Analysis of a signal processor for an antenna array
Signal processor with ratio-squared predetection combining for adaptive antenna array, discussing radiation patterns for coherent and incoherent signal and noise sources
Bickford, W. J.↗
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Results for “signal analysis”
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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Application of frequency discrimination technique to the analysis of electroencephalographic signals
A frequency discrimination technique is realized by an inexpensive frequency discriminator for direct on-line measurement of the entrainment phenomenon in EEG as entrained by the frequency of a sensory stimulus. The use of this device for detecting the presence or absence of the stimulus effect and the measurement of the time delays in the entrainment is demonstrated. The EEG signal is first filtered by a narrow-band filter with center frequency about the alpha-rhythm of the individual. It is then reasonable to consider the alpha signal as narrow-band random process with the alpha frequency f sub alpha as the mean frequency of the spectral band.
Lai, D. C.↗
Application of frequency discrimination technique to the analysis of electroencephalographic signals.
A frequency discrimination technique is described which has proved to be effective in measuring the entrainment phenomenon in EEG signals. The validity of a narrow-band-process model used to characterize the signals is demonstrated. The technique (realized by an inexpensive device described elsewhere) is shown to provide a means of studying the synchronization phenomenon as related to alertness.
Lai, D. C.↗
Diffraction analysis of Doppler signal characteristics for a cross-beam laser Doppler velocimeter
Based on scalar diffraction theory, single particle scattering characteristics for a cross-beam laser Doppler velocimeter (LDV) have been computed for different particle sizes under varied instrumentation configurations. The modulating component of the scattered signal has been shown to depend upon particle size, shape, and collecting aperture for a given probe volume fringe spacing. Experimental verifications of some of the predictions are presented, and some of the limitations using an LDV as a particle sizing instrument are discussed.
Robinson, D. M.↗
Unipolar pulse and bipolar noise testing of wideband signal noise conditioner (MC476-0132-0034)
Information is presented on performance characteristics of the shuttle orbiter wideband signal conditioner when subjected to special types of input signals. Design analysis of the signal flow path through the signal conditioning amplifier was performed followed by acutal testing of the amplifier with various signal inputs. Results indicate that the signal conditioner should perform acceptably if the shuttle orbiter flight vibration signal levels are in accord with preflight predictions.
Harris, J. E.↗
Analysis of random signal combinations for spacecraft pointing stability
Methods for obtaining the probability density function of random signal combustions are discussed. These methods provide a realistic criteria for the design of control systems subjected to external noise with several important applications for aerospace problems.
Howell, L.↗
Diagnostic analysis of vibration signals using adaptive digital filtering techniques
Signal enhancement techniques are described using recently developed digital adaptive filtering equipment. Adaptive filtering concepts are not new; however, as a result of recent advances in microprocessor-based electronics, hardware has been developed that has stable characteristics and of a size exceeding 1000th order. Selected data processing examples are presented illustrating spectral line enhancement, adaptive noise cancellation, and transfer function estimation in the presence of corrupting noise.
Jewell, R. E.↗
Roundoff noise analysis for digital signal power processors using Welch's power spectrum estimation
The noise due to finite-word-length effects is analyzed for digital-signal power processors using Welch's power-spectrum estimation technique to measure the power of Gaussian random signals over a frequency band of interest. The input of the digital signal processor contains a finite-length time interval in which the true Gaussian signal is contaminated by Gaussian noise. The roundoff noise-to-signal ratio in the measurement of the signal power is derived, and computer simulations which validate the analytical results are presented. These results can be used in tradeoff studies of hardware design, such as the number of bits required at each processing stage. The results presented in this paper are currently being used in the design of a digital Doppler processor (Chi et al., 1986) for a radar scatterometer.
