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Aerospace and Electronic Systems, IEEE Transactions on

Issue 6 • Date Nov. 1974

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  • Table of contents

    Publication Year: 1974 , Page(s): c1
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    Freely Available from IEEE
  • IEEE Aerospace and Electronic Systems Society

    Publication Year: 1974 , Page(s): c2 - c4
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    Freely Available from IEEE
  • From the Editors

    Publication Year: 1974 , Page(s): 753
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    Freely Available from IEEE
  • Atomic Power Engineering under Falsified Safety Standards

    Publication Year: 1974 , Page(s): 754 - 764
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2799 KB)  

    In July 1970 the United States Department of Justice accused the American Society of Mechanical Engineers (ASME) of violating the Sherman Antitrust Act and of acting in restraint of trade by restricting the ASME Certificate of Authorization and the use of the Code Symbol Stamps to boilers and pressure vessels manufactured in the United States and Canada. During the succeeding two years attorneys for the parties in the case formulated a Consent Decree without a public confrontation in the Court. Furthermore, the membership of ASME was kept uninformed until October of 1972, after the Consent and Final Judgment had become effective and new procedures had been developed for allowing foreign manufacturers to apply the ASME Code Symbol Stamps to their products. As a consequence, a breakdown in engineered safety standards has been sanctioned and this is undermining the engineering profession's overriding responsibility to protect the public health and safety. This breakdown of professional responsibility is especially serious in the new technology of atomic power. American insurance companies, which have traditionally written 100% insurance coverage for property damage and third party liability against explosions of high pressure steam boilers bearing the ASME Code Stamp, have refused to write such insurance coverage on nuclear reactors. In the author's opinion there is evidence that the Consent was formulated under collusive proceedings and he calls on the members and the Council of ASME to appeal for dismissal of the Consent Decree. View full abstract»

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  • Prediction of Differential Time-e-Delay Errors in HF Hyperbolic Position-Fixing Systems

    Publication Year: 1974 , Page(s): 765 - 769
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1508 KB)  

    Differential time-delay errors in HF hyperbolic position-fixing systems arising from ionospheric propagation time delays are estimated by employing a propagation prediction model for several path-pairs. A comparison of the prediction model results with experimental observations indicates that the differential time-delay errors can be reduced significantly by the use of the prediction model. View full abstract»

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  • Optimum Active Array Processing Structure and Space-Time Factorability

    Publication Year: 1974 , Page(s): 770 - 778
    Cited by:  Papers (14)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2161 KB)  

    An active array processor is concerned with the problem of detecting a signal echo, reflected from a target, in the presence of reverberation (clutter). The processor can also be used to estimate target range and bearing. It is a priori not evident whether the optimum (likelihood ratio) detector can be factored into spatial and temporal operations, thus resulting in a simpler processor implementation. This paper studies this problem for a linear continuous array in a reverberation-limited environment. Conditions on signal, reverberation, and array parameters are derived under which the optimum detector is factorable. The validity of using factorability as a criterion of signal design is briefly examined. Finally, the relationship between space-time factorability and range-bearing estimates is pointed out. View full abstract»

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  • Experimental Results of the Complex Indicated Angle Techique for Multipath Correction

    Publication Year: 1974 , Page(s): 779 - 787
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2920 KB)  

    The complex indicated angle technique, applicable to monopulse radars, is being investigated as a means of overcoming the serious degradation of elevation measurement caused by multipath when the target is within a beamwidth or so of the horizon. This technique makes use of the quadrature-phase component of the normalized difference signal, as well as the in-phase component. Results of analysis and computer simulation have been published previously. This paper reports results of a test program using a slightly modified AN/FPS-16 monopulse tracking radar and a simulated target. The results to date indicate a potential for high accuracy, though there are limitations as to the applications for which the technique appears feasible. A computer program has been developed to perform the elevation estimate and to resolve ambiguities. View full abstract»

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  • Optimal Detection of a Signala with Time-Varying Carrier Phase

    Publication Year: 1974 , Page(s): 788 - 794
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1307 KB)  

    The problem considered in this paper is the detection of a signal known except for time-varying carrier phase in white Gaussian noise. The method of attacking this problem is to model the time-varying carrier phase as a Markov process. Fourier transform techniques are then applies to yield a simple time-wise adaptive form for the phasetracking detector. Optimal accounting for the time variations in phase is accomplished via a simple algorithm which serves to update the detector memory. Furthermore, it is shown that this memory updating operation is a discrete linear filter whose impulse response is a simple function of the previous memory state and the Markov transitional statistics on the phase. A priori knowledge regarding the phase is summarized in the initial impulse response of the updating filter. View full abstract»

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  • Mean-Level Detection of Nonfluctuating Signals

    Publication Year: 1974 , Page(s): 795 - 799
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1120 KB)  

