Showing papers on "Noise measurement published in 1972"
TL;DR: A trapezoidal filter with a trapezoid weighting function is the optimum one when both noise and variations in the charge collection time are present as mentioned in this paper, which was realized by a time-variant (gated filter) system.
Abstract: A filter with a trapezoidal weighting function is the optimum one when both noise and variations in the charge collection time are present, A trapezoidal filter was realized by a time-variant (gated filter) system. This paper presents the results obtained with large germanium detectors at high rates and higher energies, showing that trapezoidal filtering is essential for good resolution in this case.
89 citations
TL;DR: The purposes, problems, and progress of radiated noise, self-noise, and ambient noise research are reviewed in this paper, where the main problems are those of noise measurement, noise reduction, and prevention.
Abstract: The purposes, problems, and progress of radiated noise, self‐noise, and ambient noise research are reviewed. Purposes are related primarily to national defense, but applications to fishery and to the utilization of other natural resources are also noted. Basic problems, most of which were recognized 20 years or more ago, involve ascertainment of properties of the noise, identification of noise sources and mechanisms of noise generation, and the discovery and definition of noise dependencies on environmental factors. Many radiated and self‐noise sources and mechanisms have been identified. Major problems are those of noise measurement, noise reduction, and prevention. In the field of ambient noise, most measurements have been of sound‐pressure level. Some of the noise sources and environmental factors have been identified, and a capability for qualitative and gross prediction has been achieved. Recommended are further investigations of the variation of ambient noise with receiver depth, directionality of t...
78 citations
TL;DR: In this paper, the authors describe the application of minimum-variance estimation techniques for in-flight alignment and calibration of an inertial measurement unit relative to another IMU and/or some other reference.
Abstract: This is the first part of a two-part paper which summarizes work pursued by the author in 1966 [1]. The paper describes the application of minimum-variance estimation techniques for in-flight alignment and calibration of an inertial measurement unit (IMU) relative to another IMU and/or some other reference. The first part formulates the problem, and the second part [2] reports numerical results and analyses. The approach taken is to cast the problem into the framework of Kalman-Bucy estimation theory, where velocity and position differences between the two IMU's are used as observations and the IMU parameters of interest become part of the state vector. Instrument quantization and computer roundoff errors are considered as measurement noise, and environmental induced random accelerations are considered as state noise. Typical applications of the technique presented might include the alignment and calibration of IMU's on aircraft carriers, the initialization of rockets or rocket airplanes which are launched from the wing of a mother ship, the alignment and calibration of IMU's which are only used in the latter phases of rocket flight, and for the initialization/updating of SST guidance systems.
56 citations
01 Sep 1972
TL;DR: The emphasis in this paper is on receiving arrays and how to take partial derivatives of the gain and output signal power with respect to the size of signal, noise and steering perturbations.
Abstract: : The theory of optimum arrays became widely known in the underwater acoustics community through the work of Bryn and Mermoz. The relationship of their work to other detection and estimation problems has been discussed. Optimum array processing structures use detailed information about the signal and noise fields. Since this information is not known precisely in advance, one is led naturally to adaptive beamformers which continually adjust their parameters based upon on-line measurements of some kind. Since adaptive processors are continually adjusting, it is natural to question how sensitive performance is to small variations of the signal field, noise field and system parameters from their assumed or estimated values. The question of sensitivities has been examined tin the past in conjunction with 'super-directive' arrays. An attempt will be made to point out the relationship of the results of this paper to those earlier results. The emphasis in this paper is on receiving arrays. In Section II an introduction to the problem is provided using an intuitive approach. The performance measures of array gain and output power are used. Section III presents the principal sensitivity results. The approach is to take partial derivatives of the gain and output signal power with respect to the size of signal, noise and steering perturbations. Section IV discusses the problem of signal suppression which arises in passive adaptive processors when measurements of signal-plus-noise are used when noise only measurements are desired. Interference rejection is also discussed. A number of optimization problems are discussed in Section V.
40 citations
TL;DR: In this article, the design of a high-sensitivity widebandwidth 10.6-μm heterodyne receiver has been established for space and ground operational use, and key elements for a satellite-to-earth communications link were demonstrated.
