Showing papers on "Spectrum analyzer published in 1997"

Pure-mode network analyzer for on-wafer measurements of mixed-mode S-parameters of differential circuits

Abstract: A practical measurement system is introduced for measurement of combined differential and common-mode (mixed-mode) scattering parameters, and its operation is discussed. A pure-mode system measures network parameters of a differential circuit in the fundamental modes of operation, and has improved accuracy over a traditional network analyzer for the measurement of such circuits. The system is suitable for on-wafer measurements of differential circuits. The transformation between standard S-parameters and mixed-mode S-parameters is developed. Example microwave differential structures are measured with the pure-mode vector-network analyzer (PMVNA), and the corrected data is presented. These structures are simulated, and the simulated mixed-mode S-parameters correlate well with the measured data.

Frequency hopping spread spectrum passive acoustic wave identification device

Abstract: A system and method for interrogating a passive acoustic transponder, producing a transponder signal having characteristic set of signal perturbations in response to an interrogation signal, comprising a signal generator, producing an interrogation signal having a plurality of differing frequencies; a receiver, for receiving the transponder signal; a mixer, for mixing the transponder signal with a signal corresponding to the interrogation signal, to produce a mixed output; an integrator, integrating the mixed output to define an integrated phase-response of the received transponder signal; and an analyzer, receiving a plurality of integrated phase-responses corresponding to the plurality of differing frequencies, for determining the characteristic set of signal perturbations of the passive acoustic transponder.

Analyzer system having sample rack transfer line

Abstract: A plurality of analyzer units for serum, a plurality of analyzer units for blood plasma and a plurality of analyzer units for urine are arranged along a main transfer line for transferring a sample rack from a rack providing portion to a rack storage portion. A reagent bottle for inspecting liver function is contained in each reagent delivery mechanism of two analyzer units among the plurality of analyzer units for serum. When the reagent for inspecting liver function in one of the two analyzer units is to be short, analysis for the liver function analysis item to samples can be continued by transferring a sample rack from the rack providing portion to the other analyzer unit.

Compact, all-optical spectrum analyzer for chemical and biological fiber optic sensors

Abstract: An optical spectrum analyzer based on optical processing of the far field interference pattern from two beams irradiated by light transmitting waveguides is described The spectrum analyzer can operate in UV, VIS, NIR and MIR ranges of spectrum and it can be based on either optical fibers (multimode or single-mode) or integrated optical waveguides It has many important applications, for example, as a simple, compact and inexpensive spectrum analyzer used with fiber optic chemical and biological sensors

Method for diagnosing malignancy diseases

Abstract: The method for diagnosing malignancy diseases involving analysis of blood plasma by laser correlational spectroscopy (LSC) techniques includes the steps of: preparing a weak diluted solution of native blood plasma, determining a spectral density of light scattering intensity fluctuations within the frequency range between 1 and 1000 Hz, distinguishing a spectrum core and making a diagnosis from a frequency of a maximum and an intensity-to-half-width ratio of a spectrum core envelope, a malignancy disease being detected when the diagnostic parameters are less than the appropriate rates. The apparatus for diagnosing malignancy diseases includes a nephelometer and a series-connected correlation spectrum analyzer. The nephelometer further includes a second scattered light detector disposed symmetrically about a first scattered light detector, a signal multiplier whose inputs are coupled to outputs of the first and second scattered light detectors, a low pass filter whose input is coupled to an output of the signal multiplier, and an output is coupled to a correlator of the spectrum analyzer, a conventional ampoule for a solvent being used as a measuring cuvette in the nephelometer.

System, device, and method for evaluating dynamic range in a communication system

Abstract: A system, device, and method for evaluating dynamic range in a communication system utilizes a narrow band multiple tone test signal for emulating a wide band composite signal equivalent to the symbol rate bandwidth of a digitally modulated carrier. The multiple tone test signal is constructed such that a significant portion of the third order intermodulation distortion products fall within the channels adjacent to the test channel so that the dynamic range can be evaluated with a commercially available industry standard CATV analyzer using a standard adjacent channel power measurement technique.

