Avoidance conditioning of heart rate in humans.
Avoidance conditioning of heart rate in humans with visual stimulus signaling availability of electric shock punishment
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SEARCH · Engineering Papers
Results for “Signal conditioning”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Adaptive interference techniques for mobile antennas
The results of a study performed to investigate effective, low cost adaptive signal processing techniques for suppressing mutual satellite interference that can arise in a mobile satellite (MSAT) communication system are discussed. The study focused on the use of adaptive sidelobe cancelling as a method to overcome undesired interference caused by a multiplicity of satellite transmissions within the field of view of the ground station. Results are presented which show that the conventional sidelobe canceller produces undesired reduction of the useful signal. This effect is due to the presence of the useful component in the reference antenna element. An alternative structure, the generalized sidelobe canceller (GSC), has been proposed to overcome this difficulty. A preliminary investigation of possible implementations of the GSC was conducted. It was found that at most 8 bits would be required to implement the GSC processor under conditions in which the desired signal-to-interference ratio is 25 dB.
Griffiths, Lloyd J.↗
Generalization of the Manley-Rowe relations for non-periodic signals constrained in bandwidth with finite energy
General relations for the energy spectral densities of nonperiodic signals constrained in bandwidth in nonlinear reactances are derived. It is assumed that the charge-voltage characteristics of the reactances are polynomials. In addition certain conditions for the frequency bands of the signals must be met. By contrast with the Manley-Rowe relations integrals with respect to frequency appear instead of the ratios power over frequency. The integrands are energy spectral densities divided by frequency. For parametric devices inequalities can be derived for the ratios of the energy levels in the different circuits and the limiting frequencies of the energy spectral densities. With these inequalities it is possible to determine limits for the energy levels.
Proksch, P.↗
EXOS-B/Siple Station VLF wave-particle interaction experiment
Preliminary results of experiments made using the EXOS-B satellite to make simultaneous observations of VLF signals transmitted from Siple Station, Antarctica and interacting particles are reported. VLF measurements carried out by the EXOS-B wideband receiver upon satellite crossings of the Siple meridian at equatorial and high latitudes were able to detect the Siple signal on about 50% of the passes, and observed four instances of artificially stimulated emissions. Two of these cases exhibit triggering with a clear relation to the transmitted frequency format, while in the remaining two this relation is absent. Electron fluxes at energies from 3 eV to 9.5 keV are observed to be enhanced during the Siple stimulated emission events, with a distribution on the equatorial passes sufficient to satisfy the cyclotron interaction condition for parallel propagation of Siple signals of frequency about half the local cyclotron frequency.
Kimura, I.↗
A direct comparison between lateralization and detection under conditions of antiphasic masking
Lateralization and detection of signals under antiphasic noise masking measured at various SNR levels
Blocker, A. S.↗
Signal conditioner for nickel temperature sensors
Simple circuit conditions output of 50 ohm sensor for readout on straingage recorder. It consists of resistors, switch, and "matching" network. Device saves time and reduced instrumentation costs when strain and temperature are measured in same setup.
Walker, R. R.↗
Analytical Investigation of an Adaptive Flight-Control System Using a Sinusoidal Test Signal
An analytical study was made of an adaptive flight-control system which measures vehicle response to small-amplitude control-surface deflections produced by a sinusoidal test signal. Changes in the response to this signal are related to environmental changes,, and the system is continuously altered to maintain this response equal to a preselected value. The system is suitable for use in high-performance aircraft and missiles and requires only the addition of a signal generator and a logic circuit consisting of a filter-rectifier network and a comparator-integrator network to a basic command-control system. Thus, it presents a relatively simple approach to the problem. The effects on system performance of variation in flight condition, system-gain level, test-signal frequency, and sensor location are included in the analysis. Longitudinal control of a high-performance research aircraft over flight conditions ranging from landing approach to a Mach number of 5.8 at an altitude of 150,000 feet, and longitudinal control of a four-stage solid-fuel missile including the first bending mode over the atmospheric portion of a launch trajectory constituted the basis for the analytical study. Results of an analog-computer study using time-varying coefficients are presented to compare the control obtained with the adaptive system with-that obtained with a fixed-gain system during the atmospheric portion of a missile launch trajectory. The system has demonstrated an ability to maintain satisfactory vehicle control-system stability over wide ranges of environmental change.
