Showing papers on "Spectrum analyzer published in 1992"

Optical generation of very narrow linewidth millimetre wave signals

Abstract: A novel method for the optical generation and distribution of millimetre waves is described. The method is demonstrated at 36 GHz and an electrical linewidth limited by the resolution bandwidth of the spectrum analyser is achieved. No broadening of the electrical linewidth could be observed after propagation through 8 km of standard fibre.

Optical Signal Processing

Abstract: : We studied optical processing techniques to detect and track frequency hopped radio signals in a dense electromagnetic environment by using cross-spectrum of two signals obtained from antenna elements spaced by one-half an RF wavelength. We decimate the array by retaining only every Mth element and scan the cross-spectrum past the decimated array. We therefore reduce the circuit complexity, but suffer some loss in system performance because we require more photodetector bandwidth to accommodate the scanning action. An extension of the decimated array concept is to decimate the reference waveform in the heterodyne spectrum analyzer. In this case, we generate only 64 optical probes in the Fourier domain instead of the 2048 that are normally required. The advantage is that all of the optical power in the reference beam can be concentrated into the reduced number of optical probes, thereby offsetting some of the intrinsic loss in performance experienced by the cross-spectrum analyzer. (JHD)

Two-port network analyzer calibration using an unknown 'thru'

Abstract: A procedure performed by using a genuine two-port reciprocal network instead of a standard 'thru' in a full two-port error correction of an automatic network analyzer is presented. Although it can be applied to any type of waveguide system, the proposed technique is particularly useful with noninsertable coaxial or one-wafer devices. Experimental comparisons show that the suggested procedure provides a great degree of accuracy. >

Acoustical method and system for detecting and controlling chemical-mechanical polishing (CMP) depths into layers of conductors, semiconductors, and dielectric materials

Abstract: A method and system for controlling the depth of removal by polishing of a selected material on a supporting underlayer where it is desired to terminate removal of the selected material, such as tungsten, at the material-underlayer interface. In accordance with this novel method and system, the selected material such as a surface metallization layer is polished to initiate removal thereof in the direction of the material-underlayer interface. A microphone is positioned at a predetermined distance from the wafer to sense acoustical waves generated when the depth of material removal reaches a certain determinable distance from the interface to thereby generate output detection signals. These output detection signals are amplified and then applied to a spectrum analyzer which operates to analyze the sound intensity-versus-frequency characteristic of the acoustical waves received by the microphone. The spectrum analyzer operates to drive a CMP computer which in turn controls the operation of a CMP polishing machine. The CMP polishing motor terminates polishing of the selected material a predetermined time after a desired output signals are received from the spectrum analyzer. The present invention is also directed to a method and system or measuring the thickness of certain materials by comparing acoustical signals in a spectrum analyzer with frequency characteristics of known materials of certain layer thicknesses.

Global flow analysis as a practical compilation tool

Abstract: This paper addresses the issue of the practicality of global flow analysis in logic program compilation, in terms of speed of the analysis, precision, and usefulness of the information obtained. To this end, design and implementation aspects are discussed for two practical abstract interpretation-based flow analysis systems: MA3, the MCC And-parallel Analyzer and Annotator; and Ms, an experimental mode inference system developed for SB-Prolog. The paper also provides performance data obtained from these implementations and, as an example of an application, a study of the usefulness of the mode information obtained in reducing run-time checks in independent and-parallelism. Based on the results obtained, it is concluded that the overhead of global flow analysis is not prohibitive, and the results of analysis can be quite precise and useful.

