Prepared By:

Dr. William M. Getter

Assistant Professor of Aeronautical Science

Embry-Riddle University

 This paper is presented in two parts. The first outlines the various type of video teleconferencing available for use in the classroom. The second provides an overview of one of the teleconferencing experiments being conducted by Embry-Riddle Aeronautical University using low cost telephone based equipment.

 Classroom video teleconferencing is not a new concept. In the last several years, many schools around the world have been using video teleconferencing equipment to link two (or more) sites together for instruction. However, in nearly all cases, these solutions have relied on very expensive equipment and high cost data links. In order to better understand the options available for classroom use of teleconfernceing, it worthwhile to review the range of technical options available. Below, five levels or types of video technologies are discussed. The techniques reviewed are satellite broadcast systems, high end digital phone line systems, low end digital phone line systems, analog phone line systems, and internet/LAN systems.

----- SATELLITE BROADCAST SYSTEMS.

Satellite systems are characterized by capturing a lecture at an originating site (normally a studio) and broadcasting the voice and image by satellite to a large number of remote sites. Each remote site "downlinks" the signal with a satellite dish much like with home satellite television. Feedback to the uplink studio is often provided by a telephone voice-only link from each remote site to the studio. The remote sites can both see and hear the instructor, but the instructor cannot see the students. We can describe this technique as "one way video, two way audio."

Satellite systems provide one of the best quality video images of all of the technologies. However, they are also the most expensive alternative--costing from hundreds to even thousand of dollars an hour to operate. Cost of equipment can also run very high (tens of thousands of dollars for remotes sites and hundreds of thousands for uplink sites).

An example of this type of system is the Air Force TV network used to teach civil service contracting classes from Wright-Patterson Air Force Base in Ohio to Air Force bases around the world.

----- HIGH-END DIGITAL PHONE LINE SYSTEMS.

High-end digital phone line video teleconference systems use digital phone lines to connect two or more sites together. They range from systems that use as few as three ISDN phone lines to as much as a full T1 line. These are true two-way video systems sharing both video and audio in both directions. They can be used either point-to-point or point-to-multipoint. A point-to-point setup connects only two sites together with the digital phone line(s). A point-to-multipoint setup uses an additional piece of equipment called a BRIDGE to multiplex the video and audio from more than two sites and retransmits the signal to all the other participating sites. A bridge service can be leased from most of the major long distance phone companies (AT&T, MCI, Sprint, and others) or a bridge can be purchased from use in an in-house system.

Procurement costs for a high-end digital system for each side can vary widely depending on the sophistication of the system. They can range from just under $10,000 to over $100,000.

Hourly operation can also be expensive. A single data line runs about 35 cents per line per minute ($21/hour) for a direct point-to-point connection. Consequently, a basic system using three ISDN lines would run about $63/hour to operate between two points (or about $2,520 for a 40 hours class). A multipoint connection using a leased bridge will run from 75 cents to $1.00 per line per minute for each site. At 75 cents/site/minute, the same basic system connecting three classrooms would run about $405/hour (or $16,200 per 40 hour class). Toward the top end, a T1 line system can run thousands of dollars an hour if bridged to multiple sites.

Examples of high-end digital systems are many. They include conference room systems made by PictureTel, V-Tel and others, the military's T-Net system, NASA's video conference system, and most of the "boardroom" video conference systems used in the corporate world.

Embry-Riddle Aeronautical University (ERAU) has begun offering selected course in a bi-located format using a high end PictureTel system. The system connects a classroom at ERAU’s Daytona Beach, Florida campus with their Prescott, Arizona campus. Some classes originate in Arizona while others originate in Florida. The system provides high quality video and good audio between the two sites. Document cameras are used to share visual aids between the two locations.

----- LOW-END DIGITAL PHONE LINE SYSTEMS.

Low end digital phone line (or desktop) systems use a single ISDN phone line to connect two or more desktop computers together to share audio, video, and data. Like the high-end systems, these can be connected point-to-point or point-to-multipoint with a bridge. Because of the limited bandwidth (data transfer capacity) of only one ISDN line, the video on the desktop systems suffers. To compensate, most of these systems use a small video window rather than displaying the video image on the full screen. The video frame rate is also considerably below the 30 frames/second we see on television and on the higher end video conference systems. However, because these systems where originally designed for project collaboration by coworkers rather than stand-up presentation, they often have excellent whiteboards that can be used for "chalk talk" or display computer graphics (like PowerPoint slides for visual aids). The also often allow computer applications to be shared by all participates simultaneously which is good for classroom demonstration of software.

