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Aerospace and Electronic Systems, IEEE Transactions on

Issue 6 • Date Nov. 1968

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Displaying Results 1 - 21 of 21
  • [Front cover]

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

    Page(s): nil1
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  • [Breaker page]

    Page(s): nil1
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    Freely Available from IEEE
  • From the Editors

    Page(s): 821
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  • Clutter Suppression Properties of Weighted Pulse Trains

    Page(s): 822 - 828
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    A common but troublesome requirement on radar sensors is the detection of a target in the interference from undesired scatterers, or clutter. Systems with coherent processing of pulse trains are uniquely suited for the purpose because, with pulse trains, it is possible to concentrate the receiver output for particular values of Doppler and thus suppress the clutter by Doppler filtering. This paper discusses to what degree the effectiveness of the method can be enhanced by tapering, or weighting, of the pulse amplitudes. The general results are illustrated by computer-plotted response functions for weighted pulse trains. The clutter suppression efficiency of weighting is calculated both for unilateral weighting in the receiver and for bilateral weighting in both receiver and transmitter. The significance of additional phase weighting is discussed and the results for pure amplitude weighting are compared with publishedwork on phase and amplitude weighting. View full abstract»

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  • A Self-Adjusting Single-Degree-of-Freedonm Free-Fall Environment Simulator

    Page(s): 829 - 836
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    The free-fall space environment can be simulated on earth by using a test apparatus enjoying the property that its center of mass and center of rotation coincide. Such a condition can be realized by appropriately distributing mass about the center of rotation. This paper describes the mechanization and operation of a system that automatically distributes mass about the test apparatus center of rotation to cause the center of mass to be located within a prescribed distance below the center of rotation. The operating concept for the single-degree-of-freedom simulator is presented. A prototype system was constructed and tested to verify the feasibility of the concept. The system functioned as predicted and test table periods in excess of 60 seconds were obtained. View full abstract»

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  • Electronically Variable Time-Delay Network for Broad-Band Phased-Array Steering

    Page(s): 837 - 844
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    This paper describes an electronically variable time-elay network that has been developed specffically for time-delay steering of a phased-array antenna. The network consists of microwave dispersive delay lines and two broad-band mixers; its delay is a function of the mixers' local oscillator frequency. The particularly advantageous feature of this network is that its phase is invariant with delay. It can, therefore, be used on a subarray basis, and at IF, without affecting the phase progression across the array. Alternative techniques, such as electron-beam delay lines and digitally switched line lengths, require external phase correction. A breadboard model of the network has been built and tested. Low-loss folded-tape meader lines provide the dispersive delay. The center frequency of the model is 3 GHz; it handles an instantaneous bandwidth of 300 MHz. Delay variation of 25 ns is provided. The spurious responses of the network are 30 dB down. View full abstract»

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  • Multiple-Target Monopulse Radar Processing Techniques

    Page(s): 845 - 854
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    The problem of determining target parameters of a known number of radar targets falling in the same range-Doppler-angle-angle resolution cell is examined for the noise-free case. The required minimum number of radar beams is determined, based upon approximating the beam patterns by a Taylor series expansion, both for the general problem and for factorable beams. Signal processors for target position estimation are developed for the two-target case and equations are presented for the general case. View full abstract»

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  • Threshold Investigation of Phase-Locked Discriminators

    Page(s): 855 - 863
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    This paper is primarily an investigaton of a second-order phased-locked loop in the threshold region, with the loop filter chosen as (1/1+¿s) or (1+¿1s/1+¿s). First-order loop results are also given. Effects of loop parameters, detuning error, and modulation are studied. It is shown that the loop with filter (1+¿1s/1+¿s) can be built two ways with same bandwidth and damping. One loop gives much better threshold than the other. The analytical results are supported by computer simulation as well as experimental work obtained by hardware simulation of the loop. View full abstract»

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  • The SDP-1 Stored-Program Computer

