Technology
Videoconferencing requires a monitor, microphone, camera, and speakers. The
camera captures local video on your side, while the monitor displays the remote
or far side. A microphone is used to capture local audio and speakers
to play remote audio. The videoconferencing unit must also include a codec
(Compressor/DECompressor), a user interface, and a network connection.
The codec converts video and audio to digital format and compresses
the signal prior to transmissions and decompresses it at the far-end. The
information in a video session is squeezed into a fraction of its
former bandwidth by a codec.
Optional Equipment may include:
- Document camera
- Scope
- Writing tablet (annotator)
- Additional cameras
- VCR/DVD
- Computer
Videoconferencing systems range from inexpensive computer-based
systems to group systems suitable for an entire class:
- Computer-based: adding an inexpensive camera (i.e.
web cam) to a computer with a microphone and speakers (suitable
for one to one conferences with comprise of quality)
- Desktop: a small videoconferencing unit connected to
a computer with microphone/camera/speakers (suitable for one
to one or small group conferences), may use IP or ISDN depending
on unit
- Group Systems: range of units using monitor or projector,
usually controlled by a remote (suitable for one to one through
entire classes)
IP/ISDN
Videoconferencing connections may be made through either ISDN or
IP connections. ISDN is the traditional means, while IP is
gaining favor.
ISDN works through digital phone lines. Generally good connection
speed and audio/video quality. You pay cost of phone connection Xs
number of lines required to connect (at least two) so this can become
very expensive in day-to-day usage.
It is only recently that Internet Protocol is offering sufficient
bandwidth to allow for quality VC connections. Day-to-day
usage costs are non-existent. IP takes advantage of the network you
already have in place. The trend in the field is for both
providers and receivers to use IP.
Gateway/Bridge
Bridge/gateway technology allows educators to take full advantage
of videoconferencing by providing the means to make all connections
and support multi-site conferences.
- Gateway: allows IP and ISDN systems to link
- Bridge: allows multi-point connections between three or more
sites
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