Journal articles: 'DIRECT BROADCAST SATELLITES'

1

Locksley, Gareth. "Direct broadcast satellites." Telecommunications Policy 11, no. 2 (June 1987): 193–207. http://dx.doi.org/10.1016/0308-5961(87)90026-7.

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2

Clausen, H. D., H. Linder, and B. Collini-Nocker. "Internet over direct broadcast satellites." IEEE Communications Magazine 37, no. 6 (June 1999): 146–51. http://dx.doi.org/10.1109/35.769289.

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3

Buntschuh, R. "First-Generation RCA Direct Broadcast Satellites." IEEE Journal on Selected Areas in Communications 3, no. 1 (1985): 126–34. http://dx.doi.org/10.1109/jsac.1985.1146169.

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4

Williams, Sylvia Maureen. "Direct Broadcast Satellites and International Law." International Relations 8, no. 3 (April 1985): 245–69. http://dx.doi.org/10.1177/004711788500800303.

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5

Watson, George F. "Whatever happened to direct-broadcast satellites?" IEEE Spectrum 24, no. 7 (1987): 16–16. http://dx.doi.org/10.1109/mspec.1987.6448956.

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6

de Sola Pool, Ithiel. "Direct-broadcast satellites and cultural integrity." Society 35, no. 2 (January 1998): 140–51. http://dx.doi.org/10.1007/bf02838137.

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7

Sultan, Nizar, W. F. (Tory) Payne, Ralph Richard Musclow, and Marcel Bouchard. "Reconfigurable dual feed antenna for direct broadcast satellites." Acta Astronautica 12, no. 1 (January 1985): 27–35. http://dx.doi.org/10.1016/0094-5765(85)90004-9.

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8

Hurwitz, B. A. "The Labyrinth of International Telecommunications Law: Direct Broadcast Satellites." Netherlands International Law Review 35, no. 02 (August 1988): 145. http://dx.doi.org/10.1017/s0165070x00007695.

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9

Johnson, Leland L., and Deborah R. Castleman. "The potential of direct broadcast satellites for the USA." Space Policy 8, no. 4 (November 1992): 351–61. http://dx.doi.org/10.1016/0265-9646(92)90068-7.

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10

Gershon, Richard A., and Tsutomu Kanayama. "Direct broadcast satellites in Japan: A case study in government-business partnerships." Telecommunications Policy 19, no. 3 (April 1995): 217–31. http://dx.doi.org/10.1016/0308-5961(94)00018-n.

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11

Goolsbee, Austan, and Amil Petrin. "The Consumer Gains from Direct Broadcast Satellites and the Competition with Cable TV." Econometrica 72, no. 2 (March 2004): 351–81. http://dx.doi.org/10.1111/j.1468-0262.2004.00494.x.

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12

Suresh, Vidhyashree, Aishika Bhattacharjee, and Kirubaveni Savarimuthu. "Dual-Layer Beamscanning Reflectarray Antenna Operating at Ku-Band." JOURNAL OF HIGH-FREQUENCY COMMUNICATION TECHNOLOGIES 01, no. 01 (February 13, 2023): 24–34. http://dx.doi.org/10.58399/sulr8973.

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This paper presents a beam scanning electronically reconfigurable reflectarray configuration for Ku-band applications using a single varactor diode. A 15×15 center-fed reconfigurable reflectarray antenna is designed consisting of 225 octagonal shaped unit cells. The proposed tunable element has a unit cell size of 9.8 mm, developed on a 1.575 mm thick Taconic TLY-5 substrate. A single varactor diode is integrated with the tunable element to produce a reflection phase variation of 340° at 14.1 GHz. In this work, both the varactor and biasing circuit are placed beneath the substrate to avoid unexpected reflections, which leads to achieving a pencil beam of 8.1° beamwidth. The simulation results of the reconfigurable reflectarray antenna (RRA) shows good beam-scanning radiation performance of scanning range ±30° and a peak gain of 27.6 dBi. This structure provides a convenient solution for Ku-band distinctive applications like uplink operation in the direct broadcast satellite system, digital video broadcasting, earth exploration satellites, space research satellites, and defense systems.