Analysis-by-synthesis 2,4 kbps linear predictive speech codec

Abstract: A linear predictive speech codec arrangement including: a spectrum synthesizer for providing reconstructed speech generation in response to excitation signals; a distortion analyzer for comparing the reconstructed speech with an original speech, and providing a distortion analysis signal in response to such comparison; and an excitation model circuit for providing excitation signals to the spectrum synthesizer, with the excitation model circuit receiving and utilizing the distortion analysis signal in an analysis-by-synthesis operation, for determining ones of excitation signals which provide an optimal reconstructed speech. The excitation model circuit can include: a voiced excitation generator and a Gaussian noise generator, both of which should optimally provide a plurality of available excitation signal models. The voiced excitation generator and Gaussian noise generator can be in the form of a codebook of a plurality of possible pulse trains and Gaussian sequences, respectively, or alternatively, the voiced excitation generator can be in the form of a first order pitch synthesizer. The optimal excitation signal and/or the pitch value and the pitch filter coefficient are determined using an analysis-by-synthesis technique.

High speed power analyzer

Abstract: A method and apparatus for rapidly and continuously sampling AC voltage and current signals in a plurality of power distribution circuits. The sampled signals are then analyzed in a sine board computer to derive the number of fundamental electrical variables. These variables include frequency, RMS volts, RMS amps and a phase angular relationship between the voltage and currents in the system. The computer also performs calibration and compensation functions. From these fundamental variables, other useful parameters can be calculated such as watts, watt-hours, VARS, and power factor.

Body composition analyzer

Abstract: A body composition analyzer provides the resistive and reactive components of a body's measure impedance as well as body fat information and ideal weight information. The analyzer includes an analog circuit under the control of a microprocessor for providing signals to the microprocessor that are representative of the voltage across the network formed by the body and of the voltage across a reference network of known impedance that is connected in series with the body network. The microprocessor calculates the body networks impedance as a function of the ratio of the body network voltage and reference network voltage signals to provide extremely accurate results. The body composition analyzer is a hand-held unit that can transmit data to a peripheral device for recording via a wireless communication network. The analyzer is further programmable so that various algorithms and constants stored therein can be updated.

Chirping characteristic and frequency response of MQW optical intensity modulator

Abstract: The spectral linewidth enhancement factor and frequency responses of electro-absorption-type optical-intensity modulators, especially InGaAs/InAlAs MQW modulators, are described. A method of exactly estimating the value of the alpha factor is presented under the nonlinearity of extinction-ratio characteristics. For measuring the frequency response of modulators, the sideband strength of the modulated output light with an optical spectrum analyzer, is analytically compared with the microwave power of photodiode direct detection with an electrical spectrum analyzer. >

Sidestream infrared gas analyzer requiring small sample volumes

Abstract: An infrared gas analyzer implementing an optically stabilized detector in a sidestream configuration. In order to reduce the pneumatic sampling volume, an "optical funnel" or collimator is used to resize the optical aperture of a multi-channel optically stabilized detector without compromising signal strength. The smaller pneumatic volume is desirable in order to minimize the time required for a gas wavefront from the sample cell to traverse the optical aperture, thereby minimizing pneumatic response time. The geometry of the sample cell of the invention is also streamlined so that sharp corners or transitions which might induce turbulent gas flow are eliminated. The sample cell of the invention thus promotes smooth, laminar flow of aspirated respiratory gases through the optical aperture so as to preserve the temporal relationship of gas concentration wavefronts within the gas stream and to thereby allow the analyzer to exhibit a faster pneumatic response.

A new on-wafer large-signal waveform measurement system with 40 GHz harmonic bandwidth

Abstract: A novel on-wafer large-signal waveform measurement system with a 40-GHz harmonic frequency range using a microwave transition analyzer is presented. Potential applications are illustrated by the measurement of the harmonic amplitude and phase spectra of the reflection and transmission response of a 0.3- mu m InGaAs pseudomorphic HEMT (high-electron-mobility transistor) under X-band sinusoidal stimulus. >

Spectrum sharing communications system and system for monitoring available spectrum

Abstract: A mobile radio communications network is provided with a system for allocating one or more ranges of transmission frequency to the communications network, in order to prevent the network from interfering with received signals of an incumbent radio system. The allocating system may be provided with a device for receiving and monitoring information indicative of the presence and location of incumbent radio stations. A signal level monitoring system monitors signals transmitted from incumbent radio stations to determine the frequency and degree of RF isolation, with respect to a monitoring antenna of the monitoring system, of the stations. The monitoring system includes monitoring antennas, a spectrum analyzer, a device for controlling the spectrum analyzer, and a device for processing and correcting the data produced by the spectrum analyzer.

