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Showing papers on "Spectrum analyzer published in 1976"


Journal ArticleDOI
TL;DR: In this article, a second harmonic analyzer has been constructed which can resolve space group ambiguities arising from Friedel's Law with a confidence level greater than 99% and is optimized for use with powdered crystalline samples.
Abstract: The existence of optical second harmonic generation has been shown to be a highly reliable and sensitive physical test for the detection of crystalline non-centrosymmetry. A second harmonic analyzer has been constructed which can resolve space group ambiguities arising from Friedel's Law with a confidence level greater than 99%. The system has been optimized for use with powdered crystalline samples so as to obviate the need for large single crystals and thus facilitates rapid determination of crystalline non-centrosymmetry. The present analyzer can routinely detect second harmonic generation at levels 1/1000 of that generated in a quartz standard, this is about an order of magnitude increase over previously reported systems. Data are reported on several materials including dibenzyldisulfide, and [(C6H5)3P]3CuBF4. The detection of structural phase transitions with the second harmonic analyzer is reported for BaTiO3, colemanite and phenanthrene. Second harmonic generation in the `cubic' phase of BaTiO3 promises to be a powerful tool for determining the dynamics of the ferroelectric phase transition. It is the most direct method for establishing the existence or nonexistence of microscopic polar regions well above the Curie point in a nominally centrosymmetric phase.

258 citations


Patent
03 Dec 1976
TL;DR: A spectrum analyzer using digital filters for providing third octave spectrum analysis comprises means for breaking up input information into a plurality of digital data blocks, each block being of a given time duration and being within respective frequency ranges as mentioned in this paper.
Abstract: A spectrum analyzer using digital filters for providing third octave spectrum analysis comprises means for breaking up input information into a plurality of digital data blocks, each block being of a given time duration and being within respective frequency ranges, means for weighting the information contained in the data blocks and means for digitally filtering the weighted digital data blocks with digital filtering devices having at least one center frequency falling within the frequency range represented by each of the data blocks, each of the data blocks comprising N samples satisfying the following equation- N >Kfo/ Bn Where K is a constant which is a function of the sampling rate and the falloff rate of the skirt of filter characteristic, Bn is the filter bandwidth and fo is the center frequency of the filter.

55 citations


Journal ArticleDOI
TL;DR: The rotating-compensator/analyzer fixed-analyzer ellipsometer configuration proposed in this paper combines the advantages of unambiguous polarization state determination and insensitivity to detector polarization response shown by rotating compensator (rotating analyzer) fixed analyzer instruments, with the self-calibration features of rotating analyzer configurations.
Abstract: The rotating-compensator/analyzer fixed-analyzer ellipsometer configuration proposed and discussed here combines the advantages of unambiguous polarization-state determination and insensitivity to detector polarization response shown by rotating-compensator (rotating-analyzer) fixed-analyzer instruments, with the self-calibration features of rotating-compensator rotating-analyzer configurations. Because such generality is not necessary for all ellipsometric applications, we compare this system to other automatic ellipsometers and suggest preferred configurations for several representative uses.

52 citations


Patent
16 Sep 1976
TL;DR: In this paper, a fully digital spectrum analyzer with a digital frequency translator is presented, which makes it possible to effectively analyze frequency bands that do not start at zero frequency, where the available spectral lines can be within the band of interest and not wasted in the range from zero frequency to the start of the band, and as a result the band is examined at optimal resolution.
Abstract: Disclosed is a fully digital spectrum analyzer which includes a digital frequency translator that makes it possible to effectively analyze frequency bands that do not start at zero frequency. With the translator, the available spectral lines can be within the band of interest and not wasted in the range from zero frequency to the start of the band, and as a result the band is examined at optimal resolution. The translation takes place after the signal to be analyzed has been digitized, and the translator time-shares much of the conventional circuitry of the spectrum analyzer, to thereby minimize the cost of translation. Additionally, the spectrum analyzer includes an analog network that reduces the frequency of very fast signals so they can be analyzed by a spectrum analyzer having a relatively low upper frequency limit.

35 citations


Patent
08 Mar 1976
TL;DR: An optical gas-concentration analyzer which utilizes the infrared absorption principle has a sample chamber and reference chamber with infrared source and detector assemblies spaced at opposite ends of an in alignment with the chambers as discussed by the authors.
Abstract: An optical gas-concentration analyzer which utilizes the infrared absorption principle has a sample chamber and reference chamber with infrared source and detector assemblies spaced at opposite ends of an in alignment with the chambers. An electronic processing system utilizes a spectral-absorption electrical signal from the detector assembly to derive the desired gas-concentration measurement for readout from a display device. Barometric correction means is provided to permit on site calibration by the user of the gas analyzer via an atmospheric pressure calibration indication obtained on the display device by switching the apparatus to a calibrating mode. Apparatus for compensating for broadening of the spectral line of a gas the concentration of which is to be measured by another gas in the sample and for the temperature of the sample gas is also provided.

