 | Issue: | Latin America II 1998 |
| Article no.: | 13 | |
| Topic: | Turning PCs and Servers intoHigh-Speed Multimedia Satellite Receivers | |
| Author: | Susan Shi | |
| Title: | Science and Technology Writer | |
| Organisation: | ComStream, USA | |
| PDF size: | 44KB |
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Article abstract
Enabling technologies like digital broadcast technology and a hot new satellite PC/server receiver card, are changing the way PCs are used. Here, ComStream introduces MediaCast™, a DVB-compliant product that can make Pentium-class PCs capable of receiving rich, multimedia content via satellite, thus opening the door to a broad spectrum of applications such as distance learning and business broadcast.
Full Article
Just when you think computer technologies have reached their pinnacle, another application comes along that pushes the boundary, usually requiring more bandwidth to exercise its potential. Indeed, more bandwidth is the cry of the computing 90s. So it is that enabling technologies, such as digital broadcast technology and a hot new satellite PC/server receiver card, are changing the way PCs are used. MediaCast™, a DVB-compliant product from ComStream, can make Pentium-class PCs capable of receiving rich, multimedia content via satellite, thus opening the door to a broad spectrum of applications such as distance learning and business broadcast. But there is more. This high-speed pipeline can also transmit data and software files, web pages, new push and streaming technology broadcasts, as well as other multimedia intranet and extranet files via satellite, to locations that have no high-speed digital wire line connection. And at up to 1,000 times faster than standard computer modems over telephone lines, the long wait usually experienced when downloading large multimedia files and very high-resolution graphics and images, is eliminated. This true high-speed broadcast via satellite opens up a whole new realm of practical and efficient distribution of data-intensive applications and services to PC users. These applications include high-resolution television audio-video broadcasts, access to multimedia magazines, ‘push’ Internet Protocol (IP) multicasting, and streaming transmissions from the Internet; high-speed intranet access among geographically dispersed organisations, multimedia training materials, corporate TV; access to corporate enterprise resource planning systems; downloading corporate documents from a centralised control; corporate audio-video messages; distance learning; and megabit per second (Mbps) data transfer on corporate Local Area Networks (LAN). The MediaCast card is fully Digital Video Broadcast (DVB) compliant and operates in either Single Channel Per Carrier (SCPC) or Multiple Channels Per Carrier (MCPC) mode, at transmission rates from 2 to 30 megasymbols per second. (The symbol rate differs from the bit rate depending on the modulation and forward error correction scheme used. The 30 Msps rate corresponds to a content data rate as high as 45 or 50 Mbps). The MediaCast card receives IP data encapsulated over DVB MPEG-2 packets. This means the card can receive Internet content such as text, graphics, MPEG-l, push technologies, and streaming audio-video. By using a separate return back channel, such as a telephone modem, the MediaCast™ card can provide an Internet link for the receiver channel. However, the limitation of the TCP/IP packet acknowledgement scheme restricts the overall transmission rate to only 500-600 kbps. The PC receiver card’s back channel requirement may affect the kinds of applications you are able to use. (However, in most cases, the asymmetrical speed of the downstream and upstream makes no difference). Many consumer and corporate data applications, such as software downloads, large database file transfers, and MPEG-2 video file delivery, are inherently asymmetrical and, therefore, require only narrowband data rates for return traffic. Leveraging the true power of satellite, the MediaCast™ broadcast receiver is ideally suited to IP multicast applications. IP multicast is a data transmission scheme in which, rather than duplicating data sent ad infinitum, the technology sends the same information just once to multiple users, which yields corresponding savings in bandwidth and makes for a scalable solution. Based on IP, IP multicast can run on almost any network carrying IP. The technology works well with video-conferencing and whiteboarding (many-to-many flows), point-to-multipoint applications like video servers, push software, and software distribution (one-to-many flows). The MediaCast card is built on open industry standards and maximises the best thinking in multimedia broadcasting worldwide. The MediaCast™ card is faster and more flexible than other products. It transmits up to 45MB/s or 30Ms and allows users to manage their own uplink and network. It handles MPEG2 video extremely well, handing off the compressed video to the PCI bus and MPEG2 decoder card. The MediaCast card is ideal for satellite service providers, corporations, schools, and governments who want to establish multimedia broadcast (IP data and MPEG2 audio and video) networks. The MediaCast card is installed into a PC like most other PCI standard cards, one card per PC. It takes the same amount of time as the installation of any other PC card with some additional time needed to install cable for the 18-inch dish, depending on the site. MediaCast card supports the standard DVB descrambler and downloadable verifier software. Conditional access systems will be supported on an opportunity-by-opportunity basis. Conclusion A whole new world of desktop access is being opened up by new high-speed technologies, and content providers will continue to find more data and higher resolution multimedia to drive the demand for more bandwidth. With PC satellite receiver cards, digital broadcast content is now easily accessible and processed by computer. This includes very large data files and high-resolution graphic images, web pages, push and streaming files as well as all kinds of multimedia applications. MediaCast addresses this market, enabling complete satellite broadcast networks to be built for LAN and single PC sites.