Rapid scanning spectrographic analyzer

Abstract: A fixed grating, detector-array type analyzer (100) rapidly multiplexes multiple channels. The analyzer (100) comprises a light source (110), a detector array-type spectrograph (150) and an optical multiplexer (130). The multiplexer (130) can select from one of a plurality of channels. Further, the multiplexer (130) can convolute light passing through it with a reference spectrum for calibration and wavelength drift compensation. Rapid multiplexing is achieved using a fiber optic slit array (140) which ''perpendicularly multiplexes'' the plurality of channels.

Optimizing the energy resolution of planar retarding potential analyzers

Abstract: The energy resolution of a planar retarding potential analyzer can be optimized by using multiple retarding grids and varying the potential applied to the outermost grids. When properly biased, such an analyzer configuration can closely approach the energy resolution of an ideal device. As an added benefit, such an analyzer can be made highly transparent without sacrificing energy resolution. Experimental results verify the solutions of particle‐tracking codes for multiple‐grid configurations.

Optical Gas Sensors

Abstract: Recent development of optical gas sensing devices are reviewed. Absorption, fluorescence, scattering, and reflection of light, and changes in refractive index and optical path length are successfully utilized for detection of gas components. Various gas sensitive materials have been reported so far. Remote sensing device with an optical fiber and non-dispersive infrared analyzer are also effective for gas composition analyses by using IR or near-IR beams.

Method of photon spectral analysis

Abstract: A spectroscopic method to rapidly measure the presence of plutonium in soils, filters, smears, and glass waste forms by measuring the uranium L-shell x-ray emissions associated with the decay of plutonium. In addition, the technique can simultaneously acquire spectra of samples and automatically analyze them for the amount of americium and γ-ray emitting activation and fission products present. The samples are counted with a large area, thin-window, n-type germanium spectrometer which is equally efficient for the detection of low-energy x-rays (10-2000 keV), as well as high-energy γ rays (>1 MeV). A 8192- or 16,384 channel analyzer is used to acquire the entire photon spectrum at one time. A dual-energy, time-tagged pulser, that is injected into the test input of the preamplifier to monitor the energy scale, and detector resolution. The L x-ray portion of each spectrum is analyzed by a linear-least-squares spectral fitting technique. The γ-ray portion of each spectrum is analyzed by a standard Ge γ-ray analysis program. This method can be applied to any analysis involving x- and γ-ray analysis in one spectrum and is especially useful when interferences in the x-ray region can be identified from the γ-ray analysis and accommodated during the x-ray analysis.

Ring resonator optical spectrum analyzer with 20-kHz resolution.

Abstract: We demonstrate a fiber-optic ring resonator operated as a high-resolution spectrum analyzer. An optical resolution of 20 +/- 3 kHz is demonstrated.

Time domain compensation for transducer mismatch

Abstract: A two channel real time octave analyzer is equipped with an adaptive time domain phase compensation filter whose poles and zeros are programmably selected to counteract phase error associated with any given pair of microphones. Precise matching of microphone phase characteristics is thereby achieved. In the preferred embodiment, the transfer function for the adaptive filter is determined using a pole/zero synthesis technique based on cross spectrum data acquired in an FFT spectral analysis of the probe microphones.

Multi-rate superresolution time series spectrum analyzer

Abstract: Parallel architectures preprocesses large matrices from sampled coherent time apertures receiving signals from distant sources to produce lower order matrices, derived from pseudo coherent time apertures, which are computationally less burdensome. The large matrices are processed by frequency shifting, low pass filtering with an FIR filter, and executing front-end decimation to create the pseudo coherent time apertures, each corresponding to different subbands of the temporal frequency spectrum. The signals representing the pseudo coherent time apertures are processed using matrix based superresolution spectral estimation algorithms such as the Tufts-Kumaresan (T-K) reduced rank modified covariance algorithm and the Linear Minimum Free Energy algorithms to produce an image of the sources.

