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Aerospace and Electronic Systems, IEEE Transactions on

Issue 1 • Date Jan. 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

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    Freely Available from IEEE
  • [Breaker page]

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  • From the Editors

    Page(s): 1
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  • Proposal Perfidy, A Poverty Syndrome (Ethics as a Prerequisite to Proposal Success)

    Page(s): 2 - 4
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    There is a direct correlation between proposal success and proposal ethics, a fact which is independent of the proposal scope or the type of customer. To be successful, a proposal must result in a profit when measured within the total environment of present and future sales. A misleading or unethical proposal has little chance of leading to an immediate contract, is most likely to incur cost penalties if a contract does result, and is certain to reduce the probabilities for future sales. Unfortunately proposals tend to deal in that gray area between fact and fiction; the normal desire to present things in their most favorable light leads to misrepresentation. In his own professional interests the proposal engineer must learn to give an honest and accurate portrayal of his plan and his product. View full abstract»

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  • Detection Probabilities for Log-Normally Distributed Signals

    Page(s): 5 - 13
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    The amplitude and power of a large family of radio signals are observed to have log-normal probability density functions. Among these are signals propagated through random inhomogeneous media, a notable example being low frequency atmospheric radio noise. Of greater importance are certain radar targets that have been observed to have essentially log-normal density functions. Both ships and space vehicles may fall into this category. Curves of probability of detection vs. signal-to-noise ratio for the case of log-normal signals in Gaussian noise have been computed and are presented in this paper. The curves apply for square-law detection with varying degrees of postdetection linear integration. Both fully correlated and completely uncorrelated fluctuating signals are considered. It is shown that for log-normal signal distributions having large variances, the probability of detection differs significantly from that obtained using curves based on an assumed Rayleigh signal distribution. View full abstract»

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  • Designing Pseudorandom Coded Ranging Systems

    Page(s): 14 - 27
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    This paper develops a set of mathematical tools for system design or analysis of a type of pseudorandom coded ranging system used in several space programs. Certain probabilities of failure of the system to perform the ranging function and the times required for the system to perform prescribed ranging functions are defined and related to system parameters. A set of sample calculations is presented for clarification of the computational techniques. View full abstract»

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  • Comments on the communication and data problems associated with a Mars trip during a conjunction phase

    Page(s): 28 - 43
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    The analysis and comments presented in this paper are meant to establish the general communication parameters associated with Martian flyby probes and with lander and manned vehicles. Fundamental data transfer problems are reviewed to define comparisons and trends of tradeoffs for future studies. Selected focal points are based upon the long propagation path length, with inherent time delays, and the high noise produced by the sun. These problems are magnified because large quantities of data must be obtained to satisfy the needs of the scientific community and the curiosity of an interested public. A comparison of two communication systems is provided: the microwave spectrum and the optical spectrum, as represented by the microwaves at 2.3 GHz and the laser at 6328 ??. A method of cost effectiveness or value received from space missions (a criterion of power input for data quantity received) is also presented. View full abstract»

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  • Cancellation of Unwanted Spectral Components in an FM Multivibrator System

    Page(s): 44 - 50
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    The performance of FM multivibrator systems for high quality communications applications is limited by the presence of unwanted spectral components. A theory is presented for an improved system in which unwanted spectral components are cancelled, achieved by generating a cancelling component in a square-law device. The cancelling component tracks the unwanted component in both frequency and amplitude over a wide bandwidth of signal frequencies. Reductions in magnitude of the unwanted components by at least 16 dB are predicted; reductions of better than 14 dB have been achieved in practice. View full abstract»

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  • Execute Command in Space Communications

    Page(s): 51 - 56
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    Two types of feedback systems for a command channel are described. a) Complex Feedback¿where, for each command, an identification is relayed back over the feedback channel. b) Decision Feedback¿where the feedback channel is used only to state whether the satellite recognized the transmission as a command word. For a), the decision as to whether a command was properly received at the satellite is made on the ground, while for b), the decision is made at the satellite, the only purpose of the feedback channel being to cause the ground station to retransmit the command word if the satellite did not recognize the initial transmission. The decision feedback system then amounts to a one-way channel, since the satellite makes a decision after the initial transmission as to whether or not a command word was sent. If the transmitted command word is interpreted as a command, whether correct or not, the ground station has no further control. The following theorem is proved rigorously: ``It is always possible to specify a decision feedback system which gives the same error performance as a given complex feedback system.'' View full abstract»

