Amplitude Resolution Research Articles

Methods for measuring amplitudes of signals from Cherenkov counters

Measurements of the pulse heights in the T0 start trigger detector of the ALICE experiment are necessary both for time-amplitude offline correction of start signal T0 used in the time-of-flight TOF detector and for monitoring the state of the Cherenkov counters in the detector. A high amplitude resolution is not required for these tasks; what is needed is fast encoding and interfacing with the data readout system in which only time channels are available. Therefore, amplitudes are measured in the detector by pulse-height-to-time conversion using two independent methods, one of which involves quasi-logarithmic charge-to-time converter (QTC) and the other employs two—leading-edge (LED) and constant-fraction (CFD)—timing discriminators. The main characteristics of both methods and results of calibrations of the appropriate devices using a pulsed laser are presented.

A high‐SFDR direct digital frequency synthesizer with embedded error‐compensation CMOS OTP ROM for wireless receivers

AbstractA direct digital frequency synthesizer (DDFS) using on‐chip CMOS one‐time programmable read‐only memory (OTP ROM) is presented. A straight‐line approximation algorithm for sinusoid with compensation is adopted such that the accuracy could be maintained and the cost is reduced. Most important of all, a CMOS OTP ROM is used as a look‐up ROM table, which is implemented by a typical logic CMOS process. Therefore, the proposed DDFS can be integrated in any CMOS‐based front‐end circuit for wireless communication systems. The proposed DDFS design is fully implemented using a typical 1P6M 0.18 μm CMOS process. It has a 12‐bit amplitude resolution with 86.89 dB spurious free dynamic range using a small ROM size of 256 bits. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1695–1699, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24422

Characteristics of the detecting equipment for the nanosecond tagged-neutron technology

Detecting equipment for the nanosecond tagged-neutron technology has been developed, and its characteristics have been studied. The principles of arrangement and operation of the readout electronics based on the selection of useful events according to specified criteria and data accumulation by a buffer-memory unit with subsequent transfer of data arrays to a remote computer for processing and visualization. The main selection criterion is the presence of signals from α- and γ detectors within the time gate and amplitude ranges in the absence of overlapped events. A prototype of a setup for testing the developed equipment was assembled and experimental studies of its characteristics were performed. The time resolution attained in the recording of α-γ coincidences is 1.0 ± 0.1 ns at an amplitude resolution of the γ detector of 3.6–3.8%.

Finite-resolution digital receiver design for impulse radio ultra-wideband communication

Receiver design for impulse radio based ultrawideband (UWB) communication is a challenge. High sampling rate high resolution digital receiver is usually difficult to implement. Some tradeoffs can be made on the digital receiver, such as limiting amplitude resolution to only one bit, which results in a previously considered monobit receiver. In this paper, we consider the design of finite-resolution digital UWB receivers. We derive the optimal post-quantization processing, and analyze the achievable bit-error rate performance using an approximation of the log-likelihood ratio. Optimal thresholds for 4- and 3-level quantization are obtained. Training-based receiver template estimation is presented. Our work discloses the incremental gain that additional quantization levels offer and the results provide useful guidelines for designing impulse radio UWB digital receivers.

Surface plasmon resonance-like integrated sensor at terahertz frequencies for gaseous analytes

Plasmon-like excitation at the interface between fully polymeric fiber sensor and gaseous analyte is demonstrated theoretically in terahertz regime. Such plasmonic excitation occurs on top of a approximately 30 microm ferroelectric PVDF layer wrapped around a subwavelength porous polymer fiber. In a view of designing a fiber-based sensor of analyte refractive index, phase matching of a plasmon-like mode with the fundamental core guided mode of a low loss porous fiber is then demonstrated for the challenging case of a gaseous analyte. We then demonstrate the possibility of designing high sensitivity sensors with amplitude resolution of 3.4 x 10(-4) RIU, and spectral resolution of 1.3 x 10(-4) RIU in THz regime. Finally, novel sensing methodology based on detection of changes in the core mode dispersion is proposed.

