Showing papers on "Spectrum analyzer published in 1986"

A zero crossing-based spectrum analyzer

Abstract: A band-limited signal can be represented by the real and complex zeros of the signal. By simple invertible techniques, it is possible to convert the signal into another one which has only real (physical) zeros. Based on a zero-based representation, a spectrum analyzer is proposed. The spectrum analyzer samples the zero crossings of the signal waveform and uses this information to determine the discrete Fourier transform coefficients in software. The zero-based spectrum analyzer alleviates many of the shortcomings of the conventional A/D converter-based spectrum analyzer. In particular, the hardware is simple and the dynamic range and speed limitations of the A/D converter are reduced. The results of a computer simulation study of the error aspects of the spectrum analyzer are presented.

High speed circuit measurements using photoemission sampling

Abstract: Apparatus for measuring the voltage waveform on the metallization lines of an integrated circuit is described. Short high powered pulses of light are coupled from a laser and focused on the metallization line of the integrated circuit which is coupled to receive a voltage waveform that is synchronized to the output laser pulses. Electrons are emitted from the metallization line due to the multiphoton photoelectronic effect induced by the pulses of light. An electron energy analyzer having a uniform extraction grid as its most remote element is positioned with the extraction grid as close as possible to the integrated circuit and the laser pulses are focused through one of the holes of this uniform grid. An output circuit is connected in a feedback arrangement which receives the output pulses of the energy analyzer and develops a voltage on a second uniform grid called the retarding grid that is positioned a predetermined distance from the extraction grid inside the electron energy analyzer. A sinusoidal voltage is superimposed on the signal provided to the retarding grid in order to eliminate the effect of noise components in the amplitude of the laser pulses.

Digital anesthetic agent analyzer

Abstract: A gaz analyzer comprising a sample cell (21) for containing a gas mixture to be analyzed, a source (11) for producing and directing infrared energy through the sample cell, a rotary filter wheel (17) having at least one filter thereon for passing infrared energy limited to a wavelength band within the characteristic absorption band of a predetermined gas and having a dark level region substantially opaque to infrared energy, a drive (19, 20) for supporting and rotating the filter wheel to successively interpose the filter and the dark level region between the source and the sample cell in the path (13) of the infrared energy directed by the source, a detector (15) for detecting infrared energy passing through the sample cell and producing an electrical signal representative thereof, and a signal processor (24) connected to the detector means for producing an output indicating the concentration of the predetermined gas in the sample cell by comparing the electrical signals produced by the detector with the filter positioned in the infrared energy path and with the dark level region positioned in the infrared energy path. The dark level region has a substantially fully reflective surface oriented toward the sample cell (21) when positioned in the infrared energy path whereby infrared energy impinging thereon is reflected.

Optical frequency analyzer using a local oscillator heterodyne detection of incident light

Abstract: An optical frequency analyzer for measuring an optical frequency spectrum with high accuracy, high resolving power and high stability by heterodyne detecting the incident light with the aid of a local oscillator, wherein the local oscillator comprises an optical frequency synthesizer/sweeper or a marker signal attached tunable laser. The optical frequency analyzer can be modified to measure the incident light itself as the object of measurement or light emerging from the object of measurement can be the incident light.

Wide band, complex microwave waveform receiver and analyzer, using distributed sampling techniques

Abstract: A microwave signal receiving apparatus comprises a delay line for distributing a microwave signal, samplers for sampling the signal spatially along the delay line and producing analog samples, analog-to-digital converters for converting the analog samples to digital samples, and digital memories associated with each converter for storing the digital samples.

Method and apparatus for detecting gas

Abstract: An analyzer to detect a specific gas in the atmosphere by infrared absorption, having a porous tube surrounding an enclosed column of air, the porous tube having an average pore size to permit gas to diffuse through it quickly, and having within the tube an infrared source, an infrared detector and an optical filter that passes those portions of the infrared spectrum most strongly absorbed by the gas, the analyzer having a time base generator to pulse the infrared source and electronic means to measure the maximum and minimum signals from the detector and a meter to indicate the difference between the maximum and minimum as a measure of the amount of the gas in the column of air.