New high luminosity “double toroidal” electron spectrometer

Abstract: In this article we describe the design and the operation of an original, high transmission, electrostatic “double toroidal” electron energy analyzer. The double toroidal analyzer allows the high resolution and high luminosity simultaneous measurement of the kinetic energy, and angular distribution of electrons, using a two-dimensional position sensitive detector. The exact shape of the electrodes is deduced from both analytical and numerical electron trajectory calculations. The electron detector is based on a charge analysis and optimized to attain a 100 kHz counting rate. The actual performances of the analyzer are illustrated with spectra obtained after resonant Auger decay of N2O excited around the nitrogen K shell (hν=401 eV), and of Kr after 3d5/2→5p excitation at hν=91.2 eV. A “etendue” of 15% of the pass energy, as well as a resolving power (Ep/δE) of 100 were measured.

Automatic correction of power spectral balance in audio source material

Abstract: An audio system that automatically corrects for variations in spectral balance in audio source material. The audio system comprises a power spectrum analyzer and a source correction equalizer unit coupled to receive an audio input signal, and an index control unit coupled to a spectral balance correction data memory. A reference spectral balance may initially be established by playing a reference source medium with desired sound attributes. The power spectrum analyzer characterizes the spectral balance of the reference source medium, storing the results in non-volatile memory. When a particular source medium is played for the first time, the index control unit reads an identifying parameter from the particular source medium. Because there is no entry for the identifying parameter in spectral balance correction data memory, the particular source medium has not been previously played on the audio system. The particular source medium is then played in its entirety, with the index control unit signaling the power spectrum analyzer to characterize the spectral balance of the particular source medium. When the particular source medium is finished playing, an equalizer settings compute unit compares the reference spectral balance and the spectral balance for the particular source medium and calculates equalizer correction settings, which are then stored in spectral balance correction data memory. These settings can be used to adjust the spectral balance of the particular source medium to match that of the reference source medium. When the particular source medium is subsequently played, the identifying parameter may be used to recall these desired equalizer settings.

Video-rate fringe analyzer based on phase-shifting electronic moiré patterns

Abstract: We have developed a fringe analyzer that delivers the phase distribution at a video rate from a fringe pattern containing a spatial carrier. It is based on parallel generations of three phase-shifted moire patterns through electronic multiplication with computer-generated reference gratings and low-pass filtering. The phase distribution is derived by the subsequent parallel processing of these patterns on the basis of a three-step phase-shifting algorithm. By modification of the bias phase distribution of the reference gratings, several functions, such as correction of an initial wave-front error, are realized in real time. The usefulness of this analyzer is demonstrated experimentally for phase measurements by grating-projection surface topography and interferometry.

On-line partial discharge detection in cables

Abstract: This paper describes an on-line partial discharge (PD) detection technique in power cables. The technique uses a digital spectrum analyzer with a high-frequency preamplifier and several types of high-frequency inductive sensors. In extruded and impregnated cables, the PD detection is made in the VHF range. The suitability and the sensitivity of the VHF technique were checked against two other conventional PD detecting methods (Pulse Phase Analyzer and Fast Digital Scope) by performing PD measurements in EPR-insulated cable under laboratory-controlled conditions. The suitability and sensitivity of the VHF method were as good as the two conventional PD detection method. The VHF method runs used to conduct on-site PD measurement in several power cables. These measurements were conducted while the cables were in service. Special care was given to distinguish between external electromagnetic noise and electromagnetic signals produced by the PD activities inside the cable insulation.