    Page(s): 864 - 870
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    A stored-program computer could be used to advantage on small scientific spaeeraft because of its flexibility. This paper describes the design and programming of a stored-program computer specifically adapted to this particular application. In order to be suitable for use in a small scientific spacecraft, a computer must have the following characteristics: reliability, low power drain, light weight, small size, problem-solving power, and flexibility. To meet these requirements, a computer was designed that has 1024 words of program memory and 512 words of data memory. The words are 12 bits in length and both memories are randomly accessed. In order to protect the program, the program memory is of the nondestrutive read-out type. The data memory is the conventional read/write variety. The computer is organized such that the power drain is small and less hardware is required by restricting parallel gating of information, number of registers, and number and complexity of instructions. Considerable effort has been devoted to programming the computer. Analysis shows that it takes on the order of two milliseconds to perform one of the floating-point operations. These limitations should be acceptable; the computer is not expected to be required to perform extremely complex or lengthy computations. View full abstract»

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  • Strapdown Gyros in a Back-to-Back Configuration

    Page(s): 871 - 873
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    A back-to-back connection of two gyros per axis is suggested that eliminates some of the errors due to cross coupling between the components of vehicle angular rates and accelerations. In particular, the error due to output axis angular acceleration, the anisoinertia error, and the spin reference axis rectification error theoretically vanish. Use of redundant and identical strapdown systems for the purpose of obtaining higher reliability makes this connection practical. View full abstract»

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  • Comparison of Electrooptic Modulation Methods

    Page(s): 874 - 878
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    A comparison is made among normal AM, wide-band analog FM, and PCM as applied to transmission of real-time TV pictures via an electrooptic space communication system. The comparison is based on the requirement to receive a subjectively noise-free TV picture. Based on the results of this comparison, it is concluded that analog-FM subcarrier modulation is the best practical choice for transmission of real-time TV pictures in space via a laser beam. In addition to providing performance equivalent to that of coherent PCM, this type of modulation can be implemented with comparatively simple equipment. View full abstract»

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  • Optical Processing Techniques for Simultaneous Pulse Compression and Beam Sharpening

    Page(s): 879 - 885
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    A technique is described in which the separate techniques of beam sharpening (by synthetic antenna methods) and pulse compression are converted into a single two-dimensional operation, which is carried out with a coherent optical processor. View full abstract»

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  • On the Design of a Large Aperture Radar for Target Imaging

    Page(s): 886 - 892
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    This paper describes the design, construction, and performance of an experimental radar, in which an electronically scanned X-band array is employed as the receiving antenna. Backscatter from targets uniformly illuminated from a separate transmitting antenna is intercepted by 128 horn antennas, unequally spaced over a nine-foot circular aperture. The received signals are processed electronically to provide a complete scan of a 30X30 degree field every ten milliseconds. Resulting target images were displayed on a cathode ray tube and recorded on 16-mm motion picture film, for varying conditions of target motion using monochromatic and frequency-modulated X-band illumination. Sequences of motion picture frames obtained from a rotating copper cone are presented, which demonstrate significant changes in the image and side-lobe interference patterns for small changes in target aspect angle. Side-lobe interference effects were reduced by integrating many antenna scans as the target rotated; a clear image of a foil letter R is presented that demonstrated this result. The main objective of this work was to test this radar technique as an approach to target recognition. View full abstract»

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  • Broadcasting of a Digitally Coded List of Transponder Equipped Aircraft Scanned by FAA Ground Radars as a Means of Collision Avoidance, Navigation, Air Traffic Structuring, and Airfield Approach

    Page(s): 910 - 911
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    An air traffic control system is proposed in which 1) all aircraft are equipped wit transponders, 2) FAA radar sites broadcast a digitally coded list of the identity, altitude, and coordinates of aircraft scanned, 3) each aircraft on receiving this list converts it into a PPI display with the blip of that aircraft branded and blips of off-altitude aircraft blanked, and 4) superimposed on this display are projected maps of airways appropriate to the particular radar and the aircraft altitude. This system could provide a fairly complete capability for air traffic control, structuring, navigation, and collision avoidance at a cost of about 3000 dollars per aircraft. It would replace most navigational and communication equipment now in use and could be operational in several years. View full abstract»

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  • Book Review

    Page(s): 912
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  • Abstracts EASCON '68

    Page(s): 913 - 923
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  • Information Transactions Available in Microfiche Form

    Page(s): 924
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  • 1968 Index IEEE Transactions on Aerospace and Electronic Systems

    Page(s): nil2 - nil21
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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