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We demonstrate in this report an envelope detection technique with maximum likelihood estimation in a least square sense for determining displacement. This technique is achieved by sampling the amplitudes of quadrature signals resulted from a heterodyne interferometer so that the resolution of displacement measurement of the order of 2/104 is experimentally verified. A phase unwrapping procedure is also described and experimentally demonstrated and indicates that the unambiguity range of displacement can be measured beyond a single wavelength. OCIS codes: 120.0120, 120.2650, 120.5050.

A two-electrode semiconductor optical amplifier that has two sections and two separated electrodes is proposed for an all-optical wavelength converter. Pattern effect reduction based on dynamic gain compensation is theoretically investigated using a time-domain model that takes into account the carrier diffusion process between the two sections, and the Q factor of the converted light is calculated to evaluate pattern effects. Simulation results show that the Q factor is greatly improved when the section lengths and the currents are appropriately selected. OCIS codes: 230.7405, 060.4510, 250.5980.

This paper addresses the use of several signal processing tools for monitoring and diagnosis of assembly faults in diesel engines through the cold test technology. One specific fault is considered here as an example: connecting rod with incorrectly tightened screws. First, the experimental apparatus concerning the vibration tests is introduced. Subsequently, the dynamic analysis of the engine has been carried out in order to calculate the connecting rod forces against the crankpin for predicting the position where mechanical impacts are expected. Then, a vibration signal model for this type of faults is introduced. It deals with the cyclostationary model in which the signal is subdivided into two main parts: deterministic and nondeterministic. Finally, the acceleration signals acquired from the engine block during a cold test cycle at the end of the assembly line are analyzed. For quality control purposes in order to obtain reliable thresholds for the pass/fail decision, a method based on the image correlation of symmetrized dot patterns is proposed. This method visualizes vibration signals in a diagrammatic representation in order to quickly detect the faulty engines in cold tests. Moreover, the fault identification is discussed on the basis of the cyclostationary model of the signals. The first-order cyclostationarity is exploited by the analysis of the time synchronous average (TSA). In addition, the residual signal is evaluated by subtracting the TSA from the raw synchronized signal, and thus, the second-order cyclostationarity analysis is developed by means of the Wigner-Ville distribution (WVD), Wigner-Ville spectrum (WVS), and mean instantaneous power. Moreover, continuous wavelet transform is presented and compared with the WVD and WVS. [DOI: 10.1115/1.4000807]

This paper shows that optical signal transmission over intersatellite links with swaying transmitters can be described as an equivalent fading model. In this model, the instantaneous signal-to-noise ratio is stochastic and follows the reciprocal Pareto distribution. With this model, we show that the transmitter power can be minimized, subject to a specified outage probability, by appropriately adjusting some system parameters, such as the transmitter gain. OCIS codes: 060.4510, 200.2605.

In two papers [Proc. SPIE 4471, 272-280 (2001) and Appl. Opt. 43, 2709-2721 (2004)], a logarithmic phase mask was proposed and proved to be effective in extending the depth of field; however, according to our research, this mask is not that perfect because the corresponding defocused modulation transfer function has large oscillations in the low-frequency region, even when the mask is optimized. So, in a previously published paper [Opt. Lett. 33, 1171-1173 (2008)], we proposed an improved logarithmic phase mask by making a small modification. The new mask can not only eliminate the drawbacks to a certain extent but can also be even less sensitive to focus errors according to Fisher information criteria. However, the performance comparison was carried out with the modified mask not being optimized, which was not reasonable. In this manuscript, we optimize the modified logarithmic phase mask first before analyzing its performance and more convincing results have been obtained based on the analysis of several frequently used metrics. OCIS codes: 110.0110, 110.1758.

