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Description  |
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CROSS-REFERENCE TO RELATED APPLICATIONS
DAISY CHAINABLE VOICE-DATA TERMINAL, Ser. No. [unknown], filed Mar. 25,
1992, inventors Gary D. ALFORD and Robert E. SELLERS, assigned to assignee
of the present invention; and
SITE CONTROLLER WITH ECHO SUPPRESSION, Ser. No. [unknown], filed Mar. 25,
1992, inventors Robert E. SELLERS and Gary D. ALFORD, assigned to assignee
of the present invention.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to computer-based remote communications
systems and specifically to methods and systems incorporating site
controllers for user keypad terminals with digital logic and microphone
pickups that can be strung in a daisy chain of identical terminals.
2. Description of the Prior Art
Technology, in its various forms, has allowed the instructional classroom
to be extended beyond the traditional campus to remote student locations
by telecommunications. Community colleges have been offering telecourses
for academic credit nationwide for at least the last ten years. Students
in their homes may tune into tape recorded video series that are broadcast
by PBS TV stations at regular times. Then, two or three times a semester,
the telecourse students may meet on campus to take mid-term and final
examinations. Usually a regular instructor has responsibility for
conducting the tests and helping enrolled students during the progress of
each telecourse. Currently, lower division undergraduate credit can be
earned in this way in oceanography, geology, mathematics, business, and
marketing, to name a few. Successful students learning with this form of
instruction do so in spite of a lack of close contact with an instructor
and sacrifice the ability to ask questions during lectures. One advantage
is that telecourses are relatively inexpensive for all those involved
because the local community college merely synchronizes itself with the
schedule decided by a local PBS TV station that typically serves a region
comprising several community college districts. The television station
bears the expense of studio and transmitter equipment and the software
when a video tape is provided in a syndication. The students need only to
tune in a television receiver he or she may already own.
Businesses very often find it easier to cover the cost of more exotic
teleconferencing and teleinstruction to conduct conferences and
instructional sessions. Teleconferencing permits two-way picture and sound
communications with the participants, but is much more expensive than
ordinary telephone conferencing since special purpose video equipment and
a video grade channel are needed to interconnect the parties.
Teleinstruction allows a special interest class to be convened and
communicated across town or across country on a secure channel if needed.
Large, international companies use teleinstruction to train their sales
forces that are physically located at various locations throughout the
world. Traditional teleinstruction has not permitted individual students
to communicate in real-time with the instructor, except as a member of a
single site with a common audio channel.
There is a need for a system for remote distance education that permits an
instructor to be informed of which students at remote sites wish to speak
and to enable students desiring to speak to the instructor to have an
individual audio channel communicating back to the instructor's studio
facility.
What is needed is a system for remote distance education that permits an
instructor to see which students at remote sites wish to speak and to
enable a selected student to have an individual audio channel back to the
instructor's studio facility.
SUMMARY OF THE PRESENT INVENTION
It is therefore an object of the present invention to provide a system for
remote educational instruction.
It is a further objective of the present invention to provide a viewer
response system that extends the traditional challenge of a classroom to
an instructional broadcast.
It is a further object of the present invention to provide an interactive
network that allows students at remote sites to ask an instructor
questions live on the network.
It is a still further object of the present invention to provide an
educational support system that allows an instructor to issue questions
that can gauge viewer comprehension in real-time during a presentation.
Briefly, a preferred embodiment of the present invention includes a viewer
response system comprising a host site and at least one remote site
interconnected by a satellite channel for host-to-remote video, an X.25
communications channel for message exchanges that establish a virtual
circuit between each remote and the host site and a dial-up public phone
network channel that allows a remote site to dial the host site in
response to a student at the remote site wanting to speak on the system to
an instructor at the host site. A touch screen monitor at the host site
allows the instructor to sequence through electronic notecards that
function as presentation cue cards. Pop questions and quizzes can be
formatted on remote site monitors and keypad terminals for each student at
each remote site thus allowing real-time answers to be entered. A computer
supporting the host site computes and displays remote site status and
student responses, and logs the responses on disk memory.
An advantage of the present invention is that a system is provided that
gets and maintains viewer interest in a presentation coming from a remote
host site by satellite because each viewer can individually request and
get a channel to talk to the instructor during the session.
