Showing papers on "Digital signal processing published in 2014"

Big Data Analysis with Signal Processing on Graphs: Representation and processing of massive data sets with irregular structure

Abstract: Analysis and processing of very large data sets, or big data, poses a significant challenge. Massive data sets are collected and studied in numerous domains, from engineering sciences to social networks, biomolecular research, commerce, and security. Extracting valuable information from big data requires innovative approaches that efficiently process large amounts of data as well as handle and, moreover, utilize their structure. This article discusses a paradigm for large-scale data analysis based on the discrete signal processing (DSP) on graphs (DSPG). DSPG extends signal processing concepts and methodologies from the classical signal processing theory to data indexed by general graphs. Big data analysis presents several challenges to DSPG, in particular, in filtering and frequency analysis of very large data sets. We review fundamental concepts of DSPG, including graph signals and graph filters, graph Fourier transform, graph frequency, and spectrum ordering, and compare them with their counterparts from the classical signal processing theory. We then consider product graphs as a graph model that helps extend the application of DSPG methods to large data sets through efficient implementation based on parallelization and vectorization. We relate the presented framework to existing methods for large-scale data processing and illustrate it with an application to data compression.

Discrete Signal Processing on Graphs: Frequency Analysis

Abstract: Signals and datasets that arise in physical and engineering applications, as well as social, genetics, biomolecular, and many other domains, are becoming increasingly larger and more complex. In contrast to traditional time and image signals, data in these domains are supported by arbitrary graphs. Signal processing on graphs extends concepts and techniques from traditional signal processing to data indexed by generic graphs. This paper studies the concepts of low and high frequencies on graphs, and low-, high- and band-pass graph signals and graph filters. In traditional signal processing, these concepts are easily defined because of a natural frequency ordering that has a physical interpretation. For signals residing on graphs, in general, there is no obvious frequency ordering. We propose a definition of total variation for graph signals that naturally leads to a frequency ordering on graphs and defines low-, high-, and band-pass graph signals and filters. We study the design of graph filters with specified frequency response, and illustrate our approach with applications to sensor malfunction detection and data classification.

A catalog of stream processing optimizations

Abstract: Various research communities have independently arrived at stream processing as a programming model for efficient and parallel computing. These communities include digital signal processing, databases, operating systems, and complex event processing. Since each community faces applications with challenging performance requirements, each of them has developed some of the same optimizations, but often with conflicting terminology and unstated assumptions. This article presents a survey of optimizations for stream processing. It is aimed both at users who need to understand and guide the system’s optimizer and at implementers who need to make engineering tradeoffs. To consolidate terminology, this article is organized as a catalog, in a style similar to catalogs of design patterns or refactorings. To make assumptions explicit and help understand tradeoffs, each optimization is presented with its safety constraints (when does it preserve correctnessq) and a profitability experiment (when does it improve performanceq). We hope that this survey will help future streaming system builders to stand on the shoulders of giants from not just their own community.

Digital Metamaterials

Abstract: Balancing the complexity and the simplicity has played an important role in the development of many fields in science and engineering As Albert Einstein was once quoted to say: 'Everything must be made as simple as possible, but not one bit simpler' The simplicity of an idea brings versatility of that idea into a broader domain, while its complexity describes the foundation upon which the idea stands One of the well-known and powerful examples of such balance is in the Boolean algebra and its impact on the birth of digital electronics and digital information age The simplicity of using only two numbers of '0' and '1' in describing an arbitrary quantity made the fields of digital electronics and digital signal processing powerful and ubiquitous Here, inspired by the simplicity of digital electrical systems we propose to apply an analogous idea to the field of metamaterials, namely, to develop the notion of digital metamaterials Specifically, we investigate how one can synthesize an electromagnetic metamaterial with desired materials parameters, eg, with a desired permittivity, using only two elemental materials, which we call 'metamaterial bits' with two distinct permittivity functions, as building blocks We demonstrate, analytically and numerically, how proper spatial mixtures of such metamaterial bits leads to 'metamaterial bytes' with material parameters different from the parameters of metamaterial bits We also explore the role of relative spatial orders of such digital materials bits in constructing different parameters for the digital material bytes We then apply this methodology to several design examples such as flat graded-index digital lens, cylindrical scatterers, digital constructs for epsilon-near-zero (ENZ) supercoupling, and digital hyperlens, highlighting the power and simplicity of this methodology and algorithm

Laser scanning code symbol reading system

Abstract: A laser scanning symbol reading system includes an analog scan data signal processor for producing digital data signals, wherein during each scanning cycle, a light collection and photo-detection module generates an analog scan data signal corresponding to a laser scanned symbol, a multi-channel parallel scan data signal processor/digitizer processes the analog scan data signal along multiple cascaded multi-stage signal processing channels, to generate digital data signals corresponding thereto, while a synchronized digital gain control module automatically processes the digital data signals in response to start of scan (SOS) signals generated by a SOS detector. Each signal processing channel supports different stages of amplification and filtering using a different set of band-pass filtering and gain parameters in each channel, to produce multiple digital first derivative data signals, and/or multiple digital scan data intensity data signals, having different signal amplitudes and dynamic range characteristics for use in decode processing.

