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Aerospace and Electronic Systems, IEEE Transactions on

Issue 4 • Date July 1967

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Displaying Results 1 - 25 of 27
  • [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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    Freely Available from IEEE
  • [Breaker page]

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

    Page(s): 585
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    Freely Available from IEEE
  • Electrical Characteristics of Silicon Solar Cells at Low Temperatures

    Page(s): 586 - 590
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    Experimentally determined values of open-circuit voltage, short-circuit current, and maximum power for p on n and n on p silicon solar cells are presented for temperatures ranging from -196°C to + 50°C under equivalent space sunlight intensities of 58 mW/cm2 and 268 mW/cm2. An anomalous behavior is observed in the n on p cells at low temperatures; namely, the open-circuit voltage becomes nearly independent of temperature below a transition temperature Tt that depends on the sunlight intensity. View full abstract»

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  • On the Acquisition Time for an Apollo Ranging Code

    Page(s): 591 - 595
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    An Apollo ranging system is considered whose phase reference is obtained by a phase-locked loop for bit synchronization. The bit phase reference is noisy, and the error probability for the ranging code is shown to depend on the input signal energy per bit to noise density ratio. The procedure of computing the acquisition time for the ranging code is then presented and the acquisition time for a lunar ranging code is plotted versus the input signal-to-noise density ratio. View full abstract»

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  • Semiconductor Surface Thermocouples for Determining Heat-Transfer Rates

    Page(s): 596 - 603
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    Possible methods of increasing the sensitivity capabilities for determining heat-transfer rates associated with wind tunnel testing have been investigated. Techniques utilizing surface thermocouples of conventional thermocouple materials do not provide the necessary temperature sensitivity to low heat-transfer rates. This need for increased sensitivity has resulted in development and evaluation of surface thermocouples fabricated from semiconductor materials. Calibration of the semiconductor surface thermocouple has disclosed temperature sensitivity on the order of 35 times that of chromel-constantan thermocouples. This increased sensitivity has established confidence in the potential value of this concept and further investigation and evaluation are presently being conducted. View full abstract»

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  • Random Characteristics of the Type II Phase-Locked Loop

    Page(s): 604 - 612
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    The results of a study of the characteristics of the second-order Type II phase-locked loop with a Gaussian noise input, and obtained by digital computer simulation, are presented. The digital simulation is described and the random state variables are defined such that their characteristics can be interpreted in terms of existing phase portraits of autonomous phase-locked loops. The statistics associated with the state variables, which are phase error and a measure of frequency error, and those associated with the number of cycles skipped and the mean time to unlock, are given. View full abstract»

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  • Continuous Measurement of Shock and Contact Discontinuities Velocity

    Page(s): 613 - 622
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    An experimental method applying microwave techniques to obtain continuous measurement of both the shock and contact discontinuities bounding an air plasma generated in a cylindrical hypersonic shock tube is developed. X-band microwave signals excited in the TE11 mode reflect from the moving shock and contact surfaces. The resulting FM interference pattern is demodulated, yielding continuous velocity versus time data. Results depicting subtle detail of velocity behavior, particularly of the shock front, were obtained over a shock Mach number range of 9 to 13. View full abstract»

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  • Autonomous Upgrading of Inertial Navigation Systems

    Page(s): 623 - 636
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    The performance of substandard inertial platform gyros can be improved through the sampled supervision of their operation by a higher grade gyroscope mounted directly on the platform. The relative drift rates of the susbstandard platform gyros are estimated on a cyclical basis. This paper describes techniques for estimating the drift rates. It deals with the method of applying these estimated values in the form of platform correction signals. View full abstract»

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  • Fourier Analysis of Commutated-Capacitor-Type Integrator Output Signal

    Page(s): 637 - 642
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    It is shown that an operational amplifier with four commutated capacitors in the feedback path produces an output signal whose fundamental is equal in magnitude but 180 degrees out of phase with the input. The analysis is carried out by expressing the output signal in a Fourier series. View full abstract»

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  • Accuracy of Star Occultation Measurements for Satellite Navigation

    Page(s): 643 - 655
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    To determine the orbital parameters of a satellite using star occultations, it is necessary to measure the intensity of stars as they occult. The accuracy of the intensity measurements is reduced by interfering sources of light and internal noise, and is expressed in terms of the magnitude of various sources of interference. Subsequently, a specific system is analyzed in detail. Moonlit cloud tops introduce the largest systematic error. Photon noise from the star radiation, airglow, and moonlit cloud tops are the largest sources of random errors. View full abstract»

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  • Synthesis of Ambiguity Functions for Prescribed Responses

    Page(s): 656 - 663
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    The synthesis of radar ambiguity functions is approached using burst-pulse time-frequency waveform coding. Noting that the parameters that define the central response of the ambiguity function for these code classes also define the waveform code, a statistical decision procedure based upon the central response is employed to obtain Bayes-type codes. The selection of the code parameters is subject to restrictions imposed by the noncentral response of the ambiguity function. Three classes of random time-frequency codes are treated: 1) uniform amplitude, uniform pulsewidth matched codes; 2) uniform amplitude, nonuniform pulsewidth matched codes; and 3) uniform amplitude, uniform pulsewidth with receiver amplitude mismatch. View full abstract»

