Opinions about the future of broadcast are anything but convergent. Talk to a dozen experts, and you get 12 different opinions of how technology will advance into the millennium, and how content will be delivered to the end user. Ask enough questions and it’s easier to believe we are headed for irreconcilable divergence.
No matter how you view the future, the marriage of some form of global data and broadcast network is inevitable. In the near-future, users – it won’t be accurate to call them viewers – will not only select the portal with which they tap into the global information net, but also the content which they retrieve.
What follows is a peek into the world of convergence. It’s a world receiving unprecedented attention and investment, and one which is still being shaped by the decisions of thousands of contemporary users.
What the !@#? does that mean?
Network: Two or more linked computer systems.
Node: A processing station on a network, such as a computer or printer.
LAN: Local Area Network. A network confined to a small area (such as an office building) allowing nodes to share information and devices. LANs transmit data faster than telephone lines.
Ethernet: The most common PC LAN architecture.
WAN: Wide-Area Network. Created when two or more LANs are connected by telephone lines or radio waves.
The Need for Speed
Bandwidth: The amount of data that can be transferred in a fixed period of time. For digital services, bandwidth is usually expressed in bits per second.
Narrowband: A transmission system that carries small amounts of information, such as copper telephone cables. (i.e. baud transfer rates of 56.6Kbps.)
Broadband: Rapidly carries large amounts of data, such as fiber-optic cable. (I.e. rates of 100Kbps and more.)
Baud rate: The transmission speed between modems.
Take the Highway
T-1: A dedicated phone connection capable of transmitting data at 1.5 Mbps. It is comprised of 24 individual phone lines, each transmitting at 64 Kbps. T-1 lines are also referred to as DSL lines.
T-3: A dedicated line transmitting data at 45 Mbps. It is made from 28 T-1 lines. T-3 lines are called DS3 lines.
ISDN: Integrated Services Digital Network, an international standard for sending voice, video and data over digital or analog phone lines. A standard ISDN line carries 64 Kbps.
DSL: Digital Subscriber Lines. DSLs compress data onto existing copper telephone lines. DSL is similar to isdn but offers faster transfer rates.
ADSL: Asymmetric Digital Subscriber Lines support data transfer rates over existing copper phone lines of 1.5 to 9 Mbps when receiving data (downstream rate) and 16 to 640 Kbps when sending data (upstream rate). ADSL requires an ADSL modem and is popular in the U.S.
SDSL: Symmetric Digital Subscriber Lines transfer data at 3 Mbps over existing copper telephone lines in high frequency digital pulses. Normal voice communication doesn’t use high frequencies, so transmission can occur simultaneously. Transfer rates are the same for receiving and sending information. SDSL requires an SDSL modem and is popular in Europe.
Making it Fit
Compression: Shrinks data so it requires less storage space. This increases transfer speed and decreases cost.
MPEG: Moving Picture Experts Group. Commonly refers to digital video compression standards and file formats developed by the group. mpeg achieves high compression rates by only transmitting changes between successive picture frames.
MP3: Compresses sound data by removing noise the human ear doesn’t hear.
Streaming: Transfers data in a continuous flow, enabling users to display data as it’s being transferred.
Protect and Decode
Firewall: A security system designed to prevent unauthorized access to or from a private network. Firewalls can be created in hardware and software.
Set-top box: A device that receives encoded (or compressed) digital signals from interactive networks and decodes (or decompresses) the signals, converting them to analog signals displayed on your TV. It also receives commands from the user and relays them back to the networks.
Units of Measurement
bit – smallest unit of digital information
byte – a set of 8 bits Bps – bits per second
Kbps – kilobits per second (1Kpbs = 1000 Bps)
Mbps – Megabits per second (1Mbps = 1 million Bps)
Gbps – Gigabits per second (1 Gbps = 1 billion Bps)
Tbps – Terabits per second (1 Tbps = 1 trillion Bps)
Sources: www.webopedia.internet.com, www.itvnews.com/whatis, www.tagish.co.uk (Ethos)