A new estimator for evolutionary spectrum (ES) based on short time Fourier transform (STFT) and modified group delay function (MGDF) by signal decomposition (SD) is proposed. The STFT due to its built-in averaging, suppresses the cross terms and the MGDF preserves the frequency resolution of the rectangular window with the reduction in the Gibbs ripple. The present work overcomes the magnitude distortion observed in multi-component non-stationary signals with STFT and MGDF estimation of ES using SD. The SD is achieved either through discrete cosine transform based harmonic wavelet transform (DCTHWT) or perfect reconstruction filter banks (PRFB). The MGDF also improves the signal to noise ratio by removing associated noise. The performance of the present method is illustrated for cross chirp and frequency shift keying (FSK) signals, which indicates that its performance is better than STFT-MGDF (STFT-GD) alone. Further its noise immunity is better than STFT. The SD based methods, however cannot bring out the frequency transition path from band to band clearly, as there will be gap in the contour plot at the transition. The PRFB based STFT-SD shows good performance than DCTHWT decomposition method for STFT-GD. Keywords--Evolutionary Spectrum, Modified Group Delay, Discrete Cosine Transform, Harmonic Wavelet Transform, Perfect Reconstruction Filter Banks, Short Time Fourier Transform., I INTRODUCTION IN general, signals like speech, seismic, biomedical signals (EEG, ECG), communication signals (frequency shift keying, radar returns involving Doppler shift, etc.) and communications over time varying channels (interference [...]

In a recent publication [J. Opt. Soc. Am. A 25, 1594-1608 (2008).] we developed expressions for the tilt errors that arise from the effects of lead-ahead and aperture mismatch when transmitting a laser beam from the ground to a satellite. We extend these results to examine the fade statistics of the irradiance at the satellite due to these tilt errors and turbulence induced scintillation. The system concept is that the light from a beacon on the satellite is received by the ground station and a derived signal is used to drive a tracking/pointing system for the uplink beam. However, the beam must be pointed ahead along the satellite track to intercept the satellite (lead-ahead), and physical constraints may require that the beam transmit aperture is different in size or location than the aperture receiving the beacon signal (aperture mismatch). These two issues cause the light entering the receiving aperture (tracker) and the beam exiting the transmit aperture (pointer) to traverse somewhat different turbulence volumes, which limits the ability of the tracking/pointing system to place the maximum flux on the satellite. OCIS codes: 010.1330, 010.3310, 010.7350, 030.6600, 060.2605.

We developed a theory that describes fast mode-hop-free tuning of an external cavity diode laser in Littrow configuration with two acousto-optic modulators (AOMs) inside the laser cavity. The theory is based on synchronous shifting of the external cavity modes and the Littrow grating selectivity. It allows calculating the driving signals of both AOMs in order to reach a desired temporal variation of the laser frequency, including particularly fast tuning as well as an arbitrary shape of the tuning function. Furthermore, we present a laser setup for which the needed signals for both AOMs are generated by two direct digital synthesizer circuits. Thereby we were able to verify the theoretical predictions experimentally, achieving, e.g., sinusoidal single-mode tuning of the laser frequency over 40 GHz at a repetition rate of 10 kHz and over 12 GHz at 25 kHz. Finally, the limitations of the theory are discussed. OCIS codes: 140.3600, 140.3570, 140.2020, 140.7300, 230.1040.

This paper proposes a new approach to magnetic recording based on shingled writing and two-dimensional readback and signal-processing. This approach continues the use of conventional granular media but proposes techniques such that a substantial fraction of one bit of information is stored on each grain. Theoretically, areal-densities of the order of 10 Terabits per square inch may be achievable. In this paper we examine the feasibility of this two-dimensional magnetic recording (TDMR) and identify the significant challenges that must be overcome to achieve this vision. Index Terms--Areal-density, capacity, granular media, magnetic recording, shingled writing, two-dimensional.

The scope of this paper is to present certain insights and advances towards the synthesis and transistor-level implementation of high dynamic range (> 120 dB), micropower, CMOS Sinh companding filters. In particular, we present detailed technical insights on a recently proposed Sinh integrator which may serve as the basic building block for higher-order filter structures. The particular integrator exhibits a promising simulated linearity performance mainly because it does not rely on the complementarity of both N- and P-type MOS transistors to achieve its Class-AB operation. Rather, it is designed with single-type devices in its signal processing path. The integrator is evaluated through detailed simulation results obtained by performing both large-signal transient and periodic steady-state (PSS) analyses in Cadence IC Design Framework[R] with the parameters of the commercially available AMS 0.35-[micro]m CMOS process. SNR, SNDR, IP3 and mismatch are some of the performance figures reported in this work. A detailed head-to-head comparison with a typical pseudo-differential Class-AB Log-domain integrator, designed in the same technology and with identical specifications, is also performed in order to reveal any potential benefits of the Sinh circuit paradigm. Index Terms--Sinh integrator, ELIN systems, log-domain, companding signal processors, class-AB.

