Multichannel Spectrum Analysis Research Articles

Determination of lanthanum, cerium, neodymium, ytterbium, and yttrium in geological samples with the use of a multichannel analyzer of atomic emission spectra

The procedure of atomic emission determination (with a photographic record of the spectrum) of yttrium and four rare-earth elements (La, Ce, Nd, and Yb) was modified on the basis of a multichannel analyzer of emission spectra (MAES) in geological samples of various contents. In addition to the increase in the rate of analysis, the detection limits were improved by a factor of two to three, correct calculation of the background was realized, and the errors of reproducibility of analysis were decreased. The validity of the results was confirmed by the comparison of the contents obtained with the accepted characteristics of the samples analyzed according to GeoPT program and with the data of MS-ICP analysis.

Direct multi-channel optical spectrum analysis of radio-wave signals using collinear waveheterodyning in the single acousto-optical cell

An attempt is made to improve the accuracy of a multi-channel parallel acousto-opticalspectrum analysis through involving an additional nonlinear conversion into dataprocessing. For this purpose we investigate the potential of exploiting a co-directionalcollinear wave heterodyning within an analysis of ultra-high-frequency radio-wave signals.The wave heterodyning under the proposal is performed via mixing the longitudinal elasticwaves of finite amplitudes. It leads to a two-cascade processing in the single-crystallinecell and makes it possible to improve the relative frequency resolution of theacousto-optical spectrum analysis by an order of magnitude at the same frequency range.Both the theoretical findings and the corresponding estimations were used inproof-of-principle experiments directed at creating a new type of acousto-optical cell. Thegeneral concept of the proposed method and the basic conclusions are confirmed byexperiments with the developed acousto-optic cell made of a lead molybdate crystal.

Structural methodological scheme to develop analysis procedures for oxide materials using atomic emission spectroscopy

A generalized structural methodological scheme for developing atomic emission analysis procedures for oxide materials with the use of a multichannel analyzer of emission spectra is elaborated. In accordance with the scheme proposed, we present the results of studies on the development of unconventional procedures for ceramic materials.

Multichannel reflectance spectral assaying of zinc and copper flotation slurries

This article extends the earlier work (Haavisto et al. 2008. Optical spectrum based measurement of flotation slurry contents. Int. J. Miner. Process. 88 (3–4), 80–88), where visible and near-infrared (VNIR) reflectance spectroscopy was used together with an X-ray fluorescence (XRF) analyzer to improve the assaying of zinc flotation concentrate. Especially the sampling interval of the assay could be drastically reduced by the presented approach. In this study, a multichannel VNIR spectrum analyzer is utilized to measure the spectrum of the seven most important slurry lines in copper and zinc flotation circuits. Recursive data-based modeling is applied to the VNIR spectrum data and XRF assays to calculate and adaptively maintain the calibration model. The accuracy of the VNIR assays is evaluated in all the lines, and the benefits of the obtained high frequency assays in detecting oscillations and sudden grade changes are demonstrated.

Multi - channel Spectrum Analyzer for High Capacity Optical Transport Networks

A simple multi-channel spectrum analyzer using an InGaAs array sensor and a diffraction grating is proposed and developed for high-capacity optical transport networks. With the developed multichannel spectrum analyzer, we could measure signal power, wavelength, and optical signal-to-noise ratio of each channel for multi-channel optical signals with 100 GHz and 50 GHz channel spacing, simultaneously. We could measure each channel power and wavelength with a deviation of less than 0.2 dB and 0.063 nm, respectively. We have obtained optical signal-to-noise ratio with a deviation of less than 1.0 dB compared with conventional optical spectrum analyzer in the wide input power range between -42 dBm and -27 dBm per channel.

