there is also the major impediment of the often announced Department of Defense policy of selective availability/anti-spoof (SA/AS) that clouds reliable access to the wideband (20 MHz) P channel of the GPS signals without cryptographic access. A technique proposed by MacDoran utilizes codeless methods for exploiting the P channel signals implemented by the use of a pair of antennas and cross correlation signal detection. Author N91-11968*# Pasadena. LAND-MOBILE FIELD EXPERIMENTS IN AUSTRALIA Loretta G. L. Ho and Khaled Dessouky In its Proceedings of the Fourteenth NASA Propagation Experimenters Meeting (NAPEX 14) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop 1 Jul. 1990 p 140-147 (For primary document see N91-11954 03-32) Avail: NTIS HC/MF A12 CSCL 20N Jet Propulsion Lab., California Inst. of Tech., The Mobile Satellite Experiment/Australia Mobile Satellite Experiment (MSAT-X/AUSSAT) experiment offered the first true land-mobile satellite configuration to evaluate the MSAT-X technologies and equipment. Both quantitative data tests and qualitative voice link demonstrations were successfully conducted. From the collected data, system performance in typical land-mobile conditions was extracted. A set of propagation characteristics corresponding to the wide range of environments encountered was also obtained. A brief description is given of the MSAT-X/AUSSAT experiment and a summary of its results analyzed to date. Author N91-11969*# Colorado Univ., Boulder. Dept. of Electrical and Computer Engineering. NASA PROPAGATION INFORMATION CENTER The NASA Propagation Information Center became formally operational in July 1988. It is located in the Department of Electrical and Computer Engineering of the University of Colorado at Boulder. The center is several things: a communications medium for the propagation with the outside world, a mechanism for internal communication within the program, and an aid to management. ACTS PROPAGATION TERMINAL PROTOTYPE PLANNING Faramaz Davarian, F. Pergal, D. Chakraborty, and Warren L. Avail: NTIS HC/MF A12 CSCL 20N The planning and design of a prototype propagation receiving terminal for beacon signals at 27 and 20 GHz bands are examined. The developmental plan is discussed, followed by technical design considerations including, the Advanced Communications Technology Satellite (ACTS) system salient features and frequency plan, beacon signal parameters and specifications, system calculations, and terminal hardware design issues. Author N91-11971*# National Aeronautics and Space Administration. Lewis Research Center, Cleveland, OH. LBR-2 EARTH STATIONS FOR THE ACTS PROGRAM Michael OReilly (Harris Corp., Melbourne, FL.), Russell Jirberg, and Ernie Spisz In JPL, California Inst. of Tech., Proceedings of the Fourteenth NASA Propagation Experimenters Meeting (NAPEX 14) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop 1 Jul. 1990 p 232-239 (For primary document see N91-11954 03-32) Avail: NTIS HC/MF A12 CSCL 20N The Low Burst Rate-2 (LBR-2) earth station being developed for NASA's Advanced Communications Technology Satellite (ACTS) is described. The LBR-2 is one of two earth station types that operate through the satellite's baseband processor. The LBR-2 is a small earth terminal (VSAT)-like earth station that is easily sited on a user's premises, and provides up to 1.792 megabits per second (MBPS) of voice, video, and data communications. Addressed here is the design of the antenna, the rf subsystems, the digital processing equipment, and the user interface equipment. Author A REVIEW OF FADE DETECTION TECHNIQUES Avail: NTIS HC/MF A12 CSCL 20N Several proposed propagation fade detection techniques are reviewed in light of general requirements presented for beacon fade characterization. The discussion includes an analysis of phase lock versus frequency lock beacon tracking loops and of excess noise injection type radiometers. The Advanced Communications Technology Satellite (ACTS) beacon fade detection schemes proposed by the Communications Satellite Corporation and the Jet Propulsion Laboratory are examined along with the fade detection technique used by Harris in the Advanced Communications Technology Satellite (ACTS) low burst rate (LBR) terminal. Author N91-11973*# Jet Propulsion Lab., California Inst. of Tech., THE TELECOMMUNICATIONS AND DATA ACQUISITION E. C. Posner, ed. 15 Aug. 1990 169 p Archival reports on developments in programs managed by the Jet Propulsion Laboratory's (JPL) Office of Telecommunications and Data Acquisition (TDA) are given. Space communications, radio navigation, radio science, and ground-based radio and radar astronomy, activities of the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, supporting research and technology, implementation, and operations are