Evaluation of a new dynamic viscometer for measuring the viscosity of whole blood and plasma

Abstract: We evaluated a new type of dynamic viscometer, the Sonoclot Coagulation Analyzer, for use in measuring the viscosity of whole-blood and plasma. Such information can be useful in monitoring patients with hyperviscosity syndromes, e.g., from multiple myeloma. A vibrating Teflon or plastic probe continuously measures dynamic viscosity. The instrument can be calibrated to measure a range of viscosities from 0.69 to 23 cP (mN X s X m-2) or more. The coefficient of variation at 0.69 cP was 3-4% for measurements with the Teflon probe, 7-9% with the plastic probe. Viscosity measured at 37 degrees C for plasma and whole-blood samples from 20 normal patients was 1.22 (SD 0.05) cP and 3.63 (SD 0.52) cP, respectively. Dynamic viscosity measured in blood samples from a single source, with contrived hematocrits ranging from 0 to 89%, increased exponentially as a function of hematocrit, confirming previous studies. Overall, we found this instrument simple and quick to operate, producing accurate, precise viscosity measurements over at least a 40-fold range of viscosity.

RF frequency spectrum analyzer subsystem

Abstract: A spectrum analyzer subsystem for analyzing the frequency content of an RF signal including an optical source means responsive to an RF signal for generating a plurality of intensity modulated optical signals and a filter means responsive to each one of the intensity modulated optical signals for providing a plurality of output optical signals each corresponding to a respective one of the intensity modulated optical signals. Each output optical signal corresponds in intensity to the frequency content of an RF signal within a different predetermined frequency bandwidth. Detector means, which is responsive to each output optical signal converts each output optical signal into a corresponding electrical signal.

Increased resolution logic analyzer using asynchronous sampling

Abstract: Techniques for a logic analyzer instrument that permit the acquisition of digital samples from a plurality of logic signals in a large mainframe computer, or other system under test, in a manner that the signals can be reconstructed for viewing and analysis of the relationship between them. Edges of the signals are located, during their reconstruction, with many times higher resolution than that of the sampling clock. A plurality of sample records, asynchronously timed, are taken of the logic signals from the system under test, and the samples are combined in a way that locates logic signal edges with precision.

Process Analyzer Technology

Abstract: Chromatography Viscosity Measurement Boiling Point Measurement Flash Point Measurement Pour Point, Cloud Point and Associated Measurements Vapor Pressure Measurement Oxygen Measurement Hydrogen Sulfide and Total Sulfur Measurement Spectrometric Measurements Moisture Measurement Air Quality Monitoring Water Quality Monitoring Measurement Measurement of Octane Number Thermal Conductivity Measurement Measurement of Refractive Index Combustion Efficiency Monitoring and Control Analyzer Data Systems Sample Handling Systems Design and Installation of Analyzer Systems Calibration and Correlation Maintenance and Performance Evaluation The Role of Analyzers in Process Control Systems Index.

Computer Generation of Digital Filter Banks

Abstract: In order to reduce the design time of digital filter bank circuits, a design system has been developed. The software consists of the filter compiler which converts high level filter descriptions to hardware descriptions and the layout generator which converts the hardware descriptions to a layout file. To verify the algorithms before fabrication, a test system is employed. The development time of this system was kept to a minimum by designing the hardware to be easily micro coded and assembled. Several circuits have been fabricated and tested that were generated with this system, including a single bandpass filter chip, a 112-pole 16-channel filter bank for a speech recognition system and a 16-channel spectrum analyzer for consumer stereo applications. The speech recognition chip achieved a SNR of 80 dB with an area of 25 mm /sup 2/ in a 4-micron NMOS technology.

Ultrasonic system for the detection of transient liquid/gas interfaces using the pulse‐echo technique

Abstract: An ultrasonic method has been chosen to examine liquid/gas interfacial areas in closed systems. Although commercial equipment was used for the transducer and ultrasonic analyzer, commercial transient memory devices were inadequate. Consequently, a real‐time data analysis and transient memory (DATM) unit was designed and constructed. A series of flight times for a succession of 1024 signals are calculated and recorded in the transient memory. The system clock operates at 10 MHz and increments a 12‐bit binary counter. The counter is capable of measuring return signal times as long as 212 μs (4.096 ms) with a 1‐μs resolution. The data are available as analog voltages for display on an oscilloscope or the digital data may be directly transferred to a microcomputer for analysis, display, or archival storage. The DATM device was successfully applied, collecting data for the analysis of rising bubbles in metallurgical systems and two‐phase flow in horizontal tubes.

