Showing papers on "Spectrum analyzer published in 1969"

Resolution and Sensitivity Considerations of an Auger Electron Spectrometer Based on Display LEED Optics

Abstract: Some of the important considerations in the design of a retarding field analyzer suitable for Auger electron spectroscopy based on display LEED optics are described. From such considerations an instrument has been built with an instrumental linewidth of less than 0.3% (resolution greater than 360). Analysis is made of the limitations insensitivity of the device due to shot noise, and on this basis a comparison is made with a 127° cylindrical electrostatic analyzer. The analysis can be readily extended to other forms of retarding field and deflection analyzers.

A Simple Pulse-Height Analyzer for Partial-Discharge-Rate Measurements

Abstract: A single-channel pulse-height analyzer with suitable pulse-shaping circuits designed for partial-discharge measurements is described. The circuit of the pulse-height analyzer has a basic resolution limit of 1.5 ?s. The unit may be used in conjunction with an RLC-type partial-discharge-detection circuit and is thus applicable to discharge measurements on high-voltage apparatus such as transformers, capacitors, and cables. Typical results, obtained with an artificial void simulated with metallic-dielectric electrodes, are presented.

The automatic classification of modulation types by pattern recognition.

Abstract: : This report presents the preliminary results of an investigation into the use of pattern-recognition techniques to rapidly and automatically identify the type of modulation on a high-frequency radio signal. Classes of modulation initially considered include double-sideband AM, upper and lower single-sideband suppressed carrier, CW, high- and low-speed teletype (single-channel FSK), multichannel FSK, and on-off keying (Morse code). The spectrum of the signal is measured by a digital analyzer whose outputs are classified by a pattern recognizer. The spectrum analyzer and classifier are realized on a PDP-8 digital computer. The new 'nearest neighbor' type of pattern recognizer has been developed that significantly increases classification accuracy. The decision surfaces of this classifier asymptotically approach the Bayes decision surfaces with simple set size. Mis-classification rates of 5 to 10 percent have been obtained with signals recorded in a typical HF environment. Important characteristics of the system are the ability to recognize the presence of a signal when the modulation format is unknown and the ability to recognize the presence of a new signal that has not been previously encountered. (Author)

New Crystal Spectrometer for Neutrons

Abstract: A new feature of the spectrometer is the monochromator unit, which contains two parallel reflecting copper crystals and delivers a beam of monoenergetic neutrons through a fixed collimator which is parallel to the incident beam from the reactor. About half the neutrons reflected by the first crystal are reflected by the second crystal, though the fraction declines at the upper end of our energy scale (about 60 meV). The beam from the monochromator is free from fast neutrons, and the background extremely low. The material, thickness, and mosaic width appropriate to efficient reflection in a monochromator crystal are discussed. The sample and analyzer form a compact separate unit on a stationary base. All the angles of the spectrometer (including those of the monochromator) are continuously variable over wide ranges, with either manual control or automatic control from a programming tape. Two spectrometers which are mirror images of one another are mounted side by side at the same reactor beam hole. They are mainly intended for measurements on phonons with comparatively high resolution. An example of the accuracy attained is given.

An Automated Retarding Potential Difference Technique Using a Multichannel Scaler

Abstract: A commercially available multichannel analyzer, used in the multiscaling mode, has been adapted so as to accumulate automatically data from electron beam experiments employing the retarding potential difference (RPD) technique for improving the electron energy resolution. The electron accelerating voltage is generated by digital‐to‐analog conversion of the ``live'' channel address, the lower and upper limits of the sweep being adjustable over a wide range. The analyzer is swept alternately in the add and subtract modes with a period which is short compared to possible drifts in electron current, collision chamber pressure, multiplier sensitivity, etc. The tedious labor involved in obtaining RPD data by conventional means, and its subsequent arithmetic reduction, is all performed automatically by the analyzer. Examples of data obtained by the technique are presented, showing the improvement in signal to noise obtainable by operating for a suitably large number of sweeps.

Real time cepstrum analyzer

Abstract: The periodicity or aperiodicity of a signal is determined, in a signal analyzer, from the so-called ''''cepstrum'''' of the signal; that is, from the Fourier transform of the logarithm of the power spectrum of the signal. The short-time cepstrum is obtained by passing the signal through a first spectrum analyzer followed by a logarithmic amplifier and a second spectrum analyzer. The cepstrum signal is characterized by a peak at a time proportional to the fundamental period during periodic portions of the signal, and by the absence of a peak during aperiodic portions of the signal.

