By Topic

Aerospace and Electronic Systems, IEEE Transactions on

Issue 3 • Date May 1981

Filter Results

Displaying Results 1 - 25 of 33
  • Table of contents

    Page(s): c1
    Save to Project icon | Request Permissions | PDF file iconPDF (881 KB)  
    Freely Available from IEEE
  • IEEE Aerospace and Electronic Systems Society

    Save to Project icon | Request Permissions | PDF file iconPDF (972 KB)  
    Freely Available from IEEE
  • Harry Rowe Mimno

    Page(s): 321
    Save to Project icon | Request Permissions | PDF file iconPDF (483 KB)  
    Freely Available from IEEE
  • Pulse Synchronizing DC-to-DC Converter

    Page(s): 322 - 328
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1291 KB)  

    The new dc-to-dc converter driven by the external pulse is presented. The principle is based on the synchronizing phenomenon in the transistor core multivibrator. There are the voltage feed- back in the OFF interval and the current feedback in the ON interval. The flux of the saturable core is changed along the minor hysteresis loop. The operations are explained by the aid of the averaged method of the state space technique. The efficiency of this converter is high and the construction is very simple. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance of a Mean Level Detector Processing M-Correlated Sweeps

    Page(s): 329 - 334
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1635 KB)  

    The performance of a mean level detector processing M-correlated consecutive sweeps is derived. Performance when sweeps are independent can be obtained simply as a special case. The background noise is assumed stationary Gaussian and pulses are fluctuating according to the Swerling I model. Results are obtained for both finite and infinite reference noise samples. It is shown that for fixed M the relative improvement over the single hit case increases when the correlation between sweeps decreases and as the probability of false alarm is kept at lower rates. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Acquisition of Pseudonoise Codes in FH Systems

    Page(s): 335 - 341
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2010 KB)  

    Acquisition schemes for acquiring pseudonoise (PN) signals in a frequency hopping (FH), spread spectrum (SS) system are presented. For the purpose of acquiring the PN code the received signal is modeled by an autoregressive (AR) process. The parameters of the AR process are determined by identifying a related set of parameters called the partial correlation coefficients. The power spectrum of the received signal and hence the PN code is estimated from the identified AR parameters. The high accuracy of the estimated PN codes permits the use of a simple error correcting logic to accelerate the acquisition process. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Concatenated Sequences for Spread Spectrum Systems

    Page(s): 342 - 350
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2436 KB)  

    Concatenated sequences are suggested and developed for use in spread spectrum (SS) systems. Special receiver realization is discussed and it is shown that the concatenated sequences offer great advantage in reducing the size of the matched filter correlators (MFC) in the SS receiver. Experimental systems have been built using concatenated sequences and their performance is reported here. It has been shown that a processing gain of 60 is obtainable with a 15 × 4 concatenated sequence which requires three tapped delay lines (TDL), two of length 15 and one of 4. Thus a total of only 34 delay units (with a nonlinear interface network, only 19 delay units) are required. Teleprinter signals can be transmitted over telephone channels using a bandwidth (BW) expansion of 60 with an input signal-to-noise ratio (SNR) of only -5.1 dB, resulting in a character- error-rate of 1 in 103. Techniques have been developed to reduce the sidelobe levels in the aperiodic autocorrelation functions (ACF) of the pseudonoise (PN) codes. For 15 length and 7 length PN sequences, sidelobes are reduced by 9 dB and 9.4 dB, respectively, using transversal filters. Application of the SS systems to the problem of multiaccessing and antijamming are discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Start-Up Transient of a DC-to-DC Converter Powered by a Current-Limited Source

    Page(s): 351 - 363
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2427 KB)  

    An analysis technique is presented which permits the designer to explore the start-up transient of a dc-to-dc converter when it is powered by a current-limited source. The current versus voltage characteristics of the source are superimposed upon those of the dc-to-dc converter. By noting the nature of the intersection of these curves in the voltage-current plane, we are able to predict whether or not the converter is able to start up while powering a specified load. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A New Class of Polyphase Pulse Compression Codes and Techniques

    Page(s): 364 - 372
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2086 KB)  