Another advantage of the present invention is that a system is provided in
which real-time viewer comprehension feedback is provided to a presenter,
even over a widely distributed network of viewers, that allows a presenter
to adjust the pace and level of the material to fit the audience.
These and other objects and advantages of the present invention will no
doubt become obvious to those of ordinary skill in the art after having
read the following detailed description of the preferred embodiments which
are illustrated in the various drawing figures.
IN THE DRAWINGS
FIG. 1 is a block diagram of an instruction system having a studio site for
an instructor and a remote site for a number of students which are
interconnected by a satellite video channel, an X.25 data channel and an
audio channel through the public phone network; and
FIG. 2 is a block diagram of the host computer included in the system of
FIG. 1;
FIG. 3 is a representation of the user interface screen presented on the
host site monitor that is included in the system of FIG. 1;
FIGS. 4A and 4B are diagrams of several icons and buttons that can appear
on the host site monitor that is included in the system of FIG. 1;
FIG. 5 is a diagram of various menus that can be displayed on the host site
monitor that is included in the system of FIG. 1;
FIG. 6 is a representation of an authoring window screen image for the
prompter authoring tool;
FIG. 7 is a diagram of the overall process of the viewer response system;
FIG. 8 is a track class hierarchy diagram that applies to the tasks and
processes of FIG. 7;
FIG. 9 is a message class hierarchy diagram that applies to the tasks and
processes of FIG. 7;
FIG. 10 diagrams the message connections and tasks associated with remote
site communication management that relates to the tasks and processes of
FIG. 7;
FIG. 11 is a diagram of the call queue management that relates to the tasks
and processes of FIG. 7;
FIG. 12 is a diagram of the messages, message connections and tasks for pop
question and quiz management;
FIG. 13 is an object diagram of the author card stack;
FIG. 14 is a block diagram of the site controller communication modules;
FIG. 15 is a menu manager interface block diagram; and
FIG. 16 is a classroom manager interaction block diagram.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates an interactive network 10 comprising a host site 12 and
at least one remote site 14. A satellite 16 establishes a first
communication channel 18 between sites 12 and 14. A second communications
channel 20 includes the X.25 public packet switched network for data. A
third communications channel 22 includes the public phone system direct
distance dialed (DDD) network for voice communications.
Host site 12 is a broadcast studio having a production control room 24 and
a studio 26 for an instructor. The studio 26 includes a touch screen
monitor 28, a site controller 30 and a plurality of response keypad
terminals 32. The control room 24 has a host computer monitor 34, a host
computer 36, an uninterruptable power supply (UPS) 38, a phone controller
40 and a broadcast equipment unit 42. The system 10 may further include a
satellite communications uplink 44 associated with host site 12. Remote
site 14 is a classroom associated with a satellite communications downlink
46, and comprising a television monitor 48, a site controller 50, and a
plurality of response keypad terminals 52 on a daisy chain cable 53. Site
controllers 30 and 50 are similar, as are response keypad terminals 32 and
52.
In operation, a video image of the instructor is sent from host site 12 to
each remote site 14 via communications channel 18. Data between the
instructor and a plurality of students individually associated with a
response keypad 52 are exchanged via communications channel 20. The voice
of a selected student is communicated to the instructor via communications
channel 22. A student wishing to speak to the instructor presses a button
for this purpose on a respective response keypad 52. The instructor
selects which, if any, student he or she wishes to enable to speak by
touching an appropriate icon displayed by touch monitor 28. Host computer
36 reads the selection at touch monitor 28 and sends an enabling signal to
site controller 50 via communications channel 20. A microphone within the
corresponding response keypad unit 52 is connected through the cable 53
and a voice channel is opened up back to the instructor via communications
channel 22. Site controller 50 dials an appropriate phone number to enable
the connection of host site 12 to communications channel 22. Phone
controller 40 manages as many as three incoming phone calls from remote
sites 14. Phone controller 40 comprises a front panel with indicators to
show ringing and off-hook status of three incoming phone lines and may be
controlled by an embedded microcomputer, such as an Intel 80C31.