reported. Also included is TDA-funded activity at JPL on data and information systems and reimbursable Deep Space Network (DSN) work performed for other space agencies through NASA. For individual titles, see N91-11974 through N91-11985. N91-11974*# Jet Propulsion Lab., California Inst. of Tech., Pasadena. Tracking Systems and Applications Section. THE FIRST GEOCENTER ESTIMATION RESULTS USING GPS MEASUREMENTS C43 R. P. Malla (Sterling Software, Pasadena, CA.) and S. C. Wu In its The Telecommunications and Data Acquisition Report 15 Aug. 1990 p 1-9 (For primary document see N91-11973 03-32) Avail: NTIS HC/MF A08 CSCL 08E The center of mass of the Earth is the natural and unambiguous origin of a geocentric satellite dynamical system. A geocentric reference frame assumes that the origin of its coordinate axes is at the geocenter, in which all relevant observations and results can be referred and in which geodynamic theories or models for the dynamic behavior of Earth can be formulated. In practice, however, a kinematically obtained terrestrial reference frame may assume an origin other than the geocenter. A fast and accurate R. T. Logan, Jr., G. F. Lutes, L. E. Primas, and L. Maleki In its The Telecommunications and Data Acquisition Report 15 Aug. 1990 P 27-33 Sponsored in part by RADC (For primary document see N91-11973 03-32) Avail: NTIS HC/MF A08 CSCL 20F The principal considerations in the design of fiber-optic transmitters for highly phase-stable radio frequency and microwave analog transmission are discussed. Criteria for a fiber-optic transmitter design with improved amplitude and phase-noise performance are developed through consideration of factors affecting the phase noise, including low-frequency laser-bias supply noise, the magnitude and proximity of external reflections into the laser, and temperature excursions of the laser-transmitter package. Author Avail: NTIS HC/MF A08 CSCL 20N The effect of very long baseline interferometry (VLBI) measurements of 2-nanoradian (nrad) accuracy has been studied for use in Galileo's approach to Jupiter's moon lo. Of particular interest is reducing the error in the minimum altitude above lo's surface. The nominal tracking strategy includes Doppler, range, and onboard optical data, in addition to VLBI data with 25-nrad accuracy. For nominal data, the altitude error is approximately 250 km with a data cutoff of 19 days before closest approach to lo. A limited number (two to four) of 2-nrad VLBI measurements, simulating a demonstration of improved VLBI data, were found to reduce the altitude error by 10 to 40 percent. Improving the accuracy of the VLBI measurements of the nominal tracking strategy to 2 nrads, to simulate the results from an operational few-nrad VLBI capability, was found to reduce the altitude error by an approximate factor of four. This reduction in altitude error is attributed to the ability that VLBI data give to help determine the along-track component of Jupiter's ephemeris. This capability complements the ability of the onboard optical data to determine Analyses of reflector antenna surfaces use a computer program based on a discrete approximation of the radiation integral. The calculation replaces the actual surface with a triangular facet representation; the physical optics current is assumed to be constant over each facet. Described here is a method of calculation using linear-phase approximation of the surface currents of parabolas, ellipses, and shaped subreflectors and compares results with a previous program that used a constant-phase approximation of the triangular facets. The results show that the linear-phase approximation is a significant improvement over the constant-phase approximation, and enables computation of 100 to 1,000 lambda reflectors within a reasonable time on a Cray computer. Author N91-11979*# Jet Propulsion Lab., California Inst. of Tech., Pasadena. Communications Systems Research Section. SITE COMPARISON FOR OPTICAL VISIBILITY STATISTICS IN SOUTHERN ARIZONA c47 K. A. Cowles In its The Telecommunications and Data Acquisition Report 15 Aug. 1990 p 57-61 (For primary document see N91-11973 03-32) Avail: NTIS HC/MF A08 CSCL 04B One of the best locations in the continental United States for astronomical telescopes is southern Arizona. The mountains surrounding Tucson have clear skies 80 percent of the year, with image quality generally better than 2 seconds on peaks. Two of the existing observatory sites in this area are being considered as locations for one of the three Atmospheric Visibility Monitoring (AVM) observatories. These sites are Mount Lemmon and Mount Hopkins. A comparison of the characteristics of each of the sites is made here to identify the more desirable of the two locations. It is recommended that Mount Lemmon be selected