Showing papers on "Spectrum analyzer published in 2002"

Thin film optical measurement system and method with calibrating ellipsometer

Abstract: An optical measurement system for evaluating a reference sample that has at least a partially known composition. The optical measurement system includes a reference ellipsometer and at least one non-contact optical measurement device. The reference ellipsometer includes a light generator, an analyzer and a detector. The light generator generates a beam of quasi-monochromatic light having a known wavelength and a known polarization for interacting with the reference sample. The beam is directed at a non-normal angle of incidence relative to the reference sample to interact with the reference sample. The analyzer creates interference between the S and P polarized components in the light beam after the light beam has interacted with reference sample. The detector measures the intensity of the light beam after it has passed through the analyzer. A processor determines the polarization state of the light beam entering the analyzer from the intensity measured by the detector, and determines an optical property of the reference sample based upon the determined polarization state, the known wavelength of light from the light generator and the composition of the reference sample. The processor also operates the optical measurement device to measure an optical parameter of the reference sample. The processor calibrates the optical measurement device by comparing the measured optical parameter from the optical measurement device to the determined optical property from the reference ellipsometer.

System and method for real-time spectrum analysis in a communication device

Abstract: A spectrum analysis engine (SAGE) that comprises a spectrum analyzer component, a signal detector component, a universal signal synchronizer component and a snapshot buffer component. The spectrum analyzer component generates data representing a real-time spectrogram of a bandwidth of radio frequency (RF) spectrum. The signal detector detects signal pulses in the frequency band and outputs pulse event information entries output, which include the start time, duration, power, center frequency and bandwidth of each detected pulse. The signal detector also provides pulse trigger outputs which may be used to enable/disable the collection of information by the spectrum analyzer and the snapshot buffer components. The snapshot buffer collects a set of raw digital signal samples useful for signal classification and other purposes. The universal signal synchronizer synchronizes to periodic signal sources, useful for instituting schemes to avoid interference with those signals.

Microphone array signal enhancement

Abstract: A system and method facilitating signal enhancement utilizing an adaptive filter is provided. The invention includes an adaptive filter that filters an input based upon a plurality of adaptive coefficients and modifies the adaptive coefficients based on a feedback output. A feedback component provides the feedback output based, at least in part, upon a non-linear function of the acoustic reverberation reduced output. Optionally, the system can further include a linear prediction (LP) analyzer and/or a LP synthesis filter. The system can enhance signal(s), for example, to improve the quality of speech that is acquired by a microphone by reducing reverberation. The system utilizes, at least in part, the principle that certain characteristics of reverberated speech are measurably different from corresponding characteristics of clean speech. The system can employ a filter technology (e.g., reverberation reducing) based on a non-linear function, for example, the kurtosis metric.

A high accuracy triangle-wave signal generator for on-chip ADC testing

Abstract: A general BIST architecture for A-to-D converters involves the integration of both an analog test signal generator and a digital output response analyzer. This paper presents a structure for the internal generation of a linear signal used with the histogram-based test technique. The structure is based on two highly linear ramp generators together with a feedback control circuitry. Results show that the proposed structure preserves the linearity of the ramp generators while accuracy of the triangle-wave is provided by means of a calibration scheme.

Power-amplifier characterization using a two-tone measurement technique

Abstract: An accurate nonlinear model is necessary to optimize the tradeoff between efficiency and linearity in power amplifiers. Gain compression (AM/AM) and amplitude-phase (AM/PM) distortion are the two primary model inputs used to characterize the nonlinearity. The amplifier's AM/AM and AM/PM characteristics are typically measured statically using a vector network analyzer. Since the input is typically a modulated signal, it is desirable to characterize the amplifier dynamically. This paper describes and demonstrates a dynamic AM/AM and AM/PM measurement and modeling technique involving a spectrum analyzer and two-tone input signals. A complete analysis of the measurement technique is presented, along with the data processing needed for the identification of a new three-box model. The test configuration and procedure are presented with special precautions to minimize measurement error. Results for a solid-state amplifier are used to accurately predict intermodulation distortion, while those for a traveling-wave tube amplifier show good agreement with that obtained dynamically using a 16 quadrature-amplitude-modulation signal.