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13

Dong, Zhenghua, and Songlin Zhang. "SISRE of BDS-3 MEO: Evolution as well as Comparison between D1 and B-CNAV (B-CNAV1, B-CNAV2) Navigation Messages." Remote Sensing 16, no. 3 (January 26, 2024): 484. http://dx.doi.org/10.3390/rs16030484.

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The signal-in-space range error (SISRE) has a direct impact on the performance of global navigation satellite systems (GNSSs). It is an important indicator of navigation satellite space server performance. The new B-CNAV navigation messages (B-CNAV1 and B-CNAV2) are broadcast on the satellites of the Beidou Global Navigation Satellite System (BDS-3), and they are different from D1 navigation messages in satellite orbit parameters. The orbit accuracy of B-CNAV navigation messages lacks analyses and comparisons with D1. The accuracy and stability of the new hydrogen and rubidium clocks on BDS-3 satellites need annual analyses of long time series, which will affect the service quality of this system. Based on precise ephemeris products from the Center for Orbit Determination in Europe (COD), the orbit error, clock error, and SISRE of 24 medium Earth orbit (MEO) satellite D1 and B-CNAV navigation messages of BDS-3 were computed, analyzed, and compared. Their annual evolution processes for the entire year of 2022 were studied. Thanks to the use of inter-satellite links (ISLs) adopted by BDS-3 MEO satellites, the ages of the ephemeris are accurate and the percent of ages of data, ephemerides (AODEs), and ages of data and clocks (AODCs) shorter than 12 h were 99.95% and 99.96%, respectively. In addition, the broadcast orbit performance was also improved by ISLs. The root mean square (RMS) values of the BDS-3 MEO broadcast ephemeris orbit error were 0.067 m, 0.273 m, and 0.297 m in the radial, cross, and along directions, respectively. Moreover, the 3D RMS value was 0.450 m. Thanks to the use of new orbit parameters in the B-CNAV navigation messages of BDS-3 MEO, its satellite orbit accuracy was obviously better than that of D1 in the radial direction. Its improved accuracy can reach up to about 1.2 cm, and the percentage of its accuracy improvement was about 19.06%. With respect to clock errors, the timescale differences between the two clock products were eliminated to assess the accuracy of broadcasting ephemeris clock errors. A standard deviation value of 0.256 m shows good performances as a result of the use of the two new types of atomic clocks, although the RMS value was 0.541 m due to a nonzero mean bias. Overall, the accuracy of atomic clocks was good. For the new hydrogen and rubidium atomic clocks, their RMS and standard deviation were 0.563 m and 0.231 m and 0.519 m and 0.281 m, respectively. The stability of the former was better than that of the latter. However, due to the nonzero mean bias the latter was better than the former in accuracy. The RMS value of the SISRE of BDS-3 MEO’s broadcast ephemeris was 0.556 m, and the value was 0.920 m when it had a 95% confidence level. In contrast, after deducting the influence of the clock error, the value of SISRE_ORB was 0.092 m. Since the satellite clock error was substantially larger than the orbit radial error, the SISRE was mainly affected by the clock error, and their annual evolutions were consistent. Because of the improvement to the B-CNAV’s navigation message with respect to orbit radial accuracy, SISRE_ORB has improved in accuracy. Compared to D1, it had a significant effect on improving the accuracy of SISRE_ORB, and the percentage of the accuracy improvement was 8.40%.

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14

Noh, Young-Chan, Agnes H. N. Lim, Hung-Lung Huang, and Mitchell D. Goldberg. "Global Forecast Impact of Low Data Latency Infrared and Microwave Sounders Observations from Polar Orbiting Satellites." Remote Sensing 12, no. 14 (July 9, 2020): 2193. http://dx.doi.org/10.3390/rs12142193.