35 citations


Journal ArticleDOI
TL;DR: An ir analyzer employing gas-filter correlation techniques has been designed and constructed to measure the concentrations of CO, NO, SO, SO(2), HCl, and HF in the stacks or ducts of stationary pollutant sources.
Abstract: An ir analyzer employing gas-filter correlation techniques has been designed and constructed to measure the concentrations of CO, NO, SO(2), HCl, and HF in the stacks or ducts of stationary pollutant sources. Use of a retroreflector allows the stack to be double passed, and no sample is extracted. For each gas, small interchangeable fixed-position grating polychromators are used as narrow (~1.5-cm(-1)) multiband spectral filters with the bands corresponding to locations of selected absorption lines. The approximate useful ranges (in parts per million-meters) over which this analyzer operates are 10-4000 for NO, 10-1500 for CO, 50-40,000 for SO(2), 10-2000 for HC1, and 5-200 for HF. The discrimination against other gases and particulates is excellent. The analyzer has been tested in the laboratory and on a variety of pollutant sources.

35 citations


01 Jan 1976
TL;DR: A review of the historical development of the electrical aerosol analyzer is given in this paper, followed by a detailed description of the operating principle of the device, including the charger, the mobility analyzer, and the electrometer current sensor.
Abstract: A review of the historical development of the Electrical Aerosol Analyzer is given This is followed by a detailed description of the operating principle of the device, including the charger, the mobility analyzer, and the electrometer current sensor The data reduction procedures are described, and in addition to the standard procedure used previously, a new procedure is described which can further reduce the data reduction errors for the instrument

35 citations


Journal ArticleDOI
P. C. Y. Yip1
TL;DR: This paper examines some of the aspects of the zoom transform, which provides for partial recovery of the ideal resolution on an analyzer of limited capcity by concentrating the analysis on selected frequency bands.
Abstract: The spectral analysis of a long time series is often hampered by the limited capacity of the Fourier analyzer The ideal frequency resolution of the analysis of N sample points cannot be realized if the analyzer cannot handle N points simultaneously This paper examines some of the aspects of the zoom transform, which provides for partial recovery of the ideal resolution on an analyzer of limited capcity by concentrating the analysis on selected frequency bands

35 citations


Patent
08 Apr 1976
TL;DR: In this paper, a portable fast analyzer is provided that uses a magnetic clutch/brake to rapidly accelerate the analyzer rotor, and employs a microprocessor for automatic analyzer operation.
Abstract: A portable fast analyzer is provided that uses a magnetic clutch/brake to rapidly accelerate the analyzer rotor, and employs a microprocessor for automatic analyzer operation. The rotor is held stationary while the drive motor is run up to speed. When it is desired to mix the sample(s) and reagent(s), the brake is deenergized and the clutch is energized wherein the rotor is very rapidly accelerated to the running speed. The parallel path rotor that is used allows the samples and reagents to be mixed the moment they are spun out into the rotor cuvetes and data acquisition begins immediately. The analyzer will thus have special utility for fast reactions.

34 citations


Journal ArticleDOI
TL;DR: A Princeton Applied Research Model 174 Polarographic Analyzer has been modified to permit additional flexibility in using the instrument as discussed by the authors, which allows changes to be made in the memory time constants, pulse width and sample width over a wide range from external controls.
Abstract: A Princeton Applied Research Model 174 Polarographic Analyzer has been modified to permit additional flexibility in using the instrument. Added circuitry permits changes to be made in the memory time constants, pulse width and sample width over a wide range from external controls. Circuitry to carry out constant potential pulse polarography and derivative measurements has also been added. Some illustrations of the use of these circuits are given.

31 citations


Journal ArticleDOI
TL;DR: In this article, a novel charged particle energy analyzer of simple geometry is described and a ray trace program using these components is discussed and results of its application are presented in graphical and tabular form also presented are experimental results for two versions of the analyzer in the form of representative spectra of well known species (Ar +, H 2 +, O 2 + ).

Journal ArticleDOI
TL;DR: In this paper, the authors optimize the mutual relation of these parameteres so that the quantities Etendue or luminosity of the spherical analyzer attain a maximum, independent of the required resolution.
Abstract: Resolution and intensity behaviour of the spherical analyzer are mainly determined by the entrance parameters (aperture angle 2αm, relative width of the entrance slita/r0) and by the relative width of the exit slitb/r0. The mutual relation of these parameteres can be so optimized that independent of the required resolution the quantities Etendue or luminosity of the spherical analyzer attain a maximum.

