Showing papers on "Spectrum analyzer published in 2013"

Single-pixel polarimetric imaging spectrometer by compressive sensing

Abstract: We present an optical system that performs polarimetric spectral imaging with a detector with no spatial resolution. This fact is possible by applying the theory of compressive sampling to the data acquired by a sensor composed of an analyzer followed by a commercial fiber spectrometer. The key element in the measurement process is a digital micromirror device, which sequentially generates a set of intensity light patterns to sample the object image. For different configurations of the analyzer, we obtain polarimetric images that provide information about the spatial distribution of light polarization at several spectral channels. Experimental results for colorful objects are presented in a spectral range that covers the visible spectrum and a part of the NIR range. The performance of the proposed technique is discussed in detail, and further improvements are suggested.

Parametric spectro-temporal analyzer (PASTA) for real-time optical spectrum observation.

Abstract: Real-time optical spectrum analysis is an essential tool in observing ultrafast phenomena, such as the dynamic monitoring of spectrum evolution. However, conventional method such as optical spectrum analyzers disperse the spectrum in space and allocate it in time sequence by mechanical rotation of a grating, so are incapable of operating at high speed. A more recent method all-optically stretches the spectrum in time domain, but is limited by the allowable input condition. In view of these constraints, here we present a real-time spectrum analyzer called parametric spectro-temporal analyzer (PASTA), which is based on the time-lens focusing mechanism. It achieves a frame rate as high as 100 MHz and accommodates various input conditions. As a proof of concept and also for the first time, we verify its applications in observing the dynamic spectrum of a Fourier domain mode-locked laser, and the spectrum evolution of a laser cavity during its stabilizing process.

Nonlinear single-spin spectrum analyzer.

Abstract: Qubits have been used as linear spectrum analyzers of their environments. Here we solve the problem of nonlinear spectral analysis, required for discrete noise induced by a strongly coupled environment. Our nonperturbative analytical model shows a nonlinear signal dependence on noise power, resulting in a spectral resolution beyond the Fourier limit as well as frequency mixing. We develop a noise characterization scheme adapted to this nonlinearity. We then apply it using a single trapped ion as a sensitive probe of strong, non-Gaussian, discrete magnetic field noise. Finally, we experimentally compared the performance of equidistant vs Uhrig modulation schemes for spectral analysis.

Design and Application of Imaging Plasma Instruments

Abstract: Imaging particle detectors based on the cylindrically symmetric top hat analyzer optics are used in plasma instruments for many of the current generation of spacecraft, including Wind, Cluster, Fast, Mars Observer, Mars Global Surveyor, Lunar Prospector, and numerous sounding rockets These instruments are designed to provide rapid measurements of particle distribution functions with good phase space resolution Design details can be optimized for measuring specific plasma populations, such a cold beams, hot distributions, or loss cone features The top hat geometry is a simple extension of traditional spherical section electrostatic analyzer optics, but there are several interacting design parameters that are not uniquely determined For specified values of geometric factor, energy resolution and angular acceptance, analytic expressions can be used to specify preliminary mechanical dimensions This initial design is then optimized by a computer trajectory-tracing program that accounts for additional design details such as input aperture collimation and particle detector location, or other optical elements such as input deflectors or time-of-flight detectors Once the optical design is specified, additional design considerations are addressed, such as the particle detection method, suppression of UV and electron scattering, contamination control, electrical interfacing, and general mechanical packaging Examples of several current flight instruments are described

