GLOSSARY OF TERMS AND CONCEPTS
Analogue:
A so-called "legacy" type of audio/video signal still predominant in broadcasting. This type of signal is represented by measurable visible qualities such as voltage. Analogue information is also characterized by constantly changing quantities and is the opposite of digital in which information is discretely measured. Analogue data (tape cassettes) and analogue methods of transmission (such as copper wire) subject the signal to decay and degeneration of sound quality by adding noise.
ANSI:
American National Standards Institute. An American standards body.
Asymmetrical:
Refers to multi-site videoconferences where at least one site is dominant and one is marginalized. This uneveness is usually due to differences in the quality of the equipment (technologically disadvantaged connections and technologically privileged connections), or the actual design and layout of the VC space, or the site from which the instructor usually broadcasts. Special effort must be paid to asymetrical sites which are marginalized in order for them to participate equally and fully.
Asynchronous Communication:
Human communication that takes place at different times. Email and threaded discussion groups would be two examples.
Attention Drift:
VC participants can easily lose interest in the broadcast because of visual distractors. While they are busy looking at the equipment (screens, mics, lights, cameras), they stop listening to what is being said.
Bandwidth:
The number of bits or kilobits of information capable of being transported within a given time interval; the width of the highway. The higher the bandwidth, the clearer the audio and visual image. The lowest amount of bandwidth used today is 128kbps (kilobytes per second). The newer equipment operates 384 kb (see ISDN below)
Back End:
The so-called "back end" of videoconferencing is the hardware, software and the protocols that make it work. Most, though not all of this is unseen, and its impact is always experienced.
bps:
bits per second. A measurement of speed and volume (bandwidth) of information that can be transported over a time interval. BPS (upper case) stands for bytes per second.
Bridge:
Hardware that allows multiple sites to send and receive information to each other. The bridge receives signal from one or more sites, and then re-distributes (disperses) it to everyone.Most bridges are programmed to prioritize audio over video, so that if too much information starts to back up, the system will "freeze" or drop the video so that all the audio can still be sent.
Broadband:
A very wide highway or communication network with large capacity lines or wireless transmission to carry the information and signals from one point to the other. Broadband transmission can be very expensive. Usually understood to be 1.5444 Mbps. Wideband transmissions usually imply a speed between 64 Kbps - 1.544 Mbps. Narrowband transmissions are low capacity transmissions, averaging 56 Kbps or less.
Camera Pre-sets:
pre-programmed camera angles and viewpoints that can be easily switched at the touch of a button by either the instructor or the technical assistant, to afford different pre-selected views.
Codec:
Compressor/Decompressor. Software that compresses the signals for transmission. The codec will also decompress and decode incoming digital signals and convert them back into analog signals. There are many "flavors" of Codecs, of which MP3 is one.
Compression (example):
File compression software searches a file for recurring characters and then finds a way to notate these recurrences. For example, in the phrase "Then they went there" there are a total or 20 characters (including spaces). The string of characters that repeats itself is "the." The compression software would then find a way to represent this recurring string with, say, an *. The new compressed version of the file would be" "*n *y went *re" and now instead of 20 characters we have 14 which is about a 30% compression rate. As you can see, in its compressed state, the file cannot really read. First it has to be decompressed. The compression in images tends to neglect pixels that that are not in the main colour palette, but file compression, as in this example, is usually performed by Winzip (tar or .gz in Unix). Zipping large media improves download time, but also means the client must have the utility to unzip the file once it is downloaded. As a courtesy, you should inform the client of the file format, the size, and what software they will need (usually Winzip) to view or hear the file.
Compressed Video:
The squeezing or compression of video signals from a large size down into a fraction of the size or bandwidth by a codec so that it can travel over a smaller carrier. In other words, compression shrinks file size by coding repeated characters as a new single character) and streaming technologies allow the file to be viewed or heard before it has been completely loaded. Compressed signal is mainly designed for transport.
Control Tablet:
A flat, board-like device that allows the instructor to control the other components of the videoconferencing system either by touch or through the use of a light pen. While the control tablet is standard among the equipment for videoconferencing, the exact model may vary from manufacturer to manufacturer. Popular models include the VTEL and PictureTel. The typical control tablet will allow the instructor to control and make adjustments on the computer, monitor, cameras, pre-sets, to switch the monitor from their image to the document camera, audio and mute, and other variables depending on the make and model.
Delay or Lag:
The dead-air or silence that is created while information is being either transported and/or processed by software such as Codecs.