CLASSIC ESSENTIAL TREMOR CHANGES FOLLOWING CEREBELLAR HEMORRHAGE

Diagnosis of essential tremor (ET) is based on clinical features.1 Presence of postural tremor (PT) is a requirement for the diagnosis of classic ET.1 Kinetic/intention tremor is present in most and resting tremor is seen in some patients with ET.1 The pathophysiology of ET remains unknown. One recent study reported significant cerebellar Purkinje cell (PC) loss in most ET cases and one autopsied patient revealed marked dentate nucleus neuronal loss.2 Since there is no suitable animal model of ET, observations in human subjects are critical to determine the pathophysiology of this disorder. The aim of this case report is to demonstrate transformation of classic ET to cerebellar ataxia and larger amplitude kinetic tremor but resolution of PT following ipsilateral cerebellar hemorrhage. ### Case report. A right-handed retired laboratory technologist with hypertension developed bilateral upper limb action tremor at age 30 years. The tremor progressed slowly but required no treatment. Family history revealed that her father had upper limb tremor and her 42-year-old daughter had ET onset at age 30 years. At age 65 she had spontaneous left cerebellar hemorrhage. Computerized …

A 12 GHz 1.9 W Direct Digital Synthesizer MMIC Implemented in 0.18 $\mu$m SiGe BiCMOS Technology

This paper presents a 12 GHz direct digital synthesizer (DDS) MMIC with 9-bit phase and 8-bit amplitude resolution implemented in a 0.18 mum SiGe BiCMOS technology. Composed of a 9-bit pipeline accumulator and an 8-bit sine-weighted current-steering DAC, the DDS is capable of synthesizing sinusoidal waveforms up to 5.93 GHz. The maximum clock frequency of the DDS MMIC is measured as 11.9 GHz at the Nyquist output and 12.3 GHz at 2.31 GHz output. The spurious-free dynamic range (SFDR) of the DDS, measured at Nyquist output with an 11.9 GHz clock, is 22 dBc. The power consumption of the DDS MMIC measured at a 12 GHz clock input is 1.9 W with dual power supplies of 3.3 V/4 V. The DDS thus achieves a record-high power efficiency figure of merit (FOM) of 6.3 GHz/W. With more than 9600 transistors, the active area of the MMIC is only 2.5 x 0.7 mm2. The chip was measured in packaged prototypes using 48-pin ceramic LCC packages.

Systems theory of ultrasound pulse echo technic (1)

The properties of diagnostic pulse echo systems, independent of instrument characteristics (ideal system) are analysed in Part 1 and it is shown in Part 2 how they are modified by "typical" instrument parameters. A simplified block diagram of an ideal system is analysed in the time and frequency domain by means of the one-dimensional system theory. The terms dynamic range, maximum penetration depth and amplitude resolution are explained.

An integrated multichannel waveform generator for large-scale spatio-temporal stimulation of neural tissue

We present an ASIC designed for electrical stimulation of neural tissue using multielectrode arrays. The ASIC is foreseen for applications in systems that require simultaneous stimulation and recording of signals from various types of neural tissue, both in vitro and in vivo. The developed ASIC comprises 64 independent stimulation channels, which are capable to generate arbitrarily defined bipolar current or voltage waveforms, controlled in real time with time resolution of 12.5 μs and amplitude resolution of 7 bits. The amplitude range of output signal can be scaled over a very wide range, which ensures compatibility with various electrode arrays of different size and geometry. Each channel is also equipped with a stimulation artifact suppressor controlled in real time, which reduces the dead time of the system after each stimulation pulse.

Environmental noise: Is there any significant influence on animals?