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The Direct Broadcast Network (DBNet) provides near-real-time delivery of low-earth-orbiting (LEO) meteorological satellites to operational numerical weather prediction (NWP) systems that need short data cut-off times to allow for the assimilation of the most recent satellite measurements. The NWP model requires timely delivery of observations including atmospheric temperature, humidity, and surface wind vectors. The World Meteorological Organization (WMO) Space Program (WSP) recommends the data latency of no more than 20 min for the satellite measurements. Currently, not all DBNet stations are delivering satellite data within the 20-min time frame. In this study, the forecast impact of the observations of LEO satellite sounders with data latency of 20 min or less was evaluated using the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS). Reducing the data latency up to 5 min increases the number of LEO infrared (IR) and microwave (MW) sounder observations delivered to the NCEP GFS data assimilation system by more than 20%. Overall, this study demonstrates a positive impact on the global weather forecasts when the IR and MW sounder data are delivered by 20 min anywhere in the world. Additional forecast benefits are not obvious for shorter data latency. Results from this study support the WSP recommendation of 20–minute data latency.

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15

Gong, Xuewen, Jizhang Sang, Fuhong Wang, and Xingxing Li. "A More Reliable Orbit Initialization Method for LEO Precise Orbit Determination Using GNSS." Remote Sensing 12, no. 21 (November 6, 2020): 3646. http://dx.doi.org/10.3390/rs12213646.

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Precise orbit determination (POD) using GNSS has been rapidly developed and is the mainstream technology for the navigation of low Earth orbit (LEO) satellites. The initialization of orbit parameters is a key prerequisite for LEO POD processing. For a LEO satellite equipped with a GNSS receiver, sufficient discrete kinematic positions can be obtained easily by processing space-borne GNSS data, and its orbit parameters can thus be estimated directly in iterative manner. This method of direct iterative estimation is called as the direct approach, which is generally considered highly reliable, but in practical applications it has risk of failure. Stability analyses demonstrate that the direct approach is sensitive to oversized errors in the starting velocity vector at the reference time, which may lead to large errors in design matrix because the reference orbit may be significantly distorted, and eventually cause the divergence of the orbit parameter estimation. In view of this, a more reliable method, termed the progressive approach, is presented in this paper. Instead of estimating the orbit parameters directly, it first fits the discrete kinematic positions to a reference ephemeris in the form of the GNSS broadcast ephemeris, which construct a reference orbit that is smooth and close to the true orbit. Based on the reference orbit, the starting orbit parameters are computed in sufficient accuracy, and then the final orbit parameters are estimated with a high accuracy by using discrete kinematic positions as measurements. The stability analyses show that the design matrix errors are reduced in the progressive approach, which would assure more robust orbit parameter estimation than the direct estimation approach. Various orbit initialization experiments are performed on the KOMPSAT-5 and FY3C satellites. The results have fully verified the high reliability of the proposed progressive approach.

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16

Rink, Tom, W. Paul Menzel, Liam Gumley, and Kathy Strabala. "HYDRA2: A Multispectral Data Analysis Toolkit for Sensors on Suomi-NPP and Other Current Satellite Platforms." Bulletin of the American Meteorological Society 97, no. 7 (July 1, 2016): 1283–94. http://dx.doi.org/10.1175/bams-d-14-00285.1.

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Abstract The Hyperspectral Data Viewer for Development of Research Applications, version 2 (HYDRA2), is a freeware-based multispectral analysis toolkit for satellite data that assists scientists in research and development, as well as education and training of remote sensing applications. HYDRA2 users can explore and visualize relationships between sensor measurements (brightness temperatures for infrared and reflectances for visible/near-infrared wavelengths) using spectral diagrams, cross sections, scatterplots, multiband combinations, and color enhancements on a pixel-by-pixel basis. HYDRA2 can be used with direct broadcast and archived data from sensors on board the National Oceanic and Atmospheric Administration (NOAA)/National Aeronautics and Space Administration (NASA) Suomi–National Polar-Orbiting Partnership (Suomi-NPP), NASA Aqua/Terra, European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Meteorological Operational (MetOp), and Chinese Fengyun-3 platforms. This paper describes HYDRA2 and presents some examples using data retrievals from the Suomi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS), Cross-Track Infrared Sounder (CrIS), Advanced Technology Microwave Sounder (ATMS), and Terra/Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) instruments.

