Analysis of satellite communications in a multipath environment
Satellite communications performance improvement by use of multipath signal for channel models including noncoherent FSK
Massey, J. L.↗
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Multipath study for a low altitude satellite utilizing a data relay satellite system Final report
Multipath operation of low altitude satellite using data relay satellite system
Eggert, D.↗
Scintillation, polarization, and multipath effects on VHF propagation between synchronous satellites and aircraft
Scintillation, polarization, and multipath effects on VHF propagation between synchronous satellites and aircraft - telecommunication systems
Mueller, E. J.↗
Integrated Multipath Program Analysis and Cost Technique (IMPACT)
Integrated multipath program analysis and cost technique to assess multiple program decision impacts on program cost
Sullivan, O.↗
The effect of multipath reflections on spaceborne interferometer accuracy
Satellite radio interferometer multipath reflections effect on accuracy
Muehldorf, E. I.↗
Multipath signal model development
The development and use of mathematical models of signals received through the multipath environmental of a TDRS-to-user spacecraft link and vice versa are discussed. The TDRS (tracking and data relay satellite) will be in synchronous orbit. The user spacecraft will be in a low altitude orbit between 200 and 4000 km.
Ghais, A. F.↗
The error probability of a wide-band FSK receiver in the presence of multipath fading.
Calculations are made for the probability of error of a wide-band FSK receiver of the type used in space telemetry when multipath reflections off the planetary surface cause signal fading. The error probability is found for both low and high fading bandwidths and for small or large reflected path delays.
Chadwick, H. D.↗
Multipath propagation study for L-band, over-ocean, satellite-aircraft communication link
The results are presented of a study of multipath propagation between an aeronautical relay satellite in synchronous earth orbit and an aircraft flying over the ocean. An analytical model for the reflected power is developed and the results of a computer solution are compared with an approximate solution obtained through integration by the method of steepest descent. The computer solution is shown to differ considerably from the approximate solution. Both methods are compared with the limited experimental results available.
Deal, J. H.↗
Simulation results for an innovative anti-multipath digital receiver
Simulation results are presented for the error rate performance of the recursive digital MAP detector for known M-ary signals in multiplicative and additive Gaussian noise. Plots of detection error rate versus additive signal to noise ratio are given, with multipath interference strength as a parameter. For comparison, the error rates of conventional coherent and noncoherent digital MAP detectors are simultaneously simulated and graphed. It is shown that with nonzero multiplicative noise, the error rates of the conventional detectors saturate at an irreducible level as additive signal to noise ratio increases. The error rate for the innovative detector continues to decrease rapidly with increasing additive signal to noise ratio. In the absence of multiplicative interference, the conventional coherent detector and the innovative detector are shown to exhibit identical performance.-
Painter, J. H.↗
Multipath study for a low altitude satellite utilizing a data relay satellite system
Technical considerations associated with a low altitude satellite operating in conjuction with a data relay satellite system are reported. Emphasis was placed on the quantitative characterization of multipath phenomenon and determination of power received via both the direct and earth reflection paths. Attempts were made to develop a means for estimating the magnitude and nature of the reflected power.
Eggert, D.↗
Optimization of MLS receivers for multipath environments
A receiver is designed for aircraft (A/C), which, as a component of the proposed Microwave Landing System (MLS), is capable of optimal performance in the multipath environments found in air terminal areas. Topics discussed include: the angle-tracking problem of the MLS receiver; signal modeling; preliminary approaches to optimal design; suboptimal design; and simulation study.
Mcalpine, G. A.↗
Discrete estimation of continuous angle-modulated signals over multipath channels for aeronautical communication
The multipath channel for communication between an aerospace vehicle and a ground terminal is modeled by a multiplicative first-order Markov process. The multiplicative process is treated as a component of the message model and the discrete-time demodulation algorithms using the extended Kalman nonlinear estimation technique are developed for continuous-time angle-modulated signals. The equivalent baseband form of the demodulator structure is derived. Two examples of the message process are discussed for an FM system. The simulation results are presented for various values of the bandwidth expansion ratio and the additive SNR. The performance of the baseband algorithms is discussed.
Takhar, G. S.↗
Limitations on Ku-band communications due to multipath
The earth and orbiter body reflections involving the Tracking Data Relay Satellite (TDRS)/orbiter communications link are evaluated. Recommendations address operational conditions in order to avoid critical multipath impacts, modulation preferences during acquisition, and preferred scan limit implementation.
Lindsey, J. F.↗
Ultrasonic simulation of MSBLS multipath fading for orbiter landing configuration
The on-shuttle antenna pattern of the MSBLS receiver, and the azimuth and elevation beamwidths were simulated by their corresponding ultrasonic transducer beams. The scanning rate for the azimuth and elevation beams was 1.75 degrees/second. The results were adjusted for full-scale maximum sinusoidal scan rates of 691 and 377 deg/sec for AZ and EL respectively. The rain drops were simulated by air bubbles, with a similar size distribution, in water. The rain volume was created along a part of the propagation path, and not on the runway, because it was found difficult to avoid an accumulation of bubbles on the runway surface and surroundings simulated by the model surface. Multipath fading from the ground, and its possible degrading effect on the orbiter received beam shape and the associated landing guidance parameters is discussed.
Hayre, H. S.↗
Optimization of MLS receivers for multipath environments
Reduced order receiver (suboptimal receiver) analysis in multipath environments is presented. The origin and objective of MLS is described briefly. Signal modeling in MLS the optimum receiver is also included and a description of a computer oriented technique which was used in the simulation study of the suboptimal receiver is provided. Results and conclusion obtained from the research for the suboptimal receiver are reported.
Mcalpine, G. A.↗
Optimization of MLS receivers for multipath environments
The angle tracking problems in microwave landing system receivers along with a receiver design capable of optimal performance in the multipath environments found in air terminal areas were studied. Included were various theoretical and evaluative studies like: (1) signal model development; (2) derivation of optimal receiver structures; and (3) development and use of computer simulations for receiver algorithm evaluation. The development of an experimental receiver for flight testing is presented. An overview of the work and summary of principal results and conclusions are reported.
Mcalpine, G. A.↗
A review of modulation techniques for use in a satellite multipath environment
Modulation techniques for use in satellite multipath environment
Schuchman, L.↗
Multipath effects in a Global Positioning Satellite system receiver
This study, as a part of a large continuing investigation being conducted by the Communications Systems Branch of the Information and Electronic Systems Laboratory at the Marshall Space Flight Center, was undertaken to explore the multipath response characteristics of a particular Global Positioning Satellite (GPS) receiver which was available in the laboratory at the beginning and throughout the entirety of the study, and to develop a suitable regime of experimental procedure which can be applied to other state-of-the-art GPS receivers in the larger investigation.
Mcdonald, Malcolm W.↗