Showing papers on "Spectrum analyzer published in 1991"

Phase noise measurements utilizing a frequency down conversion/multiplier, direct spectrum measurement technique

Abstract: An improved circuit for phase noise measurements utilizing a frequency down conversion/multiplier and direct spectrum measurement technique which uses a combination of a phase detector method and a direct spectrum approach. The circuit is particularly useful for field test environments where laboratory instrumentation is normally not available, and fast and accurate phase noise measurements are required. The phase noise measuring circuit includes a frequency mixer which has a first input signal from a device under test and a second input signal from a reference stable oscillator having ultra low phase noise with a fixed center frequency. The frequency mixer mixes the first and second input signals to produce a down converted signal comprising the frequency difference signal of the first and second input signals. A lowpass filter then passes the down converted signal to a frequency doubler circuit which produces a doubled frequency, down converted signal. A lowpass signal filter then passes the doubled frequency, down converted signal to an amplifier. The output of the amplifier is directed to a second frequency doubler circuit which produces a quadrupled frequency, down converted signal. That signal is then directed to a further lowpass filter which passes the quadrupled frequency, down converted signal to a further amplifier. Finally, a direct approach spectrum analyzer analyzes the amplifier output signal which is an intermediate frequency signal in the most sensitive range of the spectrum analyzer for phase noise measurements on the device under test.

Method and apparatus for automatic optical inspection

Abstract: An inspection system for providing high contrast images of two materials of an article (12) to be inspected is disclosed. Light with variable spectral range and large angular coverage (2α) is passed from the source (61) through a polarizer (65), reflects from or is transmitted through the article (12) to be inspected, passes through an analyzer (73) and is detected by a sensor (72). A phase compensator (66, 74) is disposed either between the polarizer and (65) and the article (12) or the article (12) and the analyzer (73). Two of the three polarization optical components, that is, the polarizer (65), the compensator (66, 74) and the analyzer (73), are separately adjusted until the maximum contrast is found in the image. This enables high contrast imaging of surfaces of objects of similar optical reflectivity, (such as surfaces consisting of two similar specular materials, or surfaces partly covered with transparent films) which cannot be imaged using normal reflective image forming techniques. The system of the invention can also be operated to measure the thickness or refractive index of transparent thin films.

Sampling signal analyzer

Abstract: A sampling signal analyzer in which the frequency of an input signal to be measured is initially ascertained, an appropriate sampling frequency is then determined, data needed to reconstruct the wave form of the input signal is acquired, and the input signal wave shape is reconstructed with a calibrated time axis and preferably displayed. The sampling signal analyzer synthesizes a sampler drive signal to enable continuous sampling of the input signal and therefore has the advantage over known data sampling signal measurement instruments that it is not triggered directly in response to the level of the input signal to be measured. Instead, sample timing is based on numerical analysis of the intermediate frequency (IF) signal produced by the sampler. The IF frequency can be an arbitrarily low frequency, which allows digitizing and digital signal processing for aligning measurement data from sweep to sweep with precision. The sampling signal analyzer operates so that all frequency components of the input signal will lie within plus or minus an IF bandwidth away from a comb tooth of a sampling frequency and will translate (i.e., mix) and compress into the IF. The sampling signal analyzer determines where to mix the input signal in the IF based on the frequency of the input signal and a display time range selected by the operator. The number of cycles of the wave form being displayed can be selected by the operator, and the time axis is automatically rescaled to display the selected number of cycles, notwithstanding a change in the input signal frequency. A pulse profiling method enables the recoverable modulation bandwith of the sampling signal analyzer to be as wide as a high-frequency input bandwidth so that the response of high-frequency devices stimulated by pulsed or otherwise modulated signals can be measured.

Systemetic and random errors in rotating-analyzer ellipsometry

Abstract: Errors and error sources occurring in rotating-analyzer ellipsometry are discussed. From general considerations it is shown that a rotating-analyzer ellipsometer is inaccurate if applied at P = 0° and in cases when π = 0° or where Δ is near 0° or 180°. Window errors, component imperfections, azimuth errors and all other errors may, to first order, be treated independently and can subsequently be added. Explicit first-order expressions for the errors δΔ and δπ caused by windows, component imperfections, and azimuth errors are derived, showing that all of them, except the window errors, are eliminated in a two-zone measurement. Higher-order errors that are due to azimuth errors are studied numerically, revealing that they are in general less than 0.1°. Statistical errors are also discussed. Errors caused by noise and by correlated perturbations, i.e., periodic fluctuations of the light source, are also considered. Such periodic perturbations do cause random errors, especially when they have frequencies near 2ωA and 4ωA.