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17

Pritchard, W. L., and M. Ogata. "Satellite direct broadcast." Proceedings of the IEEE 78, no. 7 (July 1990): 1116–40. http://dx.doi.org/10.1109/5.56927.

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18

Tydeman, J. "Direct Broadcast Satellite Systems in Europe." IEEE Journal on Selected Areas in Communications 3, no. 1 (1985): 224–32. http://dx.doi.org/10.1109/jsac.1985.1146186.

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19

Ropers, Norbert. "State responsibility and the direct broadcast satellite." International Affairs 64, no. 3 (1988): 483–84. http://dx.doi.org/10.2307/2622878.

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20

Ploman, Edward W. "State responsibility and the direct broadcast satellite." Space Policy 4, no. 2 (May 1988): 152. http://dx.doi.org/10.1016/0265-9646(88)90039-2.

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21

Lau, Tuen-yu. "From cable television to direct-broadcast satellite." Telecommunications Policy 16, no. 7 (September 1992): 576–90. http://dx.doi.org/10.1016/0308-5961(92)90023-i.

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22

Wu, T. K., and J. Huang. "Low-cost antennas for direct broadcast satellite radio." Microwave and Optical Technology Letters 7, no. 10 (July 1994): 440–44. http://dx.doi.org/10.1002/mop.4650071005.

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23

Richie, J. E., and H. N. Kritikos. "Linear program synthesis for direct broadcast satellite phased arrays." IEEE Transactions on Antennas and Propagation 36, no. 3 (March 1988): 345–48. http://dx.doi.org/10.1109/8.192116.

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24

Rubelj, M., P. F. Wahid, and C. G. Christodoulou. "A microstrip antenna array for direct broadcast satellite receivers." Microwave and Optical Technology Letters 15, no. 2 (June 5, 1997): 68–72. http://dx.doi.org/10.1002/(sici)1098-2760(19970605)15:2<68::aid-mop2>3.0.co;2-i.

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25

Chen, Tai-Lee, and Hsu-Sheng Wu. "Dual-Polarized Planar Reflector Feed for Direct Broadcast Satellite Systems." IEEE Antennas and Wireless Propagation Letters 9 (2010): 693–96. http://dx.doi.org/10.1109/lawp.2010.2055817.

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26

Encinar, Jose A., Manuel Arrebola, Luis F. de la Fuente, and Giovanni Toso. "A Transmit-Receive Reflectarray Antenna for Direct Broadcast Satellite Applications." IEEE Transactions on Antennas and Propagation 59, no. 9 (September 2011): 3255–64. http://dx.doi.org/10.1109/tap.2011.2161449.

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27

Clements, Michael E., and Stephen M. Brown. "The satellite home viewer improvement act: Price and quality impact of direct broadcast satellite companies’ provision of local broadcast stations." Telecommunications Policy 30, no. 2 (March 2006): 125–35. http://dx.doi.org/10.1016/j.telpol.2005.11.003.

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28

Jun, Young-Woo, and Hyun Kim. "Direct Broadcast Satellite in Asia and Advertising Opportunity for International Marketers." Media Asia 22, no. 1 (January 1995): 26–33. http://dx.doi.org/10.1080/01296612.1995.11726461.

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29

Briskman, Robert D., and Joseph V. Foust. "A new higher performance NGO satellite for direct audio/video broadcast." Acta Astronautica 66, no. 5-6 (March 2010): 914–21. http://dx.doi.org/10.1016/j.actaastro.2009.09.006.

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30

Alagoz, Fatih, Branimir Vojcic, Amina AlRustamani, and Raymond Pickholtz. "On the effects of traffic mixtures in direct broadcast satellite networks." International Journal of Satellite Communications 20, no. 4 (2002): 293–306. http://dx.doi.org/10.1002/sat.726.

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31

Benet, C. A., T. J. Furia, C. E. Schmidt, and T. G. Tracy. "The Attitude Determination and Control Subsystem of the STC (Satellite Television Corporation) Direct Broadcast Satellite." IFAC Proceedings Volumes 18, no. 4 (June 1985): 9–17. http://dx.doi.org/10.1016/s1474-6670(17)60865-6.