Journal ArticleDOI
TL;DR: In this paper, a directionally sensitive fringe-type laser anemometer with a Bragg cell was used to measure the mean streamwise velocity £7, the meansquare fluctuation w, and the fraction of time the flow was moving in the downstream direction yp.
Abstract: • RECENTLY an experimental study of a separating in-I^compressible turbulent boundary layer produced by an adverse pressure gradient was completed. A directionally sensitive fringe-type laser anemometer with a Bragg cell was used to measure the mean streamwise velocity £7, the meansquare fluctuation w, and the fraction of time the flow was moving in the downstream direction yp. In addition, a constant-temperature single-sensor cylindrical hot-film probe (Thermo-Systems, Inc., model 1274-10) was used to compare the behavior of this directionally insensitive sensor with the laser anemometer results. The purpose of the Note is to discuss the interpretation of signals from these two instruments in a separation region, i.e., when yp < 1. Sampling spectrum analysis of the laser anemometer signals was used because of the high-signal dropout level encountered in this flow with a relative low-particle seeding level and the high-signal frequencies produced by frequency shifting one incident beam. Most frequency trackers cannot handle either of these signal conditions. The signal from the photomultiplier tube or detector is input to a swept filter spectrum analyzer (HP 8558B). For each sweep of the analyzer when a particle (about 1 in size) is in the focal volume, a vertical voltage distribution proportional to the filter output is displayed. The simultaneous horizontal sweeping voltage is proportional to the signal frequency. The peak of the vertical voltage distribution marks the frequency of the passing particle signal and can be used as a gating signal to allow the instantaneous value of the horizontal sweep voltage to be sampled. This instantaneous voltage value is related to the instantaneous velocity £7 of the particle through the equation

Journal ArticleDOI
TL;DR: In this article, an oscillating analyzer ellipsometer (OAE) was proposed with speed and precision comparable to that achieved by the polarization-modulated ellipsometers of Jasperson et al. Significantly, the OAE does not require a special polarization modulator but uses a Faraday cell instead.
Abstract: The state of polarization of a light beam can be dynamically measured by Fourier analysis of the periodic irradiance variations detected after the beam has passed through an electrooptically oscillating analyzer (OA) composed of an ac‐driven optical rotator (Faraday cell) followed by a fixed analyzer. From the dc, fundamental, and second‐harmonic components of the photodetector current we obtain the same cosine and sine Fourier coefficients (α and β) as would be measured by a rotating analyzer (RA). An ellipsometer based on this principle, called the oscillating‐analyzer ellipsometer (OAE), is proposed with speed and precision comparable to that achieved by the polarization‐modulated ellipsometer (PME) of Jasperson et al. Significantly, the OAE does not require a special polarization modulator but uses a Faraday cell instead. Also of importance is the fact that a comprehensive analysis of the effect of systematic errors recently developed for the rotating‐analyzer ellipsometer (RAE) applies, in its entire...

Journal ArticleDOI
Fritz F. Klein1
TL;DR: The analyzer performs its analysis in the time domain and abstracts wave shape information from the original wave and from the successive mathematical derivatives of that wave, applicable to any waveform which is a single-valued function of time with continuous derivatives.
Abstract: This paper presents an approach to signal waveform analysis in the frequency range of 1 to 50 Hz. The technique is applicable to any waveform which is a single-valued function of time with continuous derivatives. The main application of this system has been on the human EEG. The analyzer, to be described, performs its analysis in the time domain and abstracts wave shape information from the original wave and from the successive mathematical derivatives of that wave. The output from this analyzer consists of six analog descriptors of the input EEG wave. These descriptors are basic amplitude and basic frequency of the original input wave, amplitude and frequency of the first derivative of the input wave, and amplitude and frequency of the second derivative of the input wave.

Journal ArticleDOI
TL;DR: In this paper, a simple analyzer is described for the determination of the degree of polarization of vacuum uv and x rays using solar blind detectors and is ideal for use in circumstances where visible and near-uv radiation is present in addition to the radiation under investigation.
Abstract: A simple analyzer is described for the determination of the degree of polarization of vacuum uv and x rays The analyzer uses solar blind detectors and, thus, is ideal for use in circumstances where visible and near‐uv radiation is present in addition to the radiation under investigation

Patent
22 Jul 1976
TL;DR: In this paper, a precision analyzer for the testing of numismatic coins or other metallic articles is disclosed whereby the article to be tested is introduced into the field generated by the inductor of an oscillator.
Abstract: A precision analyzer for the testing of numismatic coins or other metallic articles is disclosed whereby the article to be tested is introduced into the field generated by the inductor of an oscillator and the change in amplitude of the oscillations resulting from the interaction of the field generated and the article to be tested is measured.