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  • Demonstration of a Quantile System for Compression of Data from Deep Space Probes

    Page(s): 57 - 65
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    This paper describes the theory and design of an advanced engineering prototype of a quantile system of data compression for space telemetry. The basic idea is to transmit a few quantiles (or percentage points, as they are sometimes called) of a histogram of experimental values formed aboard a spacecraft. Only these quantiles are transmitted to Earth, and yet a large part of the information that was contained in the original histogram can be reconstructed on Earth. Compression ratios on the order of 100 to 1 are obtainable at 100 percent efficiency (in the sense of variances of estimates) with a simple device that performs no on-board arithmetic operations. After summarizing the theoretical background governing the use of quantiles, we then consider what the design considerations of such a system should be. Data compression ratios are computed for a typical application of the quantile system. The detail description of the advanced engineering quantile system that has been built at the Jet Propulsion Laboratory is discussed; in addition, a block diagram is given and analyzed. An important feature of the quantile system is its self-adaptive feature. Examples are given whereby quantile systems for compressing telemetry data can find application in non-military and non-space technology. Finally, experimental results using the constructed system are given. View full abstract»

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  • The Biasing Effect of Random Bit Errors on Binary Telemetry Data

    Page(s): 66 - 70
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    Random bit errors that occur in PCM data during the various phases of the telemetry-data-processing system will not only add a component of mean square error to the experimental data but will also bias it. This paper derives a formula for the bias and describes some of the characteristics of the bias. View full abstract»

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  • Experiments in Adaptive Estimation of Unknown Binary Waveforms

    Page(s): 71 - 82
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    A special-purpose adaptive machine is described which carries out estimation in real time of an unknown binary waveform which is perturbed with additive Gaussian noise. Unknown waveforms of over 103 samples in duration can be recovered. The unknown waveforms are of unknown epoch and can reappear at either random or periodic time intervals. The observed signal is received at moderate or low signal-to-noise ratios so that a single observation of the received data (even if one knew the precise signal arrival time) is not sufficient to provide a good estimate of the signal waveshape. Experimental results are described which show transient behavior waveform estimate. The transient behavior is expressed as the number of errors in the current estimate of the signal plotted vs. time. In a noisy environment, each ``learning'' transient is a random time function. These learning transients are shown for several different signal-to-noise ratios and indicate the threshold noise levels for various types of initial states of the machine memory. View full abstract»

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  • A Microwave Feedback Radiometer

    Page(s): 83 - 90
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    Two versions of a microwave feedback radiometer have been built and tested. One used an electromechanical feedback system; the other, an all-electronic system. The response of the servo loops proved to be fast enough and linear enough for almost any radiometer application. The rms noise fluctuation was the same as that of a Dicke radiometer. Stability was excellent even under adverse environmental conditions. View full abstract»

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  • Phase Compensation for Widely-Spaced Antenna Systems Employing Coherent Signal Combinations

    Page(s): 91 - 98
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    This paper describes a technique for providing phase compensation to signals received at widely-spaced antennas and processed at a central location. Self-compensation is provided for pathlength variations in reference-signal distribution systems. The technique may be adapted to include the measurement and compensation of signal-channel phase variations. Practical systems which require this type of compensation include interferometric systems used for position and position-rate measurements of missiles and spacecraft, interferometers and arrays of antennas used for radio and radar astronomy, and arrays of large-aperture antennas used for deep-space communications. View full abstract»

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  • Command and Control of Deep Submergence Vehicles

    Page(s): 99 - 106
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    The wide variety of applications for deep submergence vehicles gives rise to a complex set of command and control requirements. An over-view of the command control requirements is presented by setting forth a catalog of the deep submergence vehicle family in terms of type and mission. The vehicle types are categorized by a set of eight descriptors, manned/unmanned, free/tethered, suspended/bottomed, and propelled/inert. The missions considered are search, rescue, salvage, and exploration, implantation, exploitation. The limiting requirements for the various levels of command and control are related to this spectrum of vehicles and missions. The command/control systems for several vehicles are illustrated. View full abstract»

