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Aerospace and Electronic Systems, IEEE Transactions on

Issue 2 • Date March 1967

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Displaying Results 1 - 25 of 38
  • [Front cover]

    Publication Year: 1967 , Page(s): c1
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    Freely Available from IEEE
  • IEEE Aerospace and Electronic Systems Group

    Publication Year: 1967
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    Freely Available from IEEE
  • [Breaker page]

    Publication Year: 1967 , Page(s): nil1
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    Freely Available from IEEE
  • From the Editors

    Publication Year: 1967 , Page(s): 153
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    Freely Available from IEEE
  • A Laser Device for Remote Vibration Measurement

    Publication Year: 1967 , Page(s): 154 - 157
    Cited by:  Papers (1)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1232 KB)  

    A laboratory study has been made of concepts that utilize a laser for a vibration measurement device. The laser beam possesses the needed characteristics for a spatially directed carrier capable of detecting and transmitting vibration information to remote data processing equipment; furthermore, such a laser vibration measurement device can accomplish the measurement without mechanical contact with the structure under test. The measurement technique utilizes the Doppler shift produced on a wave reflected from a surface vibrating normal to the beam path. Several techniques are available for detecting the Doppler shift; optical heterodyne or homodyne detection and microwave subcarrier modulation methods are candidates for practical instruments. Preliminary results from laboratory experiments indicate Optical heterodyne detection to be the most practical method with present state-of-the-art equipment. View full abstract»

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  • PCM Frame Synchronization with a Self-Varying Threshold

    Publication Year: 1967 , Page(s): 158 - 164
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1557 KB)  

    An improved method for frame synchronization of PCM telemetered data is described and performance analyses are presented. This method is based on the utilization of a threshold detector whose level is selfvarying according to the characteristics of the received data. It is simple to implement and simpler from an operational point of view than the frame synchronizers currently in use in that a threshold control is altogether eliminated. Analyses show, furthermore, that a synchronizer using a self-varying threshold always has a higher probability of detecting the synchronization code no matter what the frame length, sync code length, or error level. View full abstract»

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  • Definitions of Effectiveness Terms: A Report on the Purpose and Contents of MIL-STD-721B

    Publication Year: 1967 , Page(s): 165 - 170
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1649 KB)  

    The impact of the Systems Effectiveness concept upon U.S. military terminology required for acquisition of modern weapon systems necessitated a thorough revision of MIL-STD-721A and consolidation with MIL-STD-778 and MIL-STD447. Inclusion of a number of new terms and their definitions, as well as addition of standard definitions for terms on human factors and safety, was found to be necessary. The resulting military standard has been approved by the U.S. Department of Defense for use by all of its departments and agencies. Its contents should be of great interest to management and engineers in private industry who are concerned with the development and production of weapon systems for the Army, Navy, and Air Force. This standard is now in print and will be available for distribution early in 1967; this paper is written by one of the participants in the revision and compilation of this military standard and is published here for the purpose of information on its scope and contents. View full abstract»

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  • A Model for the Radar Echo from a Random Collection of Rotating Dipole Scatterers

    Publication Year: 1967 , Page(s): 171 - 178
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1835 KB)  

    A theoretical model for the radar echo from a random collection of dipole scatterers is presented. The analysis of the model takes into account the effects of scatterer rotation which have been neglected in previous related work. It is shown that rotational motion of the scaterers can have significant effects upon the echo waveform. The fluctuating characteristics of clutter echoes are also investigated. The theory and some experimental results in the literature are shown to be in relatively good agreement. View full abstract»

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  • Estimated Flight Time for Optimum Trajectories

    Publication Year: 1967 , Page(s): 179 - 185
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    Various methods are presented for estimating the flight time for vehicles which fly an optimum trajectory. A realistic example is considered in order to display the inherent accuracy of each of these methods. Numerical integration methods are found to be the most accurate. Simple formulas are derived for the case where a less accurate estimate is acceptable. All of these methods require less computation than would be required in order to solve the overall optimization problem. Thus any one of these methods can be applied to an onboard guidance scheme or control system which requires a real time estimate of the time-to-go. View full abstract»

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  • System Worth, System Effectiveness, Integrated Logistics Support, and Maintainability

