MAKING WAVES:
New Portable Telephones Can Be Used on Ships
APRIL 23, 1996
Reaching Remote Areas
The plan to develop a portable phone service using communications satellites has been developed by a mobile phone company that separated from its parent, Nippon Telegraph and Telephone Corp. The service will make use of two geostationary satellites that were launched at the beginning of February. These satellites will cover the vicinity of Japan from a position of 36,000 kilometers above the equator. This satellite coverage will make it possible to talk on portable phones throughout Japan and in a sea area up to 360 kilometers from the coast.
The phone terminal can be carried from the shoulder. It has been designed with a dual-mode switch, so that land-based cellular communication networks can also be used. The fee for the phone service has not yet been decided, but it is expected to be more expensive than the portable phones currently in use.
In terms of the number of residents in catchment areas, existing portable phone services already cover 95% of the population. So even with ordinary usage, almost everyone in Japan can use a portable phone. In terms of land area, however, the existing services cover no more than 40% of the national land area. Therefore, apart from large-scale communications satellite systems for use in disaster countermeasures or broadcast relays, existing portable phones cannot be used in mountainous areas and on ships more than 50 kilometers from the coast. For the time being, it is expected that the new portable phone communications satellite system will be used mainly by fishing vessels.
Linking the World
The international portable phone service, called the Iridium Project, is being developed by an international consortium of companies, centered on the United States. A Japanese company has already been set up as a joint venture to participate in this project. It commenced the construction of necessary land-based facilities in the middle of February.
The 77 small polar-orbiting satellites that will be used in this project will be launched over a year, beginning this summer. This satellite system will cover almost the entire world. Since the satellites will orbit at a relatively low altitude of 780 kilometers, the required terminals will probably only be slightly larger than existing portable phones.