Shifting the frequency response of switched-capacitor filters by nonuniform sampling

Abstract: A clock with nonuniformly spaced sampling times can be used to shift the frequency response of switched-capacitor filters. By using such a clock, which deviates only slightly from a uniform sampling clock, small shifts in the frequency response of a switched-capacitor filter can be realized. The nonuniform sampling generates undesired modulation sidebands which are small if the deviation from uniform sampling is small. Computer simulations and measured data are presented to support equations that predict the frequency response shift and the amplitude of the undesired sidebands. This technique can be used to correct frequency response errors in monolithic switched-capacitor filters caused by capacitor ratio inaccuracies. It may also be useful in applications such as spectrum analyzers and tone generators. >

Spectrum and network measurements

Abstract: This book covers the theory and practice of spectrum and network measurements in electronic systems Intended for readers who have a background in electrical engineering and use spectrum or network analyzers to characterize electronic signals or systems, this classic volume successfully consolidates the pertinent theory into one comprehensive treatment of frequency domain measurements Witte's thorough coverage of critical concepts, such as Fourier analysis, transmission lines, intermodulation distortion, signal-to-noise ratio and S-parameters enables the reader to understand the basic theory of signals and systems, relate it to measured results, and apply it when creating new designs

Method for validation of calibration standards in an automatic chemical analyzer

Abstract: In an automated analyzer that measures concentration of samples by comparing changes in a detector response caused by said samples to a calibration curve or factor based on one or more different calibration standards stored in the analyzer, a replacement calibration standard is validated automatically by processing a portion of said replacement calibration standard as a sample prior to accepting the new calibration standard as a valid standard.

Adaptive scheduling system and method for operating a biological sample analyzer with variable interval periods

Abstract: An improved biological sample analyzer, and a method and system for operation thereof, wherein instrument systems used to perform assays of the biological samples loaded into the analyzer are operated in accordance with a schedule developed by a scheduler routine. The scheduler routine determines interval periods between operations performed by the analyzer instrument systems on each biological sample as a function of an entered load list unless a fixed interval period between the operations is required and schedules instrument system operations and the determined interval periods. The biological system analyzer performs assays of the biological samples by operating the analyzer instrument systems in accordance with the developed schedule.

Sound effects generating system for automobiles

Abstract: A signal synthesizer system includes signal generating detectors for detecting the operating conditions of an engine and applying the signals to at least one analyzer circuit At least one signal synthesizer combines the output of the analyzer with a control signal from a circuit programmed to generate signals indicative of a particular type of engine operating under the detected conditions The output of the synthesizer is converted to analog signals and applied to a signal transducer to produce an audible auto output

Waveform display apparatus for easily realizing high-definition waveform observation

Abstract: A measurement unit U100 measures an input signal to be measured by sweeping frequencies in a measurement range having a predetermined frequency band so as to obtain waveform data to be developed on the frequency axis such as spectrum data in, e.g., a spectrum analyzer. The waveform data obtained by the measurement of the measurement unit U100 is displayed by a display device 500 via a display data processor U20 included in a control unit U200 to be described later to be developed on the frequency axis of the display device, i.e., in correspondence with the measurement frequencies. The control unit U200 includes a measurement controller U30 for controlling the measurement unit U100 so as to display waveform data obtained by enlarging or reducing waveform data, before a measurement frequency condition is changed, at a predetermined magnification to have a predetermined point on the frequency axis as the center on the basis of a change in measurement frequency condition set by a condition setting unit U900, and an enlargement display/stable display processor U40 for controlling the display data processor U20. The enlargement display/stable display processor U40 realizes high-definition waveform observation as the gist of this invention, and substantially has a function of controlling the display device U500 as the control unit U200.

Agent gas analyzer and method of use

Abstract: An agent gas analyzer that will determine the types and measure simultaneously the concentrations of a plurality of agent gases in a respiratory gas stream of an anesthetized patient, with the analyzer self-determining the agent gas types and concentrations each time gas measurements are made.