Elements of Electronic Instrumentation and Measurement

Abstract: 1. Introduction to Electronic Instrumentation and Measurement. 2. Some Basic Measurement Theory. 3. DC and AC Deflection Meter Movements. 4. Bridge Circuits. 5. Comparison Measurements. 6. The Basics of Digital Instruments. 7. Electronic Multimeters. 8. The Oscilloscope. 9. Signal Generators. 10. Mechanical Graphics Chart Recorders. 11. Special-Purpose Laboratory Amplifiers. 12. Operational Amplifiers. 13. Sensors, Electrodes, and Transducers. 14. Probes and Connectors. 15. Handling Signals, Sensors, and Instruments. 16. Data Converters. 17. Testing Electronic Components. 18. Measurement of Frequency and Time. 19. Measurements on Untuned Amplifiers. 20. Measurements on Tuned Circuits. 21. Antenna and Transmission Line Measurements. 22. Radio Receiver Measurements and Alignment. 23. Spectrum Analyzers. 24. Radio Transmitter Measurements. 25. IEEE-488 General Purpose Interface Bus (GPIB) Instruments. Appendix A: Integration and Differentiation. Index.

Optically Multiplexed Interferometric Fiber Optic Sensor System

Abstract: A sensor system where a number of Fabry-Perot interferometer sensors are placed in series on a single-mode fiber is discussed. Each Fabry-Perot sensor is resonant within a unique bandpass of optical wavelengths and transmits with small attenuation at all other wavelengths. Fiber Fabry-Perot interferometers with narrow-band resonances are formed by placing a matched pair of bandpass reflectors on the fiber. The sensor system has three major subsystems: a swept frequency laser, frequency selective Fabry-Perot sensors, and demodulation hardware. A grating formed by holographic process is placed in the evanescent field to produce a frequency selective reflector. Individual sensors are polled by a frequency swept laser. As the laser wavelength is scanned over the resonance bandpass of the first sensor, Fabry-Perot fringes from the first sensor are read out. As the laser continues to sweep its optical frequency, the first sensor's gratings no longer act as reflectors; the sensor becomes transparent to the optical probe. After a sufficient optical wavelength guard band, the resonance band of the second sensor is reached and fringes from the second sensor are read out. Fabry-Perot phase and fringe order information are recovered by a combination of optical and electronic signal processing. The optical processor is a second Fabry-Perot interferometer which is used as an analyzer to aid recovery of the phase information.

Optimization of the Herzog correction in the hemispherical deflector analyzer

Abstract: The theoretical performance of the hemispherical deflector analyzer has been discussed on the basis of a numerical calculation of electron trajectories by taking the fringing field correctly into account. We optimized both the ‘‘Herzog region’’ and the electrode sector angle and got foci of electrons which are as good as those for the ideal‐field 180 ° analyzer. In the optimized analyzer, even electrons with their energies different from the pass energy are focused well at the exit plate. Moreover, the arriving position of electrons at the exit plate depends linearly upon their incidence energy. The possibility of using a position‐sensitive detector is discussed.

Automatic calibration and control system for a combined oxygen and combustibles analyzer

Abstract: An automatic calibration and control system for a combined oxygen and combustibles analyzer comprises a process control computer which automatically calibrates a combined oxygen and combustibles analyzer. The computer initiates a calibration sequence through a mechanical unit which introduces calibration gases to the analyzer. The computer calculates a drift adjustment for both oxygen and combustibles and applies it to the incoming oxygen and combustibles signal from the analyzer to arrive at calibrated oxygen and combustibles signals. The system allows both oxygen and combustibles signals to be calibrated automatically and concurrently with minimal operator interface.

