Bridging the Gap: Understanding the fundamentals of distance learning is the key to tapping this lucrative market.

May 1, 1998 12:00 PM, Allan Lakey

Srolling by the conference room, you overhear, "Give me 3x BRI, H320, H281, G711-722-728, 12 point MCU, FCIF, QCIF, Fractional T1, H.323, T120 Data Collaboration and H261." You might assume the dialog is a scene from an television hospital drama. Chances are, it was a group of very experienced engineers discussing the world of video teleconferencing.

Complicated? It may be hard to believe that today's videoconferencing technology is easier to use than before. The videoconferencing market is segmented into two main arenas-corporate communications and distance learning. We are, however, seeing the two areas merge. Training in the corporate market really is distance learning. As a result, the corporate market has driven distance learning to new levels.

It was not long ago that the industry had limited choices of products, manufacturers and price points, which limited the potential applications. This is not the case in today's market place. The implementation of standards-based protocol has brought tremendous growth to the video-conferencing industry and increased product variety. This standardization has also allowed standards-based products to be developed and become more cost effective to fit an increased customer base.

One such application that has benefited tremendously from these advancements is distance learning. A couple of years ago, only a few of the largest universities benefitted from distance learning. The two main causes for the delay in wide acceptance of videoconferencing in distance learning applications were the equipment costs and the service provider fees. In the early days of videoconferencing, most systems operated with transmission connectivity of Half T1 (756 kbps, 6 BRI ISDN lines) and Full T1 (1536 kbps, 12 ISDN lines). The cost to have these high-speed digital lines installed and maintained was high with respect to the rate of return on use. Prohibitive costs were not limited to the educational environment. It pushed the limit on the cost-savings benefit for the corporate market place as well.

How has the videoconferencing industry progressed to make the distance-learning market such an area of growth? There are several reasons, one of which would have to be the acceptance and usage of worldwide minimum standards-based protocol. It was just a couple of years ago when a videoconferencing system from one manufacturer could not communicate with another, and most systems were completely proprietary. The ITU (International Telecommunication Union, formerly known as CCITT) worked with the industry manufacturers to develop a standards-based set of communication code. The ITU, one of the specialized agencies of the United Nations, was founded in 1865 (before telephones were invented) as a telegraphy standards body. Some important and commonly discussed standards are:

Communication: H.320: ITU-T minimum standards-based communication protocol.

H.281: ITU-T recommendation for A-V communication and far-end camera-control aggregation.

H.231: Multipoint control units for A-V systems using digital channels up to 1,920 kbps.

H.243 : Multipoint control unit for A-V services chair control.

Video: H.263: Increased resolution video compression and decompression.

H.261: Bandwidth-efficient video compression and decompression.

CIF: Common Intermediate Format (352 x 288 pixels).

QCIF: Quarter Common Intermediate Format QCIF 4 x Common Intermediate Format (704 x 576 pixels), (H.261 Annex D).

SQCIF: Sub Quarter Common Intermediate Format (128 x 96 pixels), (Decode Only) still image 4 x CIF.

Audio (H.320 specifies three types of audio): G.711: 48 to 64 kbps narrow band.

G.722: 48 to 64 kbps wide band.

G.728: 16 kbps narrow band.

Data: T.120: Protocol standards for data collaboration using videoconference bandwidth.

This is a small sample of standards, which raises another important issue. The standards-based protocol is but a minimum specification for manufacturers. H.320 actually contains three levels of implementation. Class 1 is minimum level of support; Class 2 is Class 1 with some optional features, and Class 3 is Class 2 with all optional features. The importance of these classifications is that not all systems are created equal. A product can specify that it is H.320-compliant but not have the performance and features as a higher-level H.320 class of product.

One of the items affected by the various classifications to use H.320 is the frame rate or frames per second (fps). The ITU-T H.320 standard requires support of frame rates of 7.5, 10, 15 or 30 fps, dependent upon class position. The lower frame rate does not provide the smooth motion inherent in broadcast television. The higher the frame rates, the better the image. The specification calls for each classification to meet particular frame rate requirements. Class 1 denotes a frame rate of 7.5 fps; Class 2 denotes a frame rate of 15 fps, and Class 3 denotes a frame rate of 30 fps.