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  • Flexible Solar Cell Arrays for Increased Space Power

    Page(s): 107 - 115
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    The importance of solar cells for space power supplies continues with increased emphasis. The need for advances in the design of solar cell arrays becomes more pressing as the requirement for increased power levels is apparent. This paper discusses a flexible solar cell concept, includes a brief history of the development, describes a conceptual design for a 20-kW array, giving weight breakdown, and describes an existing design effort. View full abstract»

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  • Automatic Controller for a Sweeping Microwave Receiver

    Page(s): 116 - 122
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    The Automatic System Controller (ASC) is a very simple automatic data processing system designed to provide unattended operation of the R-31 receiver, a sweeping microwave receiver. With the receiver set to operate in the scanning mode, its video output is processed by the ASC, which recognizes by thresholding the presence of a signal in the receiver pass band. When the threshold is exceeded, a receiver sweep stop is actuated, an appropriate receiver mode is selected, and an on-site tape recorder is turned on. To enhance signal acquisition, the ASC provides noise leveling gain control, the gating of undesirable signals, and useful aids for an operator attending the receiver. View full abstract»

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  • Effects of CW Interference on Narrow-Band Second-Order Phase-Lock Loops

    Page(s): 123 - 135
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    This paper describes an experimental study of the effect of continuous wave (CW) interference and white noise on a second-order phase-lock loop. The reciprocal of the loop mean-square phase error is used as an index of performance, and the effect of interference levels that do not cause cycle skipping or loss of lock is described in terms of this index. Loop thresholds are determined by measurement of cycle-skipping rates. Stationary or slowly-sweeping CW interference caused a degradation in loop threshold of roughly 3 dB for every 6 dB of interference power above the noise power level. The effective loop signal-to-noise ratio was decreased approximately 1 dB at interference-to-noise power ratios of -3 dB. Interference levels equal to the signal level consistently caused loss of lock, regardless of the loop signal-to-noise ratio. View full abstract»

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  • Comparison of Combined Barker Codes for Coded Radar Use

    Page(s): 141 - 143
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    The autocorrelation functions ¿I(¿) and ¿II(¿) of Codes I and II are shown in Figs. 1 and 2, respectively. Several interesting points are noted from a comparison of these figures. View full abstract»

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  • Outputs of a Moving Window Cross Correlator When the Input is a Phase-Reversed Code

    Page(s): 143 - 144
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    Figure 1 shows the cross correlation ¿pp(¿) of the plus code in the moving window with a plus code followed by a plus code. Figure 2 shows the cross correlation ¿pn(¿) of the code in the window with a plus code followed by a minus code.4 The displacement variable ¿ is quantized into bit lengths. The point ¿ = 0 is where the pluss code in the Window completely overlaps the first plus code, and the point ¿ = 52 is where the plus code in the window completely overlaps the code which follows the first code.5 (This code is a plus code in the case illustrated in Fig. 1 and a minus code in the case illustrated in Fig. 2.) View full abstract»

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  • Simulation of Radar Range and of Doppler Effect by Means of a Stationary Target

    Page(s): 148 - 149
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    The subject of this correspondence is relevant to a type of passive electronic countermeasure known under the code name of "confusion chaff." It consists of metal strips or wires dispensed in a proper place in space so as to produce radar echoes similar to those of real targets of interest to the defense. We wish to concentrate here on the phase where medium in which chaff is deposited is dense, and where chaff becomes ineffective since it either burns up or slows down, thus either disappearing altogether or becoming susceptible to easy discrimination. In the following discussion, we wish to outline a method which will remedy the situation. In the proposed arrangement, chaff is deposited in the atmosphere from a dispenser in such a manner as to have negligible velocity with respect to the medium (air), which prevents it from burning up. It is then irradiated by an airborne transponder, located on the vehicle dispensing chaff, so as to simulate desired radar echoes in range and Doppler, making returns undistinguishable from echoes from the main target. 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