Proceedings ArticleDOI
01 Jan 1976
TL;DR: In this paper, a concept for performing RF spectrum analysis using the technology of Integrated Optics is described, which can achieve frequency resolution of about 1 MHz over bandwidths up to 1 GHz in a very small and potentially low cost package.
Abstract: A concept for performing RF spectrum analysis using the technology of Integrated Optics is described. Such devices could achieve frequency resolution of about 1 MHz over bandwidths up to 1 GHz in a very small and potentially low cost package. The principles of operation, design constraints, and possible circuit configurations are discussed. The state -of- the -art of key component technologies

Journal ArticleDOI
TL;DR: A software system and a hardware interface between a laser Raman spectrometer and a time-shared computer permits automatic separation of isotropic and anisotropic spectra, repetitive counting periods, instant scope display of raw, reduced or integrated data, and numerous data refinement options.
Abstract: We describe a software system and a hardware interface between a laser Raman spectrometer and a time-shared computer. This data acquisition system controls the wavelength drive of the spectrometer and the analyzer orientation using stepping motors and position sensors. With this method accurate depolarization ratios can be determined at every wavelength increment. Digitized photon counting gives good signal/noise ratios and a wide dynamic range for Raman intensity measurements. The software design permits automatic separation of isotropic and anisotropic spectra, repetitive counting periods, instant scope display of raw, reduced or integrated data, and numerous data refinement options.

Journal ArticleDOI
TL;DR: A technique for processing FFT outputs to realize banks of narrowband filters for which spectral band centers and spectral bandwidths may be arbitrarily assigned is developed.

Journal ArticleDOI
TL;DR: In this paper, a charge-coupled device (CCD) and surface acoustic wave (SAW) techniques are combined for processing coherent radar signals in order to extract target range and velocity information.
Abstract: Methods are presented for combining charge-coupled device (CCD) and surface acoustic wave (SAW) techniques to advantage for processing coherent radar signals in order to extract target range and velocity information. Experiments have validated a scheme of combined discrete CCD's to form an analog store with orthogonal input and output sequencing, feeding time-compressed data to a SAW spectrum analyzer. A design for an integrated CCD store is presented.

Patent
James T. McKinney1, Robert F. Goff1
10 May 1976
TL;DR: In this paper, the mass analyzer is tuned to pass only ions having the same mass as ions in an incident ion beam, and to reject sputtered ions, some of which may have the requisite energy to pass through the energy analyzer under a given set of conditions.
Abstract: Improved apparatus and method for measuring ions scattered from a surface, to thereby determine the mass of atoms at the surface. The apparatus includes two analyzers, preferably an energy analyzer and mass analyzer positioned in tandem. The mass analyzer may be tuned to pass only ions having the same mass as ions in an incident ion beam, and to reject sputtered ions, some of which may have the requisite energy to pass through the energy analyzer under a given set of conditions.

Journal ArticleDOI
TL;DR: A class of coherent optical spectrum analyzers for one-dimensional signals is described that is characterized by a frequency variant response to the spectral components of the input signal.
Abstract: A class of coherent optical spectrum analyzers for one-dimensional signals is described that is characterized by a frequency variant response to the spectral components of the input signal. Operations performed exploit the second degree of freedom inherent in the optical systems. One example considered is a constant proportional bandwidth, log-frequency spectrum analyzer. Experimental and analytical results are presented.

Patent
17 Feb 1976
TL;DR: An electronic image dissection means for dissecting an image transmitted by an optical system under test and producing an electric output signal representative of the beam intensity at a selected element of the image as discussed by the authors.
Abstract: An electronic optical analyzer for use in systems such as optical transfer function analyzers eliminates mechanical scanning systems and comprises entirely electronic image dissection means for dissecting an image transmitted by an optical system under test and producing an electric output signal representative of the beam intensity at a selected element of the image. The image dissection means is preferably (in the case of visible light) an image dissector tube whose positioning coils serve as an image element addressing means. The system is useable with any optical system including visible light, other electromagnetic radiation or charged particles (ions or electrons) so long as the image dissection means is responsive to the beam in question. The optical system under test must produce a real image at the image dissection surface of the image dissection means in order for readily evaluatable data to be obtained. The entire system is preferably computer controlled in order to obtain the necessary data quickly and accurately and to calculate the optical transfer function of the optical system under test on line. With this system both the modulation transfer function and the phase transfer function may be calculated. The digital computer can control the analyzer in any of several modes such as single scan, multiple scan with averaging of values to improve the signal to noise ratio and pass/fail production testing. output from the computer can be in any of several forms, such as displays on display devices, printouts or process control commands such as accept/reject commands in production testing.