as the Arizona site for this project. Author N91-11980*# Jet Propulsion Lab., California Inst. of Tech., S. J. Dolinar and F. Pollara In its The Telecommunications and Data Acquisition Report 15 Aug. 1990 p 62-72 (For primary document see N91-11973 03-32) Avail: NTIS HC/MF A08 CSCL 17B The theoretical relationship among signal power, distortion, and bandwidth for several source and channel models is presented. The work is intended as a reference for the evaluation of the performance of specific data compression algorithms. Author D. W. Brown, W. D. Brundage (National Radio Astronomy Avail: NTIS HC/MF A08 CSCL 09F The reception capability of the Deep Space Network (DSN) has been improved over the years by increasing both the size and number of antennas at each complex to meet spacecraft-support requirements. However, even more aperture was required for the final planetary encounters of the Voyager 2 spacecraft. This need was met by arraying one radio astronomy observatory with the DSN complex in the United States and another with the complex in Australia. Following a review of augmentation for the Uranus encounter, both the preparation at the National Radio Astronomy (NRAO) Very Large Array (VLA) and the Neptune encounter results for the Parkes-Canberra and VLA-Goldstone arrays are presented. Author N91-11983*# Jet Propulsion Lab., California Inst. of Tech., THE PARKES FRONT-END CONTROLLER AND T. J. Brunzie In its The Telecommunications and Data Acquisition Avail: NTIS HC/MF A08 CSCL 17B A new front-end controller (FEC) was installed on the 64-m antenna in Parkes, Australia, to support the 1989 Voyager 2 Neptune encounter. The FEC was added to automate operation of the front-end microwave hardware as part of the Deep Space Network's Parkes-Canberra Telemetry Array. Much of the front-end hardware was refurbished and reimplemented from a front-end system installed in 1985 by the European Space Agency for the Uranus encounter; however, the FEC and its associated noise-adding radiometer (NAR) were new Jet Propulsion Laboratory (JPL) designs. Project requirements and other factors led to the development of capabilities not found in standard Deep Space Network (DSN) controllers and radiometers. The Parkes FEC/NAR performed satisfactorily throughout the Neptune encounter and was removed in October 1989. Author N91-11984*# c17 Jet Propulsion Lab., California Inst. of Tech., Pasadena. Telecommunications Systems Section. THE IMPACT OF NRZ DATA ASYMMETRY ON THE PERFORMANCE OF A SPACE TELEMETRY SYSTEM T. M. Nguyen In its The Telecommunications and Data Acquisition Report 15 Aug. 1990 p 139-151 (For primary document see N91-11973 03-32) Avail: NTIS HC/MF A08 CSCL 09F The telemetry data asymmetry due to rising and falling voltage transitions can cause undesired spectral components at the output of a spacecraft transmitter. The performance of a space telemetry system can potentially degrade because of these undesired components. Here, an expression is derived for the power spectral density of an asymmetric nonreturn-to-zero (NRZ) data stream. This formula is then used to investigate how the data bandwidth varies with data asymmetry. At the receiver end, the threshold levels of undesired spectral components that fall into the carrier-tracking-loop bandwidth are determined by examining the derived spectral density. Further, based on this formula, a simple technique is developed for the computation of bit signal-to-noise ratio (SNR) degradation due to data asymmetry. The telemetry bit SNR degradations derived using this technique are compared with results obtained previously and with measurements by the Electronic Systems Test Laboratory (ESTL) at the Lyndon B. Johnson Space Center. Author S. Gulkis, F. Biraud, J. Heidmann, and J. Tarter (California Univ., Berkeley.) In its The Telecommunications and Data Acquisition Report 15 Aug. 1990 p 152-160 (For primary document see N91-11973 03-32) Avail: NTIS HC/MF A08 CSCL 03A The Nancay decimetric Radio Telescope (NRT) in Nancay, France, is described, and its potential use for Search for Extraterrestrial Intelligence (SETI) observations is discussed. The conclusion reached is that the NRT is well suited for SETI observations because of its large collecting area, its large sky coverage, and its wideband frequency capability. However, a number of improvements are necessary in order to take full advantage of the system in carrying out an efficient SETI program. In particular, system sensitivity should be increased. This can be achieved through a series of improvements to the system, including lowering the ground pickup noise through the use of ground reflectors and more efficient feed design, and by using low-noise amplifier front ends. Author N91-11986 Polytechnic Univ., Brooklyn, NY. THE INFLUENCE OF