Gas detector and analyzer

Abstract: A portable, self-contained gas detector and analyzer is disclosed which includes a carrier gas supply, and electrical power supply, a sampling loop and a chromatographic column with an electron-capture detector. A preferred embodiment is adapted to respond to a pre-selected tracer gas. If the tracer is included in a closed system whose integrity is suspect, the detector can first be operated to detect the presence of the tracer and then can signal the rate at which the tracer is being provided to a predetermined, limited volume.

Instrumental Effects in a Retarding Field Energy Analyzer

Abstract: Measurements of the well known electron impact spectra of helium show that a retarding field energy analyzer can give spurious responses; these can be minimized but not eliminated by careful adjustments of the operating potentials. Probable sources of the trouble are discussed.

Multipath delay and correlation bandwidth analyzer

Abstract: Multipath delay is analyzed by generating and transmitting a pseudorandom signal and at the receiver the reverse replica of the transmitted signal is also generated. The two signals are correlated in an optical correlator where they are passed through ultrasonic modulators while collimated light passes through them and the output is read out on an oscilloscope.

System for automatically and manually testing lines for determining if information can be accurately transmitted thereon

Abstract: A hardline monitoring system for monitoring a plurality of lines over which signals are transmitted in order to determine if the characteristics of the lines are within certain predetermined tolerances. The monitoring system includes a programmer, an electronic scanner, an analyzer, a display and control panel, a signal generator, a computer interface unit, and a checkout computer. In operation, the electronic scanner, which is under the control of the programmer, scans a plurality of hardlines or cables over which the signals are transmitted. The programmer, in turn, couples these lines through the scanner to an analyzer which analyzes the signals to determine if there is any distortion or deterioration of the line. If the signals being transmitted are out of tolerance, then the analyzer sends such information to a display and control panel to illuminate a lamp indicating such. Such information is also fed to a checkout computer through a computer interface unit and the programmer. A signal generator is provided for placing continuous data signals, FM signals and wordburst signals on the line when such is necessary.

Signal processing utilizing basic functions

Abstract: The present invention relates to the analysis and synthesis of complex time-varying signals over a wide range of frequencies and amplitudes in terms of selectable sets of expansion functions. Analysis consists of gating a time-sampled representation of the input signal stored on capacitors, into resistor matrices, which compute other desired representations. Use of the Fourier series representation in the analysis produces Fourier phazor components, which are converted to resultant vector amplitudes and phases by carrier generation through modulation by the phazors of 90*-out-of-phase, very high frequency, reference oscillators. Synchronous carrier demodulation gives resultant Fourier amplitudes. Carrier phase, relative to one of the reference oscillators, being equal to the Fourier phase, is determined by time (between zero crossings)-to-voltage conversion. Analyzer tuning may be external, voltage-controlled, or phase-controlled. When tuning is phase controlled, phase computing circuits lock the analyzer frequency to that of the input signal. The analysis bandwidth may be absolute- or voltagecontrolled fractional, the latter being achieved by a variableduty-cycle time-sampling-filter method. Frequency-tracking-system control of the voltage for controlled fractional bandwidth gives the ability to analyze with narrow bandwidth while providing wide band frequency tracking. A slowly varying phase-time derivative, when present for an appropriate length of time, is used to test for input signal coherence. The test result is used to control frequency tracking to prevent erratic tuning during attempted frequency tracking of incoherent signals. Relative phase values over a range greater than the normal range of 2 pi radians are made possible by sensing the traversals of the phase cut. For synthesis, control signals are generated and applied to a transformation matrix which, via multiplexing of the matrix outputs gives the sequential representation of a signal. Curves used to derive control signals, on film are read at high speed using a flying spot scanner. Spot intensity differentiation with zero crossing detection gives extremely high accuracy independent of spot intensity. Fourier log or linear amplitude and phase curve values are serially converted to phazor components synchronously with scanning by gated excitation and gated dissipation of high Q LC resonant circuits. Appropriate final stage gating and filtering of the time-sample representation eliminates system transients and objectionable frequency components due to the quantization of the output signal.