Advances in High-Speed DACs, ADCs, and DSP for Optical Coherent Transceivers

Abstract: We examine analog-to-digital and digital-to-analog converters (ADCs and DACs), as well as digital signal processing (DSP) functions for optical coherent modems.

Characteristic Study and Time-Domain Discrete- Wavelet-Transform Based Hybrid Detection of Series DC Arc Faults

Abstract: DC arc fault introduces major safety concerns in a wide variety of components in dc networks However, the randomness and instability of dc arc makes it difficult to be detected In this paper, an experimental system was designed and tested at different load current, dc source voltage, and gap length to evaluate the impact of each parameter to the dc arc Based on the experimental results, characteristics in the electrical behavior were studied and fault detection oriented analysis was conducted A detection algorithm utilizing both time and time-frequency domain characteristics was proposed to differentiate between dc arc fault and normal condition The detection algorithm was then realized on a digital signal processing board and tested to verify the effectiveness Experimental results show that the proposed algorithm can detect arc fault in a timely manner and is free of nuisance trip from normal circuit operations such as load change condition

Methods and arrangements for smartphone payments and transactions

Abstract: The disclosure relates to digital signal processing such as digital watermarking, and the utilization of portable devices (e.g., smartphones) for such signal processing. One claim recites a smartphone comprising: a touch screen display; memory for storing a payload and for storing a digital image depicting a virtual card; means for processing the payload with an erasure code generator, in which the erasure code generator produces a plurality of outputs corresponding to the payload; means for embedding a first of the plurality of outputs in a first version of the digital image and proceeding with embedding until each of the plurality of outputs are respectively embedded in one of a plurality of versions of the digital image; and means for displaying embedded versions of the digital image so that a receiver analyzing captured image data representing the touch screen display can recover the payload. Of course, other claims and combinations are disclosed too.

Compressed Sensing Analog Front-End for Bio-Sensor Applications

Abstract: In a conventional bio-sensor, key signal features are acquired using Nyquist-rate analog-to-digital conversion without exploiting the typical bio-signal characteristic of sparsity in some domain (e.g., time, frequency, etc.). Compressed sensing (CS) is a signal processing paradigm that exploits this sparsity for commensurate power savings by enabling alias-free sub-Nyquist acquisition. In a severely energy constrained sensor, CS also eliminates the need for digital signal processing (DSP). A fully-integrated low-power CS analog front-end (CS-AFE) is described for an electrocardiogram (ECG) sensor. Switched-capacitor circuits are used to achieve high accuracy and low power. Implemented in 0.13 μm CMOS in 2×3 mm2, the prototype comprises a 384-bit Fibonacci-Galois hybrid linear feedback shift register and 64 digitally-selectable CS channels with a 6-bit C-2C MDAC/integrator and a 10-bit C-2C SAR ADC in each. Clocked at 2 kHz, the total power dissipation is 28 nW and 1.8 μW for one and 64 active channels, respectively. CS-AFE enables compressive sampling of bio-signals that are sparse in an arbitrary domain.

Nonlinear inverse synthesis and eigenvalue division multiplexing in optical fiber channels

Abstract: We scrutinize the concept of integrable nonlinear communication channels, resurrecting and extending the idea of eigenvalue communications in a novel context of nonsoliton coherent optical communications. Using the integrable nonlinear Schrodinger equation as a channel model, we introduce a new approach - the nonlinear inverse synthesis method - for digital signal processing based on encoding the information directly onto the nonlinear signal spectrum. The latter evolves trivially and linearly along the transmission line, thus, providing an effective eigenvalue division multiplexing with no nonlinear channel cross talk. The general approach is illustrated with a coherent optical orthogonal frequency division multiplexing transmission format. We show how the strategy based upon the inverse scattering transform method can be geared for the creation of new efficient coding and modulation standards for the nonlinear channel.