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  • Satellite Tracking Simultaneous-Lobing Monopulse Receiving System with Polarization Diversity Capability

    Page(s): 664 - 680
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    A 136-MHz to 10-GHz simultaneous-lobing monopulse receiving system, utilizing polarization diversity in both coherent (phase-lock) and noncoherent (nonphase-lock) operational modes, has been developed for the National Aeronautics and Space Administration (NASA) Space Tracking and Data Acquisition Network (STADAN). This sum-and-difference monopulse system, called APDAR (Advanced Polarization Diversity Autotrack Receiver), utilizes a maximalratio polarization diversity combining technique that matches the receiving antenna polarization to the incoming variable polarization from a spin-stabilized or tumbling satellite. Autotrack performance becomes independent of the incoming polarization orientation by continuous in-phase addition of the carrier-signal components from orthogonal antenna elements. This technique relies upon the principle that fading does not occur simultaneously on oppositely polarized receiving channels. APDAR results in improved autotrack performance by eliminating adverse effects of severe (over 30-dB) cross-polarization fading. The predetection diversity combining technique employed provides an average 3-dB signal-to-noise (SNR) improvement. This paper describes a series of 136-MHz satellite tracking tests and analyzes a maximal-ratio predetection diversity combiner, a three-loop phase-lock loop system, and a frequency-switched radiometer. View full abstract»

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  • Linear Minimum Variance Estimation with Complex Phase Errors

    Page(s): 681 - 687
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    The linear minimum variance estimator of a random signal, received multiplied by a complex Gaussian phase error and added to random noise, is investigated. The results apply to the propagation of images through the turbulent atmosphere, fading channels, and synthetic-aperture radar. Among others, a result is that the multiplicative error can be replaced by an additive error, usually white. The best signal modulation is found in two important special cases. View full abstract»

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  • The Use of Environmental Stress in Conjunction with Simulation Testing

    Page(s): 688 - 696
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    Large-scale vehicle simulations in which human subjects are exposed to realistic environmental profiles are well within the engineering state-of-the-art. The Boeing Multiple-Stress Laboratory is capable of exposing subjects to heat, noise, vibration, and altitude, while measuring their performance and physiology. Data have been obtained on simulations relative to fixed-wing aircraft, helicopters, and three-stage boosters. Exposure periods have ranged from a minimum of 9 minutes to a maximum of 6 hours. Boeing experience, in the past 4 years, has evidenced that a facility of this type can provide an effective bridge between analytical studies and the operational situation. Inherently flexible, such a facility can support a wide variety of development programs. View full abstract»

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  • DF Vectoring: Application to Stationary Synchronous Satellites

    Page(s): 697 - 704
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    Several methods of using an earth-based radio reference signal to determine the three-axis attitude of a synchronous satellite, and two types of spacecraft electronic systems (amplitude measurement and phase measurement), which obtain attitude and pointing information from the radio reference signal for orientating the spacecraft and for directing large-aperture antennas aboard the spacecraft are described. The earth-based radio reference signal also enables the electronic systems to determine angles to other ground stations with respect to fixed (reference) stations on the earth. These attitude- and angle-determining techniques are applicable to communications satellites, navigational satellites, and intersatellite data relay systems. View full abstract»

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  • Delay-Doppler Ambiguity Function for Wideband Signals

    Page(s): 705 - 711
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    The conventional ambiguity function is extended to include the Doppler distortions of the modulation function. The distinctive features of the extension are the use of the complex notation for wideband signals, and inclusion of the Doppler effect on the signal amplitude. The result is an ambiguity function from which Woodward's form can be found by inspection. It is shown that the well-known volume constraint also applies, in unchanged form, to the generalized ambiguity function. For the volume to be constant, it is not required that the distortions of the modulation function be neglected. Rather, the volume constancy is related to the sinusoidal fluctuations of a modulated carrier-type signal and thus is strictly a matter of the percentage bandwidth of the signal. View full abstract»

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  • Logarithmic Compression of Digitally Telemetered Data

    Page(s): 712 - 719
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    To express a number using true logarithmic compression, at least B = log2 [log R log(1 + Q/100 1 - Q/100/)] bits are required. (R = dynamic range, Q = ±error percent.) True logarithmic compression is rarely used in practice, but quasi-logarithmic methods such as normalized floating-point format are used frequently. A partially unnormalized floating-point format provides the best performance in the case of digital data. For this method B = log2 [100 log2 (4R Q/l00 Q 1 - Q/100)]-1. This paper contains analytical and graphical results that facilitate comparison of the various systems. View full abstract»

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  • A Comparison of Second, Third, and Fourth Order Phase-Locked Loops

    Page(s): 720 - 727
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    This paper presents data describing various performance characteristics of phase-locked loops, which were obtained for the purpose of determining an optimum selection of system order in view of typical operating conditions. With the functions optimized with respect to particular performance characteristics, calculations of the integrated square error and peak error with polynomial inputs are presented in terms of the noise bandwidth; and the generalized error coefficients are also provided in terms of the bandwidth with consideration for the use of both perfect and imperfect integrators. With specific input functions as provided by signals transmitted from earth satellites, an improved performance is demonstrated with the use of the higher order loops, and experimental results verify the calculations and also demonstrate the feasibility of the fourth order loop design. 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