Abstract: The design of a high-sensitivity wide-bandwidth 10.6-μm heterodyne receiver has been established for space and ground operational use, and key elements for a satellite-to-earth communications link were demonstrated. The receiver includes a cooled HgCdTe infrared mixer diode, a conical scanner for spatial tracking, an acquisition channel for spatial search and station alignment, and an automatic frequency-control channel to maintain a fixed laser frequency offset. The infrared mixer is designed to provide nearly quantum-noise-limited operation over an extended range of mixer temperature, bias voltage, and IF. The resultant experimental receiver has a measured noise equivalent power of less than 10-19W/Hz over the 15- to 40-MHz IF band for mixer temperatures from 85 to 115 K, and less than 2 \times 10^{-19} W/Hz up to 140 K. Mixer 3-dB cutoff frequencies as high as 420 MHz were measured at a mixer temperature of 125 K. An analysis and engineering equations are given for receiver noise components, noise equivalent power, available mixer conversion gain, mixer transducer gain, and quantum-noise factor in terms of such factors as mixer parameters, quantum efficiency, mixer temperature, dynamic conductance, bias voltage, LO power, and IF amplifier characteristics.
35 citations
TL;DR: In this article, a three-phase test line has been made on four conductor configurations energized at 525 kVL_L. In addition to being energized three phase, the test line was energized single phase and a comparison is made with single-phase laboratory test results.
Abstract: Audible noise measurements on a three-phase test line have been made on four conductor configurations energized at 525 kVL_ L. A statistical analysis of the resulting noise levIels is presented. In addition to being energized three phase, the test line was energized single phase and a comparison is made with single-phase laboratory test results. The noise level from a four-bundle configuration at reduced phase spacing simulating 735-kV operation is evaluated.
33 citations
TL;DR: The noise mechanism in a well-designed magnetometer is due to small-scale magnetic moments which are probably small volumes of the core material that are not oriented by the drive field as discussed by the authors.
Abstract: The noise mechanism in a well-designed magnetometer is shown to be due to small-scale magnetic moments which are probably small volumes of the core material that are not oriented by the drive field. Design developments include the sense coil radius and the development of a drive waveform which yields considerably improved performance over the commonly used sine wave drive.
32 citations
Patent•
24 Mar 1972
TL;DR: In this article, an improved acoustic noise exposure meter for measuring acoustic noise intensity above a predetermined intensity threshold, and for visually displaying an accumulated representation of the measured noise, is presented.
Abstract: An improved acoustic noise exposure meter for measuring acoustic noise intensity above a predetermined intensity threshold, and for visually displaying an accumulated representation of the measured noise. A miniature, battery-operated personal integrating noise dosimeter is carried on a person exposed to acoustic noise. The dosimeter receives and converts acoustic noise to a DC signal directly proportional to the noise intensity. The DC signal controls a voltage controlled oscillator to produce a variable pulse signal whose frequency varies directly with the DC signal. A counter accumulates a binary pulse count of the variable pulse signal that is representative of the total noise to which a person has been exposed. A read/calibrate structure, to which the dosimeter may be detachably coupled, receives and transforms the binary count to a binary coded decimal count an provides a visual readout of the binary coded decimal count. The accumulated dosimeter binary count is transferred to and is visually displayed as a percentage of total permissible noise exposure by the read/calibrate structure when the dosimeter and read/calibrate structures are connected. A calibration checking circuit within the read/calibrate structure provides an acoustic signal of predetermined sound intensity and duration for checking the dosimeter calibration. An overexposure detection circuit of the dosimeter provides an overexposure signal, which is visually displayed by the read-calibrate structure, if a noise overexposure occurs during a noise measurement test period.
27 citations
TL;DR: In this article, the authors describe the application of minimum-variance estimation techniques for in-flight alignment and calibration of an inertial measurement unit (IMU) relative to another IMU and/or some other reference.
Abstract: This is the second part of a two-part paper which summarizes work pursued by the author in 1967 [2]. The paper describes the application of minimum-variance estimation techniques for in-flight alignment and calibration of an inertial measurement unit (IMU) relative to another IMU and/or some other reference. The first paper [1] formulates the problem, and this paper reports numerical results and analyses. The approach taken is to cast the problem into the framework of Kalman-Bucy estimation theory, where velocity and position differences between the two IMU's are used as observations and the IMU parameters of interest become part of the state vector. Instrument quantization and computer roundoff errors are considered as measurement noise, and environmental induced random accelerations are considered as state noise. In this paper, numerical results for three important IMU error parameter configurations are presented and discussed. The main results of the paper determine the effects of state and observation noise levels and the nominal trajectory on the identifications of the errors for these configurations. A discussion of the minimum number of trajectory maneuvers and of the optimal trajectory maneuvering is given.
22 citations
TL;DR: In this paper, the effects of different types of transmission-line noise on television reception are examined and tolerability criteria are derived for TV set as noise detector for TVI measurements are introduced.
