Ground segments that serve individual consumers came into their own during the 1990s. Although many U.S. consumers were enjoying direct reception of cable and TV networks using backyard dishes (typically 2m to 4m in diameter), an explosion of demand for home satellite TV did not really start until DIRECTV was introduced. The space segment for this pioneering system consisted of rather standard Ku-band Broadcasting Satellite Service (BSS) satellites operating in the assigned slot at 101 degrees west longitude (the Astra Fixed Satellite Service, FSS, and BSS satellites had already gained eminence at 19.2 degrees west longitude, based on analog transmission).
DTH receivers were installed in American homes by millions of families who either did not have access to cable TV or were unhappy with what the local cable company had to offer. Complementing the user terminals was the world's largest uplinkingcenter for DIRECTV, constructed in Castle Rock, Colorado. This center was the first to employ MPEG-based video compression and had the unique capability to originate 200 simultaneous channels of programming. The proprietary DIRECTV Satellite System (DSS) demonstrated the technical and operational viability of this type of implementation (as with many U.S. innovations, this proprietary standard has been supplanted in later DTH systems by the European Digital Video Broadcast [DVB] series of open standards).
By 2000, approximately 7 million individual subscribers were employing DSS receivers and subscribed to the service (making DIRECTV the United States third largest cable TV operator after AT&T-TCI and AOL /Time Warner). Echostar, a competitor of DIRECTV, introduced its innovative DISH Network and brought the total U.S. DTH subscriber count to over 10 million, the largest for any country in the world. France, Germany, the United Kingdom, Sweden, Thailand, Malaysia, Japan, Mexico, Brazil, and Argentina are among the nations in which consumers have access to a high degree of choice in TV entertainment. Many of these ground segments use the DVB standard, which contains MPEG-2 video compression and multiplexing, digital audio, encryption and conditional access, and online program guides. DVB provides many standard features that permit set-top boxes to be supplied from multiple vendors, but aspects of the conditional access system are very much closed. All together, 30 million subscribers enjoy this digital DTH satellite service at the time of this writing. This is a boon, not just for the operators but for manufacturers of home receiving antennas and set-top boxes, digital video compression and storage equipment, uplink earth stations, and providers of the programming itself (as well as advertisers) who gain a direct connection to viewers.
Returning to the Mobile Satellite Service (MSS) area, Inmarsat did a ood job of bringing satellite communication to the personal level. First with he Inmarsat M and then the M4 (Figure 1.8), it was demonstrated that one ould have reliable communication from a highly portable piece of equipment.Likewise, domestic MSS operators Optus Communications (Australia) nd American Mobile Satellite Corporation (AMSC) adopted similar
DTH receivers were installed in American homes by millions of families who either did not have access to cable TV or were unhappy with what the local cable company had to offer. Complementing the user terminals was the world's largest uplinkingcenter for DIRECTV, constructed in Castle Rock, Colorado. This center was the first to employ MPEG-based video compression and had the unique capability to originate 200 simultaneous channels of programming. The proprietary DIRECTV Satellite System (DSS) demonstrated the technical and operational viability of this type of implementation (as with many U.S. innovations, this proprietary standard has been supplanted in later DTH systems by the European Digital Video Broadcast [DVB] series of open standards).
By 2000, approximately 7 million individual subscribers were employing DSS receivers and subscribed to the service (making DIRECTV the United States third largest cable TV operator after AT&T-TCI and AOL /Time Warner). Echostar, a competitor of DIRECTV, introduced its innovative DISH Network and brought the total U.S. DTH subscriber count to over 10 million, the largest for any country in the world. France, Germany, the United Kingdom, Sweden, Thailand, Malaysia, Japan, Mexico, Brazil, and Argentina are among the nations in which consumers have access to a high degree of choice in TV entertainment. Many of these ground segments use the DVB standard, which contains MPEG-2 video compression and multiplexing, digital audio, encryption and conditional access, and online program guides. DVB provides many standard features that permit set-top boxes to be supplied from multiple vendors, but aspects of the conditional access system are very much closed. All together, 30 million subscribers enjoy this digital DTH satellite service at the time of this writing. This is a boon, not just for the operators but for manufacturers of home receiving antennas and set-top boxes, digital video compression and storage equipment, uplink earth stations, and providers of the programming itself (as well as advertisers) who gain a direct connection to viewers.
Returning to the Mobile Satellite Service (MSS) area, Inmarsat did a ood job of bringing satellite communication to the personal level. First with he Inmarsat M and then the M4 (Figure 1.8), it was demonstrated that one ould have reliable communication from a highly portable piece of equipment.Likewise, domestic MSS operators Optus Communications (Australia) nd American Mobile Satellite Corporation (AMSC) adopted similar
.bmp)
Figure 1.8 Examples of compact MSS user terminals for use in the Inmarsat system:
(a) Standard M; (b) Standard M4 (photos courtesy of NERA).
ground segment equipment, including Improved Multi-band Excitation IMBE) voice compression technology from Digital Voice Systems Inc.
(DVSI). While these terminals were not of the handheld variety, they nevertheless emonstrated that individual calls could be placed and subscribers ould be serviced conveniently and relatively inexpensively (e.g., as compared ith the best alternative in a remote place, on a ship, or wherever).The explosive use of the Internet during the 1990s had an impact on satellite communication ground segments. Major corporations that found it an effective way to extend their information technology (IT) systems across a broader business and geographic base adopted TCP/IP and the rest of the Internet suite of protocols. Companies like HNS, Gilat, and STM Wirelessenhanced their VSAT offerings by better supporting TCP/IP. Oddly, much
misinformation was propagated during the 1990s that TCP/IP was incompatiblewith GEO satellite links due to the combination of propagating delayand noise-induced errors. The leading suppliers of VSAT terminals and theassociated hub stations devised effective solutions through protocol spoofing (a technique also used by router vendors Nortel and Cisco to improve
performance) to allow satellite networks to challenge terrestrial solutions.HNS also introduced the first personal satellite Internet solution, DirecPC,to allow subscribers to reach 400 kbps downlink speeds. This service wasavailable in 12 countries at the time of this writing.
(a) Standard M; (b) Standard M4 (photos courtesy of NERA).
ground segment equipment, including Improved Multi-band Excitation IMBE) voice compression technology from Digital Voice Systems Inc.
(DVSI). While these terminals were not of the handheld variety, they nevertheless emonstrated that individual calls could be placed and subscribers ould be serviced conveniently and relatively inexpensively (e.g., as compared ith the best alternative in a remote place, on a ship, or wherever).The explosive use of the Internet during the 1990s had an impact on satellite communication ground segments. Major corporations that found it an effective way to extend their information technology (IT) systems across a broader business and geographic base adopted TCP/IP and the rest of the Internet suite of protocols. Companies like HNS, Gilat, and STM Wirelessenhanced their VSAT offerings by better supporting TCP/IP. Oddly, much
misinformation was propagated during the 1990s that TCP/IP was incompatiblewith GEO satellite links due to the combination of propagating delayand noise-induced errors. The leading suppliers of VSAT terminals and theassociated hub stations devised effective solutions through protocol spoofing (a technique also used by router vendors Nortel and Cisco to improve
performance) to allow satellite networks to challenge terrestrial solutions.HNS also introduced the first personal satellite Internet solution, DirecPC,to allow subscribers to reach 400 kbps downlink speeds. This service wasavailable in 12 countries at the time of this writing.
0 comments:
Post a Comment