3 bits. The goal is to obtain insight on whether DSP-centric transceiver architectures are feasible as communication bandwidths scale up, recognizing that high-precision ADC at high sampling rates is either unavailable, or too costly or power-hungry. Specifically, we evaluate the communication limits imposed by low-precision ADC for the ideal real discrete-time Additive White Gaussian Noise (AWGN) channel, under an average power constraint on the input. For an ADC with K quantization bins (i.e., a precision of log2 K bits), we show that the Shannon capacity is achievable by a discrete input distribution with at most K + 1 mass points. For 2-bin (1-bit) symmetric ADC, this result is tightened to show that binary antipodal signaling is optimum for any signal-to-noise ratio (SNR). For multi-bit ADC, the capacity is computed numerically, and the results obtained are used to make the following encouraging observations regarding system design with low-precision ADC : (a) even at moderately high SNR of up to 20 dB, 2-3 bit quantization results in only 10-20% reduction of spectral efficiency, which is acceptable for large communication bandwidths, (b) standard equiprobable pulse amplitude modulation with ADC thresholds set to implement maximum likelihood hard decisions is asymptotically optimum at high SNR, and works well at low to moderate SNRs as well.
The Transition from Analog to Digital Mammography: Overall Considerations
A. Sardo
Iranian Journal of Radiology , 2007,
Abstract: In the last decades a continuous growth of the infor-matics process around the world has been observed: paper documents, data, images…, converted into a “digital format” allow an easier and safer manage-ment, making possible its compatibility and access to internet networking. This migration confirms the huge technology progresses made especially in the image capture ways: from photography to graphic arts, from movie to healthcare imaging, where the end user/radiologist requires, at least, a digital clinical image with a quality equivalent to the previous ana-log film image. In women’s breast imaging care mammography is acknowledged as the most effective method to detect a breast cancer at an earlier stage and it is currently the only imaging modality, which has been proven to reduce mortality in women screened from 50 to 69 years. The transition to Digital Mammography represents a challenge to decide when to change the first concern is to get the money availability to purchase a Digital Mammography system and the well-trained human resources (radiologist, technician and physicist) for using it. A digital system must satisfy actual needs such as the diagnostic accuracy, dose and regulatory requirements, productivity and archive issues. The new digital modality must be integrated in a fully digital environment (PACS) and the presence of CR or DR systems for general radiography could condi-tion the choice of CR or DR Digital Mammography system. The Primary goal of mammography (both analog and digital) is to provide to the radiologist clinical images for confident interpretation. Certainly the confidence derives from radiologist’s experience in reading mammograms, but many other factors can increase it, for instance correct patient positioning, excellent and consistent image quality (photographic and artifacts free), easy use and interpretation aid (e.g. lens, CAD use) of imaging system. However, the habit in read-ing film-images on view box plays a very important role. Going to digital-images displayed on softcopy-monitors, with different contrast and image process-ing tools: the confidence in digital environment, at the start, could be reduced. The analog mammographic screen-film system is ca-pable of very high resolution, high contrast image and can provide adequate dynamic range for most breast types at a reasonable dose for patients. Excel-lent and consistent quality must be assured by proper Quality Control measurements of the x-ray unit AEC reproducibility and film processing and by a complete Quality Assurance program application. Major limita-tion
Chaotic Analog-to-Information Conversion: Principle and Reconstructability with Parameter Identifiability  [PDF]
Feng Xi,Sheng Yao Chen,Zhong Liu
Physics , 2012, DOI: 10.1142/S0218127413501988
Abstract: This paper proposes a chaos-based analog-to-information conversion system for the acquisition and reconstruction of sparse analog signals. The sparse signal acts as an excitation term of a continuous-time chaotic system and the compressive measurements are performed by sampling chaotic system outputs. The reconstruction is realized through the estimation of the sparse coefficients with principle of chaotic parameter estimation. With the deterministic formulation, the analysis on the reconstructability is conducted via the sensitivity matrix from the parameter identifiability of chaotic systems. For the sparsity-regularized nonlinear least squares estimation, it is shown that the sparse signal is locally reconstructable if the columns of the sparsity-regularized sensitivity matrix are linearly independent. A Lorenz system excited by the sparse multitone signal is taken as an example to illustrate the principle and the performance.
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