Showing papers on "Spectrum analyzer published in 1987"

Modular analyzer system

Abstract: A system of modular analyzers each adapted for independent operation and each possessing different operational characteristics adapted for particular applications. Such modular analyzers may be joined together with precise indexing means such that a single sample carousel may be accessed by fluid transfer probes from both of the analyzers to thus form a system which operates as a single analyzer of increased capacity and versatility.

Fundamental relations between the LMS algorithm and the DFT

Abstract: The digital Fourier transform (DFT) and the adaptive least mean square (LMS) algorithm have existed for some time. This paper establishes a connection between them. The result is the "LMS spectrum analyzer," a new means for the calculation of the DFT. The method uses a set of N periodic complex phasors whose frequencies are equally spaced from dc to the sampling frequency. The phasors are weighted and then are summed to generate a reconstructed signal. Weights are adapted to realize a best least squares fit between this reconstructed signal and the input signal whose spectrum is to be estimated. The magnitude squares of the weights correspond to the power spectrum. For a proper choice of adaptation speed, the LMS spectrum analyzer will provide an exact N -sample DFT. New DFT outputs will be available in steady flow after the introduction of each new data sample.

Analyzer operating method

Abstract: A method of operating a clinical analyzer wherein the analyzer includes a plurality of reaction locations divided into two groups. Predetermined operations are performed on the first and second groups during corresponding processing cycles. A process that is common to both cycles is performed simultaneously for reaction locations in the first and second groups during only one of the cycles. The other of the cycles can thus accommodate operations unique to particular tests that would not otherwise be available on the analyzer. The common process may be washing of adjacent reaction locations included in the first and second groups.

Digital speech vocoder

Abstract: A speech analyzer and synthesizer system using a sinusoidal encoding and decoding techniques for voiced frames and noise excitation or multiple pulse excitation for unvoiced frames. For voiced frames, the analyser (100) transmits the pitch, values for each harmonic frequency by defining the offset from integer multiples of the fundamental frequency, total frame energy, and linear predictive coding, LPC, coefficients (FIG. 1). The synthesizer (200) is responsive to that information to determine the phase of the fundamental frequency and each harmonic based on the transmitted pitch and harmonic offset information and to determine the amplitudes of the harmonics utilizing the total frame energy and LPC coefficients (FIG. 2). Once the phase and amplitudes have been determined for the fundamental and harmonic frequencies, the sinusoidal analysis is performed for voiced frames. For each frame, the determined frequencies and amplitudes are defined at the center of the frame, and a linear interpolation is used both to determine continuous frequency and amplitude signals of the fundamental and the harmonics throughout the entire frame by the synthesizer. In addition, the analyzer initially adjusts the pitch so that the harmonics are evenly distributed around integer multiples of this pitch.

Capacitive liquid level sensor for automatic chemical analyzer

Abstract: A capacitive liquid level sensor for an automatic chemical analyzer, wherein a pipetting tube approaches a liquid level of the sample to be analyzed and is electrically connected to one terminal of an electrical bridge network. The electrical bridge network is activated by an A.C. current and produces an A.C. signal which has a phase change produced by a change in capacitance between the pipetting tube and the liquid level as the pipetting tube approaches the liquid level. The A.C. signal is converted into a D.C. signal proportional to the phase difference by means of a phase detector. A liquid level is detected by comparison of the D.C. signal with a preselected reference level.

Digital speech sinusoidal vocoder with transmission of only a subset of harmonics

Abstract: A speech analyzer and synthesizer system using a sinusoidal encoding and decoding technique for voiced frames and noise excitation or multipulse excitation for unvoiced frames. For voiced frames, the analyzer transmits the pitch, values for a subset of offsets defining differences between harmonic frequencies and a fundamental frequency, total frame energy, and linear predictive coding, LPC, coefficients. The synthesizer is responsive to that information to determine the harmonic frequencies from the offset information for a subset of the harmonics and to determine the remaining harmonics from the fundamental frequency. The synthesizer then determines the phase for the fundamental frequency and harmonic frequencies and determines the amplitudes of the fundamental and harmonics using the total frame energy and the LPC coefficients. Once the phase and amplitudes have been determined for the fundamental and harmonic frequencies, the synthesizer performs a sinusoidal analysis. In another embodiment, the remaining harmonic frequencies are determined by calculating the theoretical harmonic frequencies for the remaining harmonic frequencies and grouping these theoretical frequencies into groups having the same number as the number of offsets transmitted. The offsets are then added to the corresponding theoretical harmonics of each of the groups of the remaining harmonic frequencies to generate the remaining harmonic frequencies. In a third embodiment, the offset signals are randomly permuted before being added to the groups of theoretical frequencies to generate the remaining harmonic frequencies.