Design Issues for a Portable Vocal Analyzer

Abstract: The aim of this paper consists in identifying the main design specifications of a portable analyzer that allows the vocal signal of a person under monitoring to be acquired and stored. Suitable calibration procedures will be also defined for the microphone used in the portable device in order to ensure the traceability of the obtained measurements. The collected data will be used to identify voice disorders, to prevent an improper use of the voice, and to evaluate the vocal effort induced by noisy and/or reverberant environments. The vocal analyzer is based on a contact microphone worn by the person under monitoring and a portable microcontroller-based unit that hosts the conditioning circuitry, analog-to-digital converter, and storing memory. Two alternative sensors are investigated as contact microphones: an accelerometer and an electret condenser microphone. The former is expected to exhibit a negligible sensitivity to airborne effects, and the latter would provide a larger bandwidth, thus allowing parameters related to the vowel quality to be estimated. Particular attention will be paid toward traceability assurance and uncertainty estimation, and a calibration procedure for each of the estimated parameters will be proposed. In this paper, a data-acquisition-board-based setup has been used instead of a portable microcontroller unit in order to easily perform tests that allow the used microphones to be characterized and the calibration procedures for the parameters of interest to be assessed. Experimental results are reported that refer to the estimation of the parameters sound pressure level $(SPL)$ and fundamental frequency $(F_{0})$ .

Perfect and robust phase-locking of a spin transfer vortex nano-oscillator to an external microwave source

Abstract: We study the synchronization of the auto-oscillation signal generated by the spin transfer driven dynamics of two coupled vortices in a spin-valve nanopillar to an external source. Phase-locking to the microwave field hrf occurs in a range larger than 10% of the oscillator frequency for drive amplitudes of only a few Oersteds. Using synchronization at the double frequency, the generation linewidth is found to decrease by more than five orders of magnitude in the phase-locked regime (down to 1 Hz, limited by the resolution bandwidth of the spectrum analyzer) in comparison to the free running regime (140 kHz). This perfect phase-locking holds for frequency detuning as large as 2 MHz, which proves its robustness. We also analyze how the free running spectral linewidth impacts the main characteristics of the synchronization regime.

Fast In Situ Airborne Measurement of Ammonia Using a Mid-Infrared Off-Axis ICOS Spectrometer

Abstract: A new ammonia (NH3) analyzer was developed based on off-axis integrated cavity output spectroscopy. Its feasibility was demonstrated by making tropospheric measurements in flights aboard the Department of Energy Gulfstream-1 aircraft. The ammonia analyzer consists of an optical cell, quantum-cascade laser, gas sampling system, control and data acquisition electronics, and analysis software. The NH3 mixing ratio is determined from high-resolution absorption spectra obtained by tuning the laser wavelength over the NH3 fundamental vibration band near 9.67 μm. Excellent linearity is obtained over a wide dynamic range (0–101 ppbv) with a response rate (1/e) of 2 Hz and a precision of ±90 pptv (1σ in 1 s). Two research flights were conducted over the Yakima Valley in Washington State. In the first flight, the ammonia analyzer was used to identify signatures of livestock from local dairy farms with high vertical and spatial resolution under low wind and calm atmospheric conditions. In the second flight, the anal...

A family of new generation miniaturized impedance analyzers for technical object diagnostics

Abstract: The paper presents the family of three analyzers allowing to measure impedance in range of 10 ohm<|Zx|<10 Gohm in a wide frequency range from 10 mHz up to 100 kHz. The most important features of the analyzers family are: miniaturization, low power consumption, low production cost, telemetric controlling and the use of impedance measurement method based on digital signal processing DSP. The miniaturization and other above mentioned features of the analyzers were obtained thanks to the use of the newest generation of large scale integration chips: e.g.. „system on a chip” microsystems (AD5933), 32-bit AVR32 family microcontrollers and specialized modules for wireless communication using ZigBee standard. When comparing metrological parameters, the developed instrumentation can equal portable analyzers offered by top worldwide manufacturers (Gamry, Ivium) but outperforms them on smaller dimensions, weight, a few times smaller price and a possibility to work in a distributed telemetric networks. All analyzer versions are able to put into medium-volume production.

Architecture Exploration for a High-Performance and Low-Power Wireless Vibration Analyzer

Abstract: Vibration based condition monitoring is considered to be the most effective method for analyzing the performance of rotating machinery and for early fault detection. Traditional vibration analyzers used for this purpose provide wired interface(s) to connect sensors with the system that analyzes the vibration data. A wireless vibration analyzer can be useful to monitor and analyze the vibration of rotating as well as inaccessible parts of the machinery. However, for a wireless vibration analyzer, both the performance and power consumption are of major concern, especially for real-time tri-axes (horizontal, vertical, and axial) vibration data processing and analyses at a high sampling rate. To evaluate the performance of such an analyzer, we explore different architectures in order to realize a high-performance and low-power wireless vibration analyzer that can be used in addition to traditional analyzers. For this purpose, four different architectures have been implemented in order to evaluate them in terms of performance, power consumption, cost, and design complexity.