Costs for procurement range from $5,000 to $15,000 per site. Cost of operation (like the high-end systems) run about 35 cents a minute/line. However, since they only use a single ISDN line, a 40 hour class would cost about $800/class for a point-to-point connection. Similarly, at about 75 cents/minute/site for a multipoint bridge, a three location multi-point class would run about $5,400/class.

Examples of these desktop digital line systems are made by PictureTel, Intel (ProShare), and their competitors. Most brands can connect to the others using industry standards.

----- ANALOG PHONE LINE SYSTEMS.

A relatively new entry into this field are desktop systems that use conventional telephone lines (also called the Plain Old Telephone Systems or POTS). These work very much like the low-end digital line systems but are even more constrained in the bandwidth available for carrying the video image. Consequently, the clarity and speed of the image is even more compromised. Frame rates rarely exceed 7 to 10 frames/second compared to 30 frames/second on TV. Some systems (like PicturePhone by Connectix) carry only video and sound. Others (like ProShare by Intel) carry only whiteboards/applications and sound. Still others (like ShareVison by Creative Labs) try to carry video, whiteboards, applications and sound. Our experience in experimenting with these systems as been that a single analog phone lines does not have enough bandwidth to successfully carry sound along with video and/or data. To get an acceptable frame rate on the video, the audio is best moved to a separate phone line. All the current analog systems are strictly point-to-point (although Intel is promising a bridgeable system by year's end). However, a plus for the POTS systems is the availability of analog phone lines is almost universal which cannot be said for digital/ISDN lines

Cost of purchase of an analog phone line system is between $5,000 and $10,000 per site depending on how elaborate the sound system is. Operating costs run about 15-20 cents per minute per phone line, so a two line system costs between $18 and $24 per hour ($750 to $960 per 40 hour class).

Examples (as mentioned) include PicturePhone by Connectix, ProShare by Intel, and ShareVision by Creative Labs .

Embry-Riddle Aeronautical University has been experimenting with a highly modified version of the ShareVision system for use in connecting two classrooms together in remote locations together for class. These remote locations do not have access to ISDN digital phone lines or high speed Internet connections. Consequently, the only option available is to use conventional phone lines. In the modified system, two regular phone lines are used. One is used to provide a good quality audio conference link between the two classrooms. This uses a half dozen microphones placed around the classroom, a microphone mixer, a phone coupler to connect to the phone line, and an amplified speaker. The second phone line is used to connect a PC computer in each classroom with the one in the other classroom. The computers carry a rough video image between the two classrooms. It also carries a high quality whiteboard for sharing visual aid (like PowerPoint slide) and "chalk talk" just like a blackboard. Computer applications can also be shared between the two classrooms. To display the computer images, the computer monitor output is feed through a scan converter and displayed on a 31’ television. The net effect is good quality sound, excellent visual aid support (for computer generated graphics, chalk talk, and shared computer applications) and fair video images of each classroom. The total capitol investment is about $6,500 per classroom and hourly operations at about $24 an hour (or about $960 for a 40 hour course).

----- INTERNET & LAN SYSTEMS.

There are several products available that allow voice, data, and audio to be shared over the Internet or a local area network (LAN). These systems operate very much like the low-end digital line systems or the analog line systems. However, instead of using phone lines to connect the desktop computers, they use the TCP/IP protocol to send the digitized voice, video and data over local area network or out to the Internet.

Within a local area network (say between desks within a building), their performance is comparable to the low-end digital phone systems. On the Internet (if all users have high speed Internet service like a T1 line), their performance is comparable to the analog phone line systems. They are little more than a novelty over a dial-up connection to the Internet (with frame rates often less then 1 frame a second).

Marginal cost of operation is near zero after the connection to a LAN or the Internet is paid for. However, the nearly total lack of high speed Internet connection in the field makes using them nearly impossible in EC.

The best known example of a TCP/IP system is CU:SeeMe developed by Cornell University, but others are beginning to emerge.

This section of this paper will provide an overview of an experiment being conducted within the Extended Campus of Embry-Riddle Aeronautical University to provide low cost video teleconference capability between selected teaching sites away from the university’s two resident campuses.

The challenge for fielding a video teleconference system for Embry-Riddle’s Extended Campus is finding a balance between cost and capability. Although high-end satellite and digital phone line systems could provide all of the capability needed, they are prohibitively expensive. Their use would price classes out of the reach of most students. Low-end digital phone systems (if modified for classroom use) provide promise for cost effective application, but digital phone lines are not universally available. In fact they are available at only a fraction of Embry-Riddle’s teaching sites in the field and they are least available at the more remotely located sites where video teleconference capabilities would do the most good. Internet & LAN systems provide an interesting combination of inexpensive hardware and software but require very high speed connections to the Internet (a dial-up modem connection is not nearly fast enough). Like digital phone lines, high speed Internet connections are simply not available to Extended Campus teaching sites. The last remaining option is to use systems that rely on conventional analog telephone lines to link two sites together. This is the option we are experimenting with in this project.