TFTR 60 GHz alpha particle collective Thomson scattering diagnostic

A 60 GHz gyrotron collective Thomson scattering alpha particle diagnostic has been implemented for the D-T period on the Tokamak Fusion Test Reactor (TFTR). Gyrotron power of 0.1–1 kW in pulses of up to 1 s can be launched in X mode. Efficient corrugated waveguides are used with antennas and vacuum windows of the TFTR Microwave Scattering system. A multichannel synchronous detector receiver system and spectrum analyzer acquire the scattered signals. A 200 megasample/s digitizer and spectrum analyzer are used to resolve fine structure in the frequency spectrum. By scattering nearly perpendicular to the magnetic field, this experiment will take advantage of an enhancement of the scattered signal which results from the interaction of energetic ions with plasma resonances in the lower hybrid frequency range. Significant enhancements are expected with D-T fusion alpha particles, which should be detectable with gyrotron power of less than 1 kW, while maintaining an acceptable signal-to-noise ratio. This diagnostic will be the first experimental test of recent collective Thomson scattering models and should also provide an indication of the presence of energetic alpha particles in the core of TFTR.

Physical design and fabrication of a multiple element slab waveguide spectrograph for multimode fiber-optic WDM systems

The materials and processes for fabricating a compact multiple-element slab waveguide spectrograph suitable for multimode fiber-optic wavelength-division-multiplexing (WDM) applications are described. A fabrication scheme based on thick-film solder glass glazing, hot-press lamination and optical finishing was chosen to produce a precisely dimensioned glass-ceramic spectrograph blank structure that is compatible with grating replication manufacturing technology and suitable for hermetic packaging. The laminated blank consists of alternating layers of glass-ceramic spacer plates and optical glass wafers bonded together with a screen-printed solder glass adhesive. The exact interlayer optomechanical registration, achieved in the laminated spectrograph blank was essential for obtaining spectral referencing functionality and a passive alignment packaging scheme. A spectrograph optical subassembly package was developed and implemented as part of a multichannel spectrum analyzer receiver in a prototype optical WDM sensor interface system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

SETI field tests with the MCSA 1.0 prototype and plans for radio astronomical observations

In order to conduct a systematic microwave search for extraterrestrial intelligence (SETI), NASA is planning to use an advanced multichannel spectrum analyzer (MCSA) capable of resolving the input bandwidth into at least 10 million narrowband channels. To verify the digital architecture that NASA is proposing to use to construct such an instrument, a 74000 channel prototype, the MCSA 1.0, has been built and deployed in the field. This paper discusses the results of the field tests, implications for other components of an automated SETI observing system, and plans to use the MCSA 1.0 to carry out some more traditional radio astronomy observations.

The MCSA 2.1: A fully digital real-time spectrum analyzer developed for NASA's SETI Project

The MCSA 2.1, the Multi-Channel Spectrum Analyzer, is a fully digital spectrometer optimized for the detection of narrow-band signals. The MCSA 2.1 has a single analog input, which is fed to an analog-to-digital (A/D) converter running at 130 M samples per second, and hence covers a 65 MHz bandwidth. The MCSA 2.1 design includes a digital downconverter, which bandpasses 10 MHz, downshifts it to baseband, and outputs complex samples at 10.833 MHz. This 10 MHz “superband” is split into 144 “bands” of 69.4 kHz, then further split into 108 “subbands” of 643 Hz, then divided into “bins” of six simultaneous resolutions: 1, 2, 4, 7, 14, and 28 Hz. The data from each resolution is normalized by the estimated noise power and then output as: (1) 4-bit power for incoherent Continuous Wave (CW) detection; (2) 8-bit thresholded power for pulsed signal detection; and (3) 32-bit complex amplitude for almost non-drifting coherent CW detection and for possible future signal detectors. The MCSA 2.2 has two inputs, exactly twice the hardware, and processes two antenna polarizations which are available at radioastronomy observatories. The MSCA 2.2 includes 70 Printed Circuit Boards (PCB), including 10 custom logic board designs and two buffer board designs. The system is under development for NASA's Search for Extra-Terrestrial Intelligence (SETI) Project. Provided adequate NASA funding is available, the MCSA 2.2 will be installed and performing SETI searches in October 1992.