Optical analysis method and apparatus having programmable rapid random wavelength access

Abstract: The optical reflectance or transmittance concentration analyzer includes an acousto-optical tunable filter (AOTF). The AOTF is tuned by a computer controlled digital-to-analog converter through a tunable sweep oscillator. Tuned beams can be selected according to their direction of propagation or according to their polarization behavior. Therefore, if desired, a pair of crossed polarizers can be used to select one of the tuned monochomatic light beams that pass from a light source through the AOTF. To obtain rapid wavelength change along with electronic chopping or wavelength modulation, the digital-to-analog converter output is combined with the output of a high speed signal generator. The modulated light is conducted directly or through a fiber optic cable to the location of the optical measurement and impinges upon the sample where it is reflected or transmitted. The emerging light is collected onto detector(s). The measurement time interval can be distributed among the required wavelengths or wavelength pairs according to an unequal scheme to decrease the error of the result in a calibration equation. The apparatus is particularly adaptable for use as an on-line concentration monitor in industrial process control because of its stability, efficiency and ability to perform quick analyses.

A 0.5-4.0-GHz Tunable Bandpass Filter Using YIG Film Grown by LPE

Abstract: A tunable bandpass filter using YIG film grown by liquid phase epitaxy (LPE) has been developed. Taking advantage of the very low resonance frequency in the perpendicular resonance of YIG film, an operation frequency of 0.5 GHz has been achieved. In order to make this filter operate up to 4.0 GHz, a new technique for multioctave tuning has been developed and applied to the filter. Over the wide tuning range from 0.5 GHz to 4.0 GHz, low insertion loss and high spurious suppression have been achieved. The performance of this filter satisfies the requirements for use as a tracking preselector in a microwave spectrum analyzer.

Scanning ellipsometer by rotating polarizer and analyzer.

Abstract: A new type of scanning photometric ellipsometer with polarizer and analyzer both rotating synchronously at rotation rates of ω0/2 and ω0 (f0 = 51 Hz), has been designed and constructed. The mechanical and electrical design, alignment, calibration, and error reduction of the system are discussed in detail. Through measuring the amplitudes of the three ac components from the photomultiplier, at frequencies of 51, 102, and 153 Hz, respectively, complex dielectric function spectra have been obtained for test samples of Au and CdTe in the 1.5–5.5-eV range and shown to be in agreement with the results of others.

A 6 × 320-MHz 1024-channel FFT cross-spectrum analyzer for radio astronomy

Abstract: A wide-band FFT spectrum analyzer, which we call FX, has been in operation since 1983 at the Nobeyama Radio Observatory for spectroscopy of radio waves from interstellar molecules. It processes an input of six 320-MHz-bandwidth data streams to produce the output of fifteen cross-power spectra of 1024 frequency channels each. Its highly parallel pipeline architecture made it possible to achieve the above speed, 1010butterfly operations per second, which is 105times that of usual mainframe computers. The FX incorporates about 4500 newly developed CMOS LSI chips. They are designed using CAD (computer-aided design) and have 3900 or 2000 gates/chip, operate at a clock rate of 10 MHz, and consume 100 mW/chip or less. For 80-MHz bandwidth signal at an optimum input level, the SNR (signal-power to noise-power ratio) of the FX is better than 10 dB, which is adequate for astronomical use.

Heavy ion beam probe energy analyzer for measurements of plasma potential fluctuations

Abstract: The operation of a Proca and Green type 30° parallel plate electrostatic energy analyzer is modeled in a new manner that permits high‐resolution heavy ion beam probe measurements of fluctuating plasma potential. Systematic calibration procedures permit detection of potential changes smaller than 0.01% of the probing beam energy at frequencies up to a megahertz. Most recent applications of beam probes have made use of this new capability.

Improved Impulse-Frequency Response Techniques for Measurement of Dynamic Mechanical Properties of Composite Materials

Abstract: The dynamic mechanical properties of composite material specimens are rapidly determined by using two new computer-aided impulse techniques. Small beam specimens are excited in either flexural or extensional vibration by an electromagnetic hammer with a force transducer in its tip, while specimen response is measured with an eddy current probe or accelerometer. A desktop computer/Fast Fourier Transform analyzer system is then used for rapid data acquisition and computation of the complex modulus by curve-fitting to the frequency response function.

