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There are several perspectives from which to view a teleconferencing
session, and from which to evaluate the effectiveness of a tele-encounter:
- From one perspective, the aim is to establish the illusion
of telepresence: the sense that others are "virtually present" through
"window," thus enabling an effective tele-encounter. From this
perspective, the aim is to use the highest bandwidth possible,
and to design an environment
where the video and audio transmission is so realistic that users
feel they are sharing the same space, and even forget that technology
is involved in creating the illusion.
- From an alternative perspective, the
aim
is to enable remote access to information and services. Here
effectiveness is based the the ability of participants to accomplish
the desired
objectives
for the tele-encounter, most specifically as related to the effectiveness
of modes of communication. The illusion of "telepresence" in not
required as long as aims are
achieved.
- From a task-oriented "systems" perspective,
a
human-technology-human connection (that includes human-technology
interfaces) is established, including human-technology interfaces.
This tele-encounter aims to accomplished a sequence
of tasks within a tele-encounter, such
as
teleconsultation,
telesupport,
teleassessment,
or teletherapy.
From the above, we see that teleconferencing can take many forms,
ranging from a simple mobile phone call that
could occur in many contexts, to a high-bandwidth
videoconference
between rooms designed for
such
conference calls. planned end videoconferencing system.
This section targets videoconferencing systems that include support
for video and
well as audio. Our primary focus will be on technical aspects,
especially through looking at videoconferencing standards.
First, however, we develop a foundation by classifying videoconferencing
environments into four types:
- Room (group) systems. Controlled environment
for group conferencing video (controlled
lighting, color scheme, camera locations, multiple
monitors),
audio (planned acoustics, audio mixing), other conferencing
media
(e.g.,
document camera, computer).
- Rollabout systems. Movable system
(including camera, monitor, microphone) on a cart, for intended
for both group and individual
teleencounters. Local environment is typically less controlled
(e.g., lighting, acoustics), and typically just one camera,
monitor and microphone.
- Desktop systems. Huge variety
of systems, ranging from videophones with a small 4"x3" screen
that is integrated
with a phoneset to settop boxes that sit on TV monitors to
computer desktop systems. Includes systems supporting all
of the videoconferencing standards.
- Mobile systems. Cell phone and
PDA (personal digital systems) such as PocketPC. Typically
video is QCIF (176x144 pixels) or less.
One can also look as systems from the perspective of their
" ...abilities":
- accessibility/usability: These have been defined previously. Access through minimization of the barrier
of distance is a fundamental motivation behind telehealth,
and was discussed previously in our section on universal access. The usability of telehealth features for individuals with diverse abilities has not be systematically evaluated, although we have an ongoing study addressing this need (PI on project: Jason Foil). In practise, there are many alternatives that related to changing control settings, implementation of audio and video.
- interoperability: Interoperability
is a key motivation behind vidoconferencing standards. It is our experience
with videoconferencing
that there are degrees of interoperability: marginally
interoperable implies
that it is possible for products to interoperate,
but
takes significant expertise
to achieve
connection and/or quality (e.g., of sound, video) diminishes
significantly below expectations once connected, which truly
interoperable means that the products readily
connect or communicate without degradation
in performance in measures related to the standard.
- reliability: It is often said that reliability is the
single most important factor is determining whether telehealth
technology is used or abandoned (and thus the growth
rate of the field of telehealth). There are also shades of
gray
that relate to reliability. Indeed, for our H.323 and
H.324 product evaluation studies, the experienced researcher
can "say" which products have been found to
be reliable; yet it is difficult to come up with objective
measures. Sometimes the connection is lost, other times
the quality temporarily degrades.
- scalability/flexibility: A ability
to change and adjust, for instance to more terminals, changes
in bandwidth allocation, product upgrades, etc.
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