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32

Stokes, Mark. "Canada and the Direct Broadcast Satellite: Issues in the Global Communications Flow." Journal of Canadian Studies 27, no. 2 (May 1992): 82–96. http://dx.doi.org/10.3138/jcs.27.2.82.

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33

Elasmar, Michel G. "The direct broadcast satellite industry in the U.S.: Development and economic concerns." Journal of Broadcasting & Electronic Media 39, no. 2 (March 1995): 200–214. http://dx.doi.org/10.1080/08838159509364299.

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34

Morris, F. "Potential Interference from Terrestrial Sources into Direct Broadcast Satellite Home Receiving Systems." IEEE Journal on Selected Areas in Communications 3, no. 1 (1985): 155–66. http://dx.doi.org/10.1109/jsac.1985.1146172.

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35

Egly, Keith, Rick Leacock, and Vasilis Riginos. "In-orbit test of the first Hughes United States direct broadcast satellite." International Journal of Satellite Communications 13, no. 5 (September 1995): 301–12. http://dx.doi.org/10.1002/sat.4600130505.

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36

Suenaga, Masashi, and Robert J. Prevaux. "MBSAT A direct broadcast satellite for mobile users in Japan and Korea." Acta Astronautica 57, no. 2-8 (July 2005): 215–23. http://dx.doi.org/10.1016/j.actaastro.2005.03.026.

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37

Xu, Hai Hua, Li Ping Liu, and Bai Chuan Liu. "Research of Digital TV Public Cultural Information Service System Based on DBS." Advanced Materials Research 1014 (July 2014): 383–86. http://dx.doi.org/10.4028/www.scientific.net/amr.1014.383.

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In the existing digital TV platform based on direct broadcast satellite, using the idle repeater resources, digital TV intelligent operating system and the core technology of middleware can present multiple functions such as broadcast TV, cable TV network etc. in one terminal without increasing the cost of existing satellite receiving terminal, realizing a variety of digital service like satellite TV channels, local channels, movies pushing Well-being community, health care, culture sharing, government affairs openness, television, newspapers and magazines. At the same time it can be transmitted to the edge server of Internet, the front of cable TV network and other network environment to realize the integration of three kinds of networks, which creates a kind of public digital cultural information service system with less investment, multiple functions, wide coverage, fast transmission speed, resource sharing, safe and controllable.

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38

Lim, T. S., and K. G. Tan. "The development of radial line slot array antenna for direct broadcast satellite reception." International Journal of Electronics 94, no. 3 (March 2007): 251–61. http://dx.doi.org/10.1080/00207210601108471.

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39

Gustiandi, Budhi, and Donna Monica. "Current development of community satellite processing package (CSPP) to support direct broadcast remote sensing satellite data processing." IOP Conference Series: Earth and Environmental Science 500 (July 4, 2020): 012016. http://dx.doi.org/10.1088/1755-1315/500/1/012016.

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40

Tienda, Carolina, Manuel Arrebola, and José A. Encinar. "Recent Developments of Reflectarray Antennas in Dual-Reflector Configurations." International Journal of Antennas and Propagation 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/125287.

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Recent work on dual-reflector antennas involving reflectarrays is reviewed in this paper. Both dual-reflector antenna with a reflectarray subreflector and dual-reflectarrays antennas with flat or parabolic main reflectarray are considered. First, a general analysis technique for these two configurations is described. Second, results for beam scanning and contoured-beam applications in different frequency bands are shown and discussed. The performance and capabilities of these antennas are shown by describing some practical design cases for radar, satellite communications, and direct broadcast satellite (DBS) applications.

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41

McKinney, J., and G. Fehlner. "The Flexible Domestic Regulatory Approach for Direct Broadcast Satellite Systems in the United States." IEEE Journal on Selected Areas in Communications 3, no. 1 (1985): 50–56. http://dx.doi.org/10.1109/jsac.1985.1146166.