    Analysis of the performance of a mean-level threshold in the detection of nonfluctuating signals is performed. Formulas for the probability of detection are derived and a simple recursive method that can be used for computations is described. Binary integration is discussed, and it is shown that the loss in sensitivity due to the use of an adaptive threshold followed by binary integration is only a fraction of a decibel when compared with optimum binary integration. Binary integration results are given for both fluctuating and nonfluctuating signals. View full abstract»

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  • The Segmented Aperture Synthetic Aperture Radar (SASAR)

    Publication Year: 1974 , Page(s): 800 - 804
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1461 KB)  

    A new concept in synthetic aperture radar, called SASAR, which uses a segmented aperture, is described. Use of the segmented aperture allows appreciable extra receiving antenna gain to be realized. Each subarray of the receive antenna is equal in length to the transmit antenna; the system performance is increased approximately by a factor equal to the number of subarrays. To allow array combination of the subarray signal outputs requires a phase-shift factor (varying with azimuth) to be applied to each subarray signal. A digital implementation of this preprocessor is sketched out; it uses a push-down storage stack to store the range histories for a synthetic aperture from each subarray. Appropriate phase shifts are added to the stacks and a sum of stack values then provides the combined output range history sequence. Possibilities of using analog delay lines for preprocessing are also discussed. Pattern errors due to subarray size and receive array near field are examined and constraints are given. View full abstract»

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  • The MOD:A Modular Urban Transportation System

    Publication Year: 1974 , Page(s): 805 - 810
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    The MOD is described as an urban transportation system which is based on a very small, two-passenger automotive rental vehicle using existing city roadways at the exclusion of the private passenger car. The proposed units of the MOD system have an empty weight of 300 pounds and have provisions for easy vertical parking. The MOD system is proposed as a self-supporting operation, run by private enterprise as a public utility. The urban transportation offered by the MOD system generates the set of institutional problems involved in proposals which exclude the private passenger car from the city. View full abstract»

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  • Frequency-Agility Processing to Reduce Radar Glint Pointing Error

    Publication Year: 1974 , Page(s): 811 - 820
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2308 KB)  

    A technique to reduce radar pointing errors due to glint using frequency agility and amplitude weighting is presented. The reduction in rms tracking error is developed into an equation dependent upon the original glint tracking error, ¿g, and the number of returns weighted, N. The rms tracking error is thereby reduced approximately by a factor of N. Finally, the equation formulated allows one to evaluate the reduction in glint error versus the number of frequencies chosen for frequency agility. View full abstract»

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  • Maximum-Likelihood Detection of Unresolved Radar Targets and Multipath

    Publication Year: 1974 , Page(s): 821 - 829
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2245 KB)  

    Interference in the form of multipath or uncooperative targets can seriously degrade the angle-of-arrival estimation accuracy of mutiplebeam processors. In this paper, the generalized likelihood ratio test is used to derive a test to detect the presence of interference for multiple beam processors. The detector performance is then analyzed in detail with respect to its dependence on signal-to-noise ratio (SNR), signal-to-interference ration (SIR), and on the relative phase between the target and interfering signals. It is shown that good detection performance can be obtained unless the phase difference between the target and interference signals is either in or out of phase. View full abstract»

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  • Application of Linear Statistical Models to Radar Location Techniques

    Publication Year: 1974 , Page(s): 830 - 834
    Cited by:  Papers (29)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1085 KB)  

    The theory of linear statistical models is implemented to obtain an algorithm which accurately locates radar sites. True bearing and navigation data are used as input. The linear model developed is adaptable and allows removal of bearing errors that are nonrandom, or systematic. The model may be written in recursive form and used for real-time applications. View full abstract»

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  • Low-Angle Radar Tracking in the Presence of Multipath

    Publication Year: 1974 , Page(s): 835 - 852
    Cited by:  Papers (43)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4971 KB)  

    This paper is concerned with the problem of tracking radar targets in the low-angle regime where conventional tracking radars encounter difficulty due to the presence of a surface-reflected ray. Starting with a classical maximum-likelihood analysis of the problem of two closely spaced targets, two different techniques are evolved which are theoretically capable of dealing with the multipath problem. The expected accuracy has been studied both analytically and by means of computer simulations. Experimental programs have demonstrated the feasibility of both techniques. The paper also includes a discussion of certain alternative solutions to the problem. View full abstract»

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  • Rapid Convergence Rate in Adaptive Arrays

    Publication Year: 1974 , Page(s): 853 - 863
    Cited by:  Papers (713)  |  Patents (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2270 KB)  

