The design of teletext broadcast cycles

Teletext is a one-way picture information system where pages of information are broadcast to all users in a continuous manner. System response time is an important consideration in designing teletext systems. Factors contributing to system response time include transmission speeds, amount of processing required at user terminals, and efficiency of picture encoding procedures. As important is the design of the teletext broadcast cycle, i.e., the order of pages to be broadcast in a cyclic manner. In this paper, we first derive a formula for the mean response time of a given cycle and a lower bound for the mean response time for any cycle. Next we present a design procedure that yields a cycle with mean response time close to the theoretical lower bound. The use of the results of this paper is demonstrated through a numerical example.