This paper presents a new procedure for generating 1/f[beta] noise sequences by filtering Gaussian white noise through a recursive filter approximating a discrete-time fractional order integrator. Power series expansion and deterministic signal modeling techniques were combined to determine a rational transfer function to approximate the ideal discrete fractional transfer function resulting from Al-Alaoui's rule raised to the power of the fractional order of integration. The proposed approach is computationally more efficient and more accurate than infinite impulse response truncation. Numerical results are provided to demonstrate the performance of the proposed method. Index Terms--Al-Alaoui's rule, fractional order integrator (FOI), power series expansion, Prony's method, Shanks' method, signal modeling, 1/f noise.

Novel building blocks for designing high-order current-mode filters by employing current mirrors as the elementary active elements are introduced in this paper. As a design example, a fifth-order elliptic current-mode filter is designed using only grounded capacitors. Simulation results using transistor parameters of a typical CMOS 0.35-[micro]m technology are in a good agreement with the theoretically expected. A comparison with the corresponding current mirror based filter topologies realized using the leapfrog and the wave techniques has been also performed. For this purpose, new leapfrog and wave filter topologies are introduced. Comparison results confirm the benefits offered by the proposed filter configurations. Index Terms--Analog signal processing, current mirrors (CMs), current-mode filters, linear transformation (LT) filters.

The recently launched LabPET[TM], a small animal Avalanche PhotoDiode (APD)-based PET scanner with quasi-individual readout and massively parallel processing, makes it possible to acquire real-time information necessary for Positron Emission Tomography (PET) image reconstruction. Since each APD is coupled to an LYSO/LGSO phoswich scintillator pair, an efficient crystal identification algorithm must be developed to sustain real-time crystal feature extraction in high PET count rate. Furthermore, a less application specific algorithm is needed to easily expand its use to a large range of crystal materials. For these reasons, a new ultra-fast crystal identification algorithm based on a Wiener filter is proposed. This optimum filter instantly recovers crystal parameters by minimizing a linear cost function. A one-dimension projection based discrimination is used to identify the scintillating crystal. The algorithm achieves a discrimination rate of ~88% for low-energy X-ray photons (~60 keV) and up to ~100% for high energy 511 keV photopeak photons, with a maximum throughput of 10 Mevents/sec when implemented in a field programmable gate array. Index Terms--Crystal identification, positron emission tomography, Wiener filter.

We describe what we believe to be novel methods for waveform synthesis and detection relying on longitudinal spectral decomposition of subpicosecond optical pulses. Optical processing is performed in both all-fiber and mixed fiber-free-space systems. Demonstrated applications include ultrafast optical waveform synthesis, microwave spectrum analysis, and high-speed electrical arbitrary waveform generation. The techniques have the potential for time-bandwidth products of [greater than or equal to] [10.sup.4] due to exclusive reliance on time-domain processing. We introduce the principles of operation and subsequently support these with results from our experimental systems. Both theory and experiments suggest third-order dispersion as the principle limitation to large time-bandwidth products. Chirped-fiber Bragg gratings offer a route to increasing the number of resolvable spots for use in high-speed signal processing applications. OCIS codes: 320.1590, 320.5540.

A new generalized asymptotic paradigm is used for analyzing the performance of sub-space-based direction-of-arrival (DoA) estimation in array signal processing applications. The results have shown that the new algorithms outperform their traditional counterparts in the small-sample-size regime.

This paper presents an adaptive processing system based on analog-digital circuits to extend the linear range of angular position sensors compensating the temperature-dependent drift. System-level simulations give a sensor output improvement higher than 70%, which drastically reduces deviations due to temperature. The building block architecture characteristics make these circuits suitable for implementing the 'smartness' part of smart sensors in embedded systems. Index Terms--Adaptive signal processing, magnetoresistive devices, mixed analog--digital integrated circuits, neural network hardware, sensor conditioning.

In modern digital signal processing and graphics applications, the shifter is an important module, consuming a significant amount of delay. This brief presents an architectural optimization approach to synthesize a faster barrel shifter block, which can be useful to reduce the delay of the design without significantly increasing the area. We have divided the problem of generating the shifter into two steps: i) timing-driven selection of multiple stages for merging, and ii) the design of the merged stage. In our proposed method, we define the notion of dual merged stage, where two stages are merged and the triple merged stage, where three stages are merged into a single composite stage. These merged stages are identified by using a timing-driven algorithm and are used in conjunction with some single stages of the traditional barrel shifter. The use of these merged stages helps reduce the depth of the proposed barrel shifter architecture, thereby improving the delay. The timing-driven nature of our algorithm helps produce a faster implementation for the overall shifter block. We have evaluated the performance of our design by using a number of technology libraries, timing constraints and shifter bit-widths. Our experimental data shows that the shifter block generated by our algorithm is significantly faster (10.19% on average) than the shifter block generated by a commercially available datapath synthesis tool. These improvements were verified on placed-and-routed designs as well.

