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Aerospace and Electronic Systems, IEEE Transactions on

Issue 5 • Date Sept. 1975

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Displaying Results 1 - 25 of 39
  • Table of contents

    Publication Year: 1975 , Page(s): c1 - 980-b
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    Freely Available from IEEE
  • IEEE Aerospace and Electronic Syatems Society

    Publication Year: 1975 , Page(s): c2 - 980a
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    Freely Available from IEEE
  • From the Editor-in-Chief

    Publication Year: 1975 , Page(s): 693
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    Freely Available from IEEE
  • Chi-Square Target Models of Low Degrees of Freedom

    Publication Year: 1975 , Page(s): 694 - 707
    Cited by:  Papers (1)
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    First Page of the Article
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  • Doppler-Tolerant Classification of Distributed Targets -- A Bionic Sonar

    Publication Year: 1975 , Page(s): 708 - 724
    Cited by:  Papers (8)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5609 KB)  

    Sonar echo analysis that is not affected by relative motion between target, transmitter, and receiver is discussed. Motion-tolerant measurement and recognition of range-distributed targets involves: 1) a determination of the effects of range rate upon echoes from non-planar reflectors and 2) the derivation of a signal, filter bank, and target parameterization scheme that is insensitive to those effects. The appropriate system is derived, simulated with a computer, and tested with actual echoes from various targets. The system's signals and filters are very similar to those found in biological sonars. View full abstract»

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  • Absolute Electron Density Measurement Techniques in Hypersonic Wakes

    Publication Year: 1975 , Page(s): 725 - 740
    Cited by:  Papers (1)
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    New techniques have been evolved for the application of Langmuir probes to the measurement of electron densities in the wakes of hypersonic projectiles flown in ballistic ranges. These techniques concern probe cleanliness, minimization of flow disturbance, minimization of reflected shocks, and the effect of plasma potential. Electron density level estimates obtained with the probes in sphere wakes were in good agreement with electron density estimates derived from simultaneous measurements with a microwave interferometer. View full abstract»

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  • A Modified Monopulse Technique for Radar Tracking with Low-Angle Multipath

    Publication Year: 1975 , Page(s): 741 - 748
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2050 KB)  

    In this paper a new monopluse technique for reducing radar multipath angle-tracking errors is proposed. The solution is achieved by using two monopulse antennas at different heights. The available signals allow one to control the antenna-height diversity so that the elevation angle control signal is not affected by reflected-wave components. The size of the antenna system may be reduced by properly using phase shifters. A possible configuration of such a system is considered and some practical data on the antenna-height diversity are discussed. View full abstract»

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  • High Range-Resolution Monopulse Tracking Radar

    Publication Year: 1975 , Page(s): 749 - 755
    Cited by:  Papers (8)
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    High range-resolution monopulse (HRRM) tracking radar which maintains wide instantaneous bandwidth through both range and angle error sensing channels provides range, azimuth, elevation, and amplitude for each resolved part of the target. The three-dimensional target detail can be used to improve and extend radar performance in several ways: for improved precision of target location, for target classification and recognition, to counter repeater-type ECM, to improve low-angle multipath tracking, to resolve multiple targets, as a miss-distance measurement capability, and for improved tracking in chaff and clutter. These have been demonstrated qualitatively except for the ECCM to repeater ECM and low-altitude tracking improvement. Initial results from an experimental HRRM radar with 3-ns pulse length show resolution of aircraft into its major parts and precise location of each resolved part accurately in range and angle. Realtime closed-loop tracking is performed on aircraft in flight using high-speed sampled, digitized, and processed HRRM range and angle video data. Clutter rejection capability is also demonstrated. View full abstract»

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  • Noise and Transmission Delays in Mutual Synchronization Systems

    Publication Year: 1975 , Page(s): 756 - 767
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2886 KB)  

    This paper considers the effects of noise and transmission delays in a phase-averaging mutual synchronization system. The basic analytical ideas are developed with respect to a two-station system which contains first-or second-order analog phase-lock loops. From the equation describing the phase error dynamics of each system, a generalized Fokker-Planck equation is derived. It is used to obtain a good approximate analytic expression for the phase error probability density function (PDF), which is confirmed by simulation. An important quantity for such mutual synchronization systems, under random disturbances, is the variance of the frequency deviation. This may be obtained directly from a knowledge of the phase error PDF. The above development is then extended to a mutual synchronization system of arbitrary size. View full abstract»

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  • Constrained Improvement MTI Radar Processors

    Publication Year: 1975 , Page(s): 768 - 780
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2889 KB)  