Network implementation of spectrum analysis

Abstract: Access devices may receive signals over a network and calculate a frequency spectrum of the received signals. An analyzer system may collect the frequency spectrum data from multiple access devices, and based on the collected data, detect, identify, and locate sources of anomalies in a communication network.

Frequency stability of a 10 GHz optical frequency comb from a semiconductor-based mode-locked laser with an intracavity 10,000 finesse etalon

Abstract: An optical frequency comb is constructed using a semiconductor gain medium with a fiber-coupled external cavity and stabilized to an intracavity 10,000 finesse etalon, which is temperature stabilized and held in a vacuum chamber at 10−6 Torr. Optical frequency stability measurements show that the comb has a reduced sensitivity to environmental fluctuations. An upper limit on the optical frequency variation of 100 kHz over >12 min of continuous operation is measured using a real-time spectrum analyzer. This measurement is limited by the linewidth of the reference source, and further measurements with a frequency counter show a fractional deviation of 2×10−11 at 50 ms. Furthermore, out-of-band ASE rejection is shown to be >36 dB, a tenfold improvement over that of a laser with a 1000 finesse FPE.

Spectrum opportunities for electromagnetic energy harvesting from 350 mhz to 3 ghz

Abstract: This paper presents spectrum opportunities for radio frequency (RF) energy harvesting identified through power density measurements from 350 MHz to 3 GHz. The field trials have been performed in two different cities (Covilha and Lisbon), by using the NARDA-SMR spectrum analyser with measuring antenna, and the Signal Hound spectrum analysers, respectively. The scope of our research considers RF energy harvesting devices, enabling to convert RF energy to direct current (DC), providing an alternative source to power supply wireless sensor network (WSN) devices. Printed antennas, able to operate at GSM (900/1800) bands, are proposed with gains of the order of 1.8-2.06 dBi and efficiency 77.6-84%. Guidelines for the choice of textile materials for a wearable antenna are also provided.

Heterodyned toroidal microlaser sensor

Abstract: Optical microcavity sensors have demonstrated success in detecting analytes with high sensitivity. Typically, the sensor output is monitored using oscilloscopes or optical spectrum analyzers; however, these instruments can significantly limit the sensing performance. In the present work, we address this limitation by developing a neodymium-doped toroid microlaser and heterodyning it with a reference laser. The resulting beat signal is analyzed on an electrical spectrum analyzer. By performing comparative temperature sensing experiments, we demonstrate that the heterodyning improves the detection limit over 60-fold while also improving the temporal resolution and the signal to noise ratio up to 50-fold.

Parametric Method of Frequency-Dependent I/Q Imbalance Compensation for Wideband Quadrature Modulator

Abstract: This paper proposes a parametric method of frequency-dependent I/Q imbalance compensation for wideband quadrature modulators using the spectrum measurement of a radio frequency (RF) signal that is easily performed by a general-purpose spectrum analyzer. The proposed method empirically estimates the frequency-dependent circuit parameters using only the magnitude of the frequency spectrum of the RF signal that is fed back from the spectrum analyzer. The frequency dependency of the I/Q imbalance effect generated by the difference between the overall frequency responses of the I and Q branches is modeled by frequency-dependent circuit parameters. By dividing the entire signal band into several sub-bands, the transmit signals are predistorted per sub-band in the frequency domain. To estimate the frequency-dependent circuit parameters, in this study, the modified method of steepest descent developed for single-band compensation is extended to the frequency-domain sub-band compensation scheme. We demonstrate the compensation effect by implementing an automatic sub-band circuit parameter estimation system.