THE UPLINK NOISE ON THE Vrinda P. Dewal 1990 218 p Avail: Univ. Microfilms Order No. DA9018398 The problem of transmission of binary phase shift keying (BPSK) modulated digital data through a bandlimited nonlinear satellite channel in the presence of uplink, downlink Gaussian noise and intersymbol interface is examined. The satellite transponder is represented by a zero memory bandpass nonlinearity, with AM/AM conversion. The proposed optimum linear receiver structure consists of tapped-delay lines followed by a decision device. The linear receiver is designed to minimize the mean square error that is a function of the intersymbol interface, the uplink and the downlink noise. The minimum mean square error equalizer (MMSE) is derived using the Wiener-Kolmogorov theory. In this receiver, the decision about the transmitted signal is made by taking into account the received sequence of present sample, and the interfering past and future samples, which represent the intersymbol interference (ISI). Illustrative examples of the receiver structures are considered for the nonlinear channels with a symmetrical and asymmetrical frequency responses of the transmitter filter. The transponder nonlinearity is simulated by a polynomial using only the first and the third orders terms. A computer simulation determines the tap gain coefficients of the MMSE equalizer that adapt to the various uplink and downlink noise levels. The performance of the MMSE equalizer is evaluated in terms of an estimate of the average probability of error. CONTRIBUTION TO THE STUDY OF CODED MODULATION (INPE-5080-TDL/414) Avail: NTIS HC/MF A06 Coded modulation systems applied to concatenated codes are studied. The analyses of some trellis and block coded modulation schemes are shown and simulations are performed to choose the most suitable internal code for the concatenated scheme. The simulations show the trade-off among several import parameters of the trellis codes analyzed, such as code decision depth, number of quantization levels (for soft decision), and number of states in the trellis. The program developed for the simulations is included in the Appendix. The performance of the concatenated code is presented and compared with the CCSDS standard code for concatenated schemes. Author N91-11988*# National Aeronautics and Space Administration. Lewis Research Center, Cleveland, OH. AN EXPERIMENTAL STUDY OF HIGH TC SUPERCONDUCTING MICROSTRIP TRANSMISSION LINES AT 35 GHz AND THE EFFECT OF FILM MORPHOLOGY C. M. Chorey, K. B. Bhasin, J. D. Warner, J. Y. Josefowicz, D. B. Rensch, and C. W. Nieh (Hughes Research Labs., Malibu, CA.) Sep. 1990 7 p Presented at the Applied Superconductivity Conference, Aspen, CO, 24-28 Sep. 1990; sponsored in part by IEEE (NASA-TM-103633; E-5758; NAS 1.15:103633) Avail: NTIS HC/MF A02 CSCL 20N Microstrip transmission lines in the form of ring resonators were fabricated from a number of in-situ grown laser ablated films and post-annealed co-sputtered YBa2Cu30(7-x) films. The properties of these resonators were measured at 35 GHz and the observed performance is examined in light of the critical temperature (Tc) and film thickness and also the film morphology which is different for the two deposition techniques. It is found that Tc is a major indicator of the film performance for each growth type with film thickness becoming important as it decreases towards 100 A. It is also found that the films with a mixed grain orientation (both a axis and c axis oriented grains) have poorer microwave properties as compared with the primarily c axis oriented material. This is probably due to the significant number of grain boundaries between the different crystallites, which may act as superconducting weak links and contribute to the surface resistance. Author The Parameter Selection Algorithm for the SURAP 4 packet radio network and the basis for its design is described. A Semi-Markov model of the algorithm operation is presented. The algorithm adaptively adjusts three radio parameters: transmitter power, FEC coding rate, and channel bit rate. These parameters can increase the perceived signal-to-noise ratio on the channel and are treated as gain mechanisms. The algorithm must maintain robust radio links between nodes whenever possible, while minimizing interference with other network transmissions. We present one heuristic approach to balancing these two goals. This approach uses barely sufficient gain to maintain the packet error probability below an acceptable threshold value. A threshold probability of 0.1 was chosen. Bit error statistics provided by the sequential decoder and error feedback packets assist the process of determining the appropriate change of gain as noise levels vary. The algorithm can adapt at a fast rate, sometimes on the order of