The challenge for making a system based on analog phone lines work well in the classroom is overcoming the inherent bandwidth limitations of conventional phone lines. Several companies are marketing "video phone" systems that use desktop computers and video cameras to let two people talk and see each other over conventional phone lines. The problem to be overcome for classroom use is the relatively poor audio and very poor video one achieves with these systems. For example, the video is a small window on the screen that is not nearly clear enough to be used to show visual aids or the blackboard.

One why to overcome the inability to show visual aids in the video window is to use electronic whiteboards and/or presentation software. An electronic whiteboard is a blank writing area on a computer screen that displays simultaneously on two computers linked over a phone line. They look very much like the Paint Brush program that comes with Windows. Using a drawing tablet, an instructor can write on the electronic whiteboard in much the same way as writing on a chalkboard. The other option is to use presentation software (such as Microsoft PowerPoint, Lotus Freelance Graphics or the like) then share the presentation slides between the two sites using application sharing software linked over the phone line. This is often called data teleconferencing. Again, several vendors market electronic whiteboards and application sharing programs that will work over analog phone lines using modems. Most of these data teleconferencing systems operate separately from the video phone software and the two cannot be used at the same time.

In our market search, we have found only one hardware/software product that tries to combine voice, video, whiteboards, and data application in one package where all the parts can be used simultaneously. The product is called ShareVision and is made by Creative Labs (the same company that makes SoundBlaster and VideoBlaster boards for PCs). ShareVision uses proprietary modems to connect two computers over conventional analog phone lines. Once connected the two sites can share video images in small video windows while talking over microphones and a speakers connected to the computers. The system also allows both sites to share a whiteboard, share slides made with presentation software and simultaneously display any computer program running on either computer. However, out-of-the-box, ShareVision could not be effectively used in classroom instruction.

The problems with using ShareVision (as is) for the classroom are two fold: size of the computer screen, and the poor quality of the audio. A computer screen is much too small to be viewed by more than just a couple of students. To solve this problem, we connected the computer to a large (31") television in each classroom using a scan converter that converts the computer monitor signal into a signal that can be displayed by a television. This not only made the whiteboard and presentation graphics readable throughout the classroom, it also increased the size of the small video window to a nearly life size head and shoulder image of the instructor.

The second challange of audio quality was more problematic. The audio in ShareVision shares the phone line with the video image, whiteboard, and shared applications. The audio is given priority on the line to avoid clipped speech. Consequently, when either side is talking a lot, the video slows to a crawl or stops. Additionally, the audio suffers from a very noticeable delay between the sites resulting in a very distinct echo heard by a speaker as his/her voice is amplified at the only site so it can be heard in the whole classroom and then picked-up again on the microphone on the other end.

To overcome the audio problem, we turned off the audio portion of the ShareVision system altogether and built a separate audio teleconference system that uses a second analog phone line working along side the ShareVision system. This removed the audio workload on ShareVision resulting in improved video and data sharing performance. It also allowed us to design an audio system that gave good voice quality at a low cost.

Keeping the audio system low cost was another challenge. Conference room style audio systems can be very expensive running easily into the tens of thousands of dollars. Conversely, speakerphones used on desktops do not have the pick-up or speaker volume to cover an entire classroom.

Once again, we experimented with off-the-shelf combinations of hardware to try to come up with a low cost audio alternative that would meet the need. Through several trial-and-error attempts, we arrived at the system we are currently field testing. It is made up of six desktop microphones connected together with a Radio Shack microphone mixer. The mixer in turn sends the audio to a piece of telephone equipment called an autocoupler made by Gentner Communications. (It was originally designed to be used for radio call-in talk lines.) The output of the autocoupler is connected to an amplified speaker so the other site can be heard in the classroom.

The resulting system of a computer running ShareVision displayed on a large television along side a multiple microphone audio system connected to a separate phone line with the autocoupler results in a system that costs under $9,000 to install at each site and about 35 cents a minute ($21/hour) to operate. This allows a 40 hour class to be conducted for less than $900 in phone changes from any site that has two conventional phone lines.

This paper has explained the various video teleconference options available on the market and shown how none of the existing products meet the need for low cost video teleconferencing for classroom instruction. It also explained, how through experimentation and innovative use of off-the-shelf hardware/software, Embry-Riddle Aeronautical University is developing video teleconferencing systems that can be used in the class at an affordable cost. The project is ongoing with new ideas being incorporated as they become available on the market. Continued testing is needed and is ongoing within Embry-Riddle’s Extended Campus.