    A new class of symmetric radar pulse compression polyphase codes is introduced which is compatible with digital signal processing. These codes share many of the useful properties of the Frank polyphase code. In contrast with the Frank code, the new codes are not subject to mainlobe to sidelobe ratio degradation caused by bandlimiting prior to sampling and digital pulse compression. It is shown that bandlimiting the new codes prior to pulse compression acts as a waveform amplitude weighting which has the effect of increasing the mainlobe to sidelobe ratios. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • DC/AC High Power Cell Structure Improves Sine Generator Performance

    Page(s): 373 - 379
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1569 KB)  

    A new generation of dc/ac sine generators, based on dc/dc, pulse-width modulation (PWM) storage converter structure operating with rectified sine wave control and associated with a controlled bridge, is described. The efficiency, harmonic distortion, and transien't behavior are better in dc/dc sine convertors than conventional dc/ac sine convertors. Continuous non-linear or linear methods previously described can be extended to design this structure. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Overlapping Pulse Trains

    Page(s): 380 - 385
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1581 KB)  

    An event happens the first time several periodic pulse trains all overlap (are all ¿on¿) simultaneously. Assuming that all pulse trains are randomly located with respect to each other, it is argued that the time required is approximately an exponential random variable. A formula for the mean of this time and the results of some tests by computer simulation are given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Turn-Off Characteristics of Power Transistors Using Emitter-Open Turn-Off

    Page(s): 386 - 391
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1419 KB)  

    As compared with conventional reverse-biased turn-off, emitteropen turn-off provides superior transistor turn-off characteristics. Not only are the storage time and the fall time of the power transsistors much reduced, but also the device reverse-biased second breakdown phenomenon, commonly associated with turn-off of inductive load, is eliminated. Furthermore the storage time tolerance due to device variation and temperature change is minimized. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Detection Performance of a Modified Moving Window Detector

    Page(s): 392 - 400
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2154 KB)  

    The modified moving window detector for binary integration has a shorter window length compared with the ordinary moving window detector because of the addition of a third threshold. When the second threshold is reached, a counter begins to count until the third threshold is reached. A graphical method using a probability chain is developed here to analyze and to calculate the detection performance of this type detector. The detection performances for some practical cases are calculated by computer and are compared with the ordinary moving window detector. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 14.5-14.8 GHz Frequency Sharing by Data Relay Satellite Uplinks and Broadcasting-Satellite Uplinks

    Page(s): 401 - 409
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2583 KB)  

    Data relay satellites are being developed to provide real-time data links between research satellites in low earth orbits and central data acquisition and processing facilities. Frequency assignments for data relay satellite links will be made in bands allocated internationally to the space research service. One of the bands which will be used lies between 14.5 and 15.35 GHz, where the space research service has had a frequency allocation as a secondary service since 1971. During the General World Administrative Radio Conference of the International Telecommunication Union, held in Geneva in 1979, a primary frequency allocation was made in the band 14.5-14.8 GHz to the fixed-satellite service, specifically for use by earth-to-space links of the broadcasting satellite service. The feasibility of shared band operation is evaluated between data relay satellite uplinks and broadcasting-satellite feeder links in the band 14.5-14.8 GHz. Relationships for predicting interference power levels are formulated, as functions of satellite separation and of earth station separation. Tradeoffs between satellite separation angle and earth station separation are explored, and conclusions are drawn regarding the feasibility of band sharing. Co-channel operation is demonstrated to be technically feasible for typical systems, provided appropriate separations are maintained. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Scanning Spaceborne Synthetic Aperture Radar with Integrated Radiometer

    Page(s): 410 - 421
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3042 KB)  

    Spaceborne synthetic aperture radar systems are severely constrained to a narrow swath by ambiguity limitations. Here a vertically scanned-beam synthetic aperture system (SCANSAR) is proposed as a solution to this problem. The potential length of synthetic aperture must be shared between beam positions, so the along-track resolution is poorer; a direct tradeoff exists between resolution and swath width. The length of the real aperture is independently traded against the number of scanning positions. Design curves and equations are presented for spaceborne SCANSARs for altitudes between 400 and 1400 km and inner angles of incidence between 20° and 40°. When the real antenna is approximately square, it may also be used for a microwave radiometer. The combined radiometer and synthetic-aperture (RADISAR) should be useful for those applications where the poorer resolution of the radiometer is useful for some purposes, but the finer resolution of the radar is needed for others. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Algorithms for Power Converter Design Optimization

