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Bell provides switch to distance learning: engineering undergrads hear lectures, take tests from afar.


Lehigh University, Bethlehem, Pa., has an Intecom IBX S/80 PBX for general voice and data communications and a video network divided into two subnetworks using different transmission techniques.

Bell of Pennsylvania developed a Lehigh Valley Video Network with several large resident corporations in mind as potential users.

Anticipating the success of this project, Bell put a Horizon HX16VA video/audio switch in the Allentown central office.

Many Lehigh engineering undergrads work near York.

Why not let coursework be acquired through video distance learning?

York College was targeted as the logical setting.

Dovetail Systems, an incubator company under the Ben Franklin Technology Center--and associated with Lehigh--assessed the feasibility of a video link to York College.

2 Networks In 1

The Lehigh University Video Network has two distinct networks.

One uses fiber to transmit analog and digital signals; the other transmits analog video signals using microwave.

The two subnetworks share the Packard Laboratory video facility, which acts as midpoint.

CLasses at Packard Lab can simultaneously be broadcast to both subnetworks.

Each subnetwork can broadcast simultaneously and independently.

Due to topography, Packard Lab is connected to the Mountaintop Campus via fiber spares placed during installation of the Intecom IBX.

Once the signal reaches Mountaintop it can be sent out over microwave using equipment to change the video analog signal into light pulse.

Lecture Area

We use an existing classroom with some minor renovations such as lighting upgrade, draperies, and floor covering to reduce noise.

The lecture area has four monitors.

Two in the front allow students to view other classmates and a graphics display.

Two in the rear allow the professor to view the signal transmitted, as well as provide a sequenced scan view of the other classrooms attending the lecture.

This cycle, which can be set by the professor, ranges from every 10 seconds to every two minutes.

A front console lets the professor choose to transmit a graphics image.

The front console, looped from the controls in the production room, can also let the professor lock onto the return link during scanning if a student in another location has a question.

Taking this one step further, the professor can lock onto a return link and turn it into the broadcast link, transmitting a student's question or graphics contribution to all other groups on line.

Programmed scan cycles are resumed after any of these events.

When network difficulties occur, tape recordings keep lesson plans on schedule.

The Bell Labs fiber network is configured around the Allentown CO.

All nodes are connected with single-mode fiber.

Two locations use analog pulse frequency modulation over dedicated fibers with a Grass Valley Group transceiver operating at 6-8 MHz.

The other three sites, farther from Allentown, send digitally via interoffice DS3 channels and a Stromberg-Carlson codec compressing the signal to 45 Mb/s. This is the same technology, comparable in quality, as that used in the New York to Washington link for the ABC program Nightline.

Must Convert

Although it is desirable to keep the signal in analog form, economics dictate the use of existing digital channels.

Distances between each leg and the video switch range from three to 35 miles.

A peripheral teleconferencing system provides a mixer, microphones at student desks, and two speakers for every class.

This system is voice-gated to assuree that microphones are not active until they are accessed by a student.

This method has been useful in keeping room noise levels to a minimum, we have found.

The instructor, however, uses a cordless microphone.

The 3B2/400 User Interface acts as a front-end processor for the video switch.

The associated software allows such features as scheduling, defining restrictions, conference setup, conference takedown, and ability to gather billing information.

This computer control is then tied into a CO LAN via Datakits using 56-kb trunks, allowing all sites the ability to access control functions.

Lehigh University, however, is not a member of this LAN and uses a 9.6-kb/s modem to communicate control functions.

The Bell Laboratories classroom sites are equipped with two monitors, one to display incoming motion and another for incoming graphics.

Request To Speak

Every two students' table has a microphone, which is activated by a "request to speak" button.

Once the microphone is activated, the student has sole control of the audio channel, eliminating room noise and contention problems.

The microphone will send out a signal to a micro-processor, which will direct the camera to focus on that specific preset station.

Every Bell Lab site has a control room in the rear of the classroom to house the control rack as well as video, audio, and graphics equipment.

The rack is connected to the network-control equipment, which links to the CO.

The Packard Laboratory to Ben Franklin microwave link will enable a second Lehigh classroom to exist at the Franklin/Dovetail facility.

Mountaintop gives the Franklin/Dovetail dish a natural line of sight.

A signal originating in Packard Lab bound for York College travels over fiber to the Mountaintop Campus, where it is directed to one of the microwave dishes on Building A to go out over the network.

Since its inception two years ago, the network has experienced one outage of about 30 seconds per year due to rain.

The Packard Lab to York College network is a two-way interactive video network, unlike the Bell Laboratories switched network. Both parties can see and speak to one another simultaneously.

The York classroom is equipped with two monitors to view the incoming signal and two cameras set a different angles to transmit classroom motion.

Graphics may also be sent by students via a graphics camera at the York site.

Unlike Bell Labs, when a graphics picture is transmitted to either York or Packard, no incoming motion will be received at the distant end.

Homework assignments are distributed using electronic mail and facsimile.

Utilizing the video network, the students can register for graduate coursework at their workplace, eliminating not only wasted time but long lines and parking difficulties.

Eager Users

The distance-learning program is readily accepted by participating professors and students.

Most agree the ease of transition depended on the individual professor's previous style of instruction.

Instructors have to be aware of others attending via remote sites.

Remarks and questions must be directed to all.

It has been suggested that being a good TV performer is also an aid and that instruction at a much slower pace with added preparation is needed for this type of medium to work.

After the first year, Bell Lab employees were able to save more than 5000 hours of travel time.

The network was invaluable during snowy winter months.
COPYRIGHT 1990 Nelson Publishing
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Copyright 1990 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Bell of Pennsylvania
Author:Brichta, William
Publication:Communications News
Date:Feb 1, 1990
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