Transmission of Navigational Aids Information to Vesseles by Teletext

Abstract

Teletext is a data transmission medium which uses the space of TV video signal. It transmits characters, figures and sounds with a high rate of 42 kbps. A common TV set can be used with a small apparatus as a receiver and a display. It has the vast service area including coastal area just as that of the TV broadcasting. Thus, it is very effective in transferring the navigational aids information such as NAVTEX, NAVAREA, EGC and etc. to vessels steaming on the Japanese waters. The authors measured a reception rate of the teletext on the ordinary navigational route around the Japanese archipelago. The packet reception rate is more than 90% during the TV transmission hour, presently 6:00〜23:59. The value is good enough to transmit the data, as the teletext is usally sent repeatedly every few minutes.