Showing papers on "Spectrum analyzer published in 1994"

Medical sensor with amplitude independent output

Abstract: The present invention provides a medical sensor for detecting a blood characteristic. The sensor includes a transducer for producing an analog signal related to the blood characteristic. The analog signal is converted into a transmission signal which is in amplitude-independent form for transmission to a remote analyzer. In one embodiment, a current-to-frequency converter converts a signal from a pulse oximeter sensor into a frequency signal which can be transmitted over a transmission line to a remote pulse oximeter.

Calibrated vectorial nonlinear-network analyzers

Abstract: The vectorial nonlinear-network analyzer concept is introduced and realized in practice. A vectorial nonlinear-network analyzer excites a nonlinear microwave device-under-test with a combination of sinewaves of different frequencies and accurately detects the phase and amplitude of all frequency components of the incident and the scattered waves. A new, statistic efficient, absolute calibration procedure is developed based on a row crest factor multisine reference generator characterized by a broadband sampling oscilloscope. This makes the calibration traceable to the accuracy of a so-called nose-to-nose measurement. >

Hand held data collector and analyzer system

Abstract: A hand held data collector and analyzer achieves superior stability, accuracy and reliability through the use of a fixed frequency anti-aliasing filter and two analog to digital converters, one for high frequency signals and one for low frequency signals. Efficient digital filtering and decimation is achieved by providing specialized hardware filters and decimators and implementing software filters and decimators in a data processor. A true zoom method is employed to take advantage of the filtering and decimation capabilities, and independent digital signal processors operate serially on incoming signals to further reduce demands on the central processing unit. In addition, the RAM system memory is formatted as a pseudo-card to facilitate use of a PCMCIA memory card or the RAM system memory.

Design of a scanning ellipsometer by synchronous rotation of the polarizer and analyzer.

Abstract: We have designed and constructed a new type of spectroscopic ellipsometer to study the optical properties of materials in the 3500-8000-A wavelength range. In the system, the analyzer and polarizer are driven 10(4) steps/revolution by two stepping motors that have hollow shafts and rotate synchronously with a speed ratio of 2:1, i.e., A = 2P. Both the polarizer and analyzer are mounted directly on the shafts to avoid mechanical transmission and vibration problems entirely and make the system simple and reliable. An additional source polarizer was placed in the optical path to reduce the slight polarization effects of the light source. The light intensity finally received by the detector contained five components, one dc and four ac, with frequencies of ω(0), 2ω(0), 3ω(0), and 4ω(0), respectively. One can independently obtain the ellipsometric parameters of ψ and Δ as well as the optical constants by calculating any one of the two sets of ac signals, with a raw data self-consistency of better than 0.5%. The incident angle, aligned precisely by a laser beam, was continuously variable through a mechanical system with a computercontrolled resolution of 0.001° or a visual resolution of 0.005°. The system operations, including data acquisition and reduction, high-voltage control of the photomultiplier, incident angle, as well as wavelength setting and scanning, were fully and automatically controlled by a 386-based microcomputer. We self-calibrated the system by adjusting and setting precisely the initial azimuthal angles of the prisms. The results from the measured spectra of the complex refractive index for a gold-film sample are presented, and we show that the data obtained at three different incident angles of 65°, 70°, and 75° are remarkably consistent with one another. A comparison of the two results from the ellipsometry and reflectance measurements is given. The experimental skills and system error reduction are discussed in detail.

A modified photo- and magnetoacoustic multigas analyzer applied in gas exchange measurements.

Abstract: The feasibility of replacing a conventional mass spectrometer (MS) with a specially modified multicomponent (O2, CO2, Freon 22, and SF6) acoustic infrared and paramagnetic (IR/PM) gas analyzer in i...

Apparatus and method for determining the size distribution of particles by light scattering

Abstract: An apparatus and method are disclosed for obtaining and analyzing light scattering data to determine the size distribution of a group of dispersed particles that scattered the light. The apparatus and method use a two-dimensional array of photosensitive pixels such as a charge-coupled device (CCD) or an array of solid-state photodiodes. The analyzer illuminates the particles with a dose of light in a collimated beam from a light source so as to scatter light of the beam, and at least a portion of the light interacting with the particles is detected with the photosensitive pixel array. The pixels are functionally equivalent and the analyzer dynamically configures and re-configures at least a portion of the pixels into a variable number of data collection areas which correspond to a selected set of scattering angles. The analyzer also determines whether and, from the pixel output data, where an unscattered center of the incident light beam intersects the pixel array. Thus, no precision mechanical alignment of the light source and the pixel array detector is required prior to operation of the analyzer. Furthermore, the ability of the analyzer to determine the unscattered beam center allows the analyzer to classify each of at least a portion of the pixels to data collection areas according to a function of the geometric relationship the pixel bears to the location of the beam center.

