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  • 1
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    Large scale rainfall diversity and satellite propagation (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: From the NOAA 15 minute precipitation file for the U.S., data was selected for 128 stations covering a 17 year period and the probability of simultaneous rainfall at several stations was calculated. We assumed that the chosen stations were located in separate beams of a multi-beam communications satellite with shared fade mitigation resources. In order to estimate the demands made on these resources, we determined the number of stations at which rainfall rates exceeded 10 to 40 mm/hr. We found a 1 percent probability that at least 5 of the 128 stations have rain at or over 10 mm/hr in any 15 minute interval. Rain at 2 stations was found to correlate over distances less than about 600 miles.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, Proceedings of the 16th NASA Propagation Experimenters Meeting (NAPEX 16) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop p 17-26 (SEE N93-26463 09-32; JPL, Proceedings of
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  • 2
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    Results of 1987 MSS helicopter propagation experiment at UHF and L band in Central Maryland (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: This effort emphasizes several important results pertaining to a mobile satellite system propagation experiment performed in Central Maryland during June 1987. Fade distributions due to multipath and roadside trees at L Band (1.5 GHz) during a period in which the deciduous trees were in full bloom are examined. The multipath statistics for roadside trees are compared with previous multipath measurements made in canyon terrain in North Central Colorado. Also examined is the repeatability of previous UHF measurements made in Central Maryland and the attenuation effects of foliage on trees at UHF. Fade duration for the multipath mode for fade levels of 5 dB and 10 dB is also presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, Proceedings of the 12th NASA Propagation Experimenters Meeting (NAPEX 12); p 18-26
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  • 3
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    The Australian experiment with ETS-V (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Land-mobile satellite propagation measurements were implemented at L Band (1.5 GHz) in South-Eastern Australia during an 11 day period in October 1988. Transmissions (CW) from both the Japanese ETS-5 and INMARSAT Pacific geostationary satellites were accessed. Previous measurements in this series were performed at both L Band (1.5 GHz) and UHF (870 MHz) in Central Maryland, North-Central Colorado, and the southern United States. The objectives of the Australian campaign were to expand the data base acquired in the U.S. to another continent, to validate a U.S. derived empirical model for estimating the fade distribution, to establish the effects of directive antennas, to assess the isolation between co- and cross-polarized transmissions, to derive estimates of fade as well as non-fade durations, and to evaluate diversity reception. All these objectives were met.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, Proceedings of the 13th NASA Propagation Experimenters Meeting (NAPEX 13); p 32-41
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  • 4
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    An overview of results derived from mobile-satellite propagation experiments (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: During the period 1983-1988, a series of Land Mobile Satellite Service (LMSS) propagation experiments were performed. These experiments were implemented with transmitters on stratospheric balloons, remotely piloted aircraft, helicopters, and geostationary satellites. The earlier experiments were performed at UHF (870 mega-Hz) and the latter at both L band (1.5 giga-Hz) and UHF. The general objective of the above tests was to assess the impairment to propagation caused by trees and terrain for predominantly suburban and rural regions where cellular communication services are impractical. This paper presents an overview of the results derived from the above experiments.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, California Inst. of Tech., Proceedings of the 2nd International Mobile Satellite Conference (IMSC 1990); p 219-224
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  • 5
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    Preliminary results of MARECS-A measurements in Central Maryland and plans for 1988 MSS experiment in Australia (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Past and future efforts are described, using L Band (1.5 GHz) satellite signals for mobile satellite system (MSS) propagation measurements. Preliminary results from the December 1987 campaign in Central Maryland with the Atlantic Ocean MARECS satellite are given. The fade level statistics from this 22 degree elevation source are consistent with helicopter measurements made along the same roads. The day to day repeatability of the fade probabilities is shown to be usually better than about 20 percent. An experiment plan is presented for measurements using the Experimental Test Satellite-V's (ETS-V's) southern beam. These measurements will be made in Australia in collaboration with Australia's National Satellite System (AUSSAT) during the July/August 1988 time-frame.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, Proceedings of the 12th NASA Propagation Experimenters Meeting (NAPEX 12); p 36-46
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  • 6