Virtual spectrum analyzer based on data acquisition card

Abstract: A virtual spectrum analyzer based on a data acquisition card is presented. The implemented functions are described. The properties of the device were examined. Such features as accuracy and speed are considered. The virtual analyzer and an instrument equipped with a DSP are compared. The integrated programming package LabView was used to design the analyzer.

Ion energy distributions at rf-biased wafer surfaces

Abstract: We report the measurement of ion energy distributions at a radio frequency (rf)-biased electrode in inductively driven discharges in argon. We compare measurements made with a gridded energy analyzer and a commercial analyzer that contains a mass spectrometer and energy analyzer in tandem. The inductive drive and the rf bias in our Gaseous Electronics Conference reference cell were both at 13.56 MHz. By varying the plasma density, we were able to examine the transition region between the “low frequency limit” for rf bias and the intermediate frequency region where, at fixed bias frequency, the ion energy distribution width varies with the plasma density. We find that the experimental ion energy distributions become narrower as the time for ion transit through the sheath approaches the rf period, but that the ion distributions still have widths which are ∼90% of their low frequency limit when the ion transit time is 40% of the rf period. Space-charge-induced beam broadening inside our analyzers appears to significantly affect our measurements of ion angular distributions, especially at low ion energies.

Acoustic phenomena in a demand mode piezoelectric ink jet printer

Abstract: This article addresses acoustic wave propagation in a piezoelectric ink jet printer. Acoustic resonances limit the operating frequency of ink jet devices and influence the timings of the electrical drive signals. In this study, the resonant frequencies in a multichannel printhead are determined through feedback from the fluid to the piezoelectric structure using an electrical impedance analyzer. We also analyze the influence of channel length on resonant frequency. In addition, the effect of different boundary conditions on the acoustic resonance of the channels was observed. Because the channels walls are compliant, the propagation of acoustic pressure waves in them is slower than the speed of sound in the fluid, which is a fluid property. The electrical impedance measurements allow the determination of the effective speed of sound in the channel and the optimal timing for the driving electrical signal. During printhead operation, the drop velocity can be modified by changing the duration of the electrical pulse sent to the piezoelectric actuator. The timing that produces the maximum drop velocity can be also related to the effective speed of sound in the channel. Comparison of the two data sets show that a printhead channel has an acoustical behavior closer to an open-open pipe.

Method and apparatus for high resolution monitoring of optical signals

Abstract: The present invention provides a method and apparatus for monitoring optical signals with an expanded frequency resolution. The invention permits high-resolution measurements of optical signal spectrums while retaining wide bandwidth operation through appropriate control circuitry. An interferometer having a periodic frequency response formed of equally spaced narrow-band peaks is used to sweep the entire signal spectrum. The interferometer frequency response is incrementally tuned in cycles so that each of its frequency response peaks cyclically scans a particular spectral band of the signal spectrum. During each cycle, the interferometer isolates multiple spectrally resolved portions of the optical signal spectrum where each portion originates from a different spectral band. In this way, a high-resolution measurement of the entire signal spectrum can be obtained. The invention may be network protocol independent and can be incorporated into an optical spectrum analyzer or directly into any optical terminal. The invention can be used for signal spectrum monitoring applications including link quality monitoring (LQM) in optical communications networks to monitor various transmission parameters such as such as carrier wavelengths, optical signal-to-noise ratios (SNR), amplified spontaneous emissions (ASE), noise levels, optical non-linearities or other signal baseband information such as data rates and formats.