30.10 A 1TOPS/W analog deep machine-learning engine with floating-gate storage in 0.13μm CMOS

Abstract: Direct processing of raw high-dimensional data such as images and video by machine learning systems is impractical both due to prohibitive power consumption and the “curse of dimensionality,” which makes learning tasks exponentially more difficult as dimension increases. Deep machine learning (DML) mimics the hierarchical presentation of information in the human brain to achieve robust automated feature extraction, reducing the dimension of such data. However, the computational complexity of DML systems limits large-scale implementations in standard digital computers. Custom analog or mixed-mode signal processors have been reported to yield much higher energy efficiency than DSP [1-4], presenting the means of overcoming these limitations. However, the use of volatile digital memory in [1-3] precludes their use in intermittently-powered devices, and the required interfacing and internal A/D/A conversions add power and area overhead. Nonvolatile storage is employed in [4], but the lack of learning capability requires task-specific programming before operation, and precludes online adaptation.

Driver Identification and Data Collection Systems for Use with Mobile Communication Devices in Vehicles

Abstract: Systems, methods, and devices for determining the location of one or more mobile devices within a vehicle comprising: (a) a controller located within the vehicle and configured to transmit at least two audio signals, a first audio signal directed generally into a driver space within the vehicle and a second audio signal directed generally into a passenger space within the vehicle, and (b) software code stored in memory of the mobile device and having instructions executable by a processor that performs the steps of: (i) detecting the at least two audio signals, (ii) sampling the at least two audio signals for a predetermined period of time; (iii) performing digital signal processing on the sampled at least two audio signals; and (iv) based on the results of the digital signal processing, determining whether the mobile device was located within the driver space of the vehicle during the predetermined period of time.

Digital subcarrier multiplexing for fiber nonlinearity mitigation in coherent optical communication systems.

Abstract: In this work we experimentally investigate the improved intra-channel fiber nonlinearity tolerance of digital subcarrier multiplexed (SCM) signals in a single-channel coherent optical transmission system. The digital signal processing (DSP) for the generation and reception of the SCM signals is described. We show experimentally that the SCM signal with a nearly-optimum number of subcarriers can extend the maximum reach by 23% in a 24 GBaud DP-QPSK transmission with a BER threshold of 3.8 × 10−3 and by 8% in a 24 GBaud DP-16-QAM transmission with a BER threshold of 2 × 10−2. Moreover, we show by simulations that the improved performance of SCM signals is observed over a wide range of baud rates, further indicating the merits of SCM signals in baud-rate flexible agile transmissions and future high-speed optical transport systems.

Reduced Complexity Digital Back-Propagation Methods for Optical Communication Systems

Abstract: Next-generation optical communication systems will continue to push the ( bandwidth · distance) product towards its physical limit. To address this enormous demand, the usage of digital signal processing together with advanced modulation formats and coherent detection has been proposed to enable data-rates as high as 400 Gb/s per channel over distances in the order of 1000 km. These technological breakthroughs have been made possible by full compensation of linear fiber impairments using digital equalization algorithms. While linear equalization techniques have already matured over the last decade, the next logical focus is to explore solutions enabling the mitigation of the Kerr effect induced nonlinear channel impairments. One of the most promising methods to compensate for fiber nonlinearities is digital back-propagation (DBP), which has recently been acknowledged as a universal compensator for fiber propagation impairments, albeit with high computational requirements. In this paper, we discuss two proposals to reduce the hardware complexity required by DBP. The first confirms and extends published results for non-dispersion managed link, while the second introduces a novel method applicable to dispersion managed links, showing complexity reductions in the order of 50% and up to 85%, respectively. The proposed techniques are validated by comparing results obtained through post-processing of simulated and experimental data, employing single channel and WDM configurations, with advanced modulation formats, such as quadrature phase shift keying (QPSK) and 16-ary quadrature amplitude modulation (16-QAM). The considered net symbol rate for all cases is 25 GSymbol/s. Our post-processing results show that we can significantly reduce the hardware complexity without affecting the system performance. Finally, a detailed analysis of the obtained reduction is presented for the case of dispersion managed link in terms of number of required complex multiplications per transmitted bit.