Design and performance of a double-pass high-resolution electron energy loss spectrometer

Abstract: The design, characterization, and performance of a high‐resolution electron energy loss spectrometer for surface studies is described. The spectrometer is based on a double‐pass 127° cylindrical deflector analyzer for both the monochromator and analyzer stages. An overall resolution of 4 meV is obtained with a current of 5×10−11 A measured at the sample. The resolving power of the double‐pass deflector, in the specific geometry utilized, is significantly greater than that of either deflector. The observed energy resolution on metal and semiconductor surfaces is contrasted; it is found that electronic excitations lead to noninstrumental broadening on semiconductor surfaces.

Magneto-optical signal read-out system using divided photodetector

Abstract: A magneto-optical signal read-out system for a magneto-optical player in which the polarized plane of linearly polarized incident light is rotated when the incident light is reflected by or passes through a magneto-optical medium having tracks thereon and the rotation angle of the polarized plane is utilized as an information signal. The read-out system includes a first analyzer, a second analyzer and a photo detector divided into first and second photo detector sections. A differential amplifier receives output signals from the first and second photo detector sections and produces a detected signal representative of the difference between the first and second output signals to reduce in-phase noise in the detected signal.

Method and apparatus for compensating fiber optic lead and connector losses in a fiber optic sensor by using a dual wavelength optical source and matched polarizer

Abstract: Apparatus and method for compensating a photo sensor for fiber optic cable lead/connector losses and optical source power fluctuations includes a specially selected broadband optical source used in conjunction with a photoelastic fiber optic transducer that uses a polarizer and an analyzer that only polarize a portion of the broadband signal. The portion of the signal that is not polarized is simply transmitted through the photoelastic element and emerges with no modulation. The portion of the signal that is polarized is modulated according to the stress on the photoelastic element. After transmitting the output light beam through a single fiber optic cable, the beam is separated into two parts. The first part is filtered so as to transmit only that portion of the broadband signal that is not affected by the polarizer and analyzer and hence is not modulated. The filtered first part is converted to an electrical signal by a photo detector. The second part of the split beam is filtered so as to transmit only that portion of the broadband signal that is affected by the polarizer and analyzer, and hence is modulated. The filtered second part is converted to an electrical signal by a second photo detector. The second signal varies according to lead and connector losses and the stress modulation on the photoelastic element. The first signal varies according to lead and connector losses only. The ratio of the second signal to the first signal then provides a measure of the changes in the transmission due to the modulation of the transducer element, without lead and connector losses, or variations due to power source fluctuations.

Transmission characteristics and fringing field effect of a 270° spherical electrostatic analyzer

Abstract: Three‐dimensional transmission characteristics of a 270° spherical section electrostatic analyzer are studied with respect to both theoretical calculation and calibration experiment. A fairly good agreement is obtained between both results which confirm a well‐defined response as a function of energy and angle of incident particles and a high‐resolution ability of a 270° analyzer in contrast with a 90° analyzer which has a strong energy‐angle coupling. A particular particle guide is used as the entrance slit of our analyzer in order to suppress the fringing field effect. When we replace this particle‐guide slit by a simple slit of square shape, the transmission characteristics of the analyzer become distant from the calculated one. The numerical solution of a two‐dimensional fringing field of an approximated model is derived and the ray tracing calculation of particles in this field is done. This model calculation approach also suggests the strong effect of the fringing field near the entrance aperture in the case of the analyzer with a simple slit. These investigations demonstrate the effectiveness of the particular slit at the entrance aperture used.

Miniature Interferometric Spectrum Analyzer

Abstract: Dynamic range is a key performance parameter in spectrum analyzers The dynamic range of a Bragg cell spectrum analyzer is generally limited by the dynamic range of the self-scanned photodetector arrays During the past four years, advances in interferometric techniques have overcome this basic limitation demonstrating spectrum analyzers with nearly twice the dynamic range (measured in decibels) as their earlier counterparts This paper will describe a system based on the interferometric architecture which is also small and compact in size

The quadrupole: System design and residual gas analyzer performance

Abstract: The relationship of the system design to the performance of quadrupole residual gas analyzers is reviewed with the emphasis on those factors that may influence stability and reproducibility. It is important to recognize the four operating regimes—source limited, analyzer limited, length limited, and imperfection limited—when making comparisons of performance or seeking to improve the system design.