Desk-top Videoconferencing:
Videoconferencing conducted through a personal computer using H.323 protocol and is perhaps best used when dealing with small groups or on an individual basis.
Digital:
Audio/visual signals represented bya series of discrete variations (in voltage, frequency, amplitude, location, etc.). In general, digital signals can be transmitted faster and more accurately than analog signals. Digital permits the simultaneous two-way transmission and receipt of multiple kinds of data (voice, data, video, etc).
Document Camera:
The document camera is similar in appearance to an overhead projector, but offers the user more features and has a built in a camera that allows you to project any image onto the monitor. Like the overhead, it has the capability to light from beneath and thus allows you to use standard overheads, but it can also provide light from above, allowing you to transmit opaque documents and images. You can also use the document camera to project objects like detailed equipment or specimens, on which you can zoom in for greater detail.
Document Sharing:
also known as white boarding. Allows multiple participants to write, edit, and modify the same document simultaneously.
Duplex:
Half duplex transmissions mean that communication can only happen in one direction at any given time; when one site or person is speaking or sending, the other cannot speak or send until the other's transmission is complete. In full duplex, all sites and/or people can speak and listen at the same time.
Echo Loop:
An echo loop happens when the transmitted audio signal from site A is received at site B's speakers, played, picked up by site B's mics and re-transmitted back to A so that A hears the echo. The only remedy is to have the remote site mute out their sound or to use an echo canceller (see below).
Echo Canceller (Echo Suppression):
A voice-activated software device that automatically detects echo loop back and mutes out the offending sources, or mutes out everything by default except the immediate mic that is receiving sound.
Fallacy of faith:
By definition, any camera angle or "point of view" is a subset -- is less than -- all that the human eye can see under technologically unmediated conditions (ie: physically, in the room itself). We are thus left with a rather startling phenomenon: the tendency to treat videoconferencing as though it actually were face-to-face, and therefore, we too readily leap to conclusions as though we were in face-to-face communication. We call this phenomenon the fallacy of faith. Remember, we only see what the camera shows us.
Frame Rate:
The frequency in which video frames are displayed on a monitor. Typical systems used to operate with 15 frames-per-second, which accounted for their jerky or motion delayed picture. Newer and more advanced systems now operate using 30 frames-per-second, which is what is used in television broadcasting and provides a seamless and fluid picture.
Front End:
The so-called "front end" of videoconferencing is the physical environment in which sender and receiver find themselves; it does not necessarily include the particular technology that makes things happen, but it can engage that.
Full Motion Video:
Sending images equivalent to TV speeds of 30 fps (Frames per Second).
GIF:
(Graphic Interchange Format): a type of image that can hold up to 256 colours. The 89a gif is transparent meaning one of the colours in the GIF's palette takes on the same colour of whatever the background happens to be, but the older 87, is not. Gifs are also interlaced. See also JPG and PNG.
H.320:
A protocol for videoconferencing in site-to-site and multi-site contexts, usually using ISDN and/or satellite technologies. This so-called "umbrella" standard includes H.261 for video compression, H.221 and H.230 and H.242 for communications (control, set up and termination of sessions), G.711, G.722 and G.728 for encoding and compressing of audio signals, H.221 for multiplexing data streams. It supports image sizes of 352x288 (known as CIF) and 176x144 (known as quarter CIF or QCIF). Some H.320 compatible equipment is manufactured by companies like Picture Tel, VTEL and Tandberg. 1 ISDN line (x2 channels) is 128 kbps, 2 lines (x4 channels) is 256 kbps, and 3 ISDN lines (x6 channels) is 384 kpbs.
H.323:
So-called videoconferencing over IP address, or webcasting or "packet-based" videoconferencing. Begun in 1992 with MBONE on Unix workstations.
Hazardous Practices:
Context is always important. Under certain conditions, one particular videoconferencing technology or pedagogy may fail miserably and even cause other problems, but in a different context (older students, another room, a different personality in a new instructor, etc.), the identical strategy may work perfectly well. It is, therefore, extremely important to understand the implications and nuances of the medium from a technical and a theoretical perspective. Any pedagogy that provides a set of "tips" or "best practices" may be a good start, but it will not make a good end if it is applied uncritically. "Best practice" can, and will, lead to hazardous practices, or even a teaching disaster if it is not understood dialectically and contextually.