Non-invasive blood glucose meter

Abstract: A non-invasive blood glucose meter includes a near-infrared energy analyzer which includes a light filter assembly of two Fabry-Perot interferometers and a photosensor. The near-infrared energy analyzer detects near-infrared energy absorbed by a human or animal body and generates spectra of such absorption so that the blood glucose content in the body may be analyzed. In order to provide stable energy absorption information of the blood, special designs are provided to stabilize the light source, to calibrate the spectrum and to obviate the noise from the heartbeats of the body. A single crystal silicon elastic power source is used to provide the driving power of the Fabry-Perot interferometer to avoid mechanical hysteresis.

Absolute optical frequency calibrator for a variable frequency optical source

Abstract: Calibration of a variable frequency light source is performed by a control unit which has a knowledge of the known transmission pattern of an optical filter, such as gas cell or a calibrated interferometer, having a number of known frequency dependent transmission characteristics in the tuning range of the optical source. This unit scans the frequency of the optical source via a frequency control signal over a frequency range and measures the optical intensity of the optical source output light after it has passed through the optical filter The measured transmission and frequency control signal values are processed and stored in memory and constitute a measured absorption pattern. Once acquired for a frequency range, this pattern is compared to the theoretical transmission pattern of the optical filter. Correspondences are made to identify the transmission features against their known counterparts. A relationship between the frequency control signal and actual frequency of the optical source is established. The frequency calibration of the optical source over many frequency points is achieved. The invention is especially suited to the frequency calibration of tunable laser sources, such as semiconductor lasers and external cavity lasers.

Method and apparatus for detecting a road pavement surface condition

Abstract: An apparatus for determining a road pavement surface condition over a wide area has a road noise sensor (12). A temporal frequency analyzer (18) converts a road noise signal from the road noise sensor (12) to a temporal frequency signal. A processing circuit (20) receives the temporal frequency signal from the temporal frequency analyzer (18) and analyzes the temporal frequency signal to determine the road pavement surface condition.

Monitoring slow speed machinery using integrator and selective correction of frequency spectrum

Abstract: A method for nonintrusive monitoring of slow speed machinery (22) incorporates a high sensitivity accelerometer (24) capable of detecting low level mechanical vibrations, and a standard data collector/analyzer (28) for processing the accelerometer output in accordance with a slow speed technology (SST) methodology that is implemented by firmware of software. An analog integrator (56) distorts the low frequency vibration components as well as the electrical noise introduced by the accelerometer (24). The distorted signal is then digitized by an A/D convertor (36) and transformed to the frequency domain by means of a fast Fourier transform (38). All peaks/amplitudes greater than the threshold noise floor are considered significant and retained as indicative of mechanical vibration occurring within the machinery, while all peaks below the threshold noise floor are considered insignificant and eliminated from further consideration.

Multitone power and intermodulation load-pull characterization of microwave transistors suitable for linear SSPA's design

Abstract: In this paper, an experimental load-pull characterization of microwave transistors operated under N-tone-excitations (2/spl les/N/spl les/32) is presented. Such characterization is very useful to investigate the linearity of high-power amplifiers via intermodulation distortion analysis. All the measurements were carried out using a newly developed multiline measurement system which uses an arbitrary waveform generator (AWG) to generate the spectrum of any N desired tones and a microwave transition analyzer (MTA) as a vector receiver. The measured intermodulation rejection (IMR) behavior, as the number of tones increases, is compared with previously published theoretical results. Constant output power contours and IMR contours in the /spl Gamma//sub L/(f/sub 0/) plane for different number of tones are presented and discussed. The dependency of the IMR on the biasing conditions and the carriers' phase distribution is also investigated.

Method and apparatus for using a spectrum analyzer for locating ingress noise gaps

Abstract: A device, system and method are disclosed for locating clean channels for upstream data carriers that are certain to have lower noise levels than the currently utilized channel used for carrying data upstream, thereby enabling intelligent placement of an upstream data carrier in a cable television system utilizing cable modems for two-way data transmission. A spectrum analyzer is placed in a cable modem termination system located in a headend of a cable television system. The spectrum analyzer contains a programmable device comprised of programmable circuitry. The circuitry is operable in a first mode to receive a signal having an associated frequency spectrum made up of several channels. The circuitry also determines a noise level for each of the channels. The circuitry is also operable in a second mode to receive the signal described above and filter the signal to generate several filtered signals where each filtered signal corresponds to one of the channels. The circuitry is also operable in the second mode to monitor another noise level associated with each of the filtered signals. The channels associated with the filtered signals are selected based on the noise levels determined in the first mode.