New imaging bandpass electron energy analyzer

Abstract: An electron energy analyzer which acts as a bandpass filter while maintaining the spatial integrity of an electron image in a uniform magnetic field is described It embodies some new electron‐optical properties Image electrons injected parallel to the magnetic field are guided, using crossed electrostatic and magnetic fields, to a low‐pass electron mirror and then through a high‐pass retardation filter Nonuniform electrostatic deflection fields are used to compensate for the energy‐dependent dispersion of the crossed fields A simple computer modeling method used to design the electrostatic fields is described A test analyzer was constructed to operate in a 00125‐T (125 G) uniform magnetic field to investigate its properties Bandpass filtered images of an 18‐eV electron source demonstrating the removal of energy‐dependent dispersion and the narrowing of the bandwidth to 100 meV are presented Another application of the analyzer, to obtain an energy spectrum from a spatially extended electron source, is demonstrated

Development of optical monitor for control of thin-film deposition.

Abstract: The design of a multichannel optical monitor for transmittance measurements of thin-film coatings during deposition is described. The system comprises a light source and one or more spectrum analyzers each incorporating a prism monochromator and a 256-element photodiode array detector. This multiple-channel design, in conjunction with an HP 1000 computer and data acquisition period of 100 ms, enables the coating uniformity to be precisely monitored and controlled. High-system throughput has been achieved with a large numerical aperture (f/1.5), while retaining excellent spectral resolution over the 350–1100-nm wavelength range. Experimental measurements indicate a practical resolution equal to the detector-limited resolution, a wavelength reproducibility of 0.1 nm at 400 nm and 0.6 nm at 700 nm, and a photometric accuracy and precision of ~1 and ±0.3%, respectively. The problem of unequal energy distribution across the spectrum is handled by optical rather than the usual electronic compensation.

Integrated interferometric acousto-optic spectrum analyzer

Abstract: Described herein is an integrated acousto-optic circuit for analyzing the spectrum of a radar signal. A waveguided optical beam is first split into two parts, one of which interacts with a surface acoustic wave generated by a reference signal and the second of which interacts with a surface acoustic wave generated by the signal to be analyzed. The two resulting phase-modulated optical waves then are recombined, Fourier transformed by a lens and finally caused to impinge on an array of photodetectors. The array of detectors is arranged so that each element of the array responds to the combination of one component of the time-varying signal to be analyzed and one component of the time-varying reference signal, that response being an output signal at some preselected radio frequency which is proportional to the amplitude of the frequency component of the radar signal to be analyzed. The several optical components are disclosed as formed on a single substrate integrated optical circuit.

Method and apparatus for characterizing a broad spectrum signal

Abstract: A method for characterizing a broad spectrum signal provides improved performance on high-noise, sloped, high variation signals by calculating separate low and high frequency average signal levels and determining low and high frequency bandwidth limits referenced to the low and high frequency average signal levels respectively. The method may be practiced using a computer system interfaced to a programmable spectrum analyzer.

Optical beam analyzer

Abstract: A system for analyzing the characteristics of a light beam is disclosed. Functionally, the system includes an optical system for collecting the light beam to be analyzed. An array of light-sensitive elements is positioned at the focal plane of the optical system. A digital system sequentially samples the output signals of the light sensors and processes the resulting data to generate signals indicative of the characteristics of the light beam.

Method for locating leaks in pipelines

Abstract: In the leak-locating method according to the invention, which employs cross-correlation analysis, the 2-channel FFT analyzer is used to measure the difference in propagation time. The cross-power spectrum is firstly subjected to equalisation, weighted with a suitable frequency weighting, if necessary, and subsequently transformed back into the time range. As a result, instead of the known cross-correlation function a different time function with optimum resolving power is obtained, and this permits the determination of leaks with higher accuracy and over a larger measurement range. The subsequent equalisation of the cross-power spectrum can be performed in a much finer fashion than could be obtained using conventional filters 3 in accordance with Figure 1. The method can be implemented without additional outlay on equipment using conventional FFT analyzers. Since the method can run automatically, the interposition of the equalisation requires no additional time outlay in practical use.