Microwave ferrite acceleration sensors

Abstract: This paper presents a new and potentially simple method of producing a frequency shift proportional to sensed acceleration in a passive microwave device. Magnetostriction effects in microwave ferrite rods are employed to convert an applied stress (acceleration) to a shift in resonant frequency. Equations for the ferrite effective permeability are derived in terms of the internal field component. Experimental verification was obtained by placing the resonant cavity on a rotatable test stand and using the earth's gravitational field as the accelerating field 0 to 1 g being applied to the device. A SHF signal generator excites the cavity, while a spectrum analyzer and digital frequency counter monitor the resonant frequency. Correction was made for spurious frequency shifts due to lead component movements. A net, non-linear frequency shift characterized by the value +1.064 kHz per gravity was obtained. Agreement as to sign and general magnitude of theory and experiment was encouraging. Magnesium-manganese ferrites have small magnetostriction coefficients, yet even the frequency shifts with these ferrites were easily detectable. This effect or application is certainly worthy of additional interest and exploration.

Baseline compensation for chromatographic analyzer

Abstract: A procedure is disclosed for compensating a chromatographic analyzer for baseline drift and irregularities. The analyzer is first operated under normal operating conditions except that a sample is not introduced. The output signal of the detector is recorded. This recorded signal is subsequently subtracted from the output signal during an actual analysis so that baseline drift and irregularities are eliminated.

Automobile connector apparatus for use with an electronic analyzer

Abstract: Connector and sensor apparatus permanently installed at probe pickup locations in an automobile''s electrical system, for connection to an electronic analyzer A current probe included by the apparatus involves the determination of a length of a battery ground cable relating voltage difference across the determined length to current passing through the cable in a calibrated manner, and connecting the determined length to the analyzer for measuring voltage difference thereacross

Automatic high-resolution mass measurement

Abstract: A hybrid analogue-digital analyzer for the online digitization of electrically recorded mass spectra. The device, which does not incorporate a digital computer, accurately selects peak maxima to provide triggering pulses for timing circuitry, and uses directly controlled buffer storage to reduce the effective rate of data acquisition to that of the average speed of the associated output channel. The analyzer is primarily intended to provide records of complete high resolution mass spectra suitable for off-line computer processing. For real time production of reduced and annotated spectra the analyzer may be used as an active interface directly coupled to a computer.

Precise pulse repetition frequency measuring device and signal sorter

Abstract: An electronic signal processing device comprised of timing and coincident ting means for utilization between one or more conventional radar receivers and a conventional visual display, multi-gun pulse analyzer to enable an electronic intelligence operator to perform precise real time measurement of the pulse repetition interval (PRI) and its counterpart, pulse repetition frequency (PRF), for any one of a group of radar signals in a multi-signal environment. The device provides an automatic gating loop for separating the received radar video signals into various known preset PRI-PRF bands, an electronic chopping circuit for enabling the device to produce an interleaved, panoramic display of all of the radar video signals within any one of the preset bands on a visual display pulse analyzer, various single-shot multivibrator and gating means for producing necessary synchronizing pulses, and a variable delay unit and pulse generator for selecting a single video signal from the panoramic display for closer examination on an expanded scale of the multi-gun analyzer and for producing a marking pulse which may be positioned by the operator to obtain an indication of the PRI and PRF of the selected signal from a calibrated dial of the variable delay unit.

A Solid State X-Ray Fluorescence Analyzer for Use in Hostile Environments

Abstract: An avalanche detector radioisotope X-ray fluorescence analyzer has been developed that has rapidly, accurately, and confidently measured the calcuim and potassium content of U. S. Geological Survey silicate rock standards. The measurements were made at room temperature with percentage errors of ±5 percent. The interference due to X-rays from adjacent elements was minimal. The precision of measurement with the solid-state instrument was such that at least 90 to 95 percent of the readings were within 1? of the mean value.

Arrangement for automatic performing and evaluating of test of the activity of functional systems of living bodies

Abstract: An arrangement for automatically performing and evaluating biological tests in which a detector for sensing the activities is connected to an analyzer. The analyzer having means for differentiating tests performed at predetermined normal conditions and at undesirable conditions. The detector providing variations in voltages and the analyzer having derivator and integrator means for obtaining a planimetric evaluation of the voltages. Final evaluation is obtained in an evaluating device deriving a signal from the analyzer via a switching device.

