Broadcast Teletext Channel Characterization Using Inverse Filtering

A method A to characterize the broadcast teletext channel is reported. The technique is commonly referred to as inverse filtering. A linear time-invariant system estimate is obtained for the channel. Computer simulations show that this estimate adequately characterize the channel behavior. A second estimate aimed at modelling the channel as a discrete multipath channel is then consturcted from the first estimate. It is found that the second estimate is inadequate to characterize the channel. Two measures of performance are used, namely the eye opening correlation coefficient and the normalized r. m. s. error. Significant difference in performance is observed in the transition from one estimate to the other. The conclusions are based on the analysis of data obtained from a recent field experiment.