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Aerospace and Electronics Conference, 1993. NAECON 1993., Proceedings of the IEEE 1993 National

Date 24-28 May 1993

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Displaying Results 1 - 25 of 181
  • Proceedings of NAECON '93 - National Aerospace and Electronics Conference

    Publication Year: 1993
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    Freely Available from IEEE
  • A refined key-lock access control system

    Publication Year: 1993 , Page(s): 583 - 587 vol.1
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    This paper derives a technique that refines the single-key-lock control system which has been proposed in recent years. We convert a number of matrix entries into an integer and then store it in memory. When access is requested, some appropriate integers are decoded into their unique original matrix entries for the system to control the accesses. The memory reduction for this refinement is more than 85%. In addition, an extension of this access system to dynamic computing environments is presented View full abstract»

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  • MLANS neural network for track before detect

    Publication Year: 1993 , Page(s): 377 - 382 vol.1
    Cited by:  Papers (2)
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    We have developed a novel approach to enhancing surveillance system capabilities by combining surveillance functions and utilizing all the available information for each function. This approach is based on a previously developed MLANS neural network. The MLANS capability for fuzzy decision logic permits combining such functions as data correlation, detection, and track estimation, or sensor fusion and correlation. This paper considers the problem of concurrently performing detection, correlation, and track initiation for multiple objects in presence of noise or clutter returns. In this case the MLANS estimates track parameters while performing a fuzzy classification of all returns in multiple scans into multiple classes of tracks View full abstract»

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  • Distance simulation in virtual audio displays

    Publication Year: 1993 , Page(s): 612 - 617 vol.2
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    Advances in the field of audio virtual reality have focused on the simulation of direction in virtual audio displays. The potential to add elementary distance cues to these displays remains largely unexploited. A number of audio cues have been identified that provide exocentric, or relative, and egocentric, or absolute, distance information. Two of these cues, intensity and first-order reflections, are examined closely in this paper. These cues can be simulated in a virtual audio display using simple geometric calculations and digital signal processing techniques. A short experiment examining the effectiveness of these cues was performed. Subjects were asked to make absolute distance judgements based on simulated sound sources while listening to loudspeakers directly or binaural recordings. Half of the trials contained intensity cues only and half contained intensity and reflection cues. The results show that the subjects were able to rank the distances correctly in each condition, but the data fail to verify the effectiveness of the reflection cue when presented over headphones View full abstract»

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  • A multiresolutional approach to target tracking

    Publication Year: 1993 , Page(s): 388 - 392 vol.1
    Cited by:  Papers (1)  |  Patents (1)
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    An approach of multiresolutional target tracking is proposed in this paper. The wavelet transform is employed to facilitate the multiresolutional approach. The application of the approach to tracking dim targets, one of the most challenging tasks in target tracking, is investigated View full abstract»

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  • Voltage-mode-controlled PWM buck DC-DC converter with a proportional controller

    Publication Year: 1993 , Page(s): 413 - 419 vol.1
    Cited by:  Papers (5)
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    Closed-loop small-signal characteristics are given for a voltage-mode-controlled PWM buck DC-DC converter with a proportional controller for continuous conduction mode (CCM). All parasitic resistances are taken into account. The following characteristics are presented at different values of the equivalent series resistance of the filter capacitor: control-to-output transfer functions, input-to-output transfer functions, and input and output impedances View full abstract»

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  • A jitter rejection technique in a satellite-based laser communication system

    Publication Year: 1993 , Page(s): 1107 - 1115 vol.2
    Cited by:  Papers (1)
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    A technique, resulting in the significant reduction of negative effects of satellite jitter on the accuracy of laser beam positioning in communication systems, is presented. It implies application of vibration monitoring instrumentation for estimation of the motion components constituting jitter. A self-tuning feedforward jitter compensation scheme is introduced to the existing mirror positioning control systems. The technique is verified by computer simulation and is in the process of experimental investigation View full abstract»

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  • Creating CASE tools by re-engineering Ada compilers