Optical sensing of combustion dynamics

Abstract: An optical radiation detector, such as a silicon carbide photodiode ultraviolet radiation detector, is employed for real time, noninvasive monitoring and diagnosis of combustion dynamics in gas turbine engines. The SiC photodiode responds to flame ultraviolet emission, and a Fast Fourier Transform spectrum analyzer peak acoustic frequency components of the detector signal as indicators of systematic gas pressure vibrations related to combustion. The combustion may be modified in accordance with the monitored acoustic frequency components.

A Vector Corrected High Power On-Wafer Measurement System with a Frequency Range for the Higher Harmomcs up to 40 GHz

Abstract: A high power on-wafer measurement system based on the new microwave transition analyzer (MTA) HP 71500A has been developed for the complete characterization of the large signal behavior of transistors. One key feature of the MTA based measurement system is that during power sweeps the harmonic behavior, up to 40 GHz, can be measured. To improve the accuracy of power measurements the vector measurement capability of the MTA is also utilized to allow full vector calibration of the measurement system. In addition, this vector measurement feature allows both the input reflection and the transmission coefficients of a device under test (DUT) to be measured as a function of frequency and input power. The input and output voltage waveforms at the transistor terminals are also calculated from the measurement data. This improved capability is possible since the vector calibrated measurement system allows both the measurement of the fundamental and the higher harmonics with respect to magnitude and phase.

Harmonic resonance at a medium sized industrial plant

Abstract: Harmonic resonance is a concern for industrial plants because approximately 50% of the normal electrical load consists of computer equipment, switch mode power supplies and AC induction motor adjustable speed controllers. Due to the nonlinear characteristics of these loads, significant harmonic voltages and currents are produced on the electrical distribution system. Measurements were made with a harmonic analyzer at several locations in an electrical distribution system to quantify harmonic currents and voltages. The system impedance diagram, prepared from the system one line diagram, was used to model the electrical system and calculate power system natural frequencies. Calculations indicated harmonic resonance occurs near the seventh harmonic frequency depending on configuration of the electrical power system. The plant equivalent circuit was prepared for several harmonic frequencies to show the amplification of currents and voltages due to the effects of harmonic resonance. Calculations to determine network harmonics are presented using a simplified system representation in combination with traditional circuit reduction methods. The results of these calculations are shown to be valid by actual system measurement. >

Methods for photometric analysis

Abstract: The present invention provides a compact, highly automated photometric analyzer for measuring the concentration of substances found in a fluid, typically a blood sample or other body fluid sample taken from a patient. The operator places a small quantity of the sample into a special rotor and then loads the rotor into the analyzer. The analyzer accepts the rotor, centrifuges and dilutes the sample, and distributes the sample into a plurality of cuvettes near the outer edge of the rotor. Some of these cuvettes hold reagents which react with the sample. The analyzer then measures light absorption within the sample at a number of preselected frequencies. According to the present invention, a pair of specially designed apertures direct light from the sample through a plurality of beam splitters, interference filters, and associated photodetectors. The system also includes means for performing automatic calibration and error checking functions. These means include a through hole through the rotor, and an opaque body carried by the rotor. Additionally, measurements may be repeated through a given cuvette and the results averaged to minimize the effect of random variations between measurements.

System and method for compensating polarization-dependent sensitivity of dispersive optics in a rotating analyzer ellipsometer system

Abstract: An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a rotating compensator, positioned between the analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The method of the present invention can include application of mathematical correction factors to, for instance, substrate system characterizing PSI and DELTA values, or Fourier ALPHA and BETA coefficients.

Traveling wave electro‐optic phase modulator using cross‐linked nonlinear optical polymer

Abstract: We report the fabrication and characterization of a high frequency traveling wave electro‐optic phase modulator made from thermally cross‐linked polyurethane‐Disperse Red 19 polymers. The device has been fabricated using a three layer structure with an integrated 50 Ω microstrip line circuit. The straight channel optical waveguides were defined laterally by standard photolithography and oxygen reactive ion etching. The measured half‐wave voltage was in good agreement with that extrapolated from the second harmonic generation measurements. Optical modulation was observed directly on a spectrum analyzer up to 18 GHz. Long‐term evaluation over an extensive length of time found no observable loss of performance.