In-service cable television measurements

Abstract: A cable television measurement system uses a modified spectrum analyzer for determining both carrier-to-noise and triple beat ratios for a cable television (CATV) system. The modified spectrum analyzer is triggered for single sweep during the vertical interval of a selected channel, and the noise amplitude, peak sync tip amplitude and frequency of the channel are determined. The carrier-to-noise ratio is determined from the noise amplitude and the peak sync tip amplitude and the ratio and frequency are displayed. For triple beat ratio measurements a headend unit coupled between a television signal source and a combiner in the CATV headend prior to distribution offsets a selected channel by a predetermined frequency for a specified number of lines in the vertical interval. The modified spectrum analyzer measures the peak sync tip amplitude and a triple beat amplitude at the end of the specified number of lines. The triple beat ratio is determined from the triple beat amplitude and the peak sync tip amplitude and displayed.

Optical compositional analyzer apparatus and method for detection of ash in wheat and milled wheat products

Abstract: An optical analyzing apparatus (20) for obtaining a quantitative correlation spectroscopy measurements of an analyte concentration in a multiple constituent sample (24). The optical analyzing apparatus (20) employs a correlation spectroscopy algorithm which uses preselected wavelength light energy from both the visible light spectrum and the near-infrared (NIR) light spectrum to analyze multiconstituent samples. The optical analyzing apparatus (20) comprises a light emitter mechanism (22) formed for irradiating the sample (24) with a predetermined first wavelength of light energy in the visible light spectrum and a predetermined second wavelength of light energy in the NIR spectrum. The first wavelength is selected to be active in response to the presence of the analyte while the second wavelength is selected to be active in response to the presence of at least one of the remaining constituents in the sample (24). A detector mechanism (50) is positioned to detect one of optical reflectance and transmissivity of the sample (24) after irradiation at the first and second wavelength, whereby the detected one of reflectance and transmissivity can be used in correlation spectroscopy algorithms to obtain a value of the concentration.

A New Scattered Circular Polarization Raman Optical Activity Instrument Equipped with a Charge-Coupled-Device Detector

Abstract: A simple and fully computer-controlled scattered circular polarization Raman optical activity (SCP-ROA) instrument is described which consists of a fast single monochromator and a thermoelectrically cooled charge-coupled-device (CCD) detector as the key spectral elements. A conventional circular analyzer, formed by a quartz zero-order quarter-wave plate attached to a motorized 360° rotator and a fixed linear dichroic sheet polarizer, is employed for the modulation between orthogonal circular polarization states in the scattered radiation within a right-angle scattering geometry. Well-resolved depolarized SCP-ROA spectra of (1S)-(–)-α-pinene and (R)-(+)-pulegone are presented within the wave-number region of ∼550 to 1200 cm−1 as typical examples of the excellent performance of this novel multichannel ROA instrument.

Waveform analyzer having function of simultaneously displaying wide- and narrow-band spectra or transmission characteristics

Abstract: Display section (2) displays, on a screen, a zone marker for indicating, on a wide-band spectrum display area, that part of a wide-band spectrum which corresponds to a selected narrow-band spectrum to be displayed, and the wide-band spectrum, as well as said narrow-band spectrum which has been enlarged. First setting section (14) changes a center frequency or a band width of said displayed narrow-band spectrum, in accordance with the change of the position or width of the zone marker. Second setting section (15) cooperating with the first setting section (14) changes the position or width of the zone marker in accordance with the movement of the center frequency or band width of the displayed narrow-band spectrum. Control section (7h) for controlling a measurement resolution and a sweep time in accordance with the magnitude of the displayed spectrum, so as to satisfy the formula: sweep time ≧ band width/(measurement resolution)².K where K = a constant.

Apparatus for controlling an internal combustion engine

Abstract: An apparatus for controlling an internal combustion engine comprises a transducer which detects acoustic emissions generated by the operation of the engine, and produces an output signal. The output signal is amplified, rectified and enveloped to produce an electrical signal. The electrical signal has its direct current component removed to leave the alternating current component of the electrical signal. The AC component of the electrical signal is rectified by a rectifier and the mean level of the AC component of the electrical signal is measured by a measurer. An analyzer monitors the mean level of the AC component of the electrical signal and sends a feedback signal to an ignition timing device of the internal combustion engine. The analyzer sends feedback signals such that the mean value of the AC component of the electrical signal lies in the region of a positive peak prior to the occurrence of preignition.