Ultra-sensitive mid-infrared cavity leak-out spectroscopy using a cw optical parametric oscillator

Abstract: We report a portable, all-solid-state, mid-infrared spectrometer for trace-gas analysis. The light source is a continuous-wave optical parametric oscillator based on PPLN and pumped by a Nd:YAG laser at 1064 nm. The generated single-frequency idler output covers the wavelength region between 2.35 and 3.75 μm. With its narrow line width, this light source is suitable for precise trace-gas analysis with very high sensitivity. Using cavity leak-out spectroscopy we achieved a minimum detectable absorption coefficient of 1.2×10-9 /cm (integration time: 16 s), corresponding, for example, to a detection limit of 300 parts per trillion ethane. This sensitivity and the compact design make this trace-gas analyzer a promising tool for various in situ environmental and medical applications.

Refraction contrast in X-ray imaging

Abstract: A two-crystal diffractometer in the non-dispersive configuration is used for measurement of the effects of refraction in weakly absorbing test objects. Characteristic Ka1 radiation from a fine-focus X-ray tube with Mo anode is used. The probing beam is about 70mm wide and 3 mm high. The sample is placed between the monochromator and analyzer, and it is scanned through the beam. The analyzer is tuned to reflect at the low-angle slope, at the top, or at the high-angle slope of the rocking curve, when the sample is not in the beam. Refraction changes the angle of incidence on the analyzer causing changes in intensity. The observed intensity distributions are exactly reproduced by a calculation, where only the effects of refraction are included. The effects of in-beam interference are negligible or very small, which is also verified by changing the distance between the object and the detector. r 2002 Elsevier Science B.V. All rights reserved.

Determination of zinc in individual airborne particles by inductively coupled plasma mass spectrometry with digital signal processing

Abstract: A high-speed digital signal processing system has been developed as an individual particle analyzer combined with ICP-MS to achieve signal profiling with a time resolution of 20 µs and a lower detection limit. When air samples are directly introduced into the plasma, the ICP-MS generates a train of pulses corresponding to the ion population of a given element in the plasma. The present system can digitally count pulses from a channel electron multiplier used as a detector in ICP-MS in a duration time of 20 µs each. A time-resolved signal profile stored in the computer memory shows that each flash signal derived from individual airborne particles has a sharp peak with a time-width of 0.1–0.5 ms. The detection limit for zinc in a particle is lowered to sub-fg levels by precisely measuring the signal strength for each particle under a condition of low background noise. The profile of the flash signal for individual particles reflects the evaporation and ionization processes of each particle in the plasma and the extraction process of ions through the sampling orifice of the mass spectrometer.

Portable difference-frequency laser-based cavity leak-out spectrometer for trace-gas analysis

Abstract: We report a portable mid-infrared spectrometer for trace-gas analysis which is based on an all-solid-state difference-frequency-generation laser. The spectrometer provides in situ absorption path lengths of more than 3 km by means of the cavity leak-out method, a cw variant of the cavity ring-down technique. The design, performance, and application of this spectrometer are presented. The light source utilizes difference-frequency generation in a periodically poled lithium niobate (PPLN) crystal pumped by two single-frequency solid-state lasers. A maximum power of 27 μW in the wavelength region near 3.3 μm is achieved using a pump power of 20 mW at 808 nm, a signal power of 660 mW at 1064 nm, and a 50-mm-long PPLN crystal. This corresponds to a conversion efficiency of 0.42 mW/(W2 cm). We demonstrate that this portable laser system is suitable as a light source in a cavity leak-out spectrometer. We achieved a minimum detectable absorption coefficient of 1×10-8/cm (integration time: 2 s), corresponding, for example, to a detection limit of 1 part per billion ethane. This compact trace-gas analyzer with high sensitivity and specificity is promising for various environmental and medical applications.

Methods to view and analyze the results from diffraction-based diagnostics

Abstract: The present invention provides an analyzer useful in determining the presence of an analyte using a diffraction based sensing device and methods and systems using this device. The analyzer may be used with a variety of different diffraction-based diagnostic methods and systems. The analyzer enhances the accuracy and/or usefulness of these devices in detecting analytes, while providing more ease-of-use and convenience to the user. The analyzer may include a light source, a photodiode, a microprocessor and a display system for informing the user of the result. Other features include mirrors, lenses, a sample holder, and a mask for blocking out some light. The analyzer and related method and system may be used in a large number of environments, including commercial, professional, and individual.