Host 36 is a UNIX-based computer that is the foundation of an interactive
network. Host 36 gives a presenter immediate two-way access to each
viewer, creating a classroom situation that captures everyone's full
attention. Straightforward touch screen or mouse driven controls let the
presenter manage incoming questions, call on specific viewers, and monitor
overall audience comprehension. Convenient prompter cue cards help the
presenter keep track of material. Visual aids in icon form show how many
people are watching and how well the material is being understood. Host 36
enables the presenter to ask pop-questions and to administer planned
quizzes. Broadcast-quality video is displayed ultimately on monitors 48,
and allows viewers to see questions and results clearly. Results data may
be stored for a later, off-line analysis. A call queue helps the presenter
field questions. Phone controller 40 is an automatic, multi-line type that
supports two-way and three-way voice conversations.
Site controller 50 is a compact communication device that coordinates voice
and data transmission between response keypad terminals 52 and host
computer 36. One site controller 50 coordinates communication for up to
sixty-four terminals 52 at a remote site. Site controller 50 controls and
places calls from viewers and electronically notifies a presenter that a
particular viewer is logged in, allowing the presenter to call on the
viewer by name and location. Two phone lines are required to complete a
connection from remote site 14 to host 36. The first line transmits voice
from microphones included in terminals 52. The second line is used to
reinforce verbal interaction by transmitting data such as call and flag
signals and numeric and multiple choice answers to questions that may be
transmitted from host 36. Site controller 50 supports multiple set-ups,
allowing remote site 14 to connect to different host sites 12. Audio
"ducker" circuitry provides an echo/feedback cancellation and can be
adjusted either locally or remotely from host site 12. The co-pending
applications referred to above provide more detail on the ducker
circuitry. A built-in modem and an automatic voice dialing circuitry
simplify equipment needs. ASCII files can be downloaded from host 36 for
output to printers (not shown) at remote site 14, allowing written
material to be distributed by a presenter quickly and easily.
The response keypad terminals 52 are small desktop devices that support an
audio and data link between a viewer at a remote site 14 and a presenter
at host site 12, e.g., during a business television broadcast. The
built-in microphones included in response keypad terminals 52 allow
viewers to speak to the presenter without requiring either to deal with
conventional phones or necessitating leaving their seats. This helps the
continuity of the presentation and enhances a classroom interaction
environment.
Pressing a call key at a response keypad terminal 52 will signal to the
presenter that a particular viewer has a question or comment. The viewer's
call request message is put in a call queue as hereinafter detailed. When
a presenter calls on a viewer, the microphone in the corresponding keypad
terminal 52 activates and everyone on the network can hear the subsequent
two-way conversation. Pressing a flag key at a keypad terminal 52
indicates to the presenter, discreetly and anonymously, that the viewer is
having trouble understanding the material. Daisy-chain connection 53
allows sixty-four terminals 52 to be connected to each site controller 50.
Viewer response system phone controller 40 is a telecommunications control
device that manages incoming phone calls from remote sites 14 to host site
12. By handling up to three incoming calls at a time, phone controller 40
eliminates the need for switchboards and telephone operators, frees a
presenter to focus on viewers statements, and reduces the costs usually
associated with live interaction. Front panel indicators on phone
controller 40 show the ringing or off-hook status of the three incoming
phone lines. Phone controller 40 can interface to an optional digital
hybrid system, which would allow viewers from sites outside system 10 to
call the presenter using standard telephones. Touch monitor 28 preferably
has a twenty inch high resolution color display. Monitor 34 may be a
sixteen inch high resolution type. Host computer 36 has a communications
interface 72 for a modem and X.25 PAD at 9.6 K baud to 64 K baud.
FIG. 2 illustrates host computer 36 which comprises a 486/33 PC/AT computer
including a central processing unit (CPU) 60, a 32 M byte random access
memory (RAM) 62, a 330 M byte disk 64 with a small computer systems
interface (SCSI), a UNIX multi-tasking operating system 66, an NTSC/PAL
video interface 68, and a mouse 70. A RS-232 serial port 74 may be
connected to studio site controller 30. A RS-232 serial port 76 provides
for connection to phone controller 40, and a RS-232 serial port 78
provides for connection to the touch screen monitor 28. UNIX operating
system 66 hosts a pair of applications programs, a viewer response system
(VRS) 80 including several independently executing processes. A prompter
authoring tool (PAT) 90 operates on MS-WINDOWS. Site controller 50 must
communicate with viewer response system 80 and include a program that
supports interaction with viewer response system 80.