Harris, Jack E.↗
Test Port for Fiber-Optic-Coupled Laser Altimeter
A test port designed as part of a fiber optic coupled laser altimeter receiver optical system allows for the back-illumination of the optical system for alignment verification, as well as illumination of the detector(s) for testing the receiver electronics and signal-processing algorithms. Measuring the optical alignment of a laser altimeter instrument is difficult after the instrument is fully assembled. The addition of a test port in the receiver aft-optics allows for the back-illumination of the receiver system such that its focal setting and boresight alignment can be easily verified. For a multiple-detector receiver system, the addition of the aft-optics test port offers the added advantage of being able to simultaneously test all the detectors with different signals that simulate the expected operational conditions. On a laser altimeter instrument (see figure), the aft-optics couple the light from the receiver telescope to the receiver detector(s). Incorporating a beam splitter in the aft-optics design allows for the addition of a test port to back-illuminate the receiver telescope and/or detectors. The aft-optics layout resembles a T with the detector on one leg, the receiver telescope input port on the second leg, and the test port on the third leg. The use of a custom beam splitter with 99-percent reflection, 1-percent transmission, and a mirrored roof can send the test port light to the receiver telescope leg as well as the detector leg, without unduly sacrificing the signal from the receiver telescope to the detector. The ability to test the receiver system alignment, as well as multiple detectors with different signals without the need to disassemble the instrument or connect and reconnect components, is a great advantage to the aft-optics test port. Another benefit is that the receiver telescope aperture is fully back-illuminated by the test port so the receiver telescope focal setting vs. pressure and or temperature can be accurately measured (as compared to schemes where the aperture is only partially illuminated). Fiber-optic coupling the test port also allows for the modularity of testing the receiver detectors with a variety of background and signal laser sources without the need of using complex optical set-ups to optimize the efficiency of each source.
Ramos Izquierdo, Luis↗
A regression technique for evaluation and quantification for water quality parameters from remote sensing data
The objective of this paper is to define optical physics and/or environmental conditions under which the linear multiple-regression should be applicable. An investigation of the signal-response equations is conducted and the concept is tested by application to actual remote sensing data from a laboratory experiment performed under controlled conditions. Investigation of the signal-response equations shows that the exact solution for a number of optical physics conditions is of the same form as a linearized multiple-regression equation, even if nonlinear contributions from surface reflections, atmospheric constituents, or other water pollutants are included. Limitations on achieving this type of solution are defined.
Whitlock, C. H.↗
Laser Doppler systems in atmospheric turbulence
The loss of heterodyne signal power for the Marshall Space Flight Center laser Doppler system due to the random changes in the atmospheric index of refraction is investigated. The current status in the physics of low energy laser propagation through turbulent atmosphere is presented. The analysis and approximate evaluation of the loss of the heterodyne signal power due to the atmospheric absorption, scattering, and turbulence are estimated for the conditions of the January 1973 flight tests. Theoretical and experimental signal to noise values are compared. Maximum and minimum values of the atmospheric attenuation over a two way path of 20 km range are calculated as a function of altitude using models of atmosphere, aerosol concentration, and turbulence.
Murty, S. S. R.↗
Signal-to-noise ratio losses in full spectrum combining of signals with a downconverted subcarrier
This article presents the results of the signal-to-noise ratio loss in the process of full spectrum combining of signals with a downconverted subcarrier under imperfect conditions. These imperfect conditions not only include the misalignment of the carrier, the subcarrier, and the symbols, but they also include the nonideal filtering in the subcarrier downconversion process, the cutoff of the data bandwidth, and the distortion in signal waveform.
Feria, Y.↗
Signal recognition as influenced by presentation schedules.