Multichannel Bragg cells: design, performance, applications

Multichannel Bragg cells are important components in many two-dimensional optical information processing systems. Multichannel Bragg cell design principles are discussed for both multichannel deflectors and modulators. Particular emphasis is placed on minimization of acoustic and electrical crosstalk and thermal effects through the use of acoustically anisotropic materials, rf stripline techniques, and high thermal conductivity materials. The use of a self-collimating shear mode in gallium phosphide (GaP) is found to substantially reduce acoustic crosstalk from that found in the commonly used tellurium dioxide cells. The use of stripline transmission lines substantially reduces electrical crosstalk over that obtained using the more conventional microstrip techniques. The performance is described of three different GaP multichannel Bragg cell deflectors and a GaP multichannel Bragg cell modulator designed using the principles Bragg cell deflectors and a GaP multichannel Bragg cell modulator designed using the principles outlined in this paper. Optical processing systems using multichannel Bragg cells for phased array antenna signal processing, multichannel rf spectrum analysis, and digital optical computing are discussed.

Diplomacy and the search for extraterrestrial intelligence (SETI)

Recent advances in astronomy indicate that the universe is spectacularly vast. Apparently, our Sun is like billions of other stars around which planets may circle; within just a thousand light years of Earth, for example, there are more than a million stars like the Sun. Within the Milky Way (only one of 100 billion observable galaxies) are an estimated 300–400 billion stars. Scientists now think that there are probably between 10 21 and 10 22 stars in the universe. With so many stars, it is highly probable that we are not alone. Just how likely extraterrestrial intelligence is or in how many places and varieties it will be found is impossible now to say. Serious scientists have constructed an equation to calculate the possibility, but the range of estimates of the number of other civilizations in the universe is so wide - anywhere from 200 million to less than 10 - and our understanding of astrophysics and cosmic evolution so primitive, that we could encounter extraterrestrials (ETs) well before it can be proved on paper that they have existed or could exist [1]. In fact, the capability to search for extraterrestrial intelligence will increase over the next five years at a rate and scale greater than at any time in human history. For example, a Harvard University observatory announced in October 1985 that it had linked a radio telescope to a new computerized multichannel spectrum analyzer and created a listening post (known as Project Meta) capable of simultaneously scanning up to 8.4 million radio channels. This development replaces a system whose capacity to search simultaneously and record radio signals was a mere 180,000 radio channels. The Hubble Space Telescope, when it is operational, will extend our present vision some seven times and possibly to the edge of the universe itself. If other planetary systems exist, this new instrument might locate them. And by the end of this decade, NASA will probably have begun a search for signals across the entire microwave spectrum while other researchers will have developed the instruments to search for large planets in orbit around some 200 nearby stars. If there is someone or thing out there trying to communicate with Earth, within the next three to five years we increasingly will know where to look and listen. This essay focuses on what to do when these or other research projects indicate that extraterrestrial intelligence exists.

Investigation of laser erosion plumes with the help of an optical multichannel spectrum analyzer

Investigation of laser erosion plumes with the help of an optical multichannel spectrum analyzer

Multichannel relative-entropy spectrum analysis

A new relative-entropy method is presented for estimating the power spectral density matrix for multichannel data, given correlation values for linear combinations of the channels, and given an initial estimate of the spectral density matrix. A derivation of the method from the relative-entropy-principle is given. The basic approach is similar in spirit to the multisignal relative-entropy spectrum analysis of Johnson and shore, but the results differ significantly because the present method does not arbitrarily require the final distributions of the various channels to be independent. For the special case of separately estimating the spectra of a signal and noise, given the correlations of their sum, multichannel relative-entropy spectrum analysis turns into a two-stage procedure. First, a smooth power spectrum model is fitted to the correlations of the signal plus noise. Then, final estimates of the spectra and cross spectra are obtained through linear filtering. For the special case where p uniformly spaced correlations are known, and where the initial estimate of the signal-plus-noise spectrum is all-pole with order p or less, this method fits a standard maximum-entropy autoregressive spectrum to the noisy correlations, then linearly filters to calculate the signal and noise spectra and cross spectra. Consideration is given to the case where only an initial estimate of the noise power spectrum is available. An illustrative example is given.

Sensitive detection of narrowband pulses

Highly monochromatic signals, such as TV carriers, can be detected sensitively by using a narrow filter ( b ⩽ 1 Hz) and performing power accumulation on its output. If instead a low-duty-cycle pulsed signal of the same total energy is present, the sensitivity of a square law device, followed by a thresholding operation (to eliminate most samples containing only noise), followed by the algorithm to be described, is greater by about 7 dB in typical cases. This is particularly interesting to SETI because such a pulsed signal is exactly what is sent by a rotating beacon with a directional antenna. Such a pulsed signal is, therefore, a good candidate for an extraterrestrial beacon. Software for detecting this signal type is now ready for field testing with the NASA Multichannel Spectrum Analyzer (MCSA).