Journal ArticleDOI
TL;DR: In this article, a greatly simplified version of the usual milti-channel spectrum analyzer of a Thomson scattering device has been developed and tested by actual measurements on the TFR Tokamak.

Patent
21 May 1976
TL;DR: In this paper, a multifunctional circuit analyzer is disclosed which is capable of determining the complete signature of an unknown electrical signal, which utilizes a high and low peak detection circuit and an analog to digital converter to determine the outer limits of the signal.
Abstract: A multifunctional circuit analyzer is disclosed which is capable of determining the complete signature of an unknown electrical signal. The circuit analyzer utilizes a high and low peak detection circuit and an analog to digital converter to determine the outer limits of the signal. The high and low threshold voltages are selected between the limits of the signal. Each time the unknown electrical signal passes through the preset high or low threshold voltage, a high or low threshold digital signal occurs. A logic circuit operates on these high and low threshold digital signals and activates the start and stop gate signals. These gate signals allow a time base signal to pass through a gate circuit into a series of decade counters. The information in the counters are thereafter transferred into decoders and then multiplexed to a display. The multifunctional circuit analyzer disclosed is capable of measuring, rise time, fall time, frequency, duty cycle, TRC counting, width, period, coincidence of two signals, the interval between two signals, count functions, frequency ratio, AC volts, DC volts and resistance.

Journal ArticleDOI
TL;DR: In this article, a circuit is described which adapts a laser Doppler velocimeter using real-time spectrum analysis for automatic velocity tracking by tracking the position of crossing of a selected intensity level on the spectrum analyzer output.
Abstract: A circuit is described which will adapt a laser Doppler velocimeter using real‐time spectrum analysis for automatic velocity tracking. The circuit provides an analog voltage which is proportional to velocity by tracking the position of crossing of a selected intensity level on the spectrum analyzer output. Examples of applications to the study of protoplasmic streaming and simulated hemodynamics are presented.

Patent
07 Dec 1976
TL;DR: In this paper, a frequency analyzer is connected to the signal output of the vibration detector for analyzing the signals on a progressive basis throughout the entire frequency range being examined to obtain corresponding data from which resonance curves are plotted and from which the natural frequencies and dampings of the system are obtained.
Abstract: An arrangement for ascertaining the parameters of natural vibrations and dampings of a multi-component dynamic system comprises a vibration detector applied to a component of the system for detecting and producing electrical signals constituting a measure of the mechanical vibrations produced by system internal excitement by stochastic disturbances. A frequency analyzer is connected to the signal output of the vibration detector for analyzing the signals on a progressive basis throughout the entire frequency range being examined to obtain corresponding data from which resonance curves are plotted and from which the natural frequencies and dampings of the system are obtained.

01 Jan 1976
TL;DR: In this article, the electrical aerosol analyzer (EAA) was calibrated by means of monodisperse aerosols generated by two independent techniques: electrostatic classification and photo-oxidation of SO/sub 2/ in a smog chamber.
Abstract: The Electrical Aerosol Analyzer (EAA) was calibrated by means of monodisperse aerosols generated by two independent techniques. In the 0.02 to 1 ..mu..m diameter range, the aerosol was generated by electrostatic classification. In the range between 0.007 and 0.03 ..mu..m, the aerosols were generated by the photo-oxidation of SO/sub 2/ in a smog chamber. Calibration data are presented showing the performance of the EAA as an aerosol detector and as a size distribution analyzer.

Patent
10 Nov 1976
TL;DR: In this article, a single optical test apparatus is used for testing various parameters of a T.V. lens system such as modulation transfer function, glare, spectral transmission, relative field illuminance, transverse color, T stop, and back focal distance.
Abstract: Optical test apparatus and method for testing various parameters of a lens system such as a T.V. lens system. A single apparatus may be used for testing the modulation transfer function, glare, spectral transmission, relative field illuminance, transverse color, T stop, and back focal distance. The apparatus comprises a pin hole light source and an analyzer means in which the lens may be mounted including a set of screens carrying varying patterns for measuring different parameters. The light transmitted through the screens is measured by a light detector means and the output signal is analyzed to provide a measurement of the parameters.