Simple and compact low‐energy Mott polarization analyzer

Abstract: A UHV compatible Mott polarization analyzer is described that employs electron accelerating voltages of ∼20 kV. The efficiency of the analyzer, ∼3×10−5, is competitive with those provided by other polarimeters. The present analyzer is considerably simpler and more compact than earlier designs and can be used to undertake energy‐ and angle‐resolved polarization measurements with input beam currents below ∼10−14 A.

Robustness against noise: The role of timing-synchrony measurement

Abstract: In a previous report (Ghitza, 1987, [1]) we described a computational model based upon the temporal characteristics of the information in the auditory nerve fiber firing patterns, which produced an "auditory" spectral representation (the EIH) of the input signal. We also demonstrated that for speech recognition purposes, the EIH is more robust against noise compared to the traditional Fourier power spectrum. This paper reports on the first step towards understanding the role of different parameters in the EIH in achieving this performance. Both, the Fourier power spectrum measurement and the EIH measurement can be partitioned into two parts, a filter-bank followed by feature analyzer. In the Fourier power spectrum, the filter bank consists of uniformly shaped Hamming filters and the analyzer is based on power measurements. In the EIH, the filter bank consists of the cochlear filters and the analyzer is based on timing-synchrony measurements. The present study examines the relative importance of the filter-bank properties as compared to the analysis principle. For this purpose a modified EIH model has been created in which the cochlear filters have been replaced by the uniformly shaped Hamming filters. The output of the filter bank is processed by the timing-synchrony analyzer, as with the original EIH. The modified EIH and the Fourier power spectrum differs, therefor, only in the kind of analysis performed on the filter bank output. The modified EIH has been used as a front-end to a Dynamic Time Warp (DTW), using the same set-up as in Ghitza, 1987, [1]. A speaker dependent, isolated word recognition test has been conducted, on a database consisted of a 39 word alpha-digits vocabulary spoken by two male and two female speakers, in different levels of additive white noise. Compared to the Fourier-based front-end, the recognition scores have been slightly improved in clean environment but significantly improved in noisy environments. Furthermore, compared to the original EIH, the recognition scores have also been improved, both in clean and in noisy environments. These results demonstrate that the timing-synchrony measurement is significantly more robust against noise compared to the power measurement. They also show that the robustness is due to the timing-synchrony analyzer and not to the unique shape of the cochlear filters.

Servovalve analyzer system

Abstract: A fully automatic servovalve analyzer system includes a data processing system, a transducer system, and a transducer interface system connecting the data processing system to the transducer system. The data processing system stores data defining characteristics of transducers connected to a unit under test as well as characteristic data for the unit under test itself and test procedures which are to be performed. After a unit under test has been hydraulically and electrically connected to the analyzer system, the system automatically performs any defined tests, analyzes the results and outputs the results in a preselected human recognizable form.

Design and calibration of the JET neutral particle analyzer

Abstract: The neutral particle analyzer with energy and mass selection capability built for JET is described. The analyzer is able to detect in the same shot both H atoms from 0.3 to 320 keV and D atoms from 0.15 to 160 keV. In order to optimize the ion optics of the analyzer an oblique entrance in the magnet has been chosen. An ion trajectory code shows that in this way a good mass separation and a high efficiency can be achieved. The problems inherent in the analyzer calibration for a wide energy range are discussed, and the calibration procedure is described. In conclusion, the calibration results obtained with five analyzers are presented, together with theoretical consideration on ion optics and atomic processes, which have enabled us to write a simple interpolation formula for the experimental data.

Solid state non-dispersive IR analyzer using electrical current-modulated microsources

Abstract: A non-dispersive infrared gas analyzer of the type typically used to measure concentrations of gases in medical and industrial applications has no moving parts and employs two or more miniature infrared sources ("microsources") which are electrical current-modulated to produce modulated infrared radiation for synchronous detection. The microsources are operated at different frequencies. The frequency-multiplexed detector signal is demodulated and ratioed to yield an output which is correlated to the gas concentration in the sampler chamber.

CAMAC time‐of‐flight analyzer for molecular beam diagnostics

Abstract: Time‐of‐flight (TOF) analysis of supersonic molecular beams is accomplished by a computer‐controlled TOF analyzer incorporated into a CAMAC module. The measured arrival times are stored in a LeCroy histogramming memory module and transferred to a minicomputer for further processing. The system features four independent multichannel analyzers which can be selected by program. Each unit has 4096 24‐bit channels. Dwell times are programmable between 1 and 255 μs and the maximum counting rate is 1 MHz. The system is intended for ordinary single pulse or pseudorandom TOF analysis and can also be used in photodissociation experiments employing pulsed lasers. The calibration of the TOF analyzer is described and exemplary measurements are presented.