Optical analyzer and method for reducing relative intensity noise in interferometric optical measurements using a continuously tunable laser

Abstract: A heterodyne optical network analyzer and method for device characterization reduces the effect of relative intensity noise (RIN) in interferometric optical measurements by subtracting the measured intensities of first and second interference signals derived from an optical interferometer. The first and second interference signals are produced by combining a first lightwave transmitted to an optical device being characterized with a second lightwave, which is a delayed version of the first lightwave. The first and second lightwaves are derived by splitting an input lightwave having a continuously swept optical frequency generated by a light source, such as a continuously tunable laser.

Correlation spectrum analyzer for direct measurement of device current noise

Abstract: This article analyzes the realization and the performance of a correlation spectrum analyzer specifically conceived to directly measure the current noise produced by electronic devices with maximum sensitivity. The text describes in detail and gives the design rules of the instrument input amplifiers taking into consideration noise, dynamic range, stability, and bandwidth, together with the effects that a device under test (DUT) having complex impedance introduce. This article shows that the proposed scheme may allow current noise measurements with a sensitivity improved by few orders of magnitude with respect to a standard spectrum analyzer and to a correlation analyzer in voltage scheme whenever the DUT has an impedance larger than few 10 kΩ. Such a sensitivity makes the proposed instrument ideal for the characterization of advanced devices, such as ultrashort channel metal-oxide-semiconductor field effect transistors, mesoscopic junctions, or spin dependent electron transfer devices where it may be nec...

The parallel cylindrical mirror electron energy analyzer

Abstract: An electrostatic energy analyzer is described that allows parallel acquisition of the energy spectrum of charged particles over a wide range of energies and over the complete range of azimuthal directions. The analyzer is similar to the cylindrical mirror analyzer except that a linear potential variation is applied in the axial direction to the outer cylinder. The analyzer can also be used in a second-order focusing mode to analyze a narrow range of energies with higher energy resolution. A position sensitive detector is required, the shape of which depends on the way in which the analyzer is used. Comparisons with existing electron energy analyzers are given.

An implantable analyzer of bio-impedance dynamics: mixed signal approach [telemetric monitors]

Abstract: An on-chip implantable lock-in analyzer of variations of the electrical bio-impedance has been designed, and pilot ASICs have been fabricated and tested. A mixed signal approach as the most suitable way for accomplishing a low-voltage and low-power ASIC for use in implantable devices for various biomedical applications is discussed in this paper.

On-chip spectrum analyzer for built-in testing analog ICs

Abstract: An on-chip spectrum analyzer using switched-capacitor techniques is described. This system is used for built-in testing analog circuits. The main property of the proposed architecture is its inherent synchronization, which facilitates the testing task saving time, power and silicon area. Simulations and breadboard results are presented in order to verify the main principles. The resolution of the on-chip spectrum analyzer is limited to 8 bits.

A new incoherent scatter technique in the EISCAT Svalbard Radar

Abstract: [1] A special incoherent scatter technique in the European Incoherent Scatter (EISCAT) Svalbard Radar (ESR) was tested in November 1999. After the 70-MHz IF stage the standard ESR receiver was replaced by a spectrum analyzer acting as a combination of a down-converter, an AD converter, and a quadrature detector and giving complex digital samples at a rate of 4 MHz. The samples were fed into a PCI-bus-based programmable digital I/O card, which performed a four-sample summing operation to give an effective sampling rate of 1 MHz, large enough to span all the frequency channels used in the experiment. Finally, the resulting samples were stored on hard disk. Hence the total multichannel signal was stored instead of separate lagged products for each frequency channel, which is the procedure in the standard hardware. This solution has some benefits; for example, the ground clutter can be eliminated with only a small loss in statistical accuracy, and the true phase of the transmitter waveform in phase-coded experiments can be measured better than in the present ESR system. In this paper the technical arrangements of this setup are presented. A new incoherent scatter experiment is also described, and the first results obtained using the hardware are shown.

