A tutorial communication system- blackboard-by-wire plus picturephone set

The combination of blackboard-by-wire plus Picturephone is analyzed as a tutorial communication system to teach engineers at their job locations. This developing system, based on use of the common-carrier telephone system, has advantages over closedcircuit (talkback) television systems. The remote blackboard can be three panels for nearly "full-wall" presentation, and two-way video may be added fairly economically. Using the common-carrier system maximizes flexibility (access to any termination in the entire switched system) and should be more cost-effective. By time-sharing the tutorial communication function with other uses, one avoids development of a separate dedicated microwave system (and associated maintenance). The current implementation of blackboard-by-wire is described and is shown to be sufficiently effective to serve as a communication system until Picturephone can be economically added. The author's experience with blackboard-by-wire is described, along with a survey of past uses. Costs are analyzed, showing that the present system requires about $5000 for equipment purchase (for one "sender" and one "receiver") and $20 to $40 per hour for transmission costs. The flexibility and low cost of the current implementation make it an easy "entry point," and it is compatible with later expansion to include Picturephone set.