    Publication Year: 1993 , Page(s): 496 - 499 vol.1
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    Many CASE tools require Ada source code analysis similar to the semantic analysis that Ada compilers perform. Since this semantic analysis constitutes a large, complex portion of existing Ada compilers, re-engineering these Ada compiler parts to serve as CASE tool parts offers significant savings. This paper uses the author's experience with re-engineering an Ada compiler into an Ada PDL Processor tool to illustrate how the re-engineering effort involves automated compiler generation technology, semantic analysis modifications, and complex system partitioning challenges View full abstract»

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  • Applications of virtual audio

    Publication Year: 1993 , Page(s): 604 - 611 vol.2
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    Technology for electronically simulating spatial sound over loudspeakers and headphones has matured in the past few decades to facilitate many new applications of virtual audio. Electronic simulation of directional and distance auditory cues has greatly expanded the areas of application of virtual audio. Some potential aerospace applications include monitoring spatially separated speech communication signals to increase understanding, navigating by an auditory beacon, and acquiring visual targets with the aid of directional audio signals. Potential non-aerospace applications include navigational aids for the blind and enhanced virtual reality simulation for entertainment and education. In the future, more applications may use virtual audio technology to display spatial auditory information. Past, present, and future applications are discussed for aerospace, research, and entertainment industries. Techniques for creating virtual audio over loudspeakers and headphones are described. It is concluded that virtual audio systems are more flexible than previous physical simulations and can improve low fidelity View full abstract»

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  • Standard generalized markup language (SGML) as a basis for an intelligent data management system

    Publication Year: 1993 , Page(s): 1017 - 1020 vol.2
    Cited by:  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    Since its inception in the late eighties by DoD, the Air Force has been chartered to monitor and implement Computer-aided Acquisition and Logistic Support (CALS) strategies throughout its infrastructure. On the heals of the CALS movement is the Corporate Information Management (CIM) initiative. This initiative uses a CIM Technical Reference Model that “defines a target framework and profile of standards” for implementing a computing and communication infrastructure that will support portability, scalability, and interoperability of applications View full abstract»

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  • Multi-resolution feature extraction from Gabor filtered images

    Publication Year: 1993 , Page(s): 819 - 824 vol.2
    Cited by:  Papers (1)
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    In this paper, we describe a hybrid learning system which combines a genetic algorithm with a neural network to classify grayscale images. The system operates on multi-resolution images which are formed by applying Gabor filters to a set of input images. The genetic algorithm evolves morphological probes that sample the multi-resolution images, and the perceptron algorithm then evaluates the extracted features. We demonstrate the use of this system by discriminating images of model tanks from other military vehicles. A multiplicity of accurate solutions, consisting of sparse morphological probes, are generated View full abstract»

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  • Spontaneous organization of “intelligent fuzzy logic networks” in atmospheric flows

    Publication Year: 1993 , Page(s): 869 - 872 vol.2
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    Spatially extended dynamical systems in nature exhibit long-range spatiotemporal correlations manifested as the fractal geometry to the spatial pattern concomitant with inverse power law form for the power spectrum of temporal fluctuations. Such non-local connections, recently identified as `self-organized criticality ', signify “intelligent” dynamic information update and storage in the overall fractal network and is analogous to “fuzzy logic” systems View full abstract»

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  • Passive location and tracking algorithm based on TOA and azimuth measurements for 3-D moving targets

    Publication Year: 1993 , Page(s): 393 - 398 vol.1
    Cited by:  Papers (4)
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    This paper presents an algorithm based on TOA (time of arrival) and azimuth measurements. The location principle and feasibility of the technique are analysed in detail. For some bistatic radar systems with receivers which locate and track 3-D moving targets by means of a passive method, it is sometimes difficult to measure the pitch angle of targets. The algorithm proposed is of great importance to the practicability of bistatic passive location and tracking systems. With the help of computer simulation, the performance of this algorithm is evaluated for typical target paths according to Monte Carlo methods View full abstract»

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  • A scalable architecture for the rapid prototyping of aircraft cockpits