Influence on hits and false alarms of response and signal events on preceding trial
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Further results of natural laminar flow flight test experiments
Flight test experiments were conducted to measure the extent and nature of natural laminar flow on a smoothed test region of a swept-wing business jet wing. Surface hot film anemometry and sublimating chemicals were used for transition detection. Surface pressure distributions were measured using pressure belts. Engine noise was monitored by a microphone attached to the wing surface to study possible acoustic effects on stability of the laminar boundary layer. Side-slip conditions were flown to simulate changes in effective wing sweep. Flight instrumentation and ground data analysis techniques and a method for measuring intermittency of turbulence are described. Correlation was obtained between the hot film gage signals and chemicals for transition detection. Cross-flow vortices were observed for some flight conditions. Results of spectral and statistical analysis of the hot film signals for various flight test conditions are presented.
Wentz, W. H., Jr.↗
International comparison of radiometers - Techniques and results.
Description of an international comparison of radiometers made on May 10 through 14, 1971, with 24 instruments, each one representing the calibration standard of a different country or a major laboratory. All were pyranometers, viewing the sun and sky, thus bypassing the conventional method of transferring the standard from Angstrom pyrheliometers. This is the first time that pyranometers from all around the globe have been brought together in order to verify the scale on which to report solar radiation data. A highly accurate data collection system measured simultaneously the output of each instrument and that of a reference standard at 20-sec intervals. Over 300,000 radiometric signals were recorded under varying atmospheric conditions, as well as data on turbidity, temperature, and other relevant parameters. Computer programs were developed for overnight analysis of the data and distribution to participants on the following day. Among major findings are that instruments of different types and independent calibration such as those of Eppley, U. S. A., World Radiation Center, Switzerland, and Melbourne, Australia, show better agreement than anticipated, that certain national standards have to be revised by as much as 16% and that the cosine factor is highly dependent on the type of instrument.
Thekaekara, M. P.↗
Increasing the time resolution of a multichannel scaler.
Description of an economical buffer unit which will extend the time resolution of a multichannel scaler to better than 100 nsec. The buffered multiscaler produces a system which has negligible dead time between the bins even at the highest resolutions. It is suitable for use in any digital signaling averaging application which meets certain conditions.
Silverberg, E. C.↗
Dynamic optometer
A dynamic optometer that electronically records the position of the anterior surface of the human lens is described. The geometrical optics of the eye and optometer, and the scattering of light from the lens, are closely examined to determine the optimum conditions for adjustment of the instrument. The light detector and associated electronics are also considered, and the operating conditions for obtaining the best signal-to-noise ratio are determined.
Wilson, D. C.↗
The equatorial aurora in the extreme ultraviolet
The extreme ultraviolet telescope on the Apollo-Soyuz mission observed the equatorial aurora from an altitude of 220 km on four separate occasions in July 1975, in quiet geomagnetic conditions (Ap = 6). In all cases signals well above ambient background in the 50-150, 114-150, 170-600, and 500-780 A bands were recorded as the spacecraft moved across the equator and the instrument viewed the atmosphere below it. The observed emissions are confined to a band roughly 10 to 20 deg in width with the peak emission occurring in the range -15 to +2 deg magnetic latitude. No enhancement on the 1350-1550 A channel was noted. The observed signals are interpreted as recombination radiation of energetic helium and, possibly, oxygen ions originating in the terrestrial ring current.
Paresce, F.↗
A tunable coherent CO2 lidar for measurements of atmospheric aerosol backscatter and attenuation
A coherent laser radar system using a grating-tunable, injection-locked TEA-CO2 transmitter is being used to measure the altitude dependence of atmospheric aerosol backscatter and attenuation at a variety of CO2 laser wavelengths in the 9-11 micron region. Injection control of the TEA-CO2 laser allows one to obtain Single-Longitudinal-Mode (SLM) pulses which will follow the frequency of the injected radiation if the TEA laser cavity length is adjusted so that a cavity resonance is in proximity with the injected signal frequency, and if various additional conditions are satisfied. Requirements for generation of SLM pulses in this manner from a TEA CO2 laser with an unstable resonator cavity will be discussed. Procedures used for quantitative range-gated measurements of aerosol backscatter and attenuation will also be discussed.
Menzies, R. T.↗