A carrier-based unipolar pulsewidth modulation (PWM) current controller is described using a one-phase PWM rectifier bridge as a test circuit. The controller PWM signal generator uses a sawtooth carrier signal to obtain both synchronized PWM waveforms and a constant switching frequency. A current-error signal and an amplitude modulation depth signal are used to create the input reference signal to the PWM signal generator. The amplitude modulation depth signal is obtained from the PWM-cycle average of the PWM signal generator output signals. This internal feedback is illustrated using a second-order low pass Butterworth filter. With an appropriately designed low-pass filter, the current-error signal is forced to be centered on zero over a PWM cycle. The maximum peak-peak magnitude of the current-error signal is used as a design guideline for deciding an appropriate gain constant in the controller current feedback loop. The low pass filter design is examined to determine a suitable gain and 20-dB attenuation frequency to minimize the current-error signal. The steady-state and transient operation of the proposed current controller is compared with a proportional-integral controller and an average current-error controller. SPICE simulations and experimental results are used to demonstrate the characteristics of the controller. Index Terms--Proportional-integral (PI) controller, pulsewidth modulation (PWM).

Circular arrays of plasma filaments induced by femtosecond laser pulses in atmospheric air are shown to support guided modes of electromagnetic radiation in the centimeter and millimeter wavelength range. With the refractive index of laser-induced filaments being lower than the refractive index of nonionized air, arrays of such filaments can serve as a structured waveguide cladding, providing an index guiding of radar signals in a nonionized gas region. In spite of attenuation of radar radiation induced by plasma absorption, filament-array waveguides are shown to enhance radar signal transmission relative to freely propagating radar beams.

This paper considers collinear lumped-parameter structures where each mass in the structure has a single degree of freedom. Specifically, we analyze the zeros and relative degree of the single-input, single-output (SISO) transfer function from the force applied to an arbitrary mass to the position, velocity, or acceleration of another mass. In particular, we show that every SISO force-to-motion transfer function of a collinear lumped-parameter structure has no positive (real open-right-half-plane) zeros. In addition, every SISO force-to-position transfer function of a spring-connected collinear lumped-parameter structure has no non-negative (real closed-right-half-plane) zeros. As a consequence, the step response does not exhibit initial undershoot. In addition, we derive an expression for the relative degree of SISO force-to-position transfer functions. The formula depends on the placement of springs and dashpots, but is independent of the values of the spring constants and damping coefficients. Next, we consider the special case of serially connected collinear lumped-parameter structures. In this case, we show that every SISO force-to-position transfer function of a serially connected collinear lumped-parameter structure is minimum phase, that is, has no closed-right-half-plane zeros. The proofs of these results rely heavily on graph-theoretic techniques. [DOI: I0.1115/1.2719764]

In this brief, we address the combined application of word-length allocation and architectural synthesis of linear time-invariant digital signal processing systems. These two design tasks are traditionally performed sequentially, thus lessening the overall design complexity, but ignoring forward and backward dependencies that may lead to cost reductions. Mixed integer linear programming is used to formulate the combined problem and results are compared to the two-step traditional approach. Index Terms--Architectural synthesis, digital signal processing, fixed-point arithmetic, word-length allocation.

Presented is a mixed-signal full-custom VLSI chip designed to receive sonar return signals from an ultrasonic microphone array, and extract input bearing angles of the incoming signals. Processing utilizes simple low-power analog spatiotemporal bandpass filters to extract wavefront velocity across the array, which translates to input bearing angle. Processing uses phase information of array signals, not onset or offset of ultrasonic burst. With such synchronous processing, multiple angle readings from different returns of the same ultrasonic transmit burst are possible. Compatible microphone arrays are compact in size--test array has a total baseline of 26.5 mm. In a test with ultrasonic beacon 65 cm from a microphone array, angular precision nf 1[degrees] was demonstrated in most instances in the range -60[degrees] to 60[degrees]. Applications include sonar localization of remote objects, sonar imaging, and improved interference rejection between objects within the field of view of the sensor microphones. The chip was fabricated on a standard 3M2P CMOS process with a 0.5-[micro]m feature size. Index Terms--Acoustic arrays, acoustic beam steering, acoustic imaging, acoustic signal analysis, analog processing circuits, array signal processing, bandpass filters, continuous-time systems, frequency-domain analysis, intelligent sensors, linear arrays, mobile robot motion-planning, object detection, phased arrays, robot sensing systems, sensor processing, signal processing, sonar arrays, sonar imaging, sonar signal processing, spatial filters, spatiotemporal filters, synchronous detection, time-frequency analysis.