Quick connect diagnostic apparatus and method for a vehicle cooling system

Abstract: A quick connect diagnostic apparatus for the cooling system of a vehicle engine includes first, second and third temperature sensors which are configured to attach to liquid hoses which circulate cooling liquid throughout the engine, the first sensor attaching to a hose directly from the engine, the second and third sensors attaching to input and output hoses, respectively, connected to the radiator. The sensors are housed within a cuff structure which is wrapped around the hoses to detect the fluid temperatures within the hoses. Each sensor is connected to an analyzer which compares the first signal to a temperature threshold signal, compares the first signal to the second signal to generate a first difference signal which is then compared to a thermostat threshold signal, and compares the second and third signals to produce a second different signal which is compared to a radiator threshold signal. The analyzer utilizes the various difference signals and temperature signals to produce output signals indicative of the engine temperature, and the operational status of the radiator and thermostat. Output circuitry electrically coupled to the analyzer provides humanly perceptible outputs in response to the output signals from the analyzer.

Optically-based chemical detection system

Abstract: An in-situe chemical gas or fluid analyzer for vehicles, industrial, environmental and process control applications. As applied to a vehicle (1) having an internal combustion engine, the analyzer includes: (i) a source of electromagnetic radiation (14, 16); and (ii) a sampling cell (12) which collects emission gases of interest and which is capable of withstanding hostile environments while preserving a "clear" optical path between the sensor sampling cell and the source of radiation. The analyzer further includes: (iii) a solid state sensor (24, 26, 28, 30, 32 ) of monolithic construction which selectively detects electromagnetic radiation that is absorbed or emitted by one or more chemical species of interest, that compensates for temporal and spatial variations in illumination level provided by the source, and that provides an electrical signal output, in either analog or digital format, that is related to the measured concentrations. The sensor includes, in combination, a plurality of highly sensitive electromagnetic radiation detectors (26), spectral filters (24) which may utilize multiple layers of deposited dielectric thin films and/or selectively absorbing layers, and low noise electronics which performs a variety of functions including amplification (28), multiplexing (30), analog to digital (A/D) conversion (33), signal processing (32), and input/output (I/O). In a presently preferred embodiment each radiation detector is a thermopile detector that is integrated upon a common substrate with the support electronics and an associated optical bandpass filter.

Hazardous air pollutants monitor

Abstract: Gases such as pollutants are discerned in a sample, preferably using a laser to emit an infrared light beam along a sight path for illuminating the gases. The beam is directed along the sight path and collects light from the gases. An optical tunable filter selects a particular optical wavelength or band, and the filtered wavelength is focused on a detector coupled to an analyzer. The analyzer can include a processor that can pulse the laser or coordinate collection of data from sample gases and from a reference cell containing known gases, e.g., using an optical chopper wheel. The processor analyzes the light levels as a function of wavelength to discriminate for the presence of selected gases by determining a characteristic pattern of light absorption and light emission by the gases. The tunable filter has an acousto-optical crystal of Tl 3 AsSe 3 , in which an RF acoustic wave is generated for varying diffraction of light by the filter, thereby selecting a wavelength. A nonlinear output crystal can in inserted controllably to selectively generate harmonics for increasing wavelength coverage, and can also be Tl 3 AsSe 3 . A broad band infrared illumination source can be used. When the infrared excitation beam is off, the filter acts on infrared emissions of the gases. Sensitivity to narrow emission lines is increased by modulating the RF drive to the tunable filter, producing derivatives of the spectra.

Linear-matrix audio-imaging system and image analyzer

Abstract: An audio-imaging system includes at least first and second input channels for receiving first and second channel audio input signals and at least first, second and third output signals which are produced as a combination of the first and second channel audio input signals and a nonzero parameter. The parameter is common to the first, second and third output signals and may be made adjustable in order to vary the width of the audio image produced in order to compensate for composition mixing of a program source applied to the input channels. A sound-image analyzer is also provided which processes a program source applied to the input channels to at least three fully separated levels representing left, right and center directions of the program source in order to determine a value of the parameter.