Using a standards-based classification, however, does not imply simplicity. The use of H.320 opens the communication compatibility for various manufacturer products. Unfortunately, even manufacturers who deliver Class 3 systems are affected by manufacturers who are not providing products of equal performance. The systems that communicate are always forced to the lowest common denominator. This translates to both transmission speeds and H.320 use. The higher-performing system will revert to the lower standard.

This collaboration in communication development created the potential for manufacturers to develop systems that could communicate on an open platform of manufacturers and still implement their own improved proprietary set of algorithms for one-to-one communications. Industry leaders quickly adapted this new set of standards.

The early days The limitations of multiply manufactured products communicating (or lack thereof) via different protocols to one another caused severe limitations in how and who could use and join a distance-learning network. If one state university chose one product line, and several community colleges chose another, they could not communicate. This did not, however, slow the interest in the potential benefits videoconferencing could bring to distance learning.

One example occurred only a few years ago at a school district that wanted to offer foreign language instruction to its high school students but did not have the budget for a full time teacher. They could afford the cost of equipping a classroom with videoconferencing along with the link to another school district within the state that already had videocon-ferencing and a curriculum that included foreign languages. The district actually purchased the videocon-ferencing hardware and had the ISDN service installed only to find out that the system was incompatible with the communications format of the main district. Whydidn't they just find out what the district had and purchase the same equipment? It could have been dependent upon if the equipment was purchased from a service provider, A-V vendor, or through a state-run agency.

Again, many schools realized the benefit and potential applications as well as the corporate world. One analogy that could sum up the videocon-ferencing industry during this time would be to ask you to think of the problems you would encounter on a daily basis if there were no way for Microsoft MSWord and WordPerfect files to open each other's files.

These early systems were already providing quality images with 30 fps, audio echo cancellation and the ability to employ control systems. However, one fact was very evident in the early stages-to obtain the optimal audio and video performance, an integrator was a necessity to combine technologies. The fact remains that there is not one manufacturer who builds every product to the identical specification, but several leaders emerged to bring the communications standards together and allow cross-platform communication.

Technology today Today's technology provides advantages on several levels. While the cost of ISDN service has declined, the availability and applications for ISDN has increased. Today, many service providers promote ISDN service for business and residential use with Internet access and videoconferencing. This rise in popularity has caused the cost of ISDN service to drop, making videoconferencing available to more users.

Hardware now had to rise to the occasion of affordability. Equipment that could provide the image and sound quality required without the necessity of Half T1 or Full T1 was necessary. Not surprisingly, the industry has seen growth in systems that use transmission connectivity of 56 to 384 kbps. A system that functions on 384 kbps requires only 3 ISDN lines while still providing image quality exceeding that of the older system with Half T1 and Full T1. A system with today's technology and runs with 384 kbps can provide full-motion video with 30 fps, echo cancellation bandwidth and increased use of data collaboration.

Another major step forward is the technological advancements in cameras. Enhanced image quality came with a reduction in system cost. Several manufacturers recognized the growing demand for videoconference cameras and began development specifically for these applications.

In the early days, most distance-learning networks or systems were custom built by integrators. These systems were complicated and difficult to operate, and the integration of a control system was almost a necessity. The majority of these offerings were developed as systems with the main focus being a closed-loop application, which typically meant that the main teaching site was the sole control center. This was before the ITU-T standards addressed remote site control. Distance-learning applications expanded when these communication standards fell into use.

Proper support One of the most important aspects of distance-learning systems is the support of the networks and individual sites. This major element should never be overlooked. These systems typically have multiple users who have a tendency to work with individual flare, meaning that the users would adjust and leave the systems in various configurations. This often requires a service call from a technician. Most codec manufacturers were developing or using remote diagnostics for software upgrades and system diagnostics. The only drawback to this engineering feature was that it did not allow remote troubleshooting for other products in the system.

Forcing a technician to make a service call every time something is not working properly can be quite costly, but this is all about to change. On a visit to the new Crestron Electronics facility in New Jersey, I saw a preview of the new products to be shown at INFOCOMM '98 in Dallas. You might ask yourself what could be so revolutionary about a control system?

Crestron has designed the next generation of control systems that are fully Ethernet compatible. I know we have not even touched on Ethernet-that is another article. This opens up a new design concept of control system integration and use. Imagine the possibilities of being able to call into any distance-learning site to check any problem as well as modify system programming. A control system that is truly Ethernet capable will allow you to use dedicated TCP/IP addresses and even permits dialing into systems via the Internet. Once you are connected to the Crestron control system, you can monitor, configure and analyze any product in the system. You can even set up a conference for a non-technical user from your office.