Invisible Technologies:
In addition to the so-called "soft" factors, videoconferenced communication is also, of course, mediated by physical technologies. Some of these, such as telephones, books, televisions, and answering machines, become invisible technologies. These machines are largely unperceived because we tend to be unaware of their presence in everyday use. Making a telephone call is a largely unconscious activity; we do not struggle over which end goes on our ear and which end goes near our mouth, nor do we wonder, or worry, about what the number pad means, or how local and long distance numbers work. We are either oblivious to the technology, or only momentarily aware of it. Technologies are not inherently invisible, but they are made that way by familiarity and common use. An invisible technology only reverts back to a visible one when it does not work, then we suddenly become re-aware of them.
I/O Devices:
Input devices accept content that is to be broadcast. Such devices include mics, cameras, control panels, and document cameras. Output devices includes monitors, TVs, large screens, and audio speakers.
IP Address:
Every computer that is connected to the Internet, whether server or client, must be assigned a unique number for the purposes of identification. Currently, that number consists of four fields, each of which contains an integer between 0 and 255; for example, 120.23.124.231 would be a specific computer address. IP numbers said to be static are permanently assigned to a machine, usually in a lab, and IP numbers said to be dynamic are more likely when your ISP assigns your computer at the moment you connect from home. You can determine your IP address in the following manner: in Windows, go to Start\Accessories\MSDos and type winipcfg (Windowx 9.x) or ipconfig (Windows NT), depending on your operating system. In cases of Point-to-Point or Multi-Point VC, you will likely need to know your IP address.
IMTC:
International Multimedia Teleconferencing Consortium. This not-for-profit organization helps develop and articulate standards and specs for full, open standard compatibility between various hardware manufacturers and software programmers in the videoconferencing industry. See their website at http://www.imtc.org.
Interlaced:
The 89a GIF is also interlaced, meaning that when it comes in to your browser from a website, you see the whole picture right away, but it is faded and sketchy. As an invisible bar scrolls down the image repeatedly, the image becomes clearer with each pass. 89a's load faster that other dense formats, but they also seem to appear faster because when they come in to your browser, not every line of the image comes in at once; instead, you might get lines 1,10,20,30,40 and so on; then on the second pass you would get 2,11,21,31,41, and so on. With each new pass the picture becomes clearer. Example
ISDN:
Integrated Services Digital Network. ISDN is a digital network that provides seamless communication of sound and video between videoconferencing systems. ISDN is expected, eventually, to replace current analogue telephone lines, otherwise known as POTS (Plain Old Telephone System) lines. ISDN is both hardware and a set of protocol and interface standards that integrate voice, data and video over high speed telephone lines. To be more precise, ISND is 3 digital signals, 2 voice (b) channels and 1 signal (d) channel.
JPG:
(Joint Photographic Experts Group). A type of image can hold up to 16.7 million colours). JPG files use a very sophisticated compression algorithm called discrete cosine transformation, a mathematical technique that reduces the image's size by as much as 100 times. JPG's also reduce the the size by getting rid of "noise" or pixels that are not part of the subject's colour palette. Because JPGs can be extremely compressed, the are said to be "lossy" because many of the peripheral colours in the image's palette are deleted. See also GIF and PNG.
KU Band:
Satellite frequency range between 10.9 - 17 Ghz (gigahertz).
LAN:
Local Area Network. A network of computers connected usually physically, but also could be wireless. Lans contain workstations, file and print servers and other devices such as Firewalls and Proxy servers.
MBONE:
A virtual internet backbone for multicast over IP addresses (Internet). This software supports a variety of platforms (Mac, Unix, Win 9.x and NT, and eve DOS).
Mics:
Microphones may be uni-directional (picking up sound from one direction only) or omni directional (picking sound from all sides). Uni-directional mics are best for an individual lecturer, and omni-directionals can be used over the heads of participants to pick up sound (questions) from many different places.
Multiplexing:
Any protocol (method) by which a number of different kinds of data can be sent simultaneously over the same circuit.
Non-verbals:
Generic term for anything other than language (vocabulary, syntax) that communciates meaning. Examples include body language (posture, gaze, orientation) and paraverbals (tone, tempo, timbre, and volume of voice, inflection, pauses, and pitch). Non-verbals are often unconscious. Instructors must always be aware of how they are being viewed by participant (check yourself in your monitors) and should *always* be reading the body language of their audience to make sure everyone is attentive. Be alert to participant body language that shows slouching, sitting back in the seat, looking around, and speaking to or otherwise communicating surreptitiously with others.