Mode structure fluctuations in a pulsed dye laser.

Abstract: We have measured and analyzed high-resolution single-pulse spectra of a typical commercial dye laser. The longitudinal mode structure was resolved by using a Fizeau interferometer as the spectrum analyzer. In mode intensities we observed strong pulse-to-pulse fluctuations that are caused mainly by the variations of the spontaneous emissions to the laser modes during the starting phase of the laser pulse. Apart from the quantum noise, frequency jitter, i.e., shifts of the whole frequency comb, was also observed. The jitter appeared to be very fast, of the order of a few megahertz and hence cannot be explained by technical noise alone. A detailed knowledge of the spectral fluctuations is needed in theoretical models of noise effects in nonlinear spectroscopy. It can also be applied to novel noise reduction techniques.

An integrated multi-element ultra-thin-film gas analyzer

Abstract: The authors reports a multi-element gas analyzer realized in silicon as the hybrid of two dual-element detector chips and a control/interface chip The detectors utilize ultra-thin metal sensing films supported by a selectively micromachined dielectric window Boron-diffused silicon heaters under the windows permit the window temperature to he varied between ambient and over 1000 degrees C with a heating efficiency in vacuum of 20 degrees C/mW The detector control chip contains interface circuitry for four such detectors Window temperature is controlled from ambient to 1200 degrees C with eight-bit accuracy Film conductivity is similarly measured to eight-bit accuracy for full-scale resistances from 5 ohms to 13 Mohms Film conductivity measurements (magnitude and phase) can be made from DC to 2 MHz using the on-chip circuitry On the output side, the interface chip utilizes a standard eight-line interface to a VLSI microcontroller, allowing the implementation of the analyzer as a smart peripheral The detectors are realized using a six-mask process while the control chip is implemented in an eleven-mask 2 mu m CMOS process in a die size of 44 mm*66 mm >

Infrared gas mixture analyzer

Abstract: A pneumatic detector, non-dispersive infrared analyzer employing detector cell chambers in optical series. The invention having an auxiliary chamber communicating with the front chamber to increase the rear chamber's signal so as to balance the signals from the front and rear chambers. The use of xenon as a diluent gas in the detector chambers in combination with a mass flow detector to improve the sensitivity. The use of an improved synchronous detection method employing a voltage-to-frequency circuit to convert the detector signal to a synchronous high resolution digital signal. The use of an improved source electrically pulsed having low thermal mass and a large radiating area.

On the Prediction of Droplet Size and Velocity distributions in sprays through maximum entropy principle

Abstract: Based on the conservation laws of mass, momentum and energy, the droplet size and velocity distributions in liquid sprays are formulated through the maximum entropy principle, without taking into account the details of liquid atomization processes such as the characteristics of disturbances and behavior of liquid bulk preceding the droplet formation. The joint probability distribution function in size and velocity of the droplets can be predicted from the atomization conditions which are represented by the Weber number and the source terms in the formulation. The model prediction agrees well with the experimental data measured by a phase Doppler particle analyzer.