    Publication Year: 1967 , Page(s): 186 - 194
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2161 KB)  

    The system worth or cost effectiveness concept covers the measure of a system in terms of total dollar value. System worth encompasses the elements of system effectiveness (a quantitative measure of a system's technical ability) as well as cost. One of the elements of system effectiveness is maintainability. Maintainability is an effective mechanism for the accomplishment of planned maintenance during the early design and development phases of a system. Planned maintenance is an element of integrated logistics support. The intent of this paper is to outline the basic elements associated with system worth, system effectiveness, and integrated logistics support, to outline the interrelation-ships of these concepts, and to cover the discipline of maintainability as an element of each concept. View full abstract»

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  • Effect of Dimensions on the Efficiency of Radiant Energy Cells

    Publication Year: 1967 , Page(s): 195 - 201
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    This paper deals with the enhancement of the quantum efficiency and photovoltaic energy conversion efficiency of a p-n semiconducting cell by optimizing the dimensions of the cell. Based on the Shockley-Read statistics a general expression for the quantum efficiency of monochromatic incident radiant energy photons has been derived in terms of the absorption coefficient of the incident photons, the minority carrier diffusion length, the built-in electrostatic field appearing in diffused cells, and the surface recombination velocity in the exposed layer of the cell. Although the expressions derived may be used for all semiconducting p-n cells, special efforts have been made in the analysis and computations of the germanium p-n cell. The germanium cells show a great potential for photovoltaic energy conversion from radiant sources other than the sun. The results for germanium indicate that the quantum efficiency strongly depends upon the thicknesses of the exposed and base layers. The built-in electrostatic field and the surface recombination velocity in the exposed layer influence the quantum efficiency greatly. Optimization studies for the thicknesses of the exposed and base layers of an n-p type germanium for different values of minority carrier diffusion length, built-in electrostatic field, and surface recombination velocity have been worked out. View full abstract»

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  • Aerial Mapping Planetary Bodies

    Publication Year: 1967 , Page(s): 202 - 206
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    Photographic mapping missions over planetary bodies present a number of interesting hardware, operational, data retrieval, and data analysis techniques. Broadly speaking, such a mapping mission can be conducted with present level state-of-the-art equipment. The space-craft and photographic equipment must perform over long periods of time unattended in the hostile space environment. Operations must support the mission and retrieve the photographic data. Maximum data are limited by photographic capacity, operations capacity, and analysis capacity. Data analysis techniques are under development and computer maps have been developed for RANGER analysis; these techniques can be especially suited to analysis of the video (analog or digital) signal transmitted back to Earth. View full abstract»

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  • Atmospheric Distortion of Signals Originating from Space Sources

    Publication Year: 1967 , Page(s): 207 - 216
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2578 KB)  

    The phasefront distortion imposed on space signals by fine-grained refractivity variations of the atmosphere is an important consideration in the design of large-aperture antennas, antenna arrays, antenna systems for measuring spacecraft position and position-rate, and radioastronomy systems. The distortion caused by ionospheric and tropospheric refractivity variations imposes fundamental limitations on the capabilities of these antennas and antenna systems, particularly on systems which must operate at low elevation angles. The purpose of this paper is to present numerical estimates of distortion imposed on signals passing through the atmosphere. Atmospheric models based on available literature are selected for this purpose. View full abstract»

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  • Synthetic Aperture Radar

    Publication Year: 1967 , Page(s): 217 - 229
    Cited by:  Papers (53)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2520 KB)  

    The general theory of side-looking synthetic aperture radar systems is developed. A simple circuit-theory model is developed; the geometry of the system determines the nature of the prefilter and the receiver (or processor) is the postfilter. The complex distributed reflectivity density appears as the input, and receiver noise is first considered as the interference which limits performance. Analysis and optimization are carried out for three performance criteria (resolution, signal-to-noise ratio, and least squares estimation of the target field). The optimum synthetic aperture length is derived in terms of the noise level and average transmitted power. Range-Doppler ambiguity limitations and optical processing are discussed briefly. The synthetic aperture concept for rotating target fields is described. It is observed that, for a physical aperture, a side-looking radar, and a rotating target field, the azimuth resolution is ¿/¿ where ¿ is the change in aspect angle over which the target field is viewed, The effects of phase errors on azimuth resolution are derived in terms of the power density spectrum of the derivative of the phase errors and the performance in the absence of phase errors. View full abstract»