Multiple band portable spectrum analyzer

Abstract: A device for detecting RF power information, for use as a stand alone purpose built device, or connectable to an external computing instrument such as a laptop, PDA, or cell phone, or other similarly capable technology. The device scans two or more bands in the wireless frequency and provides output to the user with wireless information about multiple bands of information.

Characteristics of External Loop Sensor Located Near Bushing on Partial Discharge Induced Electromagnetic Wave Measurement

Abstract: For transmitting a huge electrical energy, high voltage transmission systems are commonly operated. Due to high reliability and less space required, gas insulated substation (GIS) are widely used. In a defect experienced GIS, partial discharge (PD) usually takes place. Partial discharge (PD) monitoring technique using UHF method becomes more popular because of its higher signal to noise (S/N) ratio. Amongst novel sensors, loop sensor could be a candidate for PD detector to measure UHF signal emitted from PD source. This paper presents the experiment results on characteristics of loop sensors. The characteristics of three loop sensors with varying diameter were examined using a spectrum analyzer and a network analyzer to obtain frequency characteristic and optimum operating frequency (S11) parameter, respectively. Then, PD experiment was conducted on 66kV GIS model having floating electrode and free metallic particles as its PD source. The loop sensors were placed far external to GIS bushing to measure leaked PD signal from it. The influences of the sensor diameter and the sensor distance from GIS bushing on PD detection sensitivity were also examined. Based on IEC-60270 standard measurement, the highest sensitivity of 30 pC was obtained from this investigation. The result suggests that higher sensitivity could be achieved with proper shielding and suitable filter design against external noise.

Spectrum analyzers today and tomorrow: part 1 towards filterbanks-enabled real-time spectrum analysis

Abstract: This is Part 1 of a two-part article on spectrum analyzer technology and the future capabilities enabled by introducing filterbanks. A spectrum analyzer (SA) is the primary tool for studying the spectral composition of many electrical, acoustic or optical waveforms. It displays a power spectrum over a given frequency range, changing the display as the properties of the signal change. Today, it is an essential element of the engineer's toolbox. In this part, we will start by reviewing SA architectures in an historical perspective. The architectures and working principles of swept based and Fast Fourier Transform (FFT)-based SAs are discussed. Then, we zoom in on the so-called Real-Time Spectrum Analyzers (RTSA) and discuss the more significant performance criteria as a function of the measurement problem at hand. In the last section, we discuss several applications made possible by RTSA. The extension of RTSA with filterbanks is the main topic of Part 2 of this article which will appear in the December 2013 issue of the IEEE Instrumentation and Measurement Magazine.

Using Crosscorrelation to Mitigate Analog/RF Impairments for Integrated Spectrum Analyzers

Abstract: An integrated spectrum analyzer is useful for built-in self-test purposes, software-defined radios, or dynamic spectrum access in cognitive radio. The analog/RF performance is impaired by a number of factors, including thermal noise, phase noise, and nonlinearity. In this paper, we present an integrated circuit with two integrated RF-frontends, of which the outputs are crosscorrelated in digital baseband. We show by theory and measurements that the above-mentioned impairments are mitigated by this technique. The presented 65-nm CMOS prototype operates at 1.2 V, and obtains a noise floor below -169 dBm/Hz, an IIP3 of +25 dBm, and more than 20 dB of phase-noise reduction. In a special high-impedance mode, an even lower noise floor below -172 dBm/Hz is obtained.