    A new class of staggered PRF MTI radar processors is developed in this paper. These processors are constrained to achieve a specified value of MTI improvement and, subject to this constraint, minimize variations in processor response as a function of target Doppler frequency. The selection of both filter weights and PRF stagger sequences is discussed and a number of representative designs are presented. View full abstract»

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  • The Susceptivity of MTI Systems to White Noise

    Publication Year: 1975 , Page(s): 781 - 784
    Cited by:  Papers (1)
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    The performance of various coherent MTI systems in the presence of white noise is investigated. The single-pulse signal-to-noise ratios at the output of the filters are presented for the case of large system bandwidth. Generalized results, calculated as a function of the system's bandwidth, are given. Finally, those results are compared to the optimum signal-to-noise acheivable by a matched filter. View full abstract»

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  • Applications of Mininum Variance Reduced-State Estimators

    Publication Year: 1975 , Page(s): 785 - 794
    Cited by:  Papers (5)  |  Patents (8)
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    This paper presents an algorithm for a class of suitably constrained reduced-order filters which minimize the variance of the estimated variables. The algorithm generates both the filter gain history and the true estimation error covariance. The algorithm provides a quantitative criterion which can be used to measure the performance of any reduced-order estimator. Both continuous and discrete estimators are considered. Several examples are treated including an application of the technique to a hybrid navigation system of high order. View full abstract»

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  • Multiple Target Effects on Monopulse Signal Processing

    Publication Year: 1975 , Page(s): 795 - 804
    Cited by:  Papers (10)
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    Analysis of a typical amplitude-comparison monopulse angle-tracking radar shows that gain variation and bias in the radar error signal can occur under certain conditions involving multiple targets. The general behavior depends on the Doppler separation of the targets relative to system bandwidths; for a specific situation, the gain variation and bias are functions of the relative strengths of the targs. The analysis is shown to be consistent with experimental observations. View full abstract»

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  • Single Channel Per Carrier Satellite Repeater Channel Capacity

    Publication Year: 1975 , Page(s): 805 - 813
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4645 KB)  

    This paper analyzes the performance of a number of modulation and speech processing techniques that have been considered for single voice channel per carrier transmissions via satellite. This transmission mode is applicable to demand assignment systems, which make possible the most efficient loading of the satellite transponder in applications where the traffic at individual Earth terminals is not sufficient to justify a substantial number of dedicated channels. The analysis basically determines the operating point for the satellite transponder which minimizes the required Earth terminal G/T. The fraction of the total link noise allocated to uplink noise is treated as a parameter, so that the cost of improving G/T may be traded against the cost of providing increased Earth terminal transmitter power. Both analog and digital modulation techniques are considered, together with various practical combinations of syllabic companding, voice-actuated carriers, and error-correcting codes. The results are presented in general analytic form, applicable to any modulation technique for which carrier-to-noise density ratio, channel width, and guardband width may be specified. Curves showing required G/T as a function of the total number of voice channels per transponder are also presented for the above-mentioned signal processing techniques, assuming "CCIR/CITT type" speech quality and transponder EIRP and bandwidth typical of current domestic satellite configurations. View full abstract»

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  • Digital Automatic Flight Control

    Publication Year: 1975 , Page(s): 814 - 815
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  • Digital Flight Control: An Approach to Efficient Design

    Publication Year: 1975 , Page(s): 816 - 828
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    Previous digital design experiences provide guidance and offer solutions for one of the newest digital technology applications: The commercial transport AFCS. In addition to facing well-documented problems of software control and maintainability, operational safety adds a new dimension to the requirements for software reliability. After a general discussion of the problems encountered in past digital system programs, this paper addresses the specific requirements of the commercial transport system and their implications in terms of system architecture and software development. An immproved solution to the problem of software design is offered, and its impact on traditional and future problem areas is outlined. A description of a prototype digital AFCS under development is presented. The experiences to date with this system reinforce the correctness of techniques and approaches used in its development. View full abstract»

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  • Architecture Considerations for Digital Automatic Flight Control Systems

    Publication Year: 1975 , Page(s): 829 - 840
    Cited by:  Papers (1)  |  Patents (1)
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    Functional partitioning, redundancy structure, internal communications, and software modularization define the architecture of a digital automatic flight control system (DAFCS). Selection of a suitable system architecture for commercial transports involves such factors as the functional scope, growth provision and flexibility requirements, sensor interfaces, the aircraft's actuator and control surface redundancy, and the dispatch reliability requirements. Trade-offs concerning these various factors are discussed, and it is shown that a very versatile and almost universal DAFCS can be configured to meet the general and peculiar needs associated with each aircraft application. Specific results associated with this system's recent demonstration flights in the DC-10 aircraft, as well as examples from several other transport aircraft applications of the same DAFCS architecture, are used to illustrate the design concepts. View full abstract»