Miniaturized linear time-of-flight mass spectrometer with pulsed extraction.

Abstract: Improved resolution for a miniaturized instrument is demonstrated at high masses using a pulsed extraction, 3″ linear time-of-flight (TOF) mass analyzer. This illustrates the utility of a small and simple mass spectrometer for biological/medical analyses. Current and future applications suggested by this instrument include rapid mass spectral reading of oligonucleotides that differ in one base (single nucleotide polymorphisms), distinction of biomarker signatures from different species of bacterial spores (biological weapons detection) and point-of-care instruments for proteomics-based diagnostics. We have incorporated a two-stage, pulsed-extraction design that places the focal plane of the ions at the detector channel plate surface. The ions are accelerated to a total energy of 12 keV to enable detection of high-mass proteins in a design that incorporates a floatable flight tube set at the voltage of the front channel plate of the detector. The resultant elimination of post-acceleration at the detector is intended to improve mass resolution by reducing the difference in arrival times between ions and their neutral products. Resolutions of one part in 1200 at m/z 4500 and one part in 600 at m/z 12 000 have been achieved. Proteins with molecular masses up to 66 000 Da, mixtures of oligonucleotides, and biological spores have all been successfully measured, results that increase the potential use of this TOF analyzer. Copyright © 2002 John Wiley & Sons, Ltd.

Proposed test for detection of nonlinear responses in biological preparations exposed to RF energy.

Abstract: Demodulation of amplitude modulated radio frequency (RF) energy has been proposed as a mechanism for the biological responses to these fields. The experiment proposed here tests whether the electric and magnetic structures of biological cells exhibit the nonlinear responses necessary for demodulation. A high Q cavity and very low noise amplification can be used to detect ultraweak nonlinear responses that appear as a second harmonic of a RF field incident on the sample. Nonlinear fields scattered from metabolically active biological cells grown in monolayer or suspended in medium can be distinguished from nonlinearities of the apparatus. Estimates for the theoretical signal sensitivity and analysis of system noise indicate the possibility of detecting a microwave signal at 1.8 GHz (2nd harmonic of 900 MHz) as weak as one microwave photon per cell per second. The practical limit, set by degradation of the cavity Q, is extremely low compared to the much brighter thermal background, which has its peak in the infrared at a wavelength of about 17 microm and radiates 10(10) infrared photons per second per cell in the narrow frequency band within 0.5% of the peak. The system can be calibrated by introduction of known quantities of nonlinear material, e.g., a Schottky diode. For an input power of 160 microW at 900 MHz incident on such biological material, the apparatus is estimated to produce a robust output signal of 0.10 mV at 1.8 GHz if detected with a spectrum analyzer and a 30-dB gain low noise amplifier. The experimental threshold for detection of nonlinear interaction phenomena is 10(10) below the signal produced by a Schottky diode, giving an unprecedented sensitivity to the measurement of nonlinear energy conversion processes in living tissue.

Apparatus and program for separating a desired sound from a mixed input sound

Abstract: A sound separation apparatus for separating a target signal from a mixed input signal, wherein the mixed input signal includes the target signal and one or more sound signals emitted from different sound sources. The sound separation apparatus according comprises a frequency analyzer for performing a frequency analysis on the mixed input signal and calculating spectrum and frequency component candidate points at each time. The apparatus further comprises feature extraction means for extracting feature parameters which are estimated to correspond with the target signal, comprising a local layer for analyzing local feature parameters using the spectrum and the frequency component candidate points and one or more global layers for analyzing global feature parameters using the feature parameters extracted by the local layer. The apparatus further comprises a signal regenerator for regenerating a waveform of the target signal using the feature parameters extracted by the feature extraction means. Since both of local feature parameters and global feature parameters can be processed together in the feature extraction means, the separation accuracy of the target signal is improved without depending on the accuracy for extracting feature parameters from the input signal. Feature parameters to be extracted include frequencies and amplitudes and their variation rates for the frequency component candidate points, harmonic structure, pitch consistency, intonation, on-set/off-set information and/or sound source direction. The number of the layers provided in the feature extraction means may be changed according to the types of the feature parameters to be extracted