VIEWER RESPONSE SYSTEM
In operation, viewer response system 80 provides a computer-implemented
method for providing an interactive system that simulates the traditional
classroom environment in business television broadcasts, as briefly
described above. Viewer response system 80 puts a presenter in touch with
each member of an audience at remote sites 14 through audio and data
communications. This can encourage viewer participation and enhance
comprehension and information retention, thus making distance learning
more effective. Viewer response system 80 communicates with a presenter at
touch screen monitor 28 with a set of icons (also referred to as buttons)
displayed on screen 28 that are touched by hand to activate some
associated procedure.
FIG. 3 illustrates a user interface (UI) 92 that is presented on monitor
28. UI 92 comprises four quadrants, the first quadrant is a response group
94 which includes a response monitor 96, a response button 98, a response
check icon 100 and a stop button 102. The second quadrant of UI 92 is a
question group 104 which includes a question monitor 106, a question icon
108, a question button 110 and a question check icon 112. The third
quadrant of UI 92 is a prompter group 114 that includes a prompter monitor
116, a prompter button 118, a prompter next card button 120, a prompter
previous card button 122, a question button 124 and an icon 126. The
fourth quadrant of UI 92 is a remote group 128 that includes a pair of
remote monitor buttons 130 and 132, a pair of remote buttons 134 and 136,
a flag icon 138 associated with a tally icon 140, a viewers (students)
icon 142 and associated tally icon 144, a sites icon 146 and associated
tally icon 148, a callers icon 150 and associated tally icon 152, a tools
icon 154 and an associated tools icon 156.
In operation, response monitor 96 displays incoming answer summaries from
the remote sites 14. The displayed response represents the amalgamation of
answers from viewers that have answered a current pop question or
preformatted question before the time is up. A stop question button that
appears on screen can be used to stop an existing pop question. It also
ends any preformatted questions and exams in progress. Response check icon
100 causes the correct answer (one of the bars in the bar chart) to be
highlighted in the response window 96. The response button 98 calls up a
response pop-up menu 160, as illustrated in FIG. 4A, that includes a clear
icon 162 that removes a result graphic for a particular question and the
associated graphic text (e.g., the question window). A close log file icon
164 saves the current file and opens another. A cancel icon 166 puts the
pop-up menu away.
The question monitor 106 displays the text and possible answers to a
preformatted question. Selecting the question monitor 106 allows any text
and answer choices to be broadcast to remote sites 14. Question icon 110
calls up a pop question menu 170 (FIG. 4A) that includes a true/false
button 172, a yes/no button 174, a yes/no/undecided button 176, a AB
button 178 for two answer choices, a ABC button 180 for three answer
choices, a ABCD button 182 for four answer choices, a ABCDE button 184 for
five answer choices, a numeric button 186 and a cancel button 188. Numeric
button 186 allows a viewer to type in a number for arithmetic answers. The
question check icon 112 causes the correct answer in the question window
106 to be highlighted. The question button 110 will produce a question
pop-up menu 190 that includes a reset icon 192 which sets the pop question
number back to one, and a cancel icon 194 that puts the pop-up menu away.
A quiz/question pending alert box 196, illustrated in FIG. 4A, will appear
on the screen of monitor 28 if an attempt to issue a new question or quiz
is made while one is already pending. A yes button 198 stops the previous
quiz/question and issues the new selection. When selected, the pending
alert box 196 is put away. A no button 199 abandons the issuing of any new
question/quiz and allows the previous question/quiz to be completed.
The remote monitor button 134 or 136 causes a display of participant
calling within system 10. The monitor 130 or 132 can contain a variety of
icons and text. Selecting a remote monitor button 134 or 136 activates the
caller's microphone on a corresponding response keypad terminal 52, making
the caller live on system 10 as indicated by turning on a highlight on
monitor 28. When a call is complete, a presenter may hang up the line by
selecting the remote monitor button 130 or 132 a second time, which turns
the highlight off.
Remote buttons 134 and 136 call up a remote pop-up menu 198, as illustrated
in FIG. 4A, that includes a call viewer icon 200 that calls up a viewer
search keyboard 201 (FIG. 4A). A call site icon 202 also calls up the site
search keyboard 201. A random call button 204 calls on a viewer which has
been randomly chosen. A cancel button 206 puts the pop-up menu 198 away.