Control systems have always had the capability to operate in Ethernet communication networks. Until now, the drawback has been the method of communication-via an external box, which is just communicating to an RS-232 port on the control system. This is similar to taking a Ferrari engine and using a transmission from a Yugo to deliver power to the wheels.

The use of an Ethernet control system will allow a network to be monitored worldwide from one or several locations. If a given site has a problem, they could even alert the monitoring control system via a help button. This would then allow the technician to call directly into the location requesting assistance and see if it is a hardware or operator error. It would even allow the monitoring technician to control the system from the remote site.

Additionally, system capability has grown rapidly. One of the first signs of this growth would be the expanded list of manufacturers offering complete product lines for videoconferencing. Not only has the list of manufacturers grown, but also the product offerings. Today, systems are available in dedicated codec units, roll-about systems, desktop PC configurations, desktop videophones, briefcase videophones, portable set top systems and packaged designed systems for distance learning and telemedicine.

Several manufacturers have developed dedicated systems for the distance-learning marketplace. Such systems may have a specially designed teaching podium that houses most, if not all, of the system hardware. These companies have attempted to provide the complete turnkey solution of integrated hardware, thereby presenting a nice package that will meet many of the system requirements seen today.

NEC developed the Teaching Pro 5000 system to meet the growing demand in distance learning. The Teaching Pro 5000 provides a system featuring a codec with transmission speeds up to 1,538 kbps, echo cancellation, PC transmission with T.120 data collaboration, VCR, slide-to-video converter, graphics illustration pen for writing on top of display feeds, preview and send capability and ParkerVision camera systems. A Crestron touchscreen controls the codec and all its components. PictureTel, Tandberg and VTEL have also developed systems for this market. The Tandberg unit is designed as a presentation/teaching podium similar to NECs. The PictureTel Socrates is a smaller system housed in a portable rack.

Geting started First, you will need to determine if the system will require an MCU (multipoint control unit) or a service provider that can provide this equipment. The MCU provides the ability to have multiple locations communicating as one. A standard system operates as a one-to-one call. The MCU acts as the bridge to allow multiple sites to communicate and be seen by each other or just by one. The bridge also has ITU-T communications standards, which allows the host (teaching) site to control the activity of bridged calls. This can allow multiple windows on a single screen and lock out the audio of various sites unless activated. This is the first step in the design of a distance-learning network. Once this has been chosen, you can now analyze the particular needs of each site. The primary site will require the most intensive control package. In this example, we are working on a system with only one primary teaching area. The remote sites are classrooms that will be joining into the main site.

Next, ask these questions:

Will there be connection to multiple remote sites at one time? If yes, how many could be online together? This will determine the size and capability of an MCU.

Will the remote sites require control of the host site equipment? This answer will determine the control complexity of the remote site.

Will the remote sites be permanently installed rooms or portable? If some rooms will not be installed systems they might be able to use the newer low cost portable systems.

Do you know what transmission speeds will be acceptable for the network? (For 128 kbps with maximum of 15 fps, one BRI ISDN is line required; for 384 kbps with maximum of 30 fps, three BRI ISDN are lines required; for 756 kbps with maximum of 30 fps and increased bandwidth six BRI ISDN lines are required, and for 1,356 kbps with maximum of 30 fps and increased bandwidth, 12 ISDN lines are required. This will determine the type of codec you will require. Not all codec manufacturers have systems capable of transmission speeds higher than 384 kbps.)

How many students will each location support? (This could determine how many mics will be required. This, in turn, could dictate using an external echo cancellation system to handle the increased requirements better.)

How many locations would benefit from camera systems that use tracking features?

Does the instructor site require PC data collaboration? (This will determine the design specification for the PC display and data collaboration to be used within the codec.)

Does the instructor site require a touchscreen interface? If yes, would it benefit from color display? Would they like a touchscreen that could provide video and computer images on screen for preview and control?

Does the instructor site require wireless touchscreen control?

Would the system benefit from using a wireless mouse for the PC data collaboration? (If the instructor might need to move around the room while teaching, an RF rather than infrared mouse is a necessity. Many things, such as line of sight and fluorescent lights, can affect the infrared units. The RF wireless mouse can operate without these limitations.)