    In many applications, the practical usefulness of adaptive arrays is limited by their convergence rate. The adaptively controlled weights in these systems must change at a rate equal to or greater than the rate of change of the external noise field (e.g., due to scanning in a radar if step scan is not used). This convergence rate problem is most severe in adaptive systems with a large number of degrees of adaptivity and in situations where the eigenvalues of the noise covariance matrix are widely different. A direct method of adaptive weight computation, based on a sample covariance matrix of the noise field, has been found to provide very rapid convergence in all cases, i.e., independent of the eigenvalue distribution. A theory has been developed, based on earlier work by Goodman, which predicts the achievable convergence rate with this technique, and has been verified by simulation. View full abstract»

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  • Performance of the g-h Filter for Tracking Maneuvering Targets

    Publication Year: 1974 , Page(s): 864 - 866
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    The g-h filter is often used as a tracking filter. Assuming that the target under track is modelled as a constant-velocity system with a correlated random acceleration, equations are derived for the covariances of the filtered and predicted estimates. These equations are useful to predict the performance of the filter and to select suitable parameters so as to improve performance. View full abstract»

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  • Optimal Channelization in FDMA Communications

    Publication Year: 1974 , Page(s): 867 - 870
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    For most efficient performance in frequency-division multiple access (FDMA), a hard-limiting repeater should be operated completely channelized (i.e., each uplink carrier should be individually filtered and power-controlled prior to spacecraft limiting and downlink transmission). When there are a large number of uplink carriers involved, however, complete channelization is no longer feasible, and the uplink carriers must be grouped together (assigned frequencies), which allows joint filtering and amplification. In this correspondence, it is shown that an optimal grouping procedure always exists for minimizing required repeater power, no matter how many carriers and groups are to be used. View full abstract»

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  • Effect of Particular Gain Changes upon LFM Sidelobes

    Publication Year: 1974 , Page(s): 870 - 872
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (523 KB)  

    The envelope variation of an LFM waveform due to transmitter droop or receiver STC tends to cause range sidelobes. A parametric analysis of the magnitude of the sidelobes has been performed. It is shown that the sidelobes can be quite high at the matched filter output, but are low at the output of the sidelobe reduction filter. 40-dB sidelobes can be achieved even with a 4-dB envelope droop. It is shown that these results are consistent with conventional paired-echo theory. Similar results are shown to hold for droop variations of the filter transfer function. View full abstract»

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  • MTI Clutter Locking for Arbitrary Clutter Spectral Shapes

    Publication Year: 1974 , Page(s): 872 - 874
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    Clutter-locking criteria for various types of cancellers and clutter spectra are discussed. It is shown that the proper locking criterion for general asymmetric clutter spectra is different from that applicable to those spectra which have even symmetry or are very narrow. View full abstract»

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  • Calculation of Detection Probabilities for Automated Change Detection

    Publication Year: 1974 , Page(s): 874 - 878
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    A general model is presented for calculating detection and falsealarm probabilities for the automated change detector. The model is then applied to determine PD'PF for the ¿target-no target¿ type change; the resulting PD and PF are compared to the one-channel case. View full abstract»

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  • Correction to "Angular Accuracy of a Scanning Radar Employing a Two-Pole Filter"

    Publication Year: 1974 , Page(s): 878 - 880
    Cited by:  Papers (2)
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  • Error Analysis of a Quadrature Coherent Detector Processor

    Publication Year: 1974 , Page(s): 880 - 883
    Cited by:  Papers (19)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (662 KB)  

    A simple method is presented for computing the output signal distortion resulting from relative phase and gain errors between the two quadrature detector channels of a baseband processing system. Signal-to-noise loss and sidelobe levels are computed for two types of waveforms to illustrate the utility of the method. View full abstract»

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  • Resolution of Gaussian Images on a Photoelectrically Emissive Surface

    Publication Year: 1974 , Page(s): 883 - 887
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (764 KB)  

    Error probabilities are calculated for two detectors deciding which of two Gaussian images is present on the basis of the numbers and origins of photoelectrons ejected from the image plane. One detector is the optimum likelihood-ratio detector; the other compares the numbers of electrons from the two halves of the image plane. The results show that the performance of the former is better, although the latter is much easier to operate. View full abstract»

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  • Reconstruction of Target Reflecting Surface Using Differential Geometry

    Publication Year: 1974 , Page(s): 887 - 891
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (817 KB)  

    A procedure based on the envelope concept of differential geometry is described that permits the reconstruction of the contour of a smooth, moving, conducting target, satisfying the geometrical optics approximation. The target reflections are assumed to be specular in nature with either one reflection point or multiple resolvable reflection points. The time variation of the range to the reflection point of the target (assumed derivable from a high-resolution radar) and the general motion of the target (assumed derivable from tracking or trajectory information) are employed to reconstruct the contour of that portion of the assumed target surface that is illuminated by the radar. The reconstruction is accomplished by the simultaneous solution of two nonlinear differential equations which are derived using the envelope concept of differential geometry. Several reconstruction examples based on computer analysis are presented which indicate the results obtainable using this method. 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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Editor-in-Chief
Lance Kaplan
Army Research Laboratory