Electrochemical sensor assembly

Abstract: A plastic covered nonconducting substrate with an electrical circuit means is secured to the extent to withstand the presence of liquids in contact with the substrate. The covered substrate can have the substrate with one or more fluid preconditionable electrical components, a housing secured to the substrate to maintain contact of the preconditioning fluid with the electrical component like a sensor, and moisture impervious seals to cover openings in the housing for the disposition of the preconditioning fluid in the housing for contact with the electrical component on the substrate. The housing can have one or more parts and have one or more channels for containing the preconditioning fluid. The substrate with electrical components can be with a sensor assemblygenerally and have an improved electronic wiring board having a thermistor and at least one sensor supported, in close relation, one to the other, on one side of the board and a heater supported on the other side of the board to provide heat in response to temperature sensed by the thermistor, to at least the region where the thermistor and the sensor are positioned on the board to control the temperature of the region of the board within a narrow distribution of temperatures. The sensor assembly with or without the improved wiring board can be used in a single use disposable fluid sample collector, sensing, and calibration device. This device contains a collector like a syringe, with one or more analyte sensors, and a calibrator for calibrating the sensor. These can be pre-assembled; the analyte sensor may be connected to a self-contained monitoring instrument or analyzer which processes the signals from the sensor and displays the information to the operator. Also the sensor assembly can be used in a portable, ready-for-use analyte measuring device for the measurement of multiple sequential fluid samples. The device has a disposable cartridge, a calibrating fluid external to the cartridge and an analyzer. The cartridge has a housing, inlet for introduction of fluids into the housing, sensor element in fluid connection with the inlet, at least one unidirectional valve in fluid connection with the sensor element, and a waste collection area or reservoir in fluid connection to the valve. The sensor apparatus alone or in the single use or multiple use mode can be sealed in a hermetically sealed layer that is impervious to gas and moisture and is a diffusion-tight boundary or bar- rierand that contains at least one preconditioning fluid. The preconditioning fluid is an activating fluid when the sensor is in an unsealed housing and can be either or both the activating fluid or a controlled-content fluid when the sensor is in a sealed housing.

Method and apparatus for triggering measurements from a TDMA signal

Abstract: A measurement apparatus and method for triggering and making analog measurements of radio frequency (RF) bursts in a time domain multiple access communications system. An RF level detector or edge detector triggers an analog sampler which acquires measurement data from a spectrum analyzer or an RF peak detector. A digital signal processor processes the RF burst to detect a known bit sequence and calculates a timing relationship between the triggering of measurement samples and transmitted data bits in the RF burst. A host processor uses the calculated timing relationship to identify and analyze the measurement data pertaining to desired measurements of the RF burst.

Multichannel continuous harmonic analysis in real-time

Abstract: A flexible, modular multichannel continuous real-time harmonic analyzer with the capability of precision time stamping via Global Positioning System (GPS) satellite signals of the acquired data is described. The key design features which provide this performance are discussed. These include remote distributed data conversion modules coupled via digital fiber-optic links to parallel individual digital signal processor Multibus II based modules which were all controlled by a highly integrated 486 based module. The resultant Multibus II parallel processor system was run under the iRMXIII real-time operating system and was interfaced via Ethernet to control and display workstations using a custom-designed Windows 3 environment. The ready extension of the harmonic monitoring system to transient measurement is also described. >

A self-tuned mode-locked laser

Abstract: A self-tuning mode locked semi-conductor laser automatically adjusts itself to produce short (less than 200 ps and preferably less than 50 ps) stable optical pulses. Tuning is achieved by means of a feedback loop which includes a spectrum analyser (18) which receives a small amount of the optical output of the laser and monitors the spectral wavelength, spectral width or spectral shape of the output. A controller (19) is connected to said analyser and produces a control signal based on said spectral information. The control signal causes adjustment of one or more parameters influencing operation of said laser, such as frequency or power of an RF drive signal, level of dc bias, cavity length, for example, in order to produce said short stable pulses.

Process gas chromatographic system

Abstract: A gas chromatographic system for analyzing gas components includes an analyzer, a constant temperature oven, an analyzer case, an indicator, an integrated sample conditioner, and a coupler. The analyzer includes a sample valve having a detector and a heater built therein and first and second columns wound around the periphery of the sample valve. The constant temperature oven accommodates the analyzer unit therein. The analyzer case accommodates the constant temperature oven. The indicator is protruded from the analyzer case to display analysis processes and results. The integrated sample conditioner provides an optimal condition for analysis. The coupler couples the analyzer unit with the sample conditioner so as to supply a sample gas and one of a carrier gas and a reference gas from the sample conditioner to the analyzer unit.