Will the main instructor site require the system to be moved for operation from multiple rooms? (This will determine the type of teaching podium required to house the equipment and teaching control.)

These questions will provide a solid foundation of information to begin specification, and their answers might dictate the use of many of the pre-packaged distance learning systems available today. If the systems move beyond these capabilities, the products available will provide tremendous performance and options.

Analog transmission: The way information is transmitted over a continuously changing electrical wave. All telephone calls used to be transmitted in an analog format. Today, they are translated to digital pulses for both local and long-distance transmission.

Application sharing: a feature that allows two people to work together without the same application/software. This allows multiple participants to make changes to a shared document.

ATM (Asynchronous Transfer Mode): A standard implementation of cell relay, which is a packet-switching technique using packets (cells) of a fixed length. It is asynchronous in the sense that the recurrence of cells containing information from an individual is not periodic.

bps (bits per second): Aunit of measurement in which speed rate of data transfer can be calculated.

Bandwidth: Describes how much information can be pushed through an electronic pipe at any given time.

Baud: Rate of data transmission.

BRI (Basic Rate Interface): ISDN standard that monitors how phones and other electronic devices are connected to the ISDN switch.

Bridge: Usually made up of back-to-back codecs from different manufacturers to convert signals from one proprietary system to another.

Carrier: Refers to various telephone companies that provide local, long-distance or value-added services.

CCD (Charge Coupled Device): Used in cameras as an optical scanning mechanism.

CCITT (Consultative Committee for International Telegraphy and Telephony): Now called the International Telecommunications Union's Telecommunications Standardization Sector or TSS. An international body responsible for establishing inter-operability standards for communications systems. The world's leading telecommunications standards organization.

CIF (Common Intermediate Format): An international standard for video display formats developed by TSS.

Codec: Acronym for encoder/decoder. This device compresses (for transmission) and decompresses (once received) digital video and analog audio signals so that they occupy less bandwidth during transmission.

Compression: Any of several techniques that reduce the number of bits required to represent information in data transmission or storage, thereby conserving bandwidth and/or memory.

Continuous presence: The transmission of two or more simultaneous images.

Demodulator: A videoconference receiver circuit that extracts or demodulates the wanted signals from the received carrier.

Distance learning: The implementation of video and audio technologies into the educational process so that students can attend classes and training sessions in a location distant from that where the course is being presented.

DS-1: The Level 1 standard for digital systems operating at 1.536 Mbps (24 DS-0 channels). Also known as T1.

DS-3: Digital Signal Level 3. This term is used to refer to the 45 Mbps digital signal carried on a T3 facility.

Echo cancellation: An electronic circuit that attenuates or eliminates the echo effect on videoconference telephony links.

Echo effect: A time-delayed electronic reflection of a speaker's voice.

Encoder: A device used to alter a signal electronically so that it can only be viewed on a receiver equipped with a special decoder.

FCIF (Full Common Intermediate Format): Describes the type of video format transmitted using TSS standard coding methods.

Fractional T-1: FT-1 or fractional T-1 refers to any data transmission rate between 56 Kbps and 1.544 Mbps.

Full-motion video: Video reproduction at 30 fps for NTSC signals or 25 fps for PAL signals. Also known as continuous-motion video. Videocon-ferencing systems cannot provide 30 fps for all resolutions at all times, nor is that rate always needed for a high-quality, satisfying video image.

H.320: A recommendation of the ITU-T based on Discrete Cosine Transform, CCM, and motion compensation techniques. It can be a video system's sole compression method or supplementary algorithm used instead of a proprietary algorithm when two dissimilar codecs have need to interoperate. H.320 includes a number of individual recommendations for coding, framing, signaling, and establishing connections. It also includes three audio algorithms: G.721, G.722 and G.728.

ISDN (Integrated Services Digital Network): A telecommunications standard allowing communications channels to carry voice, video and data simultaneously.

ISDN Ordering Code: A predefined number that tells the phone company how to provision your ISDN line based on the requirements of your ISDN hardware.

ITU (International Telecommunications Union): One of the specialized agencies of the United Nations and founded in 1865 before telephones were invented as a telegraphy standards body.

Jitter: The deviation of a transmission signal in time or phase. It can introduce errors and loss of synchronization in high-speed synchronous communications.

Kbps (Kilobits per second): Refers to transmission speed of 1,000 bits per second.

Kilohertz (kHz): Refers to a unit of frequency equal to 1,000 Hertz.