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  • A Digital System for Accurate Time Sector Division of a Spin-Stabilized Vehicle

    Publication Year: 1967 , Page(s): 230 - 235
    Cited by:  Papers (1)
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    This paper describes an aspect system flown on PIONEERS VI and VII2 which incorporates an extremely accurate adaptive digital computer in order to define rigorously equal time intervals which are submultiples of the spacecraft spin period. The several submultiples which compose the complete spin period exhibit equality to within 2.5 parts in 105. This system has potential applications in other experiments involving the study of the angular dependence of cosmic radiation and other physical phenomena being measured by a single directional detector mounted on spin-stabilized spacecraft. Included here are the scientific goals for this experiment, system restraints, and the generalized system operation. Some details on specific logic and hardware implementation for the Pioneer experiments are included along with in-flight performance evaluation of the system aboard PIONEER VI. View full abstract»

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  • Telemetry Transmitters Using Solid-State Wideband Microwave Voltage-Controlled Oscillators

    Publication Year: 1967 , Page(s): 236 - 241
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2540 KB)  

    A practical approach for meeting the immediate and future needs of communication systems that require very wideband transmitters capable of operating in the S-, C-, and X-band frequency ranges is described. Included are: 1) a review of the basic studies conducted to determine the most practical transmitter approach for wideband applications; 2) a discussion of a prototype 10-watt frequency-modulated transmitter developed to demonstrate the feasibility of a wideband system; and 3) a review of the preliminary computer analyses and empirical results obtained on the development of a unit capable of wide deviation with reasonable linearity at baseband frequencies up to 10 Megahertz. View full abstract»

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  • Synthesis of Computationally Efficient Sequential Linear Estimators

    Publication Year: 1967 , Page(s): 242 - 249
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    The Kalman sequential linear estimation theory, although not always utilized because the number of computations required for many systems of practical importance becomes prohibitive, allows straight-forward synthesis of optimal estimators for many complex systems. Some systems designers have chosen to ignore variables and by such a reduction in system dimension have been able to economize with regard to the number of computations. The purpose of this paper is to demonstrate a method which allows economy of computation by partitioning the system state vector; the variables to be eliminated are placed in one subsystem and the remaining variables in one or more additional subsystems. The resultant system is computationally more efficient if some variables are eliminated. This is so because the remaining states have been partitioned into two or more subsystems. The number of computations for a subsystem varies approximately as the cube of the dimension of its state vector. By operating on several subsystems of lesser dimension than that of the unpartitioned system, the number of computations is decreased; performance will deteriorate. The method for determining the partitioning tends to keep this deterioration under control; it is illustrated by application to a marine-type inertial navigation system. View full abstract»

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  • Omnidirectional Instantaneous Direction Finding System

    Publication Year: 1967 , Page(s): 250 - 256
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3970 KB)  

    A system for providing near-instantaneous determination of the azimuthal angle of arrival of a received signal has been designed and fabricated at L band. Direction is determined by phase measurement of the outputs of a multimode antenna, which has no moving parts. Effects of multipath interference are reduced to a minimum through a combination of signal processing techniques. The position of the transmitting source is presented on a PPI display. View full abstract»

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  • A communications void - its cause and cure

    Publication Year: 1967 , Page(s): 257
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    Freely Available from IEEE
  • Opening Remarks at the 2nd International Congress on Instrumentation in Aerospace Simulation Facilities

    Publication Year: 1967 , Page(s): 258
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    First Page of the Article
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  • Plasma Sheaths of Models in Hot-Shot Wind Tunnels

    Publication Year: 1967 , Page(s): 259 - 268
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    The nitrogen flow characteristics around models is studied with a view to obtaining data which determine the physical state of the plasma. Among all possible techniques, the most adaptable to the special hot-shot conditions¿electrostatic probes and VHF microwave reflectometry¿is chosen. The experimental apparatus and results in nitrogen are described. The ionization is not homogenous during the shot; this result seems to confirm the assumption that the plasma flow is utilizable only after a delay of more than ten milliseconds following the shock formation period. The hot-shot utilization range is examined for this type of experiment. View full abstract»