Electrical parameter analyzer

Abstract: An electrical parameter analyzer analyzes samples of electrical power by executing program instructions stored on a PCMCIA compatible program card. The analyzer has a central processing unit including a microprocessor which reads the program card and passes program instructions to an acquisition control processor and an input/output controller, each of which has its own microprocessor. A series of values for a characteristic parameter of the electrical power are generated by the acquisition control processor, and these values are printed under control of the input/output controller upon request of the central processing unit.

A review of experimental transverse Doppler studies

Abstract: The possibility of detecting useful Doppler information when the ultrasound beam is transversely oriented to the flow, has so far been studied by several authors. A new theory, in particular, has demonstrated that the focusing properties of piezoelectric transducers involve a Doppler signal bandwidth proportional to the transverse velocity component. The key element to perform reliable "transverse" Doppler experimental studies is thus an efficient spectrum analyzer, capable of performing accurate and repeatable bandwidth measurements. The authors review here experimental tests of the new theory, independently done in several laboratories by means of a specially developed computerized spectrum analyzer. The results of these tests include the demonstration that the "transverse" Doppler bandwidth is invariant with the range of cell depth and dimensions. It is also discussed how the basic transverse Doppler technique can be conveniently extended to allow the two- and three-dimensional estimation of the flow vector. Experimental evidence about the possibility of using the new theory to give a correct interpretation of in vivo transverse spectrograms is also presented. >

Bragg diffraction optics in high resolution strain measurements

Abstract: Using Bragg diffraction optics focusing conditions for a triple-axis setup equipped with a bent Si single crystal monochromator and analyzer for investigation of stress fields in polycrystalline materials are derived. Results of experimental tests of such a setup are presented. Further it is demonstrated that if certain focusing conditions for a bent monochromator are fulfilled the beam diffracted by a polycrystalline sample becomes quasi-parallel which enables high resolution measurements directly with a PSD without the use of a collimator or a crystal-analyzer. In the three axis setup maximum sensitivity in determination of Δdd ≤ 10−4 can be achieved permitting profile-broadening analysis for reasonable sample volumes and counting times.

Clipping-induced impulse noise and its effect on bit-error performance in AM-VSB/64QAM hybrid lightwave systems

Abstract: We demonstrate that the impulse noise generated from clipping AM signals limits QAM bit-error performance in AM-VSB/M-QAM hybrid optical transmission systems. A new technique is developed to adequately predict QAM bit-error rate by defining a measurable parameter which can be obtained from impulse counting using a standard spectrum analyzer. >

Hydrogen sulfide analyzer with protective barrier

Abstract: A field test kit for determining quantity of hydrogen sulfide in a liquid st sample. The test kit includes a test container with an opening for a liquid test sample containing hydrogen sulfide gas and a cap provided over the opening. The cap has colorimetric particulate indicator on its top inside surface. A silicone barrier disposed over the indicator protects the indicator from contact with the test sample.

Oto-acoustic emission analyser

Abstract: A hand-held, battery-driven, oto-acoustic emission analyzer has a measuring probe, introduceable into the patient's ear, having a first acoustic generator and an acoustic detector. An electronic circuit is connected to the first acoustic generator to generate first oto-acoustic stimulus signals transmitted by the first acoustic generator and connected to the acoustic detector to measure and process oto-acoustic emission signals received by the acoustic detector. A display is coupled to display data processed by the electronic circuit. A housing holds the electronic circuit and the display, the housing being adapted to be held in a user's hand.

Spectrophotometer and radiometric measurement apparatus

Abstract: A handheld portable spectrophotometer is provided including keys for input of instructions by a user, an illuminator for illuminating a sample, and a spectral analyzer for separating light reflected from the sample into spectral components to produce a signal corresponding to the level of each spectral component. A processor is provided for executing the user instructions and for analyzing the signal. The results of the signal analysis are presented on a display. A power source is provided for providing power for operation of the handheld portable spectrophotometer.

Speech signal distortion measurement which varies as a function of the distribution of measured distortion over time and frequency

Abstract: Telecommunications testing apparatus includes an analyzer arranged to receive a distorted signal which corresponds to a test signal when distorted by telecommunications aparatus to be tested. The analyzer periodically derives, from the distorted signal, a plurality of spectral component signals responsive to the distortion in each of a plurality of spectral bands, over a succession of time intervals. The analyzer generates a measure of the subjective impact of the distortion due to the telecommunications apparatus, the measure of subjective impact being calculated to depend upon the spread of the distortion over time and/or over the spectral bands.