Combined thermal analyzer and x-ray diffractometer

Abstract: Scientific apparatus and a method are described for observing simultaneously both structural and thermodynamic properties of materials. An X-ray diffractometer and a thermal analyzer and mounted to cooperate and coact on the same sample and to complete a meaningful analysis in a very few minutes. The diffractometer is equipped with a rapid position-sensitive detector connected to a multichannel analyzer to record and display X-ray diffraction data from the sample over an angle of 20° (two theta) or more. The thermal analyzer is preferably a differential scanning calorimeter. By correlating X-ray diffraction and thermal data taken simultaneously while the sample is passing through a range of temperatures and/or environments, structural changes corresponding to thermal events can be identified and elucidated.

Soil analyzer and penetrator

Abstract: A soil analyzer and penetrator for driving into the ground, having a hydraulic ram with a longitudinal opening with a hollow tubing extending through the opening. A two-way chucking mechanism engages the outside of the tubing for driving the tubing into the ground and pulling the tubing from the ground. A coiling and straightening mechanism is positioned above the ram engaging the tubing for coiling the tubing as it is removed from the ground and straightening the tubing when it has been driven into the ground. A cone is connected to the bottom end of the tubing and may be of various types for measuring various ground parameters and inserting or removing materials into/from the ground.

Light absorption analyser

Abstract: A light absorption analyzer can work in either a reflection or a transmission mode, according to which probe head is fitted to it. Light is caused to be of a desired wavelength for the analysis by passing non-monochromatic light from a high-intensity flash tube source (which is not a point source) to an interference filter. Only parallel light emanating from the filter is focused by a concave parabolic mirror on a point where at least one fibre-optic collector is positioned. This light can then be passed directly to the probe for passage through the sample, since it is only light of a specified wavelength which will have travelled parallel from the filter and will therefore be focused at the point. Some of the light is taken off a reference detector to provide a reference signal for comparison with that derived from a test detetor fed by a return fibre-optic from the probe. A comparator is programmed to give a quantitiative readout of the absorption by the test sample.

Experimental tests of a toroidal electrostatic analyzer

Abstract: A toroidal electrostatic analyzer of a design suitable for space plasma instrumentation has been constructed and tested Experimental results are compared with second-order ion optical theory and are in good agreement Verifying the ion optics of the toroid was simplified by use of a position-sensing microchannel-plate detector mounted on a positioning system with three translational degrees of freedom located at the toroid exit The toroidal analyzer described here is the first optical element in a fully toroidal mass spectrograph intended for analysis of kilovolt magnetospheric plasmas

Oxygen system analyzer

Abstract: Test and man-rating of an oxygen generation system required analytical methods for evaluating system performance both in the laboratory and on the aircraft. The Oxygen System Analyzer is capable of monitoring four performance variables which include: (1) system gas flow rate, (2) product oxygen concentration, (3) system outlet pressure, and (4) aircraft cabin pressure. The analyzer is a portable tester designed to be used on a frequent basis to ascertain system performance and assure reliability and safety. The device may be used either in preflight system checkout mode or to assess in-flight performance characteristics and compliance with design specifications. The analyzer is packaged in a flight worthy case (20×13×8.5 inches, 31 pounds) and operates from a 12 volt rechargeable power system for 8-10 hours. Data is handlogged from digital panel meters. The analyzer is also capable of being adapted to assess system performance for other types of oxygen systems whether onboard aircraft, at sea or at land-based locations.

Video display simulator and analyzer.

Abstract: The display simulator analyzer is a fully integrated processor controlled instrument used for testing video display devices. The test signals may be generated by a video function generator, a high resolution graphics generator, a modulator or combinations thereof. As the name implies, the simulator-analyzer also measures and analyzes parameters generated from an euipment under test by means of its analyzer, which has incorporated therein a counter-timer, a real time digitizer and a sync stripper.

Error analysis of circular polarizer-analyzer systems for phase retardation measurements.

Abstract: The accuracy and the related advantages of circular polarizer–sample–circular analyzer systems used for measuring optical phase retardations are considered, particularly in relation to their property of having (ideally) a transmission independent of the azimuths of their components. An analysis is presented of errors resulting from retardation imperfections and azimuthal misalignments in practical systems. Important precision benefits are obtained with circular polarization systems having parallel polarizer and analyzer axes when compared with results obtained with conventional linear polarizer–sample–linear analyzer or Senarmont-type polarizer–sample–compensator–analyzer systems. The effects of temperature and wavelength variations are additionally examined and found to be comparatively weak. A discussion on the virtues and drawbacks of the above systems concludes the paper.