Comparative Performance Analysis of Hamming, Hanning and Blackman Window

Abstract: In the emerging field of medical image processing, computer vision, pattern recognition and other digital signal processing applications, window technique is vastly used. A window function is a mathematical function that is zero-valued outside of some chosen interval. When another function is multiplied by a window function, the product is also zero-valued outside the interval. In this paper, the performance of Hamming, Hanning and Blackman window have been mainly compared considering their magnitude response, phase response, equivalent noise bandwidth, sidelobe transition width, response in time and frequency domain using MATLAB simulation. To observe the responses, a FIR filter of low pass, high pass, band pass and band stop type have been designed and encountered them with each parameters stated above. The results that have been found is as same as its to be as stated in the theory. Comparing simulation results of different window, this paper has found Blackman window with best performance among them which is also expected from the theory. These windows have also been encountered with speech signal using MATLAB simulation and found the same expected result.

A Fully Self-Contained Logarithmic Closed-Loop Deep Brain Stimulation SoC With Wireless Telemetry and Wireless Power Management

Abstract: Although closed-loop deep brain stimulation (DBS) promises treatment of many neurological disorders, an implantable system-on-chip (SoC) implementing an effective closed-loop DBS algorithm has not been demonstrated. This work introduces a logarithmic, closed-loop DBS system that detects and processes low-frequency brain field signals to control and adapt stimulation currents. The system records and processes neural signals with four low-noise neural amplifier (LNA) channels, a multiplexed logarithmic ADC, and two high-pass and two low-pass digital logarithmic filters. Logarithmic processing saves power and achieves high dynamic range. A logarithmic domain digital signal processor (DSP) and PI-controller controls eight current stimulator channels and enables closed-loop stimulation. An RF transceiver, a clock generator, and a power harvester are also included in the system to achieve a complete implantable SoC. The 4 mm 2 180 nm CMOS prototype consumes a total of 468 μW for recording and processing neural signals, for stimulation, and for two-way wireless communication.

Rate-Adaptive Coded Modulation for Fiber-Optic Communications

Abstract: Rate-adaptive optical transceivers can play an important role in exploiting the available resources in dynamic optical networks, in which different links yield different signal qualities. We study rate-adaptive joint coding and modulation, often called coded modulation (CM), addressing non-dispersion-managed (non-DM) links, exploiting recent advances in channel modeling of these links. We introduce a four-dimensional CM scheme, which shows a better tradeoff between digital signal processing complexity and transparent reach than existing methods. We construct a rate-adaptive CM scheme combining a single low-density parity-check code with a family of three signal constellations and using probabilistic signal shaping. We evaluate the performance of the proposed CM scheme for single-channel transmission through long-haul non-DM fiber-optic systems with electronic chromatic-dispersion compensation. The numerical results demonstrate improvement of spectral efficiency over a wide range of transparent reaches, an improvement over 1 dB compared to existing methods.

Bandwidth-Variable Transceivers based on Four-Dimensional Modulation Formats

Abstract: In this invited contribution, we discuss technology options for bandwidth-variable transceivers which are key components for the realization of flexible software-defined optical networking. Bandwidth-variable transceivers enable the software-controlled adaptation of physical layer parameters such as transmitted bit rate, spectral efficiency and transparent reach according to the traffic demands at hand. In particular, we focus on recent advances in four-dimensional modulation formats and in modulation format transparent data-aided digital signal processing. It is argued that four-dimensional modulation formats present an attractive complement to conventional polarization-multiplexed formats in the context of bandwidth-variable transceivers, where they enable a smooth transition with respect to spectral efficiency while requiring marginal additional hardware effort. Results of numerical simulations and experiments supporting this statement are presented. For the cost-efficient hardware implementation of bandwidth-variable transceivers supporting several polarization-multiplexed and four-dimensional modulation formats, digital signal processing algorithms are required which operate format transparent and consume little hardware resources. We discuss data-aided signal processing as one possible option, in particular with respect to carrier frequency recovery and channel estimation in combination with frequency domain equalization.

Digital DCM Detection and Mixed Conduction Mode Control for Boost PFC Converters

Abstract: This paper presents a novel mixed conduction mode (MCM) digital controller with a digital signal processor (DSP)-based discontinuous conduction mode (DCM) detection technique to realize total harmonic distortion (THD) and power factor improvements in boost power factor correction (PFC) converters operating in both continuous conduction mode (CCM) and DCM during a single ac line half-cycle. By using the integrated comparators found on many DSPs, simplification and cost-reductions over existing DCM and zero-current detection methods are made possible. Additionally, performance improvements over a conventional CCM digital control technique are possible with simple software modification, and can be extended to existing boost PFC converter designs provided a compatible DSP is present. At an output power of 98 W, an experimental 650 W boost PFC converter operating in the MCM controlled by a TMS320F28035 provides a THD reduction of 40.2% and power factor improvement of 1.5% over a conventional digital controller.