    Publication Year: 1993 , Page(s): 523 - 528 vol.1
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    This paper discusses the design of a scalable hardware and software architecture for the rapid prototyping of cockpit designs in flight simulation. This architecture uses the Unix operating system and a homogeneous computing environment of Silicon Graphics workstations that rely heavily on replicated shared memory (also known as reflective memory) and Ethernet networks. The design includes three software layers that provide the programmer with a simplified standard interface for integrating applications for flight simulation. The lowest layer controls the overall simulation environment that manages software objects, controls simulation start and stop functions, and routes messages by way of message queues to the upper layer applications. The second layer contains standard applications that are common to most cockpits. The majority of these applications are configured through configuration files for the applicable cockpit. The third layer consists of applications that cannot be configured through files. These applications are aircraft/cockpit-specific components that define the functions for each unique configuration View full abstract»

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  • Neural network hardware implementation for emitter identification

    Publication Year: 1993 , Page(s): 897 - 903 vol.2
    Cited by:  Papers (1)
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    This paper presents the results of a neural network hardware implementation for emitter identification. In future electronic warfare environments, pulse densities on the order of hundreds of thousands of pulses per second can be expected in any given mission. To identify hostile radar systems, a processor must be able to store enough signatures for emitters of interest that proper identifications of unknown emitters can be made. Furthermore, the processor must make this identification in “real-time”. This paper presents the results obtained when the Electronically Trainable Neural Network (ETANN) hardware is used to perform emitter identification from time-sampled emitter waveforms. The ETANN is a low (4-6 bit) resolution, high speed (2 billion operations/sec) parallel processor implementing sigmoidal-based backpropagation networks. This hardware was chosen due to minimal interlayer processing times, 3 us per layer, which can allow threat identifications to be made in a matter of microseconds. For this paper, a sigmoidal-based neural network was developed, via simulation on a DEC VAX station, to discriminate between 30 emitters. The network weights were loaded on the ETANN for performance comparisons. Due to resolution constraints, the accuracy of the ETANN was typically 10%-12% lower. However, the ETANN was able to make classifications in less than 6 us. This significant processing speed, with only slight degradations in performance, makes neural network architectures viable alternatives for emitter identification View full abstract»

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  • Improving power quality in a 20-kHz distribution system

    Publication Year: 1993 , Page(s): 420 - 427 vol.1
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    The electrical performance of a 20-kHz actuator system is considered. It is found that the line voltage distortion of the 20-kHz bus degrades system performance. Several methods of alleviating this problem are investigated. These methods include increasing the relative size of the 20-kHz source, increasing the size of the shunt bus filter, and changing the control and topology of the load. These latter two methods are shown to yield improvement without introducing additional energy storage into the system View full abstract»

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  • Transfer function method for diagnostics of electronic circuit boards exposed to mechanical vibrations

    Publication Year: 1993 , Page(s): 468 - 475 vol.1
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    Environmental stress plays a critical role in failure and long term reliability of aerospace electronics. Vibration monitoring can provide information characterizing the structural integrity of a circuit board assembly. A frequency domain diagnostic technique extracting this information is proposed. It allows for on-line monitoring of the mechanical integrity of circuit boards, detection of existing degradation trends, and prediction of possible failures View full abstract»

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  • Comparison between optical interconnection processors: folded perfect-shuffle versus 3-D butterfly

    Publication Year: 1993 , Page(s): 1100 - 1106 vol.2
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    A comparative study has been carried out to quantify the differences between folded perfect shuffle and three-dimensional (3-D) multi-channel butterfly optical interconnection architecture. An application of 3-D butterfly network to implement Hartley transform is also presented View full abstract»

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  • Measurement of distance perception using virtual audio

    Publication Year: 1993 , Page(s): 597 - 603 vol.2
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    Relative auditory distance perception of a direct path signal by itself, with synthetic reflection(s), reverberation, presented over headphones, was measured using a 2AFC task. The stimulus, either a 500 millisecond pink noise burst or a two second phrase of male speech, was presented twice, first at a reference distance and second at an incremental distance from the reference. Reference distances include five, fourteen, and twenty-two feet, and the incremental distances included multiples of 0.25, 0.5, and 1 foot, respectively. Stimulus pairs at each of the three distances were presented from four directions: front, back, left, and right. For each stimulus pair, the task of three subjects was to indicate which of the two sounds appeared closer to himself/herself. From histograms for each condition, the just noticeable difference (JND) was calculated by determining the minimum interval at which the subjects could respond correctly seventy-five percent of the time. Virtual audio may help a pilot to perform a variety of functions in the military cockpit. The visual workload may be reduced by providing a spatial auditory beacon for navigation waypoints View full abstract»