A (normal) caller icon 208 (FIG. 4A) displays the name and location of an
individual viewer (student) who wants to ask a question and is requesting
to be acknowledged. A red expert caller icon 210 shows in monitor 130 when
an expert caller is waiting to be acknowledged. Expert callers have
priority over normal callers. A green speaking icon 214 is displayed when
a caller is currently switched on and is live on system 10. A green expert
icon 216 is displayed when an expert is currently speaking and is live on
system 10.
A dialing icon 218 (FIG. 4A) is displayed when the instructor has called on
a participant, and that the participant has not yet connected. After
connecting, the icon 218 will change to a speaking icon.
The viewer/site search keyboard 201, as illustrated in FIG. 4A, is used
(after it pops up on screen) to select an audio channel from a specific
viewer or remote site 14 to be received. The user (instructor) touches-in
the first three letters of the last name of the viewer or site 14. After
entry of the third letter, viewer response system 80 will begin searching
for those sites/viewers that are currently logged into the system. The
viewers or sites that have names that match are displayed in the search
display on monitor 28. If more than five matches are found, a pair of up
and down arrow buttons 220 and 222 appear on screen to allow the user to
scroll up and down to the previous or the next page. Viewers and sites to
be selected are chosen by pressing a search display button containing
particular name of the individual or remote site 14. A pair of icons 224
and 226 denote the search keyboard type, site or student. An input display
228 shows the text characters as they are entered via a set of typewriter
buttons 229. A descriptor 230 reminds a user what is needed to begin the
search. Five positions of a search display 232 present the search
findings. The first and last names of viewers and/or site locations will
be written out. When the desired display is touched, the corresponding
viewer is called on and the viewer/site search keyboard 201 is put away.
The selected viewer is then placed in the remote monitor window 130 or 132
(FIG. 3) from which the search was initiated. A clear button 234 clears
any input and/or search findings, thus allowing new text to be entered. A
enter button 236 accepts input from one or two characters, rather than the
three to begin a search. A cancel button 238 cancels the operation and
puts the keyboard away. A random button 240 selects randomly throughout
system 10 to chose one viewer or site. Random button 240 brings up list
items at random.
A callers display 242, as illustrated in FIG. 4B, shows the current number
of non-speaking callers that are not represented in the remote monitors
130 and 132. A callers icon button 244 calls up a callers pop-up menu 246
that includes a clear queue button 248 that clears the entire call queue
including disconnecting any calls and removing icons and names from remote
monitor buttons. It does not, however, clear those individuals already
speaking. A cancel button 250 puts the pop-up menu 246 away.
A sites display 252 (FIG. 4B) shows in a legend box the current number of
remote sites 14 that are then currently logged onto host site 12. A sites
icon button 254 calls up a sites pop-up menu 256 that includes a connect
enable button 258 which allows sites to connect to the system. A
disconnect sites button 260 logs off all sites currently logged on. A
sites list button 262 calls up the sites list display. A cancel button 264
puts pop-up menu 256 away. A sites list display 266 contains an
alphabetical list of all remote sites 14 currently logged on. No commands
can be executed at this level except to cancel.
A viewer display 268 (FIG. 4B) shows the current number of participants
logged onto system 10. A viewer icon button 270 calls up a viewer pop-up
menu 272 that includes a logon enable button 274 that controls login by
toggling enable/disable of login. A logoff viewers button 276 logs off all
currently logged in viewers. A viewers list button 278 calls up the site
search keyboard 201 for the selection of a particular site. A set special
button 280 calls up a make expert selection box 281 and allows the user to
designate expert status to a particular viewer. A cancel button 282 puts
the pop-up menu 272 away. A viewer list display 284 contains an
alphabetical list of all the viewers currently logged on at the selected
site 14 with site search keyboard 201. The make expert selection box 281
has an expert button 286 that calls up the viewer search keyboard and
allows the user to designate particular viewers as experts and to give
them a priority status when they call in. A normal button 288 returns a
specified viewer to normal status. A cancel button 290 puts the popup menu
281 away.
SYSTEM COMMUNICATIONS
In further explaining the concepts of host-to-remote and remote-to-host
communications, the site login is initiated after a virtual circuit has
been established between the site controller 50 and the viewer response
system host system 80. A site registration request message, including the
site address, is sent to the host site 12 from the site controller 50. If
a site with a corresponding address is found in the sites database on the
host, the host 12 will respond with a site number assignment message
indicating that the login request was successful. If the login attempt was
not successful, the host 12 responds with a site login failure message
with a one byte type code indicating the cause on the failure.