X-Ray optics for observing dark-field and bright-field refraction-contrast images

Abstract: A new X-ray optics for observing dark-field and bright-field refraction-contrast images is proposed. The optics consists of a collimator and an analyzer in the Bragg geometry with a sample between them. Phase gradients produced by the sample are resolved by the analyzer and the transmitted X-rays are recorded on an X-ray film. When the analyzer is tuned at an angle inside its selective reflection region, clear dark-field images are observed. On the other hand, when the analyzer is tuned in the vicinity of, but outside, the selective reflection region, bright-field images are observed. This optics was tested at a vertical wiggler beamline, BL-14B, at the Photon Factory. The analyzer images were taken at various points in the rocking curve. Both dark-field and bright-field images were successfully observed.

Theoretical and experimental results of power converter frequency modulation

Abstract: Most of the power converters are controlled by a PWM signal based on a constant frequency and variable duty-cycle. A very large harmonic is expected at this frequency, spreading itself to the rest of the system. This paper is dedicated to spread spectrum clock generation (SSCG) theory applied to the reduction of EMI when a carrier or controlling constant frequency signal is present. SSCG is used to modulate square clock lines, PWM signals in a converter or data frames in a communication system to reduce EMI emissions. Instead of maintaining a constant frequency, SSCG systems modulate the switching (or clock) frequency following certain modulation profiles. Two goals are intended in the paper: (a) review the theoretical fundamentals of SSCG; and (b) compare the results of theoretical simulation with experimental tests to evaluate the possibilities of the method. For the experimental part, a "pure" sinusoid was modulated following several modulation profiles by using an arbitrary signal generator. The results were analyzed with an EMI compliant spectrum analyzer.

A robust, fast, and accurate deconvolution algorithm for EM-field measurements around GSM and UMTS base stations with a spectrum analyzer

Abstract: In this paper, we present a new robust, fast, and accurate deconvolution algorithm for correcting noise disturbed measurements and eliminating the influence of the resolution filter of a spectrum analyzer used for EM-field measurements around a GSM and UMTS base station. Our purpose is to be able to determine immediately the field values at a measurement site. Therefore the algorithm has to be fast and accurate. Furthermore, because of the presence of noise, our algorithm has to be robust. Our algorithm that uses windowing and filtering meets those demands and reduces the present noise by an additional convolution with a square wave function.

Monitoring upstream frequency band

Abstract: The spectrum analyzer includes an input (115) adapted to receive an input signal and a mixer (30), coupled to the input. The mixer is adapted to produce a down converted signal from the input signal. The spectrum analyzer further includes an adjustable decimation circuit (112), coupled to the mixer, that selectively decimates the down converted signal, a decoder (108), coupled to the mixer, that selectively controls the frequency of the down converted signals from the mixer to measure power over a frequency spectrum of the input signal.

Compact high-resolution retarding field energy analyzer for space-charge-dominated electron beams

Abstract: We have developed a compact high-resolution retarding field energy analyzer for measuring the energy spread of space-charge-dominated electron beams. This energy analyzer has a cylindrical electrode to overcome the defocusing effects due to space-charge forces, beam trajectories, aperture effect, etc. The device provides excellent spatial and temporal information on the beam energy spread. Single-particle simulation shows that this energy analyzer has very good resolution for low-energy electron beams of several kilovolts and with large divergence angles. The energy analyzer has been tested with 2.5 keV, 60 mA electron beams. The measured energy spread is also compared with the theoretical calculations taking into account two main energy spread sources, namely, the Boersch effect and the longitudinallongitudinal relaxation.