The robust filtering for two-dimensional (2-D) state-delayed systems with uncertainties represented by nonlinear fraction transformation (NFT) is presented. Two examples are given to illustrate the usage of the proposed methods and advantages of using the NFT model over the linear fraction transformation (LFT).

This paper investigates the performance of a fuzzy-logic-controller (FLC)-based cost-effective drive system of interior permanent-magnet synchronous motor (IPMSM) for high-performance industrial applications. In this paper, the FLC is used as a speed controller and the motor is fed from a four-switch three-phase (4S3Ph) pulsewidth-modulation (PWM) inverter instead of a conventional six-switch three-phase (6S3Ph) inverter. This reduces the cost of the inverter, the switching losses, and the complexity of the control algorithms and interface circuits to generate six PWM logic signals. Furthermore, the proposed control approach reduces the computation for real-time implementation. The closed-loop vector control scheme of the proposed 4S3Ph-inverter-fed IPMSM drive incorporating the FLC is implemented in real time using the digital signal processor (DSP) TI TMS320C31 for a prototype l-hp motor. The robustness of the proposed FLC-based 4S3Ph-inverter-fed IPMSM drive is verified by theoretical and experimental results at different operating conditions. A comparison of the proposed 4S3Ph-inverter-fed IPM drive with a conventional 6S3Ph inverter system is also made in terms of performance and harmonic analysis of the stator current. The proposed inverter-fed IPMSM drive is found quite acceptable considering its performance, cost reduction, and other inherent advantageous features. Index Terms--Fuzzy logic and digital signal processor, interior permanent-magnet motor, inverter, vector control.

A low-voltage low-power signal processing chip for electrocardiogram measurements has been designed and manufactured. The circuit includes a continuous time, offset-compensated preamplifier with an amplification of 40 dB, an eighth-order Butterworth switched-opamp switched-capacitor (SO-SC) filter with a passband of 8-30 Hz, a 32-kHz crystal oscillator, an SO-SC postamplifier, and a bias circuit. The whole circuit operates with supply voltages from 1.0 to 1.8 V and the measured average current consumption is only about 3 [micro]A. The circuit is therefore very suitable for portable applications such as heart rate detectors. Index Terms--Heart-rate detector, low-voltage low-power biomedical devices, switched-capacitor (SC) filters, switched opamps (SO).

In this paper, a current control scheme, based on proportional-integral regulators using sinusoidal signal integrators (SSIs), is proposed for shunt type power conditioners. The aim is to simplify the implementation of SSI-based current harmonic compensation for industrial implementations where strict limitations on the harmonic distortion of the mains' currents are required. To compensate current harmonics, the SSIs are implemented to operate both on positive and negative sequence signals. One regulator, for the fundamental current component, is implemented in the stationary reference frame. The other regulators, for the current harmonics, are all implemented in a synchronous reference frame rotating at the fundamental frequency. This allows the simultaneous compensation of two current harmonics with just one regulator, yielding a significant reduction of the computational effort compared with other current control methods employing sinusoidal signal integrators implemented in stationary reference frame. A simple and robust voltage filter is also proposed by the authors to obtain a smooth and accurate position estimation of the voltage vector at the point of common coupling (PCC) under distorted mains' voltages. The whole control algorithm has been implemented on a 16-b, fixed-point digital signal processor (DSP) platform controlling a 20-kVA power conditioner prototype. The experimental results presented in this paper for inductive and capacitive loads show the validity of the proposed solutions. Index Terms--Digital signal processor (DSP), shunt type power conditioner, sinusoidal signal integrators (SSIs).