Pace Changers:
An often unrecognized but essential fact of lecturing life is the length of our students' attention span. It is not 50 minutes. Classroom research indicates that 15-20 minutes is the most we can hope for before the minds of most of our audience wander off to other things. As mentioned earlier, the problem of distraction is magnified by nature of "remote" situations and by the transmission limitations of videoconferencing. Work with this limitation not against it. Find ways to stop talking and change the pace at or around the 20 minute mark in order to help students re-focus their attention and re-engage their thinking processes.
Typical "pace changers" might include a video clip, followed by a question and answer period; a short, structured experiential exercise followed by sharing within and between the live and remote sites. The use of "buzz groups" is excllent, both to re-focus attention after the 20 minute mark, and also to enhance understanding of the material being presented. This technique involves asking students to discuss a clearly structured question with their neighbors (usually in pairs or triads) for a short period of time (not longer than 5 minutes). You then ask for feedback on discussion outcomes and process it for clarification before moving on.
For videoconferencing this means asking students at a remote site to talk together and then share their thoughts with you and the students at your site (and other sites, if that's appropriate). You can repeat this process if there is more than one remote site. You can also ask the folks at one remote to comment on the thoughts of those at another, just as you would different groups in the same large lecture hall.
Paraverbals:
Pertaining to qualities of voice that usually communicate to others unconsciously: tone, tempo, timbre, volume, inflection, pauses, and pitch).
PIP:
(Picture-in-Picture) is a small moveable window that appears on your monitor. You can "assign" any number of feeds to it. Many instructors use PIP to preview material before broadcasting it, or to view lcoal or remote sites.
PNG:
(Portable Network Graphics) were designed specifically to replace GIFs on the WWW. This file type also combines the compression power of JPGs, but unlike JPGs, PNGs are lossless. See also GIF and JPG.
Signposting:
It is essential that the content of VC-mediated communication (and large lectures) is clearly and explicitly organized into units. Use signposts to let students know where you are and thus where they are in your presentation.
1. The opening. Tell them what you are going to do and indicate in general how you the presentation and the class as a whole is going to operate.
2. The closing. End clearly. Summarize what you've said and connect to things covered earlier and to be covered next.
3. The transitions. As you move from topic to topic announce it.
4. The high points. Emphasize key points. Students want to know what is really important. Tell them.
If you don't take the time to explain what you are doing while you are doing it, your best efforts to structure the content of your presentation are likely to be lost on your listeners, particularly if the quality of your message is already somewhat degraded by the videoconferencing medium. Moreover, your efforts to sustain this parallel dialogue about what's going to happen next, will be seen by your students as positive commitment on your part to show that you care about their understanding and recognize the situation they are in as "remote" learners.
Smartboard:
is a large electronic blackboard that allows you to "write" things out by hand, using special "pens" (usually in Red, Green and Blue). The result is then transmitted to the participants and can be saved as an image file for later use or for archiving on a course website. It is best used by the instructor, and works like a chalkboard. See also whiteboard.
T1 or Fractional T1:
A kind of digital bandwidth capability that transports data at rates of speed up to 1.54 Mbps (Megabytes per second).
T3:
A kind of digital bandwidth capability that transports data at rates of up to 45.304 Mbps
Technologically Disadvantaged Connections /Technologically Privileged Connections :
VC sites whose cameras, software, physical environment and supporting technologies are not the same as other sites who are involved in the broadcast.
Uplink:
the earth station used to transmit or relay videoconference information to a satellite.
Video Bridge:
Computerized switching system or input-output device that allows mutliple-site or enterprise videoconferencing to occur. The bridge is both hardware and software. Bridges can also transcode H.320 into H.323 protocols and vice versa.
Visual Distractors:
Anything in the VC environment that causes participants to shift their attention away from the main point of discussion. Examples of visual distractors include: flashy jewellery worn by the instructor, wearing the colour red which can cause oscillation in the broadcast, cameras, technical problems, switching camera angles of views too frequently, poor Power Point design, and low visual intimacy.
VoIP:
Voice Over Internet Protocol is a protocol used to compress and transmit speech over the Internet, using G.729 and G.723. Example: Skype.
A whiteboard:
A shared computer application, electronic workspace. It allows multiple participants to type, write, and draw freehand on it simultaneosuly, regardless of where they are. It is best used for collaborative work, but can also be used by one person to draw and broadcast in a pinch. See also Smartboard
WAN:
Wide Area Network. The largely unseen network of computers that make the Internet work, including routers, who transport and direct the packets of information, DNS (Domain Name Servers) who "resolve" or translate our alpha requests for computer access (ex: http://www.uottawa.ca) into numeric IP addresses (137.122.14.100)
Video Bridge:
Computerized switching system that allows multiple-point videoconferencing to occur.