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42

Wolff, R. "An Assessment of the Potential Terrestrial Interference Due to Direct Broadcast Satellite Television Receivers." IEEE Journal on Selected Areas in Communications 3, no. 1 (January 1985): 148–54. http://dx.doi.org/10.1109/jsac.1985.1146171.

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43

Alagoz, F., B. R. Vojcic, D. Walters, A. AlRustamani, and R. L. Pickholtz. "Fixed Versus Adaptive Admission Control in Direct Broadcast Satellite Networks With Return Channel Systems." IEEE Journal on Selected Areas in Communications 22, no. 2 (February 2004): 238–49. http://dx.doi.org/10.1109/jsac.2003.819972.

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44

Agyei Karikari, John, Stephen M. Brown, and Amy D. Abramowitz. "Subscriptions for direct broadcast satellite and cable television in the US: an empirical analysis." Information Economics and Policy 15, no. 1 (March 2003): 1–15. http://dx.doi.org/10.1016/s0167-6245(02)00069-0.

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45

Antonelli, Paolo, Henry E. Revercomb, Graziano Giuliani, Tiziana Cherubini, Steven Businger, Ryan Lyman, Stephen Tjemkes, Rolf Stuhlmann, and Jean-Luc Moncet. "Regional Retrieval Processor for Direct Broadcast High-Resolution Infrared Data." Journal of Applied Meteorology and Climatology 56, no. 6 (June 2017): 1681–705. http://dx.doi.org/10.1175/jamc-d-16-0144.1.

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AbstractThe Space Science Engineering Center, in collaboration with the Mauna Kea Weather Center at the University of Hawai’i at Mānoa, has developed a regional retrieval processor for high-spectral-resolution infrared data. The core of the processor makes use of an inversion system, referred to as Mirto, which combines, in a Bayesian way, the a priori knowledge of the atmospheric state, based on available numerical weather prediction forecasts, with the physical information embedded in satellite observations. Forecast temperature and water vapor mixing ratio fields over the central North Pacific Ocean are adjusted to produce synthetic radiances closer and closer to the Suomi NPP Cross-track Infrared Sounder (CrIS) observations taken in clear-sky conditions. The paucity of synoptic observations over this area and the highly homogeneous background represented by the ocean provide a good framework for the implementation of this hyperspectral data inversion system. Nearly real-time (less than 60 min from overpass time) Internet publication of retrieved atmospheric profiles is made possible by the availability of a direct broadcast system that provides data from the Suomi NPP platform (CrIS and VIIRS). The main goal for the implemented system is to provide the forecasting community with products suitable for nowcasting applications and for optimal data assimilation. The implemented processor has been running routinely since August 2013. Validation based on the comparisons of retrievals with rawinsonde data from Hilo, Hawaii, and Lihue, Hawaii, and GPS-derived total precipitable water from four stations, performed over a time period of more than 1 year, shows a statistically significant improvement on the background atmospheric state used as a priori information.

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46

Ujan, Sahar, Neda Navidi, and Rene Jr Landry. "Hierarchical Classification Method for Radio Frequency Interference Recognition and Characterization in Satcom." Applied Sciences 10, no. 13 (July 3, 2020): 4608. http://dx.doi.org/10.3390/app10134608.

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The Quality of Service (QoS) and security of Satellite Communication (Satcom) are crucial as Satcom plays a significant role in a wide range of applications, such as direct broadcast satellite, earth observation, navigation, and government/military systems. Therefore, it is necessary to ensure that transmissions are incorruptible, particularly in the presence of challenges such as Radio Frequency Interference (RFI), which is of primary concern for the efficiency of communications. The security of a wireless communication system can be improved using a robust RFI detection method, which could, in turn, lead to an effective mitigation process. This paper presents a new method to recognize received signal characteristics using a hierarchical classification in a multi-layer perceptron (MLP) neural network. The considered characteristics are signal modulation and the type of RFI. In the experiments, a real-time video stream transmitted in the direct broadcast satellite is utilized with four modulation types, namely, QPSK, 8APSK, 16APSK, and 32APSK. Moreover, it is assumed that the communication signal can be combined with one of the three significant types of interference, namely, Continuous Wave Interference (CWI), Multiple CWI (MCWI), and Chirp Interference (CI). In addition, two robust feature selection techniques have been developed to select more informative features, which leads to improving the classification precision. Furthermore, the robustness of the trained techniques is assessed to predict unknown signals at different Signal to Noise Ratios (SNRs).