It is stated that there is no convincing evidence that animals are deterred by intense sounds (Heffner 2007). Nevertheless, it must be thoroughly examined to what extent animals are impaired by specific environmental noise with regard to their orientation, communication, behavior, etc. Such interferences would significantly influence the animals’ life. Similar to the auditory sensitivity of animals, the human hearing system shows a high performance in amplitude, frequency, and time resolution. It pays attention to more factors and noise features than only to absolute SPLs. Psychoacoustic parameters as well as further hearing-related parameters can capture such specific factors and features of noise, which allow us to draw conclusions concerning noise annoyance or, respectively, the pleasantness of noise. The adequate measurement and use of such parameters resulting in an advanced analysis and description of environmental noise—beyond simple sound pressure level considerations—provide valuable information with respect to noise annoyance, stress-related reactions, and interference of daily life activities of humans. The presentation will highlight the relevance, the determination, and interpretation of psychoacoustic and other hearing-related parameters in the context of environmental noise, with respect to the hearing sensation of humans.

An FPGA-Based Optical Transmitter Design Using Real-Time DSP for Advanced Signal Formats and Electronic Predistortion

Advances in the performance and flexibility of future optical networks will be brought about through the use of high-speed digital signal processing (DSP) for the generation of advanced optical signal formats and the compensation of transmission impairments. The use of field-programmable gate arrays (FPGAs) to implement experimental transceivers employing novel DSP techniques is attractive, as they are of low cost and are reprogrammable. In this paper, the design of a reprogrammable FPGA-based 10-Gb/s optical transmitter using real-time DSP is described and assessed through simulation. Using a single Xilinx Virtex-4 FPGA, digital filtering based on lookup tables with up to 12-bit addressing could be implemented. We also present, for the first time, a simulation technique using industry-standard digital design simulation tools (mentor graphics modelsim) in combination with a simulation of analog microwave components, optical transmission, and bit-error-rate estimation to assess the performance of the full transmission system. This simulation technique is used to demonstrate 10-Gb/s transmission over 550 km of standard single-mode fiber (SSMF) using electronic predistortion (EPD) and the generation of optical single sideband signals. A proof-of-principle experiment is described in which a single 10.7-Gb/s Mach-Zehnder modulator drive signal with 4-bit amplitude resolution and 1-sample/bit temporal resolution was generated. This was used as the input to Monte Carlo simulations to assess EPD transmission performance over SSMF links of up to 640 km.

Enhancement of subharmonic emission from encapsulated microbubbles by using a chirp excitation technique

Subharmonic contrast imaging promises to improve ultrasound-imaging quality by taking advantage of an increased contrast to tissue signal. However, acoustic pressures beyond the subharmonic generation threshold using common ultrasound pulses may induce significant contrast microbubble destruction. In this work, a chirp excitation technique is presented to enhance the subharmonic emission from encapsulated microbubbles. Chirp signals with a center frequency of 5 MHz, variable frequency range and duration time are employed to drive microbubbles in numerical simulation and experimental studies. We provide a theoretical evaluation of the chirp excitation pressure threshold and the acoustic pressure dependence of subharmonic based on Church's model and demonstrate that the amplitude and axial resolution of the subharmonic can be optimized by proper selection of the frequency range and time duration of the chirp signal. Measurements are qualitatively in agreement with the simulation. Moreover, we demonstrate that chirp excitation may be able to improve the amplitude of the subharmonic component up to 22 dB over the pulse excitation. The chirp excitation technique could potentially be used for improving the subharmonic contrast imaging quality.

Optimal Design of Selective Excitation Pulses in Magnetic Resonance Imaging using Genetic Algorithms

� Abstract—The proper design of RF pulses in magnetic resonance imaging (MRI) has a direct impact on the quality of acquired images, and is needed for many applications. Several techniques have been proposed to obtain the RF pulse envelope given the desired slice profile. Unfortunately, these techniques do not take into account the limitations of practical implementation such as limited amplitude resolution. Moreover, implementing constraints for special RF pulses on most techniques is not possible. In this work, we propose to develop an approach for designing optimal RF pulses under theoretically any constraints. The new technique will pose the RF pulse design problem as a combinatorial optimization problem and uses efficient techniques from this area such as genetic algorithms (GA) to solve this problem. In particular, an objective function will be proposed as the norm of the difference between the desired profile and the one obtained from solving the Bloch equations for the current RF pulse design values. The proposed approach will be verified using analytical solution based RF simulations and compared to previous methods such as Shinnar-Le Roux (SLR) method, and analysis, selected, and tested the options and parameters that control the Genetic Algorithm (GA) can significantly affect its performance to get the best improved results and compared to previous works in this field. The results show a significant improvement over conventional design techniques, select the best options and parameters for GA to get most improvement over the previous works, and suggest the practicality of using of the new technique for most important applications as slice selection for large flip angles, in the area of unconventional spatial encoding, and another clinical use. Keywords—selective excitation, magnetic resonance imaging,