    Page(s): 422 - 432
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3148 KB)  

    A practical optimization approach for power converters is established which allows conception of a design to meet all powercircuit performance requirements and concurrently to optimize a defined quantity such as weight or losses. In addition to facilitating a cost effective design, the computer-aided approach provides a means to readily assess a) the weight-efficiency tradeoff, b) impacts of converter requirements and component characteristics on a given design, and c) optimum power-system configurations. The following two popular algorithms for nonlinearly constrained optimization are utilized to design the power converter: 1) the sequential unconstrained minimization technique, SUMT Version 4; 2) the ALAG penalty function technique, ALAG5. These algorithms are compared, and suggestions are made for improving the efficiency of the optimization algorithms for power converter design. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Tracking Accuracies with Position and Rate Measurements

    Page(s): 433 - 437
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1200 KB)  

    Tracking accuracies for the radial component of motion are computed for a track-while-scan radar system which obtains position and rate data during the dwell time on a target These results will be of interest to persons developing trackers for pulse Doppler surveillance radars. The normalized accuracies, computed for a two state Kalman tracking filter with white noise maneuver capability, are shown to depend upon two parameters, r = 4¿0/¿aT2 and s = ¿dT/¿0. The symbols ¿0 and ¿d are the position and rate measurement accuracies, respectively, ¿a is the standard deviation of the white noise maneuver process and T is the antenna scan time. The scalar tracking filter equations are derived and numerical results are presented. Lower steady state tracking errors plus the earlier attainment of steady state accuracies are the direct consequence of incorporating the rate measurements into the tracking filter. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High-Order Intermodulation Effects in Digital Satellite Channels

    Page(s): 438 - 445
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1959 KB)  

    The phenomenon of intermodulation generation due to passive and normally linear components is sometimes called passive intermodulation. A unique characteristic of passive intermodulation interference in communications satellites is that the products causing trouble are of high orders. Due to the immense combinatorial complexity of the problem, both exact analysis and direct simulation are almost impossible. In this paper the problem is simplified by considering a composite interference model consisting of 1) the lowest order intermodulation product (of those high-order ones) at a frequency of interest, 2) a constant-envelope carrier with random phase to account for all other intermodulation interferences by direct overlap or spectrum spreading in the vicinity, and 3) white Gaussian noise (receiver noise). An approximation of the tail statistics of this composite interference is derived, and numerical results (checked by simulation) show that the tail distribution may be very different from Gaussian; careful consideration must be rendered before resorting to the a priori Gaussian assumption. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Omega Lane Ambiguity Resolution Using Methods of Statistical Decision Theory

    Page(s): 446 - 460
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2380 KB)  

    Lane ambiguity is an inherent problem of navigation systems using phase measurements. A lane ambiguity resolution technique combining methods of hyperbolic and range-range modes of navigation has been developed. The basis of this approach is that the ensemble of received phases at any location forms a unique set and therefore the lane resolution problem reduces to finding a position such that the expected set of phases (or the phase predicted for the position of the navigator) matches the received set. This method of lane resolution is not constrained by lane widths and using the phase data of 10.2, 13.6, and 11¿ kHz; lane resolution has been accomplished for distances of up to 120 nmi. This method of lane resolution requires phase data from at least four stations at any frequency and is very sensitive to uncompensated propagation phase shifts. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the Extraction of Features from Slowly Wandering Patterns

    Page(s): 461 - 466
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (805 KB)  

    The problem of feature extraction with slowly wandering patterns is considered. Models are proposed to characterize the moving patterns. Using the perturbation theory of symmetric matrices, recursive relationships between the features at successive time intervals are obtained. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Doppler Radar Tracking of Hostile Fire

    Page(s): 469 - 471
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (354 KB)  

    Two fixed parameters define a two-dimensional projectile track relative to a radar: an arrival angle, and the expected distance of closest approach (miss distance). Both parameters can be obtained explicitly, the angle from the history of the phase difference between two elements of an interferometer antenna, and the miss distance from the history of the Doppler frequency. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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