ESTIMATION ERRORS IN 1/f γ NOISE SPECTRA WHEN EMPLOYING DFT SPECTRUM ANALYZERS

Abstract: Spectra estimation in the field of low frequency noise measurements (LFNMs) is almost always performed by resorting to Discrete Fourier Transform (DFT) based spectrum analyzers. In this approach, the input signal is sampled at a proper frequency fs and the power spectrum of sequences of N samples at a time are calculated and averaged in order to obtain an estimate of the spectrum at discrete frequency values fk = k∆f , where the integer k is the frequency index and ∆f = fs/N is the frequency resolution. As the number of average increases, the statistical error, which is inversely proportional to the resolution bandwidth, can be made very small. However, if the spectrum of the signal is not a slowly changing function of the frequency, as in the case of 1/f γ processes, spectra estimation by means of the DFT also results in systematic errors. In this paper we discuss the dependence of these errors on spectral parameters (the spectrum amplitude, the frequency f , the spectral exponent γ and the DC power) and on measurement parameters (the spectral window, the resolution bandwidth ∆f and the instrumentation AC cutoff frequency). Quantitative expressions for the systematic errors are obtained that, besides helping in the interpretation of the results of actual LFNMs, can be used as a guideline for the optimization of the measurement parameters and/or for the estimation of the maximum accuracy that can be obtained in given experimental conditions. This quantitative analysis is particularly important since while we find that, in general, the systematic error at a given frequency fk = k∆f can be made small ifk is made large, which implies that ∆f must be much smaller than fk, possibly in contrast with the need for a ∆f as large as possible in order to reduce the measurement time, the magnitude of the error depends on the selected spectral window. The role of the instrumentation AC cutoff frequency fAC on the systematic error is also investigated and quantified and it is demonstrated that the error increases as fAC reduces. This last result is very important since, often, fAC is chosen much lower than the frequencies of interest and this choice may result in an increase of the systematic error.

Design of a lens table for a double toroidal electron spectrometer

Abstract: We report here on the method we developed to build a lens table for a four-element electrostatic transfer lens operated together with a double toroidal electron energy analyzer designed by one of us, and whose original design and further improvements are described in detail in Miron et al. [Rev. Sci. Instrum.68, 3728 (Year: 1997)10.1063/1.1148017] and Le Guen et al. [Rev. Sci. Instrum.73, 3885 (Year: 2002)10.1063/1.1511799]. Both computer simulations and laboratory instrument tuning were performed in order to build this lens table. The obtained result was tested for a broad range of electron kinetic energies and analyzer pass energies. Based on this new lens table, allowing to easily computer control the spectrometer working conditions, we could routinely achieve an electron energy resolution ranging between 0.6% and 0.8% of the analyzer pass energy, while the electron count rate was also significantly improved. The establishment of such a lens table is of high importance to relieve experimentalists from the tedious laboring of the lens optimization, which was previously necessary prior to any measurement. The described method can be adapted to any type of electron/ion energy analyzer, and will thus be interesting for all experimentalists who own, or plan to build or improve their charged particle energy analyzers.

BOTDA (Brillouin Optical Time-Domain Analysis) system based on pulse coding and coherent detection

Abstract: A BOTDA system based on pulse coding and coherent detection comprises a narrow linewidth laser device (10), a first polarization-maintaining coupler (11), a second polarization-maintaining coupler (12), a microwave signal source (17), testing optical fibers (18), an optical circulator (19), a 3dB coupler (20), a balance photoelectric detector (21), a scrambler (16), a spectrum analyzer (22) and a digital signal processing unit (23), wherein continuous light emitted by the arrow linewidth laser device (10) is divided into two channels of continuous light, namely, a first channel of the continuous light and a second channel of the continuous light, through the first polarization-maintaining coupler (11); and the system further comprises a frequency shifter (9), a first electrooptical modulator (13), a pulse signal source (14) and a second electrooptical modulator (15). The system adopts a pulse coding technology and a coherent detection method, so that the signal to noise ratio of the BOTDA and the measurement accuracy can be improved, the sensing distance is increased, and the system has the function of breakpoint detection.

Tandem time-of-flight mass spectrometry with non-uniform sampling

Abstract: A method and apparatus are disclosed for parallel all-mass tandem mass spectrometry employing multi-reflecting time-of-flight analyzer for both MS stages, preferably arranged within the same analyzer to secure ultra-high resolution. Sensitivity and speed of TOF-TOF tandem are enhanced by non-redundant multiplexing based on signal sparseness and on avoiding repetitive signal overlaps at multiple repetitions of true fragment signals. Non-redundant matrices of gate and delay timing are constructed by extending orthogonal Latin square matrices. The method is generalized for multiplexing of any multiple repetitive signal sources being sparse either spectrally, or spatially, or in time.