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  • Density and Temperature in Wind Tunnels Using Electron Beams

    Publication Year: 1967 , Page(s): 269 - 284
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3312 KB)  

    In a paper presented at the last meeting of the International Congress on Instrumentation in Aerospace Simulation Facilities, a method of measuring gas density by radiation scattering was presented. Since that time, the method has been further developed using scattering of 50-keV electrons and has been applied in a wind tunnel using air as a test gas. Test section temperature and density were in the neighborhood of 150°K and 6×10-8 g/cm3. In this application, accuracies better than 1.0 percent appear to be attainable, together with excellent spatial and temporal resolution. The application is described, and comprehensive design data are presented. In addition, the density measurements have been supplemented by measurements of the local rotational temperature, utilizing nitrogen molecular band radiation excited by a second electron beam. Comparisons between the density and temperature measurements and flow properties obtained by standard gas-dynamic calculations are made. View full abstract»

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  • Absolute Radiometer for the Flow Field of a Hypervelocity Projectile

    Publication Year: 1967 , Page(s): 285 - 296
    Cited by:  Papers (1)
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    As part of a hypervelocity instrumentation development program, it was desirable to include a radiometer system for measuring absolute radiation from projectile flow fields. A system employing a photomultiplier tube was designed, and laboratory and range experiments were conducted to investigate its performance characteristics. The laboratory experiments show that the linearity, saturation, and noise characteristics are suitable for this measurement; the system bandwidth is adequate to allow low frequency calibrations to be applied to high frequency measurements; and a derived expression for radiometer sensitivity variation as a function of photomultiplier supply voltage is reasonably correct. The results of the range experiments imply that the system response is sufficient to reproduce accurately input pulses as narrow as one microsecond and that a particular analytical technique for calculating the form of the radiative input to the radiometer from the projectile stagnation region is valid. Principles involved in the design of photomultiplier radiometer circuits of this type are discussed in detail. View full abstract»

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  • In-Flight Mass Measurement of Small Fragments and Projectiles

    Publication Year: 1967 , Page(s): 297 - 302
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2271 KB)  

    Penetration and cratering studies at hypervelocities make use, primarily, of light gas guns and explosive devices to accelerate projectiles for the impact study. The highest velocities achievable to date with other than micron-sized projectiles are obtained from explosive accelerators (shaped charge) or modified light gas guns incorporating a third stage. Such devices produce one or more randomly shaped particles of undetermined mass; and meaningful impact studies at very high velocities require a method of accurate measurement of the mass of a small fragment after acceleration but before impact. An experimental technique for mass measurement, which is simple in concept and operation, has been developed and demonstrated. A high-speed flash X-ray system is used to photograph the projectile or projectiles in flight. A theoretical treatment utilizing the X-ray mass absorption coefficient of the projectile material, and the linearity of the film density as a function of the logarithm of the exposure, is used to demonstrate that the density change over a finite area of the film is directly proportional to the mass in the path of the X-ray beam. The measurement is independent of ``blurring'' due to the finite exposure time and tumbling of the projectile. Analysis of the exposed film can be conducted in a few minutes and requires only the measurement of average density at five or six positions on the film. Independent measurements of the masses of all projectiles in the field of view are possible. The demonstrated accuracy of the technique is better than ±5 percent. View full abstract»

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  • Doppler Radar for Impact Drag Measurements

    Publication Year: 1967 , Page(s): 303 - 308
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2594 KB)  

    A Doppler radar tracking system has been used successfully to measure impact drag coefficients for several water-entry configurations. Hemisphere-cylinder and cone-cylinder models were launched vertically into a tank of water at velocities between 100 and 200 feet per second. These launchings were evaluation tests for a system to be used in a new facility at the Naval Ordnance Laboratory¿the Hydroballistics Tank. Planned launchings in that facility will be at velocities up to 3000 feet per second. Knowledge of the drag coefficient profile (CD versus depth of penetration) is important in the design of high-velocity water-entry weapons. View full abstract»

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Aims & Scope

IEEE Transactions on Aerospace and Electronic Systems focuses on the equipment, procedures, and techniques applicable to the organization, installation, and operation of functional systems designed to meet the high performance requirements of earth and space systems.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Lance Kaplan
Army Research Laboratory