SiPM and ADD as advanced detectors for astro-particle physics

In recent years, a few scientific groups are developing a novel type light sensor. These so-called silicon photo multipliers (SiPM) operate at relatively low bias voltage of 20–60 V, show unprecedented amplitude resolution and already now can provide photon detection efficiencies (PDE) comparable to or better than that of classical photo multipliers (PMT). We are developing the novel sensors for the astro-particle physics experiments MAGIC [J. Albert, et al., Astrophys. Lett. 642 (2006) L119. [6]] and also for EUSO [M. Teshima, et al., EUSO (The Extreme Universe Space Observatory), in: Scientific Objectives Proceedings ICRC, 2003, p. 10690. [7]]. The front-illuminated SiPM are developing with the group from MEPhI in Moscow and the back-illuminated Avalanche Drift Diodes (ADD) with the semiconductor laboratory (HLL) attached to the MPI for Physics. Our goal is to produce 5–10 mm size ultra-fast, low-noise and very high PDE (60–80%) sensors operating in the wavelength range 300–600 nm. Together with MEPhI, we have already produced and successfully tested 1.3×1.3, 3×3 and 5×5 mm 2 size SiPMs. Very recently, the first ADD test structures were produced and are under evaluation at the HLL. In this report, we want to outline the main parameters of the new sensors for the needs of astro-particle physics experiments.

Laser-scanning confocal vibrometer microscope: Theory and experiments

In this article we present a new laser-scanning confocal microscope for vibration measurements in microscopic mechanical and biological structures. Our system can map out-of-plane vibrations with picometer amplitude resolution while the locus transverse and depth resolutions are in the submicrometer regime. We have achieved this performance by using the measurement beam of a heterodyne laser-Doppler vibrometer as the scanned laser beam of a confocal microscope. The power of the heterodyne carrier is a measurement of the detected light intensity. Therefore, the laser-scanning confocal laser-Doppler vibrometer microscope (CVM) can also be used as common confocal microscope to image and measure geometries of three-dimensional structures. The focus of this article is on the analysis of the transverse resolution, which cannot be adopted from other techniques. Our realized CVM allows vibration measurements up to 20MHz. The measured minimum 1∕e2-power spot diameter of 730nm enables vibration analysis of submicrometer structures. In this article we discuss the fundamental limits of this new microscope type and we demonstrate the results of our realized system.

High Resolution Atomic Coherent Control via Spectral Phase Manipulation of an Optical Frequency Comb

We demonstrate high resolution coherent control of cold atomic rubidium utilizing spectral phase manipulation of a femtosecond optical frequency comb. Transient coherent accumulation is directly manifested by the enhancement of signal amplitude and spectral resolution via the pulse number. The combination of frequency comb technology and spectral phase manipulation enables coherent control techniques to enter a new regime with natural linewidth resolution.