Abstract: The effects of different types of transmission-line noise on television reception are examined. Curves relating annoyance with measured signal-to- noise ratios are produced. Tolerability criteria are derived. Finally, the use of a TV set as noise detector for TVI measurements is introduced.
TL;DR: In this article, the authors present a guide on the measurement of audible noise from transmission lines in EHV-powered transmission lines, including a survey of the results of research and experience.
Abstract: The trend toward extra-high-voltage (EHV) has focused attention on acceptable audible noise levels due to corona. The Radio Noise Subcommittee whose members are intimately concerned with the audible noise problem, has consolidated the results of research and experience to present this guide on the measurement of audible noise from transmission lines.
TL;DR: In this article, the current status of time-domain metrology in material and distributed network research is described and the causes and magnitude of system errors are discussed along with continuing work to improve system performance.
Abstract: The current status of time-domain metrology (TDM) in material and distributed network research is described. After a brief summary of earlier work, the operation and features of two prototype material measurement units are discussed. These semiautomated systems utilize a 5-V step recovery diode pulse generator and computer-controlled scanning procedures incorporating time-window stabilization and variable-dwell-time averaging. The larger, 10-ns time-window unit measures the complex permittivity and permeability over a frequency range of 0.1-10 GHz in about 10 min. The causes and magnitude of system errors are discussed along with continuing work to improve system performance. In distributed network research, the capabilities of TDM for calibration are being determined. From measured signal-to-noise ratios, it was calculated that random noise contributes less than 1 percent error for insertion loss measurements up to 50 dB over the frequency range 0.4-8 GHz. Other topics discussed include: identification and evaluation of error sources, pulse generator development, measurement configurations and procedures, and testing of waveguide and ferrite components.
TL;DR: In this paper, a generalized equation is derived that represents relations between properties of a device under test and an indication of a measuring instrument having signal generators and an input port, which can be applied to most narrow-band radiometers or reflection-measuring instruments.
Abstract: A generalized equation is derived that represents relations between properties of a device under test and an indication of a measuring instrument having signal generators and an input port. The equation can be applied to most narrow-band radiometers or reflection-measuring instruments. Considering only factors measured outside the instrument, the equation permits exact measurements of properties of the device under test or easier evaluation of errors in the measurements without any consideration of structures or inner properties of the instrument. In addition, according to this concept, a new method permitting direct measurements of mismatch factors or delivered powers and a possibility of a radiometer to be used for reflection measurements are suggested.
TL;DR: In this article, a bundle of 4 subconductors 2-in (5.08 cm) in diameter was tested on the Project UHV single-phase test line.
Abstract: A bundle of 4 subconductors 2-in (5.08 cm) in diameter was tested on the Project UHV single-phase test line. Radio noise, corona loss, audible noise, electrostatic field effects were continuously measured in order to investigate the effects of weather variables. Translation of the results to a 1000-kV, 3-phase line shows that audible noise will be the main obstacle to the use of this bundle.
TL;DR: In this correspondence a more analytic and simpler method than the above one is presented and it is shown that the simplest deadbeat observer can be refined.
Abstract: In Section IV of the above paper a method is developed for obtaining one explicit minimal-order optimal observer-estimator for the case in which some measurements are noisy while others are noise free. In this correspondence a more analytic and simpler method than the above one is presented. It is also shown that the simplest deadbeat observer given in Section V of the above paper can be refined.
TL;DR: In this paper, a nuclear magnetic resonance detection system for the vhf-uhf frequency range is described in detail, which consists of a radio frequency bridge built around a coaxial hybrid T. The system is thus fully tunable over wide ranges of frequency from a remote location.
Abstract: A nuclear magnetic resonance detection system for the vhf‐uhf frequency range is described in detail. It consists of a radio frequency bridge built around a coaxial hybrid T. The sample is contained in a tunable L‐C resonator coupled with an adjustable impedance transformer to a 50 Ω airline. The system is thus fully tunable over wide ranges of frequency from a remote location. For example, using a two‐turn copper ribbon coil, the range 270–710 MHz is covered: The system may be set to any desired point in this range within a few minutes. The system was used with standard lock‐in detection to obtain the absorption derivative ∂χ″/∂H. An absolute noise measurement was made at a radio frequency of 300 MHz and an audio detection frequency of 200 Hz. This showed that the root mean square noise at the lock‐in output was between four and seven times the value corresponding to the rf Johnson noise at the bridge. The system was used to observe a proton resonance in a Bitter type solenoid at 125 kG.