Life pattern analysis and enunciation system

Abstract: PURPOSE: To analyze the life pattern and living condition from the way an electric apparatus is used for selt-checking of changes and abnormality of life of a high-aged person and for protection by an external organization. CONSTITUTION: A current detecting section 31 is mounted on an electric wire and an output thereof is inputted into an analyzer 3 having a communication interface 38 from a pretreatment section 32. The analyzer 3 possesses data of reference power spectrum of consumed current corresponding to apparatuses in a memory. A current signal is digitized with a pretreatment section 32 and undergoes a fast Fourier transform with a processor 9 to make an extraction power spectrum. The spectra are compared with the reference power spectrum and when the reference power spectrum of a specified apparatus is contained in an extraction power spectrum, the use of the apparatus is stored into a memory together with time. The results are displayed on an output section 36 at any time to be sent to an external organization through a communication circuit 37. This enables self-checking of living condition and rhythms from the way an electric appratus is used and thus, life information can be transmitted to the external organization with the communication circuit. COPYRIGHT: (C)1992,JPO&Japio

Bidimensional electromagnetic emission level monitoring equipment

Abstract: Bidimensional electromagnetic emission level monitoring equipment for detecting the electric fields or the magnetic fields of RF (Radio Frequency) emissions from equipment under test by moving an electromagnetic probe bidimensionally. The measuring frequency, the scanning range of the probe, and the distance between measuring points are entered on a keyboard of a controller. A spectrum analyzer selectively receives RF emissions of a designated frequency from the probe in response to an instruction from the controller and feeds emission level signal data to the controller as digital signals. A probe scanning section loaded with the probe is moved bidimensionally by a motor driver under the control of the controller. The controller delivers to a display an emission level distribution signal representative of an electromagnetic distribution based on the emission level data and position data associated with the probe.

General purpose system for digitizing an analog signal

Abstract: A general purpose programmable optical analyzer employs a nonlinear gain at the input stage of an analog to digital converter in order to limit the number of bits used to resolve shot noise.

Method and apparatus for measuring the frequency of a spectral line

Abstract: A method and apparatus are disclosed, that is suitable for digital or analog spectrum analyzers, for accurately and rapidly ascertaining the frequency of a spectral line by interpolating its location from the response of two Gaussian shaped filters whose center frequencies bracket the frequency of the spectral line. The difference is taken between the amplitudes in decibels of the responses of the two Gaussian filters to the spectral line input signal. The frequency of the spectral line is then found from the linear relationship fx = delta-log-ampl.*c1 + c2, where c1 is proportional to the square of the standard deviation of the Gaussian filters and inversely proportional to the difference between the center frequencies, f1 and f2, of the Gaussian filters times the logarithm of e, and where c2 is the midpoint between the center frequencies, f1 and f2, of the Gaussian filters, G1 and G2. Alternatively, a sweeping local oscillator output can be mixed with the signal containing the spectral line of unknown frequency and the resulting signal applied to one Gaussian filter at two different times to produce equivalent results. In this case, c1 is proportional to the square of the standard deviation of the Gaussian filter and inversely proportional to the difference between the local oscillator frequencies, f,LO-t1 and f,LO-t2, at times t1 and t2, times the logarithm of e, and c2 is the average of the local oscillator frequencies, f,LO-t1 and f,LO-t2, plus f, the center frequency of the Gaussian filter.

A 640 MHz 32 megachannel real-time polyphase-FFT spectrum analyzer

Abstract: A 2/sup 25/ (33,554,432) channel, 640 MHz wide polyphase-fast Fourier transform (FFT) spectrum analyzer is being designed at the Jet Propulsion Laboratory for the Search for Extraterrestrial Intelligence (SETI) Sky Survey. By replacing the time-domain multiplicative window preprocessing with polyphase filter processing, much of the processing loss of windowed FFTs can be eliminated. Polyphase coefficient memory costs are minimized by effective use of run-length compression. Finite word length effects are analyzed, producing a balanced system with 8 bit inputs, 16 bit fixed-point polyphase arithmetic and 24 bit fixed-point FFT arithmetic. Fixed-point renormalization midway through the computation is seen to be naturally accommodated by the matrix FFT algorithm proposed. >

Spark ignition analyzer

Abstract: A spark ignition analyzer comprising a probe having a first and second pick-up responsive to a voltage from an ignition wire, a high tension detector for detecting an absolute voltage increase from the first pickup and triggering a first visual signal for a predetermined time period, and a spark detector for detecting a high frequency voltage fluctuation from the second pick-up and triggering a second visual signal for a predetermined time period. The combination of visual signals is used to analyze the ignition system of an engine.