Magneto-optical information reproducing apparatus in which the azimuth angle of the transmission axis of an analyzer is optimized so that the C/N ratio of a reproducing signal is maximum

Abstract: In a magneto-optical information reproducing apparatus, the angle θA formed between the optic axis of an analyzer for analyzing reflected or transmitted light from a recording medium and a predetermined direction corresponding to a light polarization direction satisfies the following conditions: ##EQU1## where the average of the intensities of polarized components entering a photodetector for detecting light from the analyzer and not modulated by the magneto-optical effect is Ir, the square mean of the intensity fluctuation in a magneto-optical signal observation frequency is ΔI r 2 , ξ=ΔI r 2 /Ir 2 , the quantity of light of the incident light beam on the recording medium is I O , the amplitude reflectance of the recording medium is R, the light utilization efficiency of an optical system from the recording medium to the photodetector except the analyzer is e, the photoelectric conversion efficiency of the photodetector is k, the amount of charge is e, the thermal noise of an amplifier for amplifying the signal detected by the photodector in the magneto-optical signal observation frequency is T, the band width of the detection signal is ΔB, the amplitude transmittance of the analyzer is tA, and the extinction ratio of the analyzer is ηA. Also, in case that the apparatus includes a beam splitter therein, the condition of the angle θA is decided.

Distributed temperature sensor with optical-fiber sensing element

Abstract: The distributed temperature sensor employs an optical fiber as sensing element located in an ambient or near a body of which the temperature is to be monitored or measured. A source of light pulses sends into the fiber, pulses of predetermined duration. The backscattered radiation is collected for each pulse and the frequency spectrum variations in the backscattered radiation with respect to the incident radiation are analyzed. A computer obtains the temperature from said variations. The source and the spectrum variation analyzer are part of an optical time domain reflectometer which allows the temperature information to be associated with the information on the position of the backscattering point along the fiber.

Magneto-optical information reproducing apparatus in which divided reproducing lights are differentially detected by a photodetector having no amplifying action through an analyzer whose transmission axis azimuth is optimized

Abstract: In a magneto-optical information reproducing apparatus comprising means for applying a light beam polarized in a predetermined direction onto a recording medium on which information is magnetically recorded, means for dividing the reflected or transmitted light beam from the recording medium modulated into a polarized state in conformity with the information by the magneto-optical effect, a plurality of analyzer means having their optic axes inclined in opposite directions with respect to the predetermined direction and analyzing the divided light beams, a plurality of photodetectors having no amplifying action and photoelectrically detecting the light beams transmitted through the plurality of analyzer means, and a signal processing circuit for amplifying the detection signals of the plurality of photodetectors, differentiating them and reproducing the information, the angle θ A formed between the optic axes of the plurality of analyzer means and the predetermined direction satisfies the following conditions: ##EQU1## where I 0 is the quantity of light of the incident light beam on the recording medium, R is the amplitude reflectance of the recording medium, e is the light utilization efficiency of the optical system from the recording medium to the photodetectors except the analyzer means, κ is the photoelectric conversion efficiency of the photodetectors, e is the amount of charge, T is the thermal noise of the amplifying means in a magneto-optical signal observation frequency, ΔB is the band width of the detection signals, t A is the amplitude transmittance of the analyzer means, and η A is the extinction ratio of the analyzer means.

Theoretical modeling and experimental testing of a multimode optical system and energy analyzer for electron spectroscopy

Abstract: An electron‐optical system and hemispherical electrostatic energy dispersing element for quantitative electron spectroscopy over a wide range of kinetic energies is described. The electron optics were modeled using several calculational techniques, in order to determine the theoretical conditions under which a fixed linear magnification could be obtained. By designing an optical system with a plane of reflection symmetry, fixed magnification focus was possible over a calculated range of retard ratios from 1/40 to 40/1. The optics can be run in two different modes, one with and one without a retarding field grid to achieve the energy retardation. Comparisons between the predictions made using the various computational methods are reported, as well as experimental verification of the actual performance of the electron optics and energy analyzer. A method is described by which the angular acceptance of the electron optics can be varied by changing the excitation potentials on the lenses. The completed system allows for the simple installation of single‐channel, multichannel, and spin‐polarization detectors without modification of the analyzer.