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47

Mosco, Vincent, and Sara Fletcher Luther. "The United States and the Direct Broadcast Satellite: The Politics of International Broadcasting in Space." Contemporary Sociology 18, no. 6 (November 1989): 938. http://dx.doi.org/10.2307/2074221.

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48

Noll, Roger. "The United States and the direct broadcast satellite: The politics of international broadcasting in space." Information Economics and Policy 4, no. 1 (January 1989): 83–84. http://dx.doi.org/10.1016/0167-6245(89)90035-8.

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49

Wang, Pei, Jun Li, and Timothy J. Schmit. "The Impact of Low Latency Satellite Sounder Observations on Local Severe Storm Forecasts in Regional NWP." Sensors 20, no. 3 (January 24, 2020): 650. http://dx.doi.org/10.3390/s20030650.

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The forecasts of local severe storms (LSS) are highly dependent on how well the pre-convection environment is characterized in the numerical weather prediction (NWP) model analysis. The usefulness of the forecasts is highly dependent on how frequently the forecast is updated. Therefore, the data latency is critical for assimilation into regional NWP models for it to be able to assimilate more data within the data cut-off window. These low latency data can be obtained through direct broadcast sites and direct receiving systems. Observing system experiments (OSE) were performed to study the impact of data latency on the LSS forecasts. The experiments assimilated all existing observations including conventional data (from the global telecommunication system, GTS) and satellite sounder radiance data (AMSU-A (The Advanced Microwave Sounding Unit-A), ATMS (Advanced Technology Microwave Sounder), CrIS (Cross-track Infrared Sounder), and IASI (Infrared Atmospheric Sounding Interferometer)). They were carried out in a nested domain with a horizontal resolution of 9 km and 3 km in the weather research and forecasting (WRF) model. The forecast quality scores of the LSS precipitation forecasts were calculated and compared with different data cut-off widows to evaluate the impact of data latency. The results showed that low latency can lead to an improved and positive impact on precipitation and other forecasts, which indicates the potential application of LEO direct broadcast (DB) data in a high-resolution regional NWP for LSS forecasts.

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50

Zou, Xiaolei, Xiaoxu Tian, and Fuzhong Weng. "Detection of Television Frequency Interference with Satellite Microwave Imager Observations over Oceans." Journal of Atmospheric and Oceanic Technology 31, no. 12 (December 1, 2014): 2759–76. http://dx.doi.org/10.1175/jtech-d-14-00086.1.

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Abstract The geostationary satellite television (TV) signals that are broadcasted over various continents can be reflected back to space when they reach ocean surfaces. If the reflected signals are intercepted by the antenna of the microwave imager on board polar-orbiting satellites, they are mixed with the thermal emission from the earth and result in direct contamination of the satellite microwave imager measurements. This contamination is referred to as television frequency interference (TFI) and can result in erroneous retrievals of oceanic environmental parameters (e.g., sea surface temperature and sea surface wind speed) from microwave imager measurements. In this study, a principal component analysis (PCA)-based method is applied for detecting the TFI signals over oceans from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) Aqua satellite. It is found that the third principal component of the data matrix of the AMSR-E spectral difference indices from each AMSR-E swath captures the TFI contamination. The TFI-contaminated data on the AMSR-E descending node at both 10.65- and 18.7-GHz frequencies can be separated from uncontaminated data over oceanic areas near the coasts of Europe and the United States based on the intensity of the data projection onto the third principal component (PC). Compared to the earlier methods, the proposed PCA-based algorithm works well on the observations without a priori information and is thus applicable for broader user applications.

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Journal articles on the topic 'DIRECT BROADCAST SATELLITES'

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