A Direct Digital Frequency Synthesizer With Fourth-Order Phase Domain<tex>$DeltaSigma$</tex>Noise Shaper and 12-bit Current-Steering DAC

This paper presents a direct digital frequency synthesizer (DDFS) with a 16-bit accumulator, a fourth-order phase domain single-stage /spl Delta//spl Sigma/ interpolator, and a 300-MS/s 12-bit current-steering DAC based on the Q/sup 2/ Random Walk switching scheme. The /spl Delta//spl Sigma/ interpolator is used to reduce the phase truncation error and the ROM size. The implemented fourth-order single-stage /spl Delta//spl Sigma/ noise shaper reduces the effective phase bits by four and reduces the ROM size by 16 times. The DDFS prototype is fabricated in a 0.35-/spl mu/m CMOS technology with active area of 1.11mm/sup 2/ including a 12-bit DAC. The measured DDFS spurious-free dynamic range (SFDR) is greater than 78 dB using a reduced ROM with 8-bit phase, 12-bit amplitude resolution and a size of 0.09 mm/sup 2/. The total power consumption of the DDFS is 200mW with a 3.3-V power supply.

Pulse-Width Modulation Pre-Emphasis Applied in a Wireline Transmitter, Achieving 33 dB Loss Compensation at 5-Gb/s in 0.13-<tex>$muhbox m$</tex>CMOS

A transmitter pre-emphasis technique for copper cable equalization is presented that is based on pulse-width modulation (PWM). This technique is an alternative to the usual 2-tap symbol-spaced FIR (SSF) pre-emphasis. The technique uses timing resolution instead of amplitude resolution to adjust the filter transfer function, and therefore fits well with future high-speed low-voltage CMOS processes. Spectral analysis and time domain simulations illustrate that PWM pre-emphasis offers more relative high frequency boost than 2-tap SSF. Only one coefficient needs to be set to fit the equalizer transfer function to the channel, which makes convergence of an algorithm for automatic adaptation straightforward. A proof-of-concept 0.13-/spl mu/m CMOS transmitter achieves in excess of 5 Gb/s (2-PAM) over 25 m of standard RG-58U low-end coaxial copper cable with 33 dB of channel loss at the Nyquist frequency (2.5 GHz). Measured BER at this speed and channel loss is <10/sup -12/.

Playback performance of ultrahigh-capacity tape media with nanosized composite advanced particle (NanoCAP)

We have developed nanosized composite advanced particles (NanoCAP) with spherical shape and high coercivity, and fabricated dual coated tape to evaluate playback performance. The spherical shape contributes to smooth surfaces and reduced boundary variation between the magnetic layer and underlayer. The fine particle size, 17 nm, yields low media noise and high signal-to-noise ratio. The high coercivity, compared to metal particulate media, contributes to high amplitude resolution (D50=170 kfci). We confirmed that write demagnetization is well restrained and that NanoCAP tape should show very good playback performance with a superior writer.

25.3: Observations of Luminance, Contrast and Amplitude Resolution of Displays

contrast ratio and amplitude resolution are rapidly growing display specifications. Through a series of human factor studies we have developed simple guidelines for these specifications including viewer preference for luminance, optimal contrast ratio and amplitude resolution under realistic conditions. 1. Introduction past, conventional displays have been largely limited to a dynamic range similar to paper under office lighting conditions - approximately two or three orders of magnitude starting at a grayish black and finishing in the hundreds of cd/m 2 . This paradigm of hundreds-to-one contrast ratio, limited luminance and an amplitude resolution in the hundreds of steps is shifting today. Novel display technologies are emerging with the potential of much higher contrast and brightness. Moreover, even existing display technology is being pushed to the limit with a strong increase in display performance. This trend proceeds unevenly with contrast ratio rising faster than luminance, and amplitude resolution remaining largely static. As a result, many display designs make sub-optimal use of the device capabilities. This paper presents a series of human factor studies that aim to provide a basic framework of luminance, contrast ratio and amplitude resolution and their interaction. The use of a High Dynamic Range (HDR) display (1) as the imaging tool for the study, allows a large enough range for each variable to encompass all current and most near-future display technologies. The results of the study can be used to make design decisions for future displays as well as more realistic comparisons of existing devices. 2. Background Video Electronics Standards Association (VESA) and International Organization for Standardization (ISO) provide common guidelines for display specification including luminance and contrast ratio. Peak luminance is generally easy to measure and reported relatively accurately by the industry. Contrast ratio is significantly more challenging. A proper contrast ratio