Page 56 - Intelligent Communication Systems

40 INTELLIGENT COMMUNICATION SYSTEMS
(1) The image information server retrieves information requested by the
terminal from information storage and sends it to the terminal. An
image information server stores the information provided by the
information provider (IP).
(2) The IP creates image information for the information service and sends
it to the image information server via the telephone network.
(3) Users can issue a request for information retrieval from a terminal and
receive the information.
(4) The communication control unit controls information or command
exchanges among the server, the IP terminal, and the user terminal,

5.4 DISTANCE EDUCATION SYSTEM

Advances in telecommunication technology led to the development of practical
distance education systems. To provide education to rural areas with no schools, a
distance education system is installed by which lectures are broadcast from a main
campus to satellite schools. Students come to the satellite school to attend classes.
The main campus and satellite schools are connected via the network, and lectures
are transmitted from the main campus to the satellite.
Exchange of lectures among countries and universities is increasing year by
year. For example, a Japanese instructor teaches Japanese history to New Zealand
students via the system, and a New Zealand instructor teaches the economics of
his or her country to Japanese students.
Using the telecommunication networks, many kinds of distance education sys-
tems have been developed and put into practical use. Some of them are described
here.

5.4.1 Audio Conferencing System
The audio conferencing system uses telephone lines to transmit audio signals. It is
less expensive than other distance education systems. Two or more sites are inter-
connected via the telephone network. Users can hear the transmitted voices but
cannot see one another. Instead, pictures of the students attending classes at the
remote sites are posted on a board. A diagram of the setup is shown in Figure 5.4.

5.4.2 Audiographic Conferencing System
In the audiographic conferencing system, two telephone lines are used to transmit
both audio and graphics. Two or more sites are interconnected via the telephone
network. Because it takes a lot of time to transmit text or graphics through a tele-
phone line, it is desirable to download such information before the class starts.