one packet time. It maintains acceptable packet error probability and can recover from estimation and decision errors. A Semi-Markov model can be used to compute the steady state packet error probability and packet transmission overhead due to noise. The model is general enough to include a stationary model of transceiver blocking probability, dynamic CDMA interference, and alternative algorithms based on similar operating principles. Although the model does not incorporate bit error statistic, a way is proposed to model the effect of these statistic without compromising the simplicity of the semi-Markov description. GRA N91-11991# Naval Research Lab., Washington, DC. Communication Systems Branch. EFFECT OF WORST-CASE MULTIPLE JAMMERS ON CODED FH/SSMA SYSTEMS Interim Report, Jan. 1988 - Jun. 1989 Evaggelos Geraniotis (Maryland Univ., College Park.) 31 Jul. 1990 41 p Sponsored by ONR, Arlington, VA (AD-A224911; NRL-MR-6688) Avail: NTIS HC/MF A03 CSCL 17/4 The effect is characterized and evaluated of simultaneous multiple partial band noise or tone jammers and other-user interference on a single communication link employing frequency hopped spread spectrum (FH/SS) signaling, M-ary frequency shift keying (FSK) modulation with noncoherent demodulation, and Reed-Solomon coding. For the symbol error probability of these systems, exact expressions were derived in the absence of multiple access (MA) interference and tight upper bounds in the presence of other-user interference. Although the analytical methods are valid for any number of multiple jammers, the numerical study was restricted to the cases of two and three partial band noise and tone jammers. For fixed values of the spectral densities of noise jammers, or the energies per symbol of tone jammers, the worst case fraction was evaluated of the band that each jammer should use in order to maximize the error probability of the FH/SS or FH/SSMA system. For the range of the signal-to-jammer power ratios examined, multiple noise or tone jammers appear to have no advantage over a single noise or tone jammer of equivalent spectral density or energy per symbol but achieve approximately the same worst-case performance by jamming smaller fractions of the band. GRA N91-11992# United International Engineering, Inc., Albuquerque, NM. HARDENING SURVEILLANCE ILLUMINATION USING AIRCRAFT ANTENNAS Final Report, Mar. 1989 - Jan. 1990 J. P. Donohoe and C. D. Taylor Jun. 1990 139 p (Contract F29601-88-C-0001; AF Proj. 3763) (AD-A225143; WL-TR-90-27) Avail: NTIS HC/MF A07 CSCL 20/15 Aircraft maintenance depots and main operating bases need to be able to perform quick checks of the electromagnetic pulse (EMP) hardness of their systems without removing them from service for any length of time. Preliminary tests have shown that the onboard HF antennas of the EMP Test-Bed Aircraft (EMPTAC) may be capable of providing the HF excitation required to effectively monitor the EMP hardness of aircraft systems. The surface current and charge distributions on the EMPTAC which result from swept frequency excitation of the HF radio antennas are computed over a range of 0.5 to 100 MHz using various antenna drive configurations. The computational analysis is performed by using two separate frequency-dependent techniques: the method-of-moments technique and the physical optics approximation. These calculations are then compared with the excitation provided from an overhead plane wave and with measured data from EMPTAC tests. GRA N91-11993# European Space Agency. European Space RADIO FREQUENCY AND MODULATION STANDARD (ESA-PSS-04-105-Issue-1; ISSN-0379-4059; ETN-90-97995) Radio communication techniques to be used for the transfer Werner Meyer and Thomas Jank (Deutsche Forschungsanstalt fuer Luft- und Raumfahrt, Oberpfaffenhofen, Germany, F.R.) Aug. 1990 60 p Transl. into ENGLISH of Dopplerspektren aus Inkohaerenter Rueckstreuung: Prinzip und Anwendungsbeispiele fuer POLDIRAD (Oberpfaffenhofen, Fed. Republic of Germany, DFLR), Aug. 1989 49 p Original language document was announced as N90-18630 (ESA-TT-1197; DLR-FB-89-48; ETN-90-98011) Avail: NTIS HC/MF A04 It is possible with the aid of Doppler radars to measure the distribution of radio velocities of scattering particles in the measuring volume. The parameters represented by the mean velocity and width of the distribution of radial velocities can be determined from the first two moments of these Doppler spectra. The principles for interpretation of Doppler spectra obtained from incoherent backscatter are summarized. How accurately the mean velocity and spectra width can be determined with POLDIRAD is investigated using simulations of spectra. An example of application is given. N91-11995# European Space Agency, Paris (France). ON THE RANGE RESOLUTION OF POINT