TL;DR: In this article, the noise present in the detected optical output of three types of small-area electroluminescent diodes (GaAs diffused junctions (Al-GaAs single and double heterostructures), operated continuously at high current densities in a room-temperature ambient, has been measured in the frequency range of 300 Hz to 300 kHz.
Abstract: The noise present in the detected optical output of three types of small-area electroluminescent diodes (GaAs diffused junctions (Al-Ga)As single and double heterostructures), operated continuously at high-current densities in a room-temperature ambient, has been measured in the frequency range of 300 Hz to 300 kHz. The best unit showed noise, with an 1/f -type frequency dependence, which was less than twice the theoretical detector shot-noise limit at 350 Hz and that approached this shot-noise limit near 1.2 kHz.
Journal Article•
TL;DR: In this article, the authors consider some of the errors that may result from several short-cut statistical analysis methods and propose a more complete statistical analysis of the fluctuating levels of community noise.
Abstract: Making full-fledged statistical analysis of the fluctuating levels of community noise can be a time-consuming and expensive procedure. In order to economize on time and money, various short-cut methods have been proposed. This article considers some of the errors that may result from several such methods. (Author)
TL;DR: Wiener filter theory is used to design the filter system that gives the optimal signal estimate, based upon the moveout distributions and the power spectra of the various components of the data.
Abstract: Many seismic experiments result in multiple time series which can be decomposed into signal and additive noise, where the noise has both a coherent and an incoherent component. The signal and the two noise components are stationary second-order random functions. The time shifts, called moveouts, of the signal and coherent noise are random variables with known distributions. Wiener filter theory is used to design the filter system that gives the optimal signal estimate, based upon the moveout distributions and the power spectra of the various components of the data. Velocity filters are useful in seismic data processing to separate signal from noise on the basis of moveout (velocity) differences without distorting the basic shape of the signal.
TL;DR: In this article, a measurement method and system was devised to automatically measure the effective input noise temperature of 55-65 GHz receivers using a bolometric Y-factor measurement, a working "hot" noise source consisting of a waveguide argon gas tube mount developed at the National Bureau of Standards, and a minicomputer system controller operating in Basic.
Abstract: As part of a millimeter-wave development program at the National Bureau of Standards, a precision measurement method and system was devised to automatically measure the effective input noise temperature of 55-65-GHz receivers. Salient features of the system include a bolometric Y-factor measurement, a working "hot" noise source consisting of a waveguide argon gas tube mount developed at the National Bureau of Standards, and a minicomputer system controller operating in Basic. System design considerations and measurement uncertainties are discussed.
01 Jan 1972
TL;DR: In this paper, measurements of noise in 32, 64 and 128 bit 2-phase silicon/aluminum gate CCD's are discussed, which tend to confirm low noise predictions.
Abstract: Various workers have predicted that the CCD should be a low-noise device. This paper will discuss measurements of noise in 32, 64 and 128 bit 2-phase silicon/aluminum gate CCD's which tend to confirm these low noise predictions. The various noise sources expected in CCD's (i.e.: Shot noise of signal and background charge, incomplete transfer noise, fast interface state noise, and output amplifier channel and reset noise) will be briefly discussed along with the spectral density anticipated for uncorrelated and correlated noise sources.
TL;DR: In this article, an analysis of the output of three alternative matched filter configurations in an infrared scanning system model is presented, where the sensor is corrupted by thermal noise, generation-recombination noise, photon noise, and modulation noise, the latter providing an extreme discoloration in the signal passband.
Abstract: An analysis of the output of three alternative matched filter configurations in an infrared scanning system model is presented. The sensor is corrupted by thermal noise, generation-recombination noise, photon noise, and modulation noise, the latter providing an extreme discoloration in the signal passband. Expressions for the signal voltage density spectrum, signal pulse shape, noise power spectrum, and average noise power at the matched filter output are derived where the integral evaluations attendant to these derivations do not appear elsewhere in the literature. The paper also provides graphical displays of the signal-to-noise power ratio at the filter output versus various system parameters, noise power spectrum out of the matched filter versus ?, and the signal pulse shape out of the filter versus time. Also included are discussions of practically realizable approximations to the matched filters and curve fitting techniques for the signal pulse shape function.
TL;DR: Results for the sound fields set up by single tones, multitones, and bands of noise are considered together with the effects of the discrete‐ and continuous‐space sampling of these fields, and the variance for such sampling gives a basis for sampling in such a way as to get results of prescribed accuracy.