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    Propagation effects by roadside trees measured at UHF and L-band for mobile satellite systems (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Propagation field tests were performed in Central Maryland and involved a helicopter and mobile van as the source and receiving platforms, respectively. Tests were implemented at both UHF (870 MHz) and L-band (1.5 GHz) during a period in which the trees were in full blossom and contained maximum moisture. Cumulative fade distributions were determined from the data for various fixed elevation angles, side of the road driving, and road types for both worst and best case path geometries and for overall average road conditions.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Jet Propulsion Lab., Proceedings of the Mobile Satellite Conference; p 87-94
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  • 7
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    K-band mobile propagation measurements using ACTS (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An overview of two planned propagation campaigns employing land-mobile scenarios with ACTS is presented. The campaigns will be undertaken through a joint effort involving the Johns Hopkins University, Applied Physics Laboratory (APL), The University of Texas at Austin, Electrical Engineering Research Laboratory (EERL), and the NASA Lewis Research Center (NASA LeRC). Propagation campaigns are planned in Central Maryland in November 1993 (elevation angle approx. equals 40 deg.) and in Fairbanks, Alaska in June 1994 (elevation angle approx. equals 8 deg.) employing a computer controlled antenna tracking system located atop a van containing a receiver/data acquisition system. The antenna will track (in azimuth) downlink transmissions at 19.914 GHz from ACTS during the mobile propagation measurements. The major objectives of the campaigns are to measure the fade and multipath effects of trees and terrain at 20 GHz for rural and suburban scenarios and to extend existing models which were previously validated at UHF to S-Band.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, Proceedings of the Third International Mobile Satellite Conference (IMSC 1993); p 325-330
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  • 8
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    LMSS drive simulator for multipath propagation (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A three-dimensional drive simulator for the prediction of Land Mobile Satellite Service (LMSS) multipath propagation was developed. It is based on simple physical and geometrical rules and can be used to evaluate effects of scatterer numbers and positions, receiving antenna pattern, and satellite frequency and position. It is shown that scatterers close to the receiver have the most effect and that directive antennas suppress multipath interference.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, Proceedings of the 13th NASA Propagation Experimenters Meeting (NAPEX 13); p 42-47
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  • 9
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    L- and K-band LMSS propagation measurements using MARECS-B, OLYMPUS, and ACTS (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: L-band measurements of land mobile satellite systems (LMSS) propagation effects were last made at the end of 1988, but some voids were left in the database, making modeling of low elevation roadside tree shadowing and multipath reflections difficult for some path geometries. Transmission of a pilot tone from MARECS-B at 55 deg West during Sep. and Dec. 1991 gave an opportunity to fill the gaps in the experimental results. Two campaigns during which fade data were obtained at elevation angles from 7 deg to 40 deg are described. Below 15 deg, specular terrain reflections in a non-shadowing, hilly environment were observed to introduce significant fading. Although the reflecting surface was at a distance of up to several km, it is shown that the reflected signals are delayed by less than 1 microsec. Mobile measurements were also attempted receiving the 20 GHz Olympus beacon, but antenna pointing problems restricted first results to straight-line driving.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, Proceedings of the 16th NASA Propagation Experimenters Meeting (NAPEX 16) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop p 27-33 (SEE N93-26463 09-32; JPL, Proceedings of
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  • 10
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    Satellite sound broadcast propagation measurements (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Power transmitted from atop a 17.9 m tower in simulation of a satellite signal, emitted by a tone generator sweeping from 700 to 1800 MHz, was received using a 90 deg beamwidth linearly scanning antenna at many locations inside six buildings of solid brick, corrugated sheet-metal, wood-frame, mobile home, and concrete wall construction. The signal levels are found to have much structure in the spatial and frequency domain but were relatively stable in time. Typically, people moving nearby produced less than 0.5 dB variations, whereas a person blocking the transmission path produces 6 to 10 dB fades. Losses, which at an average position in a room increased from 6 to 12 dB over 750 to 1750 MHz, could be mitigated to 2 to 6 dB by moving the antenna typically less than 30 cm. Severe losses (17.5 dB, mitigated to 12.5 dB) were observed in a concrete wall building, which also exhibited the longest multipath delays (greater than 100 ns). Losses inside a mobile home were even larger (greater than 20 dB) and independent of antenna orientation. The losses showed a clear frequency dependence.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, Proceedings of the Fifteenth NASA Propagation Experimenters Meeting (NAPEX 15) and the Advanced Communications Technology Satellite (ACTS) Progagation Studies Miniworkshop p 123-131 (SEE N94-1603; JPL, Proceedings of
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