On-line fault detection and correction in anesthesia delivery system

Abstract: An anesthesia delivery system having a means of determining the functioning of its gas mixer, vaporizer and analyzers, their accuracies and other characteristics by comparing, at high flow conditions, the input of oxygen concentration and agent concentration set by a clinician and delivered by the system, the input from a feedback respiratory analyzer of the inspired O2 and agent concentrations and the input of a monitor analyzer that determines the O2 and agent concentrations in the patient circuit. A CPU compares the three sets of input data to make various determinations since, at high flow conditions, all of the three sets of data should be consistent. Thus the CPU can determine from a comparison, whether one set of data is indicative of a faulty device, can provide a bias adjustment if an analyzer is merely off in its readings or carry out other safety and corrective functions based on comparing the three data inputs.

Design of a compact 1 MV AMS system for biomedical research

Abstract: The widespread use of accelerator mass spectrometry in biomedical research will require the development of cost-effective, laboratory-sized AMS systems which can be used in conjunction with conventional gas and liquid phase separation techniques. This paper describes the design of a low energy AMS system for the detection of 14C and 3H in labeled biological samples. The system utilizes a compact 1 MV tandem accelerator which incorporates a foil stripper. The low energy analyzer, accelerating column, and high energy analyzer are designed for efficient transport and analysis of both carbon and hydrogen beams using the minimum number of optical elements. The resulting instrument is very compact: the entire AMS system including the injector, ion source and high energy analyzer is just under 3 m wide and is approximately 1.3 m high and 1 m deep. The relatively small size of this system will allow its installation in most biomedical laboratory facilities. The system is predicted to provide a statistical precision of better than 2% for the quantitation of attomole samples.

Frequency translating device transmission response system

Abstract: A three-pair measurement method determines the amplitude and phase transmission response of frequency translating devices including a device under test and two test devices using a vector network analyzer and a controller where one of the devices has reciprocal frequency response characteristics. The characterization of single sideband and double sideband devices such as mixers, is preferably performed by combining data from analyzer two-port swept measurements. The measurement method provides a low-pass equivalent transmission response of the devices.

Radiation field analyzer using interference patterns

Abstract: A radiation field analyzer (10) provides means for analyzing the spatial mode spectrum of radiation received from a scene. In a multimode waveguide embodiment, light from a laser (24) is directed towards a scene through an alumina waveguide structure (12). A portion of the laser light is directed towards a mode generator (28) which selectively converts the laser radiation into one of a series of modes. Laser light returning from the scene is mixed with the light from the mode generator to produce interference signals. These signals are measured by a detector (34) and analyzed by a programmed computer (36). By sequentially altering the mode generated by the generator (28) and analyzing the resulting signals, a spectrum of the modes returning from the scene is obtained.

Self-contained electronic system for monitoring purgers, valves and installations in real time

Abstract: Self sufficient electronic system for monitoring and continuous surveillance of steam traps, valves and installations using fluids. The system comprises three essential elements: a multiple sensor, an electronic analyzer and an optional receiver. The sensor measures fluid conductivity, pressure and temperature. The electronic analyzer continously controls the status (pressure, temperature) and conductivity of fluid, supplying optical, acoustic and digital information, in situ or from a remote point, in accordance with the results of analysis carried out. The receiver centralizes and processes the signals emitted by the analyzer. The analyzer electronic circuits are fed by batteries recharged through photovoltaic cells incorporated in the equipment. The multiple probe also incorporates an ultrasonic sensor which detects ultrasounds generated in the steam trap or valve. The analyzer and the remote receiver also add the corresponding electronic circuits for a continuous surveillance of ultrasounds level. This system may be applied to the continuous surveillance and control of steam leaks in steam traps and, generally, to the control fluid flow in any installation. The system can solve the problem of automatic inspection and continuous monitoring of energy losses in steam traps, without human attention. It substantially reduces power consumption by detecting steam losses simultaneously and instantly at all points of installation.