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  • Use of Fiber Optics in Digital Automatic Flight Control Systems

    Publication Year: 1975 , Page(s): 841 - 850
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4832 KB)  

    The availability of digital MSI and LSI has made digital flight control systems more cost effective than analog systems for all but the simplest systems. The organization of a digital flight control system is concerned not only with implementation of the control laws and associated logic but also with the management of the data used in these computations and the organization of the computation. The configuration taken by a digital flight control system is dominated by the integrity and data handling requirements. This paper considers the impact of these factors on the design and operation of digital flight control systems with particular emphasis on the use of fiber optics for transmission of data between lanes. View full abstract»

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  • Digital Computation Makes AFCS More Reliable

    Publication Year: 1975 , Page(s): 851 - 861
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    In airline service the reliability of a system is more than the confirmed failures for the system; it is the total removal experience of the system. Thus, the reliability of a system lies not only in the piece part failure rates, but also in the capability to verify and isolate failures. The application of digital technology brings several significant reliability improvements to automatic flight control systems (AFCS) when compared to contemporary analog systems. These advantages are demonstrated by the experience of the digital air data computer (DADC) of the DC-10 and the digital AFCS of the JA-37 Viggen. Experience with this equipment is reviewed, and the results are interpreted in terms of projections for airline DAFCS reliability. The digital system built-in test implemented by a stored program and the central processor gives a system integrity and dispatch reliability unequaled by analog systems. This high-integrity self-test reduces removal rates by giving line personnel a trustworthy tool and more complete automatic test processes for verifying maintenance actions. Digital circuit technology is directly suitable to largescale integrated circuits (LSIC) which reduce piece part counts and improve LRU reliability. Digital circuits are less subject to drift and the attendant difficulty to detect failures. These factors, coupled with the inherent high-integrity self-test, provide the basis for a significant improvement in reliability by the use of a digital automatic flight control system. View full abstract»

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  • Digital Automatic Flight Control is the Answer - What is the Question?

    Publication Year: 1975 , Page(s): 862 - 882
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    Beginning with process controls in the mid fifties, digital control systems have seldom met all the claimed advantages and in many cases have been outright failures. Airborne digital computers have just begun to appear in the commercial jet transport market after several years of experimental and military development. The success of these systems in meeting user expectations has not been overwhelming, which leads to the question: Why change from known analog flight control technology to digital? This paper examines that question by reviewing the state of the art in analog flight control system technology and evaluating this against current airline problems. A realistic means of evaluating claimed advantages for new technology is thus established. The advertised solutions of digital technology to analog problems are examined and, in some cases, debunked. However, consideration of the real problems and the capabilities of digital systems leads to the conclusion that there is a real payoff. Evidence from background studies at Boeing is offered to support this conclusion. A description of the digital flight control system electronics (FCSE) development program for the new Boeing 7×7 airplane is also provided. This program is currently in progress, and its specific objective is to assure that the real payoff is achieved for the subsequent production system. View full abstract»

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  • Some Aspects of SST Airborne Equipment Application

    Publication Year: 1975 , Page(s): 883 - 889
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    This paper begins with a review of the advantages of SSTs over subsonic aircraft for long-range travel in Russia. It then describes the navigation and control equipment used in the Russian SST. the TU-144. The reliability of this automatic navigation and control equipment (as well as other equipment) is increased through the use of redundant components. Weight, space, and serviceability requirements and their effect on equipment design are discussed. View full abstract»

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  • Software in Digital System: An Engineer's Approach

    Publication Year: 1975 , Page(s): 890 - 897
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  • Digital Automatic Flight Control

    Publication Year: 1975 , Page(s): 898
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  • Improvement Factor of the Phase-Sensitive Noncoherent MTI

    Publication Year: 1975 , Page(s): 899 - 902
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    The phase-sensitive noncoherent MTI detects targets by relative motion between the target and an extended clutter background. In this type of MTI, the phase of the target is compared with the phase of the clutter in an adjacent range bin. Theoretical analysis of the system's performance is presented. The improvement factors for single- and double-delay periodic filters are derived and computational results are included. View full abstract»

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  • The Effect of Rotating Antennas and Signal Polarization on Doppler Shift

    Publication Year: 1975 , Page(s): 903 - 905
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    A study is made of a transmitting antenna spinning relative to a receiving antenna, showing that the received signal undergoes a phase shift which depends upon the relative orientation and the ellipticity conditions of the two antennas. It is shown that this phase shift is important in Doppler distance measuring equipment because it must not be confused with the phase shift caused by the changing distance between the antennas. 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.

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Meet Our Editors

Editor-in-Chief
Lance Kaplan
Army Research Laboratory