After a successful login, site controller 50 sends a initialize site
message with an initialization request level, at which point the host site
12 responds will all messages required to initialize a site controller 50.
These messages include define response keypad terminal 52 display
messages, followed by a login setup message and finally a initialize site
end message. The define response keypad terminal 52 display message is
used to load common display messages into the response keypad terminal 52
display table. They are also stored locally in site controller 50 such
that when a response keypad terminal 52 is reinitialized the display
messages can be retrieved locally and sent instead of being downloaded
again from the host site 12. The login setup message defines the student
login prompts and the ID input field width to be used for student login on
the keypads. This information is also stored locally. On receipt of the
initialize site end message, login is complete. At this point, site
controller 50 will setup login prompts on initialized keypads if student
logins are enabled (flag included in site number assignment field).
Site logoff can be initiated by site controller 50 or by the host site 12.
A site logoff is initiated by the site controller 50 upon sending a site
logoff request to the host site 12 system. If the site is currently
registered on the host site 12, the host site 12 responds with a site
logoff with corresponding command code. Upon receipt of the site logoff
message, site controller 50 checks the command code, if a normal code
(zero) is received, site controller 50 forwards all existing buffered
message packets then clears the virtual circuit. If an abrupt code (one)
is received, site controller 50 will not forward any existing message
packets, but will immediately clear the virtual circuit. The site
controller 50 logs off all logged in keypads at this time.
Student login enabling is controlled by the viewer response system 80 with
student login enable messages and by the site number assignment message
during site login. The student login enable message contains both a
response keypad terminal 52 address and a login enable state. After
receiving a login enable message site controller 50 checks the state of
the enable flag, if the state is zero (disabled), site controller 50
downloads display messages with a login disabled message to all response
keypad terminals 52 not logged in. If the login state is one (enabled),
site controller 50 sets up all response keypad terminals 52 not already
logged in with a login prompt utilizing terminal input messages. The
response keypad terminal 52 address field is currently unused and must be
zero.
A flag rate display 292 (FIG. 4B), which appears in icon 138 (FIG. 3),
indicates the percentages of viewers who have pressed their respective
flag key on terminals 52 within a last-flag-reset time. For example, if
the flag reset time is set to one minute, then the display shows the
percentages of viewers who have pressed their flag during the last minute.
A flag icon button 294 calls up a flag pop-up menu 296 that includes a set
reset time button 298 that calls up a set reset time menu 299. A set
threshold button 300 calls up a set threshold menu 301 (FIG. 4B). A reset
flags button 302 resets all flags on system 10. A cancel button 304 puts
the pop-up menu 296 away.
The set flag reset time menu 299 lets a presenter choose the length of time
a viewer can be included in the computation of the flag rate percentage by
a thirty second button 306, a one minute button 308, and a three minute
button 310. A cancel button 312 puts menu 299 away.
The set flag threshold menu 301 (FIG. 4B) allows the user to set the flag
threshold to a desired level. The threshold is the percentage at which the
user interface 292 changes color from normal (e.g., blue color) to another
status (e.g., red color). A set of buttons 314-320 are used to enter the
percentages indicated on the buttons; A cancel button 321 puts menu 301
away.
A tools display 324 shows the current time and allows the user to access
maintenance a::d configuration tools. A tools icon 326 calls up a tools
pop-up menu 328 that includes an audio control button 330 that calls up an
audio control panel 331. A voice lines button 332 brings up a panel 333
(FIG. 5) so the user can modify or enter phone numbers for the three
incoming voice lines. A database button 334 allows the user to view and
modify the current database of participants and sites. A login button 336
allows the user to enter a login message for the keypads. A terminal
button 338 allows the user to directly access the operating system. A
shutdown button 340 shuts down viewer response system 80. A conventional
confirming dialog box will appear prior to the execution of the command to
verify the user intends to do this particular action. A cancel button 342
puts the pop-up menu 328 away.
Audio control panel 331 (FIG. 5) allows a user to adjust a set of digitally
adjusted audio potentiometers included in site controllers 50 via host 36.
Control panel | | |