Comb-calibrated laser ranging for three-dimensional surface profiling with micrometer-level precision at a distance

Abstract: Non-contact surface mapping at a distance is interesting in diverse applications including industrial metrology, manufacturing, forensics, and artifact documentation and preservation. Frequency modulated continuous wave (FMCW) laser detection and ranging (LADAR) is a promising approach since it offers shot-noise limited precision/accuracy, high resolution and high sensitivity. We demonstrate a scanning imaging system based on a frequency-comb calibrated FMCW LADAR and real-time digital signal processing. This system can obtain three-dimensional images of a diffusely scattering surface at stand-off distances up to 10.5 m with sub-micrometer accuracy and with a precision below 10 µm, limited by fundamental speckle noise. Because of its shot-noise limited sensitivity, this comb-calibrated FMCW LADAR has a large dynamic range, which enables precise mapping of scenes with vastly differing reflectivities such as metal, dirt or vegetation. The current system is implemented with fiber-optic components, but the basic system architecture is compatible with future optically integrated, on-chip systems.

Multi-level signaling in the Stokes space and its application to large-capacity optical communications.

Abstract: The Stokes vector of an optical signal does not depend on its absolute phase; therefore, we can construct the phase-insensitive optical communication system, using the Stokes vector as a modulation parameter. In such a system, multi-level optical signals can effectively be designed in the three-dimensional Stokes space and demodulated either by direct detection or by coherent detection, where low-complexity digital-signal processing (DSP) is employed. Although this system has the disadvantage that adaptive equalizers can hardly be implemented in the digital domain, it is still an attractive solution to large-capacity (≥ 100 Gbit/s) and medium-or short-reach (≤ 100 km) transmission. In this paper, we discuss the receiver configuration for the multi-level signal in the Stokes space and the efficient DSP algorithm for demodulating such a signal. Simulation results demonstrate that 2-, 4-, 8-, 16-, and 32-ary signals in the Stokes space have good bit-error rate (BER) characteristics. Especially, the 16-ary signal at the moderate symbol rate of 25 Gsymbol/s can reach the bit rate of 100 Gbit/s even by using direct detection.

System and Method for High Input Capacitive Signal Amplifier

Abstract: In accordance with an embodiment, a method includes determining an amplitude of an input signal provided by a capacitive signal source, compressing the input signal in an analog domain to form a compressed analog signal based on the determined amplitude, converting the compressed analog signal to a compressed digital signal, and decompressing the digital signal in a digital domain to form a decompressed digital signal. In an embodiment, compressing the analog signal includes adjusting a first gain of an amplifier coupled to the capacitive signal source, and decompressing the digital signal comprises adjusting a second gain of a digital processing block.

Systems and methods for phase noise mitigation

Abstract: A system for phase noise mitigated communication including a primary transmitter that converts a digital transmit signal to an analog transmit signal, a primary receiver that receives an analog receive signal and converts the analog receive signal to a digital receive signal, an analog self-interference canceller that samples the analog transmit signal, generates an analog self-interference cancellation signal based on the analog transmit signal, and combines the analog self-interference cancellation signal with the analog receive signal and a digital self-interference canceller that samples the digital transmit signal, generates a digital self-interference cancellation signal based on the digital transmit signal, and combines the digital self-interference cancellation signal with the digital receive signal.

Advanced DSP Techniques Enabling High Spectral Efficiency and Flexible Transmissions: Toward elastic optical networks

Abstract: In this article, we describe advances in digital signal processing (DSP) techniques that enable Tb/s transmission, and software-defined flexible transponders that support adaptive modulation formats and elastic optical networks (EONs).

Systems and methods for non-linear digital self-interference cancellation

Abstract: A system and method for non-linear digital self-interference cancellation including a pre-processor that generates a first pre-processed digital transmit signal from a digital transmit signal of a full-duplex radio, a non-linear transformer that transforms the first pre-processed digital transmit signal into a non-linear self-interference signal according to a transform configuration, a transform adaptor that sets the transform configuration of the non-linear transformer, and a post-processor that combines the non-linear self-interference signal with a digital receive signal of the full-duplex radio.

Generation and transmission of 100-Gb/s PDM 4-PAM using directly modulated VCSELs and coherent detection

Abstract: We generate a 100-Gb/s polarization-division-multiplexed 4-level pulse-amplitude-modulation signal with two directly modulated 1.5-μm single-mode VCSELs. Coherent detection and digital signal processing enable the transmission over 400-km standard single-mode-fiber (SSMF) with 20% overhead hard-decision forward-error-correction.