UCL multichannel time-resolved system for optical tomography

Abstract: A multichannel time resolved imaging system is being developed at University College London (UCL) suitable for optical tomography of the human breast and neonatal brain. The system utilizes the time correlated single photon counting technique, operating in reverse start-stop mode. The detectors are custom made multi-anode microchannel plate photomultipliers (Hamamatsu R411OU-05MOD). Signal processing is implemented using fast NIM logic, and the system is based upon the ORTEC 9308-D picosecond time analyzer in place of a conventional time to amplitude converter. The system is designed to acquire 32 channels of time-resolved data simultaneously, with sub-100 ps temporal resolution, and at count rates of at least 2 multiplied by 104 photons per second per channel. This paper discusses the theoretical considerations which led to the final design, and describes the detector and electronic hardware on which the system is based.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A frequency doubling electro-optic modulation system for Pockels effect measurements: Application in LiNbO3

Abstract: A novel system is presented which is capable of measuring with high accuracy the linear (Pockels) electro-optic effect by means of a new dynamic (ac) method. This method is based on the observation of the photodetected output obtained from a Senarmont-type ellipsometric system with an ac (modulating) voltage being applied onto the electro-optic sample under test. This observation is made on a high sensitivity oscilloscope and allows us to determine accurately the null point of the system by locating the position of the analyzer that produces in the output a characteristic and abrupt doubling of the (modulation) frequency. By locating this frequency doubling position without and with electric field one can finally determine the corresponding electro-optic coefficients. Theoretical analysis and considerations of practical interest are presented in the article and show that the system in question can ensure reduced errors and increased sensitivity. Also, experimental evidence in support of the expected performance is obtained by implementing and applying the system for the measurement of the composite electro-optic coefficient rc of LiNbO3 for various temperatures in the range of 17–20 °C.

Multiple-gas ndir analyzer

Abstract: A non-dispersive infrared (NDIR) multi-gas analyzer (405) has an optical element (950) that is positioned with respect to the axis of incident IR radiation such that it passes nearly all of the IR energy within a narrow band pass to one detector (540) and reflects nearly all of the IR energy outside the narrow band pass to another detector (535). Thus, the optical element (950) simultaneously functions both as a narrow band pass filter and a beam splitter, which transmits nearly all the IR radiation within a band pass and reflects nearly all the IR radiation outside the band pass. Additionally, the separation of the incoming energy can be achieved without an extended roll off. This allows using a reference transmission band that is very close to the absorption band of the gases of interest. It more specifically allows using a reference transmission band that is located between the absorption bands for hydrocarbons and carbon dioxide in an infrared analyzer that uses beam splitters.

Laser gas analyzer and a method of operating the laser to reduce non-linearity errors

Abstract: A method of operating a laser and a gas analyzer to reduce low frequency and high frequency power non-linearity errors passes a laser beam through a sample gas to a detector. Intensity measurements are taken and compared to a reference set of measurements. The reference set of measurements can be calculated by measuring pressure and temperature of the sample gas. The laser wave number tuning width is locked to tune a high frequency of an absorption path fringe to a predetermined reference value. The analyzer can be operated without taking a reference set of measurements and the analyzer is much smaller than previous analyzers.

Hyperspectral radiometric mine detector based upon sensing microwave brightness temperature and interference contrast signatures

Abstract: A passive mine detection apparatus useful for searching out buried mines, exploits natural soil emissions at microwave frequencies and unique interference-induced spectral reflection signatures from planar surfaces of buried mines interacting with the soil emissions. The apparatus comprises a focussed beam antenna, low noise amplifiers for respective polarizations, baseband converter, spectrum analyzer, A to D converter, signature recognition processor, display and/or alarm. Hand-held and vehicle-mounted implementations are disclosed.