TARGETS WITH FMCW RADAR SYSTEMS ESA Reinhard Hammel (Deutsche Forschungsanstalt fuer Luft- und (ESA-TT-1206; DLR-FB-89-47; ETN-90-98013) Avail: NTIS The spectral analysis of the low pass filtered echo signals of a stationary point target was carried out starting with the precise position of the transmit signal of a Frequency Modulated Continuous-Wave (FMCW) radar operated with sawtooth modulation and assuming a signal transit time which is short compared with the modulation period. It can be stated that the minimum detectable spacing between two point targets in the line of bearing is approximately given by 2.2 times the quantization width. To improve the target detection and for increasing the contrast in microwave images, the low frequency difference signal is frequently smoothed in the time domain by means of a trigonometric weighting function: An approach of linearizing the frequency/time characteristic is described. ESA N91-11996# Air Force Systems Command, Wright-Patterson AFB, OH. Foreign Technology Div. DEVICE FOR IRRADIATING LARGE PARABOLIC-REFLECTOR ANTENNAE E. A. Dudkovskiy 27 Jun. 1990 6 p Transl. into ENGLISH of Russian Patent no. 146365, 17 Jul. 1962 p 1-2 (AD-A225262; FTD-ID(RS)T-0683-90) Avail: NTIS HC/MF A02 CSCL 20/6 Devices are described that irradiate large parabolic reflector antennae. The described device is different from the known devices because the parabolic reflector used in it is cofocal with the basic mirror, which is irradiated by a cophasal emitter grid with a uniform amplitude distribution. This makes it possible to obtain the maximum utilization factor of the mirror opening cross section. The figure shows a schematic diagram of the device for irradiating large parabolic aerials. GRA N91-11997# Naval Ocean Systems Center, San Diego, CA. A point-to-point link analysis model has been developed for the Super High Frequency (SHF) band. It was developed to evaluate ship-to-ship and ship-to-air links. The SHF Link Analysis Model (SLAM) evaluates a communication link and determines system margin. The link margin is determined after a user defines the transmitter subsystem, the receiver subsystem, the specified level of system performance, and the propagation channel. The propagation channel incorporates the Engineer's Refractive Effects Prediction System (EREPS) and includes the effects of the evaporation duct. A rain model developed by NASA is also included in the channel. SLAM provides a detailed discussion of the link equation, the propagation effects, the rain model, and the antenna characteristics. In addition, a detailed explanation of the operation of the SLAM computer program is given. Two communication links are evaluated and these examples are used to demonstrate the computer program's capabilities. GRA N91-11998# Harry Diamond Labs., Adelphi, MD. 43 P Ronald J. Wellman and Jerry L. Silvious Apr. 1990 Sponsored by Army Materiel Command, Alexandria, VA (AD-A225334; HDL-TR-2178) Avail: NTIS HC/MF A03 CSCL 17/9 A computer simulation is presented of the signals received by a coherent, frequency-agile, two coordinated monopulse radar from an array of point reflectors. A FORTRAN program for analyzing these simulated signals is used to obtain down-range and cross-range locations of the reflectors. Inverse Synthetic Aperture Radar (ISAR) techniques also are used to obtain a radar-cross-section-density image of a two-dimensional array to reflectors. The effects of system phase and amplitude noise also are examined. GRA N91-11999# Naval Postgraduate School, Monterey, CA. Dept. of Administrative Sciences. NATIONWIDE MOBILE COMMUNICATION SYSTEMS, VOLUME 1, CHAPTERS 1 THRU 4 M.S. Thesis William Joseph Schworer, III Jun. 1990 247 p This thesis provides a basic understanding of nationwide terrestrial and satellite mobile communications and tracking technologies. Covered are systems currently available and in development. An analysis of user costs is performed for comparison. A more detailed satellite cost/benefit analysis for use by the trucking industry is also presented. Follow-on chapters contain discussions of the basic economic issues faces by satellite system operators and the regulatory history of mobile satellite services. Contained in the appendices are a more detailed discussion of mobile satellite systems and a layman's explanation of communication and navigation technologies. The conclusion presents comments on the possible future direction of these new mobile communication services and makes recommendations for trucking industry use. GRA N91-12000# Naval Postgraduate School, Monterey, CA. Dept. of Administrative Sciences. NATIONWIDE MOBILE COMMUNICATION SYSTEMS. VOLUME 2, CHAPTER 5: APPENDIX A M.S. Thesis William Joseph Schworer, III Jun. 1990 252 p (AD-A225367) Avail: NTIS HC/MF A12 CSCL 25/2 |