SATELLITE TELEMETRY OF TIDAL DATA IN THE HYDROGRAPHIC SERVICE OF THE ROYAL-AUSTRALIAN-NAVY

zThe Hydrographic Service of the Royal Australian Navy (RAN) is respon sible for charting of the area extending from the middle of Indian Oce an to the equatorial waters of Papua New Guinea to the Antarctic, with tidal regimes varying from fully diurnal to fully semi-diurnal and fr om less than Im to over 12m. Accurate tidal information is vital in su rveying and charting, and to provide it, three years ago, Hydrographic Service RAN with assistance from InterOcean developed the then larges t network of unattended INMARSAT-C telemetry units in the world by usi ng an array of digital tide gauges linked to the INMARSAT-C satellite telemetry by a remote data acquisition system. This application of mod ern technology was a major step from the previous practice of manned t ide camps.During the last three years, the equipment has been further improved and modified to rectify minor problems encountered during tha t period. In general, the introduction of modern technology to tidal d ata acquisition and telemetry has been a success for the RAN hydrograp hers. Tide gauges, telemetry equipment and ancillary gear have proved their value, giving reliable service with low maintenance and operatio nal costs.