Optical multichannel spectrum analyzer with a charge-coupling unit working with an �lektronika-60 computer

The authors have developed and built an automated multichannel recording system of spectra on the basis of a linear videosignal shaping unit with a A-1033 and a-1034 charge coupling devices and an Elektronika-60 minicomputer. The system makes it possible to store spectral distributions as individual pulse signals and to output the distributions on peripheral devices. It is also possible to accumulate and average spectral information obtained with intraresonator laser spectroscopy in which broadband CW or pulse lasers are used.

Software Implementation of Detection Algorithms for the MCSA

The NASA Multichannel Spectrum Analyzer (MCSA) supplies data in several formats and in a wide range of frequency resolutions. To decide if an extraterrestrial signal is present, this data is searched using detection algorithms particularly sensitive to signals concentrated in frequency and/or time. The algorithms, whose ultimate sensitivities are determined by theoretical considerations, are also constrained by available computing power. At present, practical detection of repetitive pulses is possible at an average power about five times lower than that for incoherent CW detection. After a period of field testing, the best detection algorithms, presently implemented in software, will be converted to hardware to increase their speed.

Application of an Ion Exchange Method for Sensitivity Improvement of an Automated Radionuclide Analysis System

A high sensitivity radionuclide analysis system has been developed. An automated system employs an ion exchange method to concentrate target nuclides in reactor coolant water. The system consists of sample treatment equipment and an automatic sample changer in conjunction with a multichannel gamma-ray spectrum analyzer. The sample treatment equipment performs sampling, filtration, sample volume selection, and ion exchange. These four processes are fully automated. Performance tests show that the lowest analysis level is 10/sup -6/ ..mu..Ci/ml of /sup 131/I within 10% reproducibility. The processing time from sampling to ion exchange is within 10 min for samples <100 ml.

Real-time audio spectrum analyzer

A propeller modulation enhancement and display system which suppresses hullcho and displays propeller modulation of a return sonar signal in real time. The real-time operation is obtained through the use of a multichannel frequency spectrum analyzer having a plurality of narrow bandpass filters covering the frequency of interest. Suppression of the hull echo is obtained through the use of a narrow band-reject filter having a variable center frequency. The filter precedes the multichannel frequency spectrum analyzer.

Experimental Profiles of the Balmer Line Hβ Emitted from an Afterglow Plasma Without and With a Superposed Magnetic Field up to 10 Tesla

Abstract The profile of the Hβ line emitted from an afterglow plasma in pure hydrogen gas and a mixture of hydrogen and helium has been measured in axial direction using a multichannel spectrum analyzer with additional temporal resolution. Measurements were performed without and with a superposed magnetic field (B ≦ 10.8 Tesla) in axial direction. With magnetic field we observed a rather strong dependence of the wavelength positions of the two lateral "Zeeman components" (intensity maximum due to combined Stark-Zeeman effects). This feature is important in radiative transfer calculations and for the spectroscopic determination of magnetic fields in plasmas. - Both with and without magnetic field we always observed a line structure superposed on the Hβ profile. The structure disappeared in an active electrical discharge and changed with gas composition. The line structure is interpreted as being due to electronic transitions of molecular hydrogen. It is very probable that the "satellite structures" of Balmer lines observed by other authors under quite different experimental conditions and interpreted as dynamical Stark effect splitting due to fluctuating electric fields have in most cases the same molecular origin. Our earlier published line profiles of Hβ for B = 0 [J. Ramette and H. W. Drawin, Z. Naturforsch. 31 a, 401 (1976) ] are revised in the present paper.

Multi-channel analyzer of energy and mass spectra of atomic particles. (USSR): V V Afrosimov et al, Zh Tekh Fiz, 45 (1), 1975, 56–63 ( in Russian)

Multi-channel analyzer of energy and mass spectra of atomic particles. (USSR): V V Afrosimov et al, Zh Tekh Fiz, 45 (1), 1975, 56–63 ( in Russian)