Chi, Chong-Yung↗
Analysis of SO2 signals in SBUV/TOMS data
Absorption bands between 300 nm and 315 nm were observed in spectral scans of the atmospheric albedo made by the Solar Backscatter Ultraviolet (SBUV) spectrometer following the eruption of El Chichon. It is shown that those bands coincide with peaks in the absorption coefficient spectrum of SO sub 2. The magnitude of the absorption is used to the column content of present SO sub 2. These observations confirm that the differential absorption between 312.5 nm and 317.5 nm in Total Ozone Mapping Spectrometer (TOMS) data can be used to measure SO sub 2 with high spatial resolution. A maximum concentration of SO sub 2 of 15 matm-cm was observed by SBUV on April 15, 1982. The measurement based on direct measurement of band intensity can be used to calibrate the TOMS algorithm for deriving SO sub 2 amounts.
Mcpeters, Richard↗
Process Studies and Data Analysis for Surface Signals in the Convectively Active Regions of the Polar Seas
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Polar Seas Surface Signals Ocean Convection↗
Measuring Luminescence Lifetime With Help of a DSP
An instrument for measuring the lifetime of luminescence (fluorescence or phosphorescence) includes a digital signal processor (DSP) as the primary means of control, generation of excitation signals, and analysis of response signals. The DSP hardware in the present instrument makes it possible to switch among a variety of operating modes by making changes in software only.
Danielson, J. D. S.↗
Rotating Rake Mode Measurement System – Signal Collection and Analysis Techniques
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Duct Modes↗
Active Source Seismic Analysis of Seismic Signal Using Rocket Launch Events at Kennedy Space Center, Florida
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Rocket Launch↗
Detecting and Analyzing Power System Disturbances in PMU Data with the Open-Source Archive Walker Tool
As the number of Phasor Measurement Units (PMUs) deployed in power systems increases, so do the archives of synchrophasor measurements stored by utilities. Significant value can be extracted from these archives by using them to support studies such as frequency response analysis, small-signal stability analysis, and power plant model validation. To better enable utilities to perform these studies, the open-source Archive Walker tool was developed. This tool examines PMU data for grid disturbances and periods of interest. Once identified, the data can be further analyzed inside Archive Walker or exported to specialty tools. In this paper, the various disturbance detectors available in Archive Walker are described, and its interactions with other openly-available tools are highlighted.
Follum, James D.↗
AviSense: A Real-time System for Detection, Classification, and Analysis of Aviation Signals
We present AviSense, an SDR-based real-time, versatile system for monitoring aviation bands. AviSense detects and characterizes signal activities to enable practical and effective anomaly detection. We identify and tackle the challenges posed by a diverse set of critical aviation bands and technologies. We evaluate our methodology with real-world aviation signal measurements and demonstrate that we can classify aviation signals as normal with 99% accuracy. We also provide an exhaustive evaluation of our anomalous signal detection capability and show that we can accurately classify anomalous signals with 99% accuracy, with few exceptions. We also demonstrate that AviSense can effectively distinguish between different types of anomalies. We build a prototype implementation of AviSense for distributed monitoring.
42 ENGINEERING↗
Employing Principal Component Analysis for XRD Signal Extraction of Germanium Antimony Telluride Thin Films During Crystallization.
Abstract not provided.
Rodriguez, Mark A.↗
Collection and analysis of specific ELINT Signal Parameters
This report was a followup to, Collection and Analysis of Specific ELINT Signal Parameters, DTIC A166507, 23 June 1985. The programs and hardware assembled for the above mentioned report were used to analyze two types of radar, the PPS-6 and the HOOD radars. The typical ELINT parameters of frequency, pulse width, and pulse repetition rate were collected and analyzed.
Wilson, Lonnie A.↗
An overview of data acquisition, signal coding and data analysis techniques for MST radars
An overview is given of the data acquisition, signal processing, and data analysis techniques that are currently in use with high power MST/ST (mesosphere stratosphere troposphere/stratosphere troposphere) radars. This review supplements the works of Rastogi (1983) and Farley (1984) presented at previous MAP workshops. A general description is given of data acquisition and signal processing operations and they are characterized on the basis of their disparate time scales. Then signal coding, a brief description of frequently used codes, and their limitations are discussed, and finally, several aspects of statistical data processing such as signal statistics, power spectrum and autocovariance analysis, outlier removal techniques are discussed.
Rastogi, P. K.↗