Low impedance remote control system for engine analyzers

Abstract: A remote control system for use in an internal combustion engine analyzer is described. The system permits a given cylinder of the engine to be shorted as well as a particular display pattern on an oscilloscope to be selected by a switch remotely located with respect to the analyzer. A plurality of gates such as NAND gates, located at the analyzer and controlled by the remote switch selectively transfer high frequency control pulses to a cylinder shorting switch and to an oscilloscope sweep generator located at the analyzer. The remote switch enables a selected NAND gate by controlling a DC voltage level, thereby rendering the remote switch and connecting cable immune from noise.

Proportional bandwidth frequency analyzer

Abstract: A SIGNAL PROCESSING METHOD FOR THE REAL-TIME ANALYSIS OF FREQUENCY COMPONENTS WITHIN AN INPUT SIGNAL EMPLOYS LOWPASS FILTER MEANS CAPABLE OF PASSING AT LEAST THE HIGHEST FREQUENCY TO BE ANALYZED, THE FILTERED INPUT SIGNALS ARE SAMPLED AT A RATE EQUAL TO OR GREATER THAN THE NYQUIST RATE FOR THE HIGHEST FREQUENCY TO BE ANALYZED. THE SAMPLED SIGNAL DATA IS THEN STORED IN AN APPROPRIATE MEANS AND THE STORED DATA IS CAUSED TO BE REPETITIVELY READ OUT AT VARIABLE RATES WHICH ARE GREATER THAN THE SAMPLING RATE WHEREBY FREQUENCY MULTIPLICATION FACTORS ARE PRODUCED AS A FUNCTION OF THE INSTANTANEOUS READOUT RATE AND THE SAMPLING RATE. A FIXED BANDWIDTH FILTER RECEIVES THE READOUT DATA, THE CENTER FREQUENCY OF THE FILTER BEING EQUAL TO THE PRODUCT OF THE INSTANTANEOUS FREQUENCY BEING ANALYLED AND THE INSTANEOUS MULTIPLICATION FACTOR, FURTHER SAMPLING MEANS MAY BE ARRANGED TO RECEIVE THE OUTPUTS OF THE FIXED BAND WIDTH FILTER AND A OPERATE AT A RAGE WHICH IS A FUNCTION OF THE VARIABLE RATE READING OUT THE STORED DATA FOR PRODUCING SAMPLE DATA WITHIN A SELECTED FREQUENCY SPECTRUM TO BE ANALYZED.

Stationary probability integrator system

Abstract: A stationary probability integrator system for facilitating spectral anals of detected signals by suppressing random frequency background noise, such as ocean disturbances and marine life, and by enhancing spectral signatures of discrete sound sources, such as generated by submarines in water. A raw 0 to 100 Hertz frequency spectrum of noise and spectral signature from a frequency analyzer having 500 increments or elements is divided into ten assemblies of 50 elements per ensemble. The ensemble averages, which are the average simultaneous energy levels of all elements in respective ensembles, of each sample is negatively combined with the energy level of each element of the corresponding ensemble of the next consecutive raw sample. Each combination and the cumulative algebraic sum of each combination is then displayed in the same frequency spectrum as the samples. The cumulative energy levels of background noise elements will be substantially zero, while the cumulative energy levels of spectral signature elements will build up in a positive direction to an extent limited only by the display's capability. Thus, pronounced spectral signatures of discrete underwater sound sources is presented.

Spectrum analyzer utilizing relative phase slope difference of pairs of lines in spectrum to measure relative phases of individual lines

Abstract: The relative amplitudes and phases of individual lines of a wide band line spectrum are determined by dividing the spectrum analyzer into two parallel branches. One branch process a fixed reference pair of lines in the spectrum and the other branch processes an arbitrary tunable line pair. This allows the instantaneous relative phase slop difference of two pairs of lines in the spectrum to be measured.

Use of Dispersive Delay Lines for Signal Processing in Underwater Acoustics

Abstract: Signal processors incorporating dispersive delay lines can be designed for matched filters in active sonars, for spectrum analyzers in passive listening, and for generators of frequency‐modulated codes. Depending upon its bandwidth and its duration, the signal to be processed is fed into a dispersive delay line that is matched to it in the case of wide‐band systems, or matched to an homothetic signal (a signal having the same modulation characteristics, the same time‐bandwidth product as the original signal, but having a frequency scale multiplied or divided by a factor k and a time scale divided or multiplied by the same factor k) with a larger bandwidth in the case of narrow‐band systems. In this last case, the signal is previously time compressed with an appropriate unit, such as a recirculating memory or a magnetic recorder.