Nonlinear distortion of bandlimited signals results in spectral spreading. This paper develops a blind nonlinear compensation method for bandlimited signals by suppressing the spectral content of the distorted signal above the original signal bandwidth by means of adaptive nonlinear filtering. The nonlinear compensator is constructed using a power series filter with adaptive coefficients. The adaptive coefficients are identified blindly by applying a least-squares criterion to the out-of-band spectral content of the nonlinear compensator output. The extraction of the out-of-band signal is efficiently performed by the discrete cosine transform. The effectiveness of the blind nonlinear compensation method is demonstrated by way of simulation examples involving periodic, colored noise, and bandlimited speech signals. Index Terms--Blind identification, communication system non-linearities, least squares, discrete cosine transform, nonlinear systems, nonlinear compensation, pth-order inverse, power series, recursive least squares.

Space-time-Doppler coded systems that guarantee the maximum possible space-Doppler diversity, along with the largest coding gains within all linearly coded systems are presented. The analytical results are confirmed by simulations and reveal the relative of merits of three designs in comparison with an existing approach.

A hardware implementation of a sound localization algorithm that localizes algorithm that localizes a single sound source by using the information gathered by two separated microphones is presented. The custom digital signal processor implementing the algorithm was designed in a 0.18-mum CMOS process and tested successfully.

A series of mathematical arguments is presented to justify the use of splines in signal processing applications. The proposed formalism yields the optimal discretization of the classical Wiener filter, together with a fast recursive algorithm.

We have developed a compact ultra-high-resolution gamma camera (UGC), based on an electron-multiplying charge-coupled device (EMCCD) coupled to a columnar CsI(Tl) scintillator. The EMCCD is suitable for photon-counting gamma-camera imaging, since it has an extremely low readout noise, even at high frame rates ( Index Terms--Charge-coupled device (CCD), digital signal processor (DSP), electron-multiplying charge-coupled device (EMCCD), gamma camera, molecular imaging, photon-counting, readout electronics, single photon emission computed tomography (SPECT).

Abstract--A special case of floating point data representation is block floating point format where a block of operands are forced to have a joint exponent term. This paper deals with [...]

Crosstalk and echo can be reduced in multiconductor interconnections, using (truly) matched terminations and a different modal variable for each transmission channel. We first study a conventional technique for reducing reflections, using grounded linear two-terminal circuit elements. Using the concepts of modal voltages and modal currents, we define a new method for the reduction of crosstalk and echo, which involves specific terminations, specific transmitting circuits to send signals, and specific receiving circuits to receive signals. We establish the design equations and show that the new method is related to a particular choice of eigenvectors, called associated eigenvectors. Simulations of two examples of implementation of this method confirm that it provides reduced crosstalk and echo. We also discuss the implementation of the new method with an interconnection having identical propagation constants for all modes. Finally, we compare the new method with a different concept based on modal variables and unspecified terminations. Index Terms--Crosstalk, interconnection, multiconductor cable, signal integrity, transmission.

The recent pairwise model, which generalizes the hidden Markov chain, one to the unsupervised restoration of hidden data is aimed at. They show the advantages of the pairwise Markov chain model with respect to the classical hidden Markov chain one for supervised and unsupervised restorations.

In this paper, we develop analytical tools for the performance analysis of coded, coherent communication systems on independent and identically distributed Nakagami-m fading channels with selection combining (SC) diversity. First, we derive an exact expression for the moment generation function (MGF) of the signal-to-noise ratio (SNR) of a code symbol at the output of the selection combiner. Next, based on Gauss-Chebyshev quadrature and Gauss-Laguerre quadrature rules, we propose a simple to compute, yet accurate, numerical solution for the pairwise error probability (PEP) of coded M-phase-shift keying (PSK) signals. Using the PEP expressions, we present the union bound-based bit-error performance of trellis-coded modulation schemes and turbo codes. Finally, we derive an exact expression for the computational cutoff rate of a coded system with M-PSK signaling and SC diversity, and show that the cutoff rate expression is a simple function of the MGF of the SNR at the output of the diversity combiner. Index Terms--Coded systems, cutoff rate, Nakagami fading, selection combining (SC), trellis-coded modulation (TCM), turbo codes.

A convenient, iterative method for determining injection current generated two -dimensional carrier distributions, and consequent control of refractive index profiles, in optical guided-wave devices is presented. This method is readily adaptable to a variety of materials and geometries and is 'user-friendly'.