BigBand: GHz-Wide Sensing and Decoding on Commodity Radios

Abstract: The goal of this paper is to make sensing and decoding GHz of spectrum simple, cheap, and low power. Our thesis is simple: if we can build a technology that captures GHz of spectrum using commodity Wi-Fi radios, it will have the right cost and power budget to enable a variety of new applications such as GHzwide dynamic access and concurrent decoding of diverse technologies. This vision will change today’s situation where only expensive power-hungry spectrum analyzers can capture GHz-wide spectrum. Towards this goal, the paper harnesses the sparse Fourier transform to compute the frequency representation of a sparse signal without sampling it at full bandwidth. The paper makes the following contributions. First, it presents BigBand, a receiver that can sense and decode a sparse spectrum wider than its own digital bandwidth. Second, it builds a prototype of its design using 3 USRPs that each samples the spectrum at 50 MHz, producing a device that captures 0.9 GHz — i.e., 6× larger bandwidth than the three USRPs combined. Finally, it extends its algorithm to enable spectrum sensing in scenarios where the spectrum is not sparse.

Systems and methods for using protocol information to trigger waveform analysis

Abstract: Systems and methods are disclosed herein to provide communication test systems for the testing of packet data communication devices, systems and networks. According to one aspect of the subject matter described herein, a test system containing an integrated traffic, protocol and waveform analyzer is disclosed that includes a traffic generator/analyzer and a protocol engine that triggers a waveform analyzer to analyze the signal waveform of a device under test at a predetermined point. Such a test system may offer improved capabilities such as a more selective and accurate measurement of complex signal waveforms, more automated measurements of waveforms pertaining to wireless communication data streams, and more rapid identification and measurement of waveforms corresponding to errored packets.

Performance of parametric spectro-temporal analyzer (PASTA)

Abstract: Parametric spectro-temporal analyzer (PASTA) is an entirely new wavelength resolving modality that focuses the spectral information on the temporal axis, enables ultrafast frame rate, and provides comparable resolution and sensitivity to the state-of-art optical spectrum analyzer (OSA). Generally, spectroscopy relies on the allocation of the spectrum onto the spatial or temporal domain, and the Czerny-Turner monochromator based conventional OSA realizes the spatial allocation by a dispersive grating, while the mechanical rotation limits its operation speed. On the other hand, the PASTA system performs the spectroscopy function by a time-lens focusing mechanism, which all-optically maps the spectral information on the temporal axis, and realizes the single-shot spectrum acquisition. Therefore, the PASTA system provides orders of magnitude improvement on the frame rate, as high as megahertz or even gigahertz in principle. In addition to the implementation of the PASTA system, in this paper, we will primarily discuss its performance, including the tradeoff between the frame rate and the wavelength range, factors that affect the wavelength resolution, the conversion efficiency, the power saturation and the polarization sensitivity. Detection bandwidth and high-order dispersion introduced limitations are also under investigation. All these analyses not only provide an overall guideline for the PASTA design, but also help future research in improving and optimizing this new spectrum resolving technology.

System and method for vibration analysis

Abstract: An exemplary analyzer, such as a circuit breaker analyzer, method, and system are provided for use in determining the mechanical condition of a device, such as a circuit breaker, appliance, machine, equipment, or other mechanical system. In one embodiment the analyzer is implemented using a smartphone or other smart device to couple to the device being analyzed to measure mechanical vibrations generated at a surface of the device during an operational event using a force detector, such as an accelerometer, and then comparing such measured values to a known, good signature of mechanical vibrations for the same type of operational event for same type of equipment.

Optical Rotatory Dispersion Measurement of D-Glucose with Fixed Polarizer Analyzer Accessory in Conventional Spectrophotometer

Abstract: In the sample compartment of a conventional spectrophotometer, mounting of a polarizer before sample and an analyzer behind sample allows the determination of the optical rotatory dispersion of optical active media by measurement of the transmission ratio of crossed and parallel arranged polarizer and analyzer. A formula for the determination of the angle of rotation is derived from the transmission ratio. The arrangement is applied to determine the molar optical rotation of D-glucose in water in the wavelength range from 220 nm to 820 nm.