For the NON-technoheads, here's a little primer (slightly dated again but the fundamentals are there)...
OVERVIEW OF VIDEO TELECONFERENCING SYSTEMS
"What is Video Teleconferencing?"
Video teleconferencing (VTC) allows two or more individuals in different geographic locations to conduct educational, administrative and/or collaborative meetings without unnecessary travel.
VTC, also known as compressed video, uses digital telephone lines (ISDN lines) to send video and audio signals to participants at different sites to hold a "virtual meeting."
VTC is fully interactive - participants at both sites see and hear each other simultaneously.
"Is VTC flexible? Can only same manufacturer systems communicate?"
The International Telecommunications Union (ITU) (formerly CCITT) defined a videoconferencing standard (ITU H.320) to promote system interoperability between different manufacturers.
Most compressed video equipment manufactured today complies with international standards for VTC that allow communications between different manufacturers' systems.
Almost all VTC systems manufactured since 1993 are standards compliant and many older systems can be economically upgraded to the new standard.
This standardization along with reductions in the transmission and VTC equipment costs have revolutionized the industry. VTC has become a much more cost effective tool and the base of existing sites continues to grow.
"What are the components of a Video Teleconferencing system and how does it work?"
All basic VTC systems include an enCOder DECoder (CODEC), camera, control interface, speakers and a microphone.
The CODEC is the system brain that converts wideband analog video signals to digital format and compresses the signal. It operates at speeds ranging from 56 kbps to 1.544 Mbps.
A CODEC is analogous to a computer MODEM. Just like a MODEM, a CODEC must be located at each end to receive and transmit the incoming and outgoing signal.
The control interface enables the user to control the conference functions such as: calling other sites, selecting cameras, and previewing and sending graphics.
Good quality microphones are an essential important component in any VTC system. Most group systems rely on tabletop microphones that allow sound to be retrieved from most parts of the room.
"What are the types of Video Teleconferencing systems and their differences?"
There are two primary types of videoconferencing systems in use today, desktop or PC-based personal systems and modular or group systems.
Desktop Systems
Desktop systems were first introduced in 1992 for one-to-one conferencing primarily for PC application sharing.
Initially, these systems did not have very good video quality, nor were they compatible with other manufacturers' systems. Desktop systems have since been engineered to accommodate the industry's requirements for standards-based videoconferencing.
Prior to 1995, desktop VTC systems were sold as part of an entire personal computer package. With the advent of drop and insert CODEC cards, cameras and audio add-ons and the increased computing power of the latest microprocessors, desktop VTC quality has improved and prices have dropped dramatically.
Add-on cards and components can be purchased for approximately $1000 - $2000, making your existing Pentium processor computer ready for VTC.
Group Systems
Modular systems are group conferencing systems, unlike the desktop systems designed for one-to-one conferencing.
Modular videoconferencing systems come in multiple configurations and can be equipped with different features and auxiliary items that have an impact on price.
Modular systems may have multiple monitors, cameras and microphones, depending on the application.
Small roll-about systems have a single monitor and generally a lower-end CODEC capable of 128 kbps to 384 kbps transmission speeds. These systems are best for small group (1-3 persons) meetings.
Large group or gallery systems have large (27" and up) monitors and are geared toward group conferences with three or more people.
Modular systems range from $20,000 to $60,000 each, depending on the size and capabilities of the equipment.
" What type of auxiliary equipment is available for VTC?"
There is a wide variety of ancillary equipment that can enhance VTC systems to support many different applications. Some of them are described below:
Voice activated cameras track the speaker and are particularly useful in a classroom.
Document cameras are used to take a snapshot of an object or a slide and transmit the still graphic to the remote end.
Scan converters take a VGA computer display and convert it to National Television Standards Committee (NTSC) format for display on the video monitors. Participants can have collaborative work group sessions through document sharing and PC applications.
Video printers print the television monitor screen image.
Ancillary equipment such as auxiliary cameras, document cameras, and additional microphones can enhance the system but will also increase the price.
The VTC system can have one or more cameras. Multiple cameras are generally auxiliary items for larger systems.
Most rollabout systems come with a moveable camera that can pan, tilt, zoom and focus on individuals, pairs and/or combinations of things.
Dual monitor systems allow participants to share still graphics and other documents while maintaining eye contact.
"Can Video Teleconferencing systems connect to more than one site simultaneously?"
Originally a point-to-point system prior to 1991, videoconferencing now allows three or more sites to connect at once through the use of a video bridge called a Multi-Point Control Unit (MCU). Although this type of hardware can be expensive, certain applications, such as distance learning to multiple classrooms, can be more effective in a multi-point configuration.
Videoconferencing offers a host of benefits to its users, including reduced travel needs, greater efficiency and increased productivity. Many professors would rather take a trip across campus than across the country to participate in a lecture series. Videoconferencing makes unproductive travel time almost non-existent.
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