An extensive small-signal analysis of a voltage-mode controlled interleaved dual boost (IDB) converter operating in continuous current mode based on signal flow graph approach is proposed. Small-signal flow graph is developed, from which open-loop small-signal transfer functions are derived using well known Mason's gain formula. Closed-loop small-signal input-to-output, control-to-output transfer functions are also derived and frequency response characteristics are determined at different duty ratios. Voltage-mode compensator designed using K-factor approach is used for closed-loop operation of IDB converter. Load voltage regulation against supply voltage and load disturbances are demonstrated through experimental results. Keywords: Interleaved dual boost converter; Small-signal analysis; K-factor; Voltage-mode control

Vector rotation is the key operation employed extensively in many digital signal processing applications. In this paper, we introduce a new design concept called Angle Quantization (AQ). It can be used as a design index for vector rotational operation, where the rotational angle is known in advance. Based on the AQ process, we establish a unified design framework for cost-effective low-latency rotational algorithms and architectures. Several existing works, such as conventional COordinate Rotational DIgital Computer (CORDIC), AR-CORDIC, MVR-CORDIC, and EEAS-based CORDIC, can be fitted into the design framework, forming a Vector Rotational CORDIC Family. Moreover, we address four searching algorithms to solve the optimization problem encountered in the proposed vector rotational CORDIC family. The corresponding scaling operations of the CORDIC family are also discussed. Based on the new design framework, we can realize high-speed/low-complexity rotational VLSI circuits, whereas without degrading the precision performance in fixed-point implementations. Index Terms--Angle Quantization (AQ), Angle Recoding (AR), greedy searching algorithm, trellis-based searching (TBS) algorithm, vector rotational COordinate Rotational DIgital Computer (CORDIC) algorithm.

A highly dynamic control scheme with very low torque ripple-direct self control (DSC) with torque hysteresis control--for very high-power medium-voltage induction motor drives fed by a double three-level inverter (D3LI) is presented. In this arrangement, two three-level inverters that are connected in parallel at their dc sides are feeding the open motor windings. The DSC, well known from two- and three-level inverters, is adapted to the D3LI and optimized for a minimum torque ripple. An 18-corner trajectory is chosen for the stator flux of the induction machine since it is approaching the ideal circle much better than the hexagon known from DSC for two-level inverters, without any detriment to the torque ripple. The machine and inverter control are explained and the proposed torque quality and dynamics are verified by measurements on a 180-kW laboratory drive. Index Terms--Converter control, digital signal processor, direct self control, drives, highly dynamic drives, induction machines, multilevel converters, power converters, torque control, variable-speed drives.

This paper proposes a new nth order two-input/output filter in module for two-phase signal processing. The filter can make the distinction between positive and negative frequencies of two-phase signals and can allow for processing the signals based on frequency polarity. The filter can also change dynamically its filtering characteristics by simply injecting a shift signal to the filter. The filtering effects equivalent to ones by parallel-arranged filters with vector rotators can be obtained, but in a much simpler manner. Unified analyses about attractive general properties of the proposed filter are given for easy designs and realizations as well. Effectiveness of the analyses and usefulness of the filter are examined and confirmed through numerical experiments. The proposed two-input/output filter in module has potential usefulness in a variety of polyphase signal filtering applications, including three-phase power systems with active filtering function and sensorless vector controls of three-phase ac motors. Index Terms--D-module, filter, magnetic bearing, negative phase, positive phase, power system, sensorless vector control.

Auscultatory blood pressure measurement uses the presence and absence of acoustic pulses generated by an artery (i.e., Korotkoff sound), detected with a stethoscope or a sensitive microphone, to noninvasively estimate systolic and diastolic pressures. Unfortunately, in high noise situations, such as ambulatory environments or when the patient moves moderately, the current auscultatory blood pressure method is unreliable, if at all possible. Empirical evidence suggests that the pulse beneath an artery occlusion travels relatively slow compared with the speed of sound. By placing two microphones along the bicep muscle near the brachial artery under the occlusion cuff, a similar blood pressure pulse appears in the two microphones with a relative time delay. The acoustic noise, on the other hand, appears in both microphones simultaneously. The contribution of this paper is to utilize this phenomenon by filtering the microphone waveforms to create spatially narrowband information signals. With a narrowband signal, the microphone signal phasing information is adequate for distinguishing between acoustic noise and the blood pressure pulse. By choosing the microphone spacing correctly, subtraction of the two signals will enhance the information signal and cancel the noise signal. The general spacing problem is also presented. Index Terms--Array signal processing, biomedical acoustics, biomedical measurements, biomedical signal processing, blood pressure measurement.