Abstract: The work of Schroeder, Lubman, Maling, Andres, Tichy, Ebbing, and the author is reviewed. Results for the sound fields set up by single tones, multitones, and bands of noise are considered together with the effects of the discrete‐ and continuous‐space sampling of these fields. The variance for such sampling can be calculated for the above cases, and gives a basis for sampling in such a way as to get results of prescribed accuracy. Some areas that seem to merit attention at present are mentioned. These include (a) reverberation chamber measurement of the power output of a source radiating a steady single‐frequency tone, the accuracy to be expected in such measurements, and the comparability of such results with free‐field results; (b) the use of moving reflectors, such as rotating vanes, the improvements they afford, and their effect on the sound field and the power radiation of the source.
TL;DR: In this article, the authors deal with problems of the evaluation or selection of testing methods for fuels, and they use signal/noise ratio, suggested by Taguchi 1, as a useful statistical criterion for the above purposes.
TL;DR: In this paper, the authors describe a typical direct-detection noise-measuring system, with particular attention given to the use of Schottky-barrier diodes as envelope detectors.
Abstract: This paper describes a typical direct-detection noise-measuring system, with particular attention given to the use of Schottky-barrier diodes as envelope detectors. The rise of threshold at low modulation frequencies encountered in these systems has been found to be mainly attributable to FM-to-AM conversion occurring in comparatively narrow-band detectors rather than to diode-flicker noise and thus is largely removable. A sensitivity improvement of 10-20 dB may result at low frequencies, yielding a noise-to-carrier ratio threshold range of about -150 to -155 dB/100 Hz at modulation frequencies from 100 Hz to 50 kHz for measurements of AM noise, and below 0.01 Hz/100 Hz for FM noise, of microwave oscillators at C band.
01 Apr 1972
TL;DR: A theoretical investigation of the noise-induced error in correlograms is presented and it is shown that the rms error is inversely proportional to the square root of the record length for virtually any noise which might be encountered.
Abstract: There is a continuing increase in the use of correlation in engineering. In these applications some or all of the signals to be analyzed may be obscured by noise. Since determination of the autocorrelation or cross correlation requires knowledge of the signals for all time, one must use the observed signals to obtain an estimate of the desired correlation function. These estimates, autocorrelograms or crosscorrelograms, are affected when the signal is obscured by noise. A theoretical investigation of the noise-induced error in correlograms is presented. It is shown that the rms error is inversely proportional to the square root of the record length for virtually any noise which might be encountered. This provides a guide for the reduction of the noise error to any desired level. In addition, bounds on the error are determined for some more common types of noise. Experimental results are described which verify the theoretical developments. The theoretical results are applied to a study of the transmission of action potentials through the cockroach ganglion.
TL;DR: Methods of synchronization for an unknown signal sequence by learning procedure, which computes a posteriori probabilities for the signal location, are presented and some results of computer simulation are presented.
Abstract: Methods of synchronization for an unknown signal sequence by learning procedure, which computes a posteriori probabilities for the signal location, are presented. First, to avoid the difficulties of the interference between successive intervals, a signal sequence with ample guard spaces for getting rid of the interference is treated. Next, the case without guard space is treated. To the nonsupervised case, some methods are applied. The methods proposed in this paper have a form of double learning with respect to the unknown signal form and the signal location. Also some results of computer simulation are presented.
TL;DR: In this paper, the accuracy of a commonly used noise-measuring system at microwave frequencies is calculated under actual measuring conditions, and serious deviations are shown to occur, which impose a lower and upper frequency limit on "double-channel" AM and FM noise measurements, respectively.
Abstract: The accuracy of a commonly used noise-measuring system at microwave frequencies is calculated under actual measuring conditions. Serious deviations are shown to occur, which impose a lower and upper frequency limit on "double-channel" AM and FM noise measurements, respectively.
TL;DR: An analysis is presented for the effect of noise on the output of the velocimeter system under conditions of high scattering center concentrations and Steady flows and analogies are drawn where the current analysis is applicable to other areas of communication.
Abstract: Laser Doppler velocimeters provide a noncontact method for the measurement of velocities. These measurements are, in general, corrupted by noise arising in the transmission and reception of the optical carrier. An analysis is presented for the effect of noise on the output of the velocimeter system under conditions of high scattering center concentrations and Steady flows. Principally, the so-called Gaussian beam optical setup is considered where the intensity distribution of the intersecting laser beams at the observation volume (fringe pattern) is Gaussian. Output noise spectral densities, noise power, and signal-signal-to-noise ratios are derived in terms of the input signal (Doppler carrier)-tonoise ratios and bandwidths of the processing systems. Also, threshold levels for input signal-to-noise ratios are determined and the photodetector performance analyzed. Finally, analogies are drawn where the current analysis is applicable to other areas of communication.