Accurate measurement of signals close to the noise floor on a spectrum analyzer

Abstract: Because most spectrum analyzers are calibrated to read the true power of a sinusoidal signal, a correction factor is necessary to read the true power of a nonsinusoidal signal, such as noise. Consequently, when noise and a sine wave are both present, a correction factor that is a function of the signal-to-noise ratio is necessary to find the true signal power. For some spectrum analyzers the correction factor for pure noise is incorporated into the software, but the correction factor for signal-plus-noise is generally ignored. The authors derive this correction factor, which is significant where the signal-to-noise ratio is near unity. >

Apparatus for and method of producing ion beams

Abstract: Apparatus (28) for implanting ions into a target element (26) comprising a circular array of hot cathode, arc discharge, ion sources (29) mounted on a rotary carousel (13) or a linear mechanism. An annular rotary support (15) around the carousel supports a plurality of extraction electrodes (18). A housing (20, 23) defines an outlet path (32) for the ion beam from the ion source (29). The ion beam is directed through a beam analyzer (24) and through acceleration stages (25) to means (27) for scanning the beam relative to the target (26) to be implanted. The carousel (13) and the annual support (15) can both be rotated, so as to bring into cooperating relationship required combinations of ion source (29) and extraction electrode (18).

Fiber length analyzer

Abstract: A measuring cell (22) in a fiber sample analysis system (10) contains housing member (76) which removably supports a transparent flow tube (82) and an optical device (26) which projects a beam (124) across the tube for detecting and measuring individual fibers in a dilute sample fluid which flows through the tube at a constant velocity. The tube includes a gradually narrowing transition portion (86) leading to a measurement portion (88) situated at the optical device and having a flow diameter in the range of about 1.0 to 3.0 mm.

An electrostatic time‐of‐flight analyzer for simultaneous energy and mass determination of neutral particles

Abstract: A neutral particle energy analyzer has been developed to measure both the energy and the mass of the incoming particles with only one array of detectors. Energy analysis is performed by means of deflection in an electrostatic field. The mass of the particle is determined by measuring the flight time from a stripping foil to a channel electron multiplier in the focal plane of the analyzer. The application of a stripping foil instead of a gas cell increases the stripping efficiency and simplifies the vacuum system. Monte Carlo simulation studies and first calibration experiments show that the analyzer can be used even at energies down to 1 keV, as long as the stripping foil does not exceed a thickness of 2.0 μg/cm2. These simulations take into account the angular and energy straggling processes that take place in the foil. A triple‐coincidence technique can be applied to decrease the sensitivity of the analyzer to neutron and gamma background radiation considerably, as will be shown by calculations.

An automatic system for the measurement of dropping mercury electrode impedances

Abstract: A fully automated setup for impedance measurements at the dropping mercury electrode (DME) is described. It is based on the Solartron 1250 frequency response analyzer, and it incorporates an infrared drop-fall detector. Synchronization with the DME as well as calibration procedures are considered in some detail. Experiments on dummy and electrolytic cells, with and without electroactive species, were performed, and data are compared with earlier results on the same systems.

The energy component analyzer and spectrum analysis of end‐loss ions in a tandem mirror

Abstract: Features of the electrostatic energy analyzer of a cylindrical type are described with the aim of measuring the end‐loss ions in the tandem mirror GAMMA 10. The analyzer provides us with information about ion density distributions in a loss‐cone region of velocity space as well as plug potential in the tandem mirror. Application of the analyzer to the tandem mirror experiments and the energy spectrum analysis are discussed.

Device for measuring reflection in optical frequency area

Abstract: PURPOSE: To reduce the fluctuation of a signal value to be caused by fading, and measure the signal strength accurately by overlapping the temporal modulation waveform with the single sawtooth frequency sweep waveform, and shifting the frequency obtained by the measurement of multiple times, and sampling the data to perform the addition meaning processing. CONSTITUTION: The laser beam 1 from a light source system 1 is divided-into the measuring light MS and the reference light RF by a first directional coupler 2. The light MS enters an object 7 to be measured, and the light RF enters a heterodyne receiver 4. The reflected light RL at any position of the object 7 is divided by a second directional coupler 3 to enter the receiver 4. The receiver 4 performs the coherent wave detection of the reflected light with the light RF as the local light. The output light of the receiver 4 is sampled by a spectrum analyzer 5, and the output thereof is measured multiple times by a signal processing system 6, and the addition meaning processing is performed. Fluctuation of a measured signal value to be caused by fading is thereby reduced. COPYRIGHT: (C)1993,JPO&Japio