We discuss the application of digital pulse shape algorithms to n/[gamma] pulse shape discrimination (PSD) in boron-10 enriched liquid scintillator, where the use of digital techniques has potential applications for neutron monitors. High-speed flash analog-to-digital converters have opened up new possibilities for scintillator detector systems based upon digital event-by-event data acquisition. Using an 8-bit 1-GS/s waveform digitizer, we sampled the scintillation detector signals with nanosecond time resolution to extract event parameters such as pulse height and rise time. Hence, we have studied the variations in pulse shape and rise times for gamma rays and neutrons and the quality of separation of these events. Even using a simple 10-90% rise-time algorithm, we observe good gamma/neutron separation. We present the PSD figure-of-merit obtained using this digital technique. Index Terms--Digital signal processors, neutron detectors, pulse shaping methods.

A compact and accurate readout system has been developed for high-rate spectroscopy with multi-element detectors. The fully self-triggered system multiplexes the signals from 32 detectors into a novel peak detector, which also serves as a derandomizer. The captured pulse heights are stored as analog samples before being presented to the ADC along with the corresponding channel addresses. The peak detector incorporates a new two-phase configuration that cancels offsets and other errors found in conventional designs. Offset cancellation gives the peak detector rail-to-rail sensing and driving capability and permits two or more peak detectors to be operated in parallel to serve as a data-driven analog memory. First experimental results on the new peak detector and derandomizer (PDD) circuit, fabricated in 0.35 [micro]m CMOS technology, include a 0.2% absolute accuracy for pulses with 500-ns peaking time, 2.7-V linear-input range, 3.5-mW power dissipation, 250-mV/s droop rate, and negligible dead time. We have tested the system with 32 CZT detectors and a [sup.241]Am source. The spectra collected from the 32-channel system show that the noise performance of the preamp/shaper is not degraded by the multiplexing, peak detecting, and derandomizing operations. Index Terms--CMOS, derandomizer, peak detector.

In this paper, we present a multichannel very large scale integration implementation of ROTOR, a time-variant parameters shaping amplifier designed for the readout of high-rate asynchronous signals from multi-element solid-state X-ray detection systems. In particular, ROTOR was optimized for high-rate X-ray spectroscopy with multi-element semiconductor drift detectors (SDDs) in applications using synchrotron light sources such as X-ray holography or extended x-ray absorption fine structure (EXAFS) experiments. A 30 channels circuit has been implemented in the 1 [micro]m/5 V JFET/CMOS technology of the Fraunhofer-Institut, Duisburg, Germany. Each analog channel features a trapezoidal weighting function, 1.6 [micro]s wide, obtained by means of a switched-current technique. A digital section, directly integrated on the ROTOR chip, allows the timing and control of all the analog switches of the amplifiers as required for the circuit functionality, without the need of external signals. The main features of the circuit design and the results obtained in the experimental characterization of the prototype, also in spectroscopy measurements by using an SDD, are presented. Index Terms--Integrated readout circuits, shaping amplifiers, silicon drift detectors, X-ray spectroscopy.

An improved method for fast scanning and fluorescence detection on multimicrochannel microchips is presented using acousto-optic-deflection-driven laser-beam scanning. A microprocessor embedded subsystem used in conjunction with LabView program as the human-machine interface for control of laser-beam scanning and data preprocessing allowed faster scanning and addressing speeds to be attained and improved attenuation calibration and the data sampling speed. This system allows for flexible, high-resolution fluorescence detection for multimicrochannel electrophoresis in a manner that can be applied to a number of high-throughput analysis applications. Incorporating an F-theta focusing lens into the optical set-up allowed for a laser spot as small as 10 [micro]m to accurately be addressed to the center of microchannels. With this spot size, it will be possible to further increase the channel density in the scanning range without encountering crosstaik. Using a six-channel microchip (four separation channels, two alignment channels), the simultaneous separation and fluorescence detection of amino acids and DNA digest samples in four channels is illustrated. User-friendly interpretation of the separation data is facilitated not only by a peak alignment/normalization routine developed within the software, but also through improved signal-to-noise ratios obtained through exploitation of signal processing. Index Terms--Acousto-optical deflector (AOD), capillary electrophoresis (CE), laser-induced fluorescence (LIF) detection, microchannel, microchip, microprocessor, signal processing.