Active temperature and humidity compensator for anesthesia monitoring systems

Abstract: The humidity and/or temperature of a gas sample is monitored so that these system parameters can be accounted and/or actively monitored and controlled. In one embodiment, a gas analyzer system (10) includes an input flowline (12) for receiving a sample stream from a patient respiratory circuit via a patient input module (14), an analyzer instrument (16) for obtaining composition information regarding the gas sample, a humidity sensor module (18) containing a temperature sensor (40) and a humidity sensor (42), and a vacuum pump (22) for drawing the gas sample through the analyzer system (10). A processor (28) receives information from the analyzer instrument (16) and the humidity sensor module (18) and determines composition information regarding the gas sample based on such inputs. The analyzer system (10) thereby allows for improved composition measurements and for monitoring the humidity of the gas sample to stay within specifications or preferred operating ranges of certain analyzer instruments.

A spread spectrum communications channel sounder

Abstract: The design of a microwave channel probing analyzer is presented and discussed. Special attention is paid to the characteristics of the transmission path to be measured; the choice of spread spectrum probing signal; the signal processing methods used; modulation, demodulation, and synchronization at the transmitter and receiver sites; the path model to be fitted to the measured data and finally, the impact of all of these issues upon the necessary hardware and software. Following a formulation of the channel-probing problem, transfer function regression techniques are reviewed to illustrate the advantages of periodic averaging over established correlation methods. The construction of an experimental sounder based on these methods is described. The equipment has been used to measure the time-variant frequency-selective channel dynamics of a short (158 km) troposcatter transhorizon link at a frequency of 11.647 GHz over a 31.25-MHz bandwidth. Off-line, nonlinear spectrum analysis, based on Prony's method and singular value decomposition, is used to estimate parameters of a high-resolution delay model that accurately reflects the underlying ray structure of the transmission path.

Calibration of the monochromator bandpass function for the X-ray Rietveld analysis

Abstract: In this paper we propose a fitting procedure to describe the bandpass effect on all x radiation that passes through a focusing graphite monochromator used on the diffracted beam. The proposed bandpass function is: M (2θ)=1/(1+ K mon 1 s K mon 2 ), with s =(2 sin θ)/λ, where K mon 1 and K mon 2 are constants which have been refined by means of a Rietveld analysis, using a physically modeled background (Riello et al. , J. Appl. Crystallogr. 28 , 115–120). We have investigated two polycrystalline powders: α- Al 2 O 3 and a mixture of α and β- Si 3 N 4 . The so-obtained bandpass functions for these materials are close enough to conclude that they depend only on the used experimental setup (in the present case the X-Pert-Philips diffractometer with a graphite focusing monochromator). Knowledge of the bandpass function is important to suitably model the Compton scattering, which is a component of the background scattering. The present procedure allows one to avoid the direct experimental determination of the bandpass function, which requires the use of another monochromator (analyzer) and another tube with an intense white spectrum.

Moisture/yield monitor grain simulator

Abstract: A monitor for measuring the moisture content of grain comprises an AC signal source for transmitting a measurement signal along a measurement signal path that includes a sensor region in which grain may, or may not, be present, and an analyzer for determining the attenuation of the measurement signal along the path, the analyzer producing an indication of the moisture content of grain in the sensor region that is dependent on the attenuation. A simulator is provided to permit calibration, testing, maintenance and/or demonstration of the monitor without the requirement of grain in the sensor region. The simulator includes a programmable attenuator that is selectively electrically inserted in the measurement signal path and a control circuit for controlling the attenuator so that the measurement signal is attenuated and the analyzer produces an indication of grain moisture content even though no grain is present in the sensor region. The attenuator may be a PIN diode or a programmable capacitor.