LAN (Local Area Network): a computer network linking workstations, file servers, printers, and other devices within a local area, such as an office. LANs allow the sharing of resources and the exchange of both video and data.

Mbps: Megabits per second.

Megahertz (MHz): Refers to a frequency equal to one million Hertz, or cycles per second.

Microwave: Line-of sight, point-to-point transmission of signals at high frequency.

Modulation: The process of manipulating the frequency or amplitude of a carrier in relation to an incoming video, voice or data signal.

Modulator: A device which modulates a carrier. Modulators are found as components in broadcasting transmitters and in videoconference transponders.

MPEG (Moving Picture Experts Group): MPEG has established standards for compression and storage of motion video.

Multiplexing: Techniques that allow a number of simultaneous transmissions over a single circuit.

Multipoint: Communication configuration in which several terminals or stations are connected. Compare to point-to-point, where communication is between two stations only.

Multipoint Control Unit (MCU): A device that bridges multiple inputs so that more than three parties can participate in a videoconference. The MCU uses fast switching techniques to patch the presenter's or speaker's input to the output ports representing the other participants.

NT 1 (Network Termination Type 1): A device that converts the two-wire line coming from your telephone company into a four-wire line. The NT-1 is physically connected between the ISDN board of your videoconferencing system and your ISDN phone line.

NTSC (National Television Standards Committee): A video standard established by the United States (RCA/NBC) and adopted by numerous other countries. This is a 525-line video with 3.58 MHz chroma subcarrier and 60 cycles per second. Frames are displayed at 30 fps.

Packet switching: Data transmission method that divides messages into standard-sized packets for greater efficiency of routing and transport through a network.

Pan: To pivot a camera in a horizontal direction; tilt is to pivot in the vertical direction.

PBX (Private Branch Exchange): A telephone switch, usually located on a customer's premises, connected to the telephone network but operated by the customer.

Pixel: The smallest element of the computer or television display on the raster scale.

POTS (Plain Old Telephone Service): Conventional analog telephone lines using twisted-pair copper wire. This is used to provide residential service.

Real time: The processing of information that returns a result so rapidly that the interaction appears to be instantaneous. Telephone calls and videoconferencing are examples of real-time applications.

RJ-11: The most common telephone jack in the world. This is a six-conductor modular jack wired with four wires. You probably have RJ-11 jacks in your house.

RJ-45: An 8-pin connector jack used with standard telephone lines and required by some ISDN hardware. A little larger than an RJ-11 jack.

Scrambler: A device used to alter a signal electronically so that it can only be viewed or heard on a receiver equipped with a special decoder.

Service Profile Identifier (SPID): A number or set of numbers assigned to your ISDN line by your phone company. In the United States, one SPID is assigned to each channel. The switch uses SPIDs as unique identification numbers for each ISDN line, so that it can determine where to send calls and signals.

Signal to Noise Ratio (S/N Ratio): The ratio of the signal power and noise power. A video S/N ratio of 54 dB to 56 dB is considered to be excellent, that is, of broadcast quality.

Splitter: A passive device (one with no active electronic components) that distributes a television signal carried on a cable in two or more paths and sends it to a number of receivers simultaneously.

Spread spectrum: The transmission of a signal using a much wider bandwidth and power than would normally be required.

Synchronization (sync): The process of orienting the transmitter and receiver circuits in the proper manner in order that they can be synchronized.

10Base-T: Standard Ethernet; a variant of IEEE 802.3 that allows stations to be attached via twisted pair cable.

T1: The transmission bit rate of 1.544 Mbps.

T.120: A standard for audiographics exchange. Although H.320 does provide a basic means of graphics transfer, T.120 will support higher resolutions, pointing and annotation. Users can share and manipulate information much as they would employ if they were in the same room though they are working over distance and using a PC platform.

TELCO: Generic term for telephone company.

Telemedicine: The practice of using videoconferencing technologies to diagnose illness and provide medical treatment over a distance.

WAN: Wide Area Network.

Whiteboarding: A term used to describe the placement of shared documents on an on-screen shared notebook or whiteboard. Desktop video-conferencing software includes snapshot tools that enable you to capture entire windows or portions of windows and place them on the whiteboard.

X.25: A set of packet switching standards published by the CCITT.

Y/C: In component video, the "Y" or luminance signal is kept separate from the "C" (hue and color saturation signal) to allow greater control and enhance image.