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  • Simulation of a strapdown magnetic azimuth detector for wing tip mounted applications

    Publication Year: 1993 , Page(s): 340 - 344 vol.1
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    This paper addresses the instrument performance issues of a wing tip mounted solid state magnetic azimuth detector (MAD). The approach taken here dynamically tracks the wing tip deflections so that when used in conjunction with a fuselage mounted inertial reference unit (IRU), wing tip sensed magnetic measurements can be used to derive heading. Presented is a discussion of other strapdown approaches and their shortcomings with respect to wing mounted applications. This discussion is followed by a definition of the error sources associated with the new approach and a simulation illustrating the expected performance View full abstract»

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  • Enterprise modeling: user-driven requirements analysis

    Publication Year: 1993 , Page(s): 1010 - 1016 vol.2
    Cited by:  Papers (1)
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    This paper examines the traditional requirements analysis determination model and discusses some of its shortcomings. General principles of systems analysis are discussed and an alternate method of identifying and describing functional user systems requirements is described. The alternate method requires extensive user participation with minimal input from data processing technicians in an approach that enhances effectiveness of the process by focusing on the user's view of his needs rather then the systems analyst interpretation of them View full abstract»

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  • Neural networks based signal detection

    Publication Year: 1993 , Page(s): 814 - 818 vol.2
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    The aim of this paper is to present different neural networks able to realize a radar detector. Multilayer perceptrons are considered with different structures which make use of different backpropagation algorithms during the learning phase of the neural network. The reference detection scheme assumed for comparison purposes is a coherent integrator followed by an amplitude detector and optimum thresholding. The comparison (in the Neymann-Pearson sense) with the optimum detector performances allows to assess the signal-to-noise losses pertaining to the different neural network detector structures View full abstract»

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  • Development of practical logic for aircraft group recognition in a set of observations

    Publication Year: 1993 , Page(s): 248 - 254 vol.1
    Cited by:  Patents (1)
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    The military application of target tracking is discussed. Formation flights of military aircrafts are considered (e.g. for attacks on distributed target areas and for penetration). The dense target situation occurs in the observation of multiple weapon systems. An efficient algorithm for formation (group) recognition in a set of observations is discussed. Results of simulation experiments for a radar tracking problem are presented which demonstrate the effects of the procedure View full abstract»

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  • Compensation for distorted LFM signal

    Publication Year: 1993 , Page(s): 61 - 66 vol.1
    Cited by:  Papers (1)
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    A compensation method for non-ideal performance of the system using STRETCH processing (or full-deramp), and for modulation nonlinearity of LFM signal is presented. An analysis is developed to show that the effect caused by the non-ideal performance of the system on the signal output is time-invariant, and the effect caused by the nonlinearity of LFM signal on the output is time-variant. A series of simulation results demonstrate the efficiency of the method. Under some conditions, the sidelobe level as high as -5.76 dB may be reduced to -41 dB. If the tolerable sidelobe level is -30 dB, the target size may be extended to 120 m View full abstract»

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  • Associative memory comparison for target identification

    Publication Year: 1993 , Page(s): 262 - 268 vol.1
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    This paper presents the execution speed comparison of two associative memory organizations used to identify weapon platforms from intercepted radar emanations. The two associative memory organizations were chosen because of their fundamentally different levels of processing granularity. The CAM was chosen because its processing is performed within the memory cell, while the bit-serial word-parallel associative memory was chosen because its processing is performed at the memory word level. Both organizations were designed, modelled and simulated to determine which was the faster in comparing 8-bit, and 32-bit target parameters. The associative memories were designed to store the parameters of at least 72 weapon platforms, with each platform consisting of six parameters, and each parameter consisting of an upper and lower limit. The number of bits per word and the number of words within the memory were varied to accommodate the target parameters and to enhance the comparison speed. The comparison speed was calculated by summing the critical path delays through each memory. The comparison speed results indicate which associative memory organization is the more appropriate for identifying the weapon platform View full abstract»

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