Speech signal bandwidth compression and expansion apparatus, and bandwidth compressing speech signal transmission method, and reproducing method.

Abstract: A speech signal bandwidth compression and expansion apparatus and its method. On the transmitting side, system parameters are extracted from a speech signal by a linear prediction analyzer. A prediction residual signal is obtained by inverse filtering processing by using the system parameters. The prediction residual signal is lowered in sampling rate by a down-sampler and converted to a baseband signal. From the baseband signal, a time series signal is derived by a linear prediction synthesizer. Thereafter, the time series signal is converted to an analog signal and transmitted. On the receiving side, a received signal is subjected to inverse filtering processing to reproduce a baseband signal. The sampling rate of the reproduced baseband signal is raised to derive a time series signal. From the time series signal, a high frequency band component is generated. The high frequency band component is added to the baseband signal to generate an excitation signal. From the excitation signal, the original speech signal is reproduced by a linear prediction synthesizer.

A Submersible Flow-through Analyzer for in situ Colorimetric Measurement down to 2000 m Depth in the Ocean.

Abstract: We developed a flow-through chemical analyzer usable in seawater up to a depth of 2000m. The analyzer, which can measure silicate and hydrogen sulfide dissolved in seawater, consists of the following four parts: (i) an acrylic oil-filled vessel containing the flow-through analyzer, (ii) a pressure housing containing electronic circuits (CPU, data logger and drivers to control the analyzer), (iii) a bundle of plastic bags keeping analytical reagents and waste solutions and (iv) batteries for powder supply. Si and H2S are determined colorimetrically using the Molybdenum Blue method and the Methylene Blue method, respectively. After the test operation up to a pressure of 2×107 Pa in a shore-based laboratory, the system was submerged in seawater down to 1200m depth to perform successful in situ Si measurements.

Method and device for signal synthesis

Abstract: PURPOSE: To provide the signal synthesizing device which synthesizes a signal of high sound quality by converting a band-limited input signal into a wide-band signal having a wide frequency band covering the frequency band that the input signal has. CONSTITUTION: The device is equipped with an acoustic analyzer 101 which extracts spectrum information by taking a sound analysis of the band limited input signal, a narrow-band data processor 102 which extracts narrow-band spectrum information from learning data, a wide-band data processor 103 which extracts wide-band spectrum information from the learning data, a mapping function estimation unit 104 which estimates a mapping function from the narrow-band spectrum information and wide-band spectrum information, a band widening unit 105 which converts the spectrum information on the input signal into wide-band spectrum information by widening the band with the mapping function, and a signal synthesizer 106 which synthesizes a wide-band signal having a wide frequency band covering the frequency band of the input signal from the band-widened spectrum information. COPYRIGHT: (C)1996,JPO

On-wafer large signal power, S-parameter and waveform measurement system

Abstract: An on-wafer measurement system has been developed for the complete characterization of the large signal behavior of transistors up to 40 GHz based on the microwave transition analyzer HP 71500A. The vector measurement capability of the MTA is utilized to allow full vector calibration of the measurement system for the fundamental and the higher harmonics. The error corrected waveforms at the transistor terminals are derived from the measurement data. Novel analysis concepts have been developed for the extraction of transistor characteristics and parameters from large signal RF measurements, i.e., RF current and voltage constraints associated with the output characteristic and the RF large signal transfer characteristic. These parameters, measured under real RF operating conditions, can be compared directly with DC or small signal S-parameter measurements. This is essential if large signal RF measurements are used for the optimization of high power transistor structures and in the development of accurate non-linear CAD models.

Digital pulse-shape analyzer based on fast sampling of an integrated charge pulse

Abstract: A novel configuration for pulse-shape analysis and discrimination has been developed. The current pulse from the detector is sent to a gated integrator and then sampled by a flash analog-to-digital converter (ADC). The sampled data are processed digitally, thus allowing implementation of a near-optimum weighting function and elimination some of the instabilities associated with the gated integrator. The analyzer incorporates pileup rejection circuit that reduces the pileup effects at high counting rates. The system was tested using a liquid scintillator. Figures of merit for neutron-gamma pulse-shape discrimination were found to be: 0.78 for 25 keV (electron equivalent energy) and 3.5 for 500 keV. >