| 摘要 |
PROBLEM TO BE SOLVED: To provide a unidirectional wireless transmitting method for data by which a large amount of data can be sent by switching a transmitting method to a transmitting method in which a modulation system is changed and making a transmission rate fast when and in the area where the line state of an HF line is relatively excellent. SOLUTION: When a ship during voyage transmits a message to a control station, the ship sends a modulation system selection signal consisting of a combination of a plurality of predetermined high-speed modulation systems and modulation speeds that the ship desires for an inspection of a line state by the control station to the control station, which inspects the line state from the reception state of the received modulation system selection signal, further selects a proper modulation system suited to the inspection results of the line state from among the received modulation system selection signals, and furthermore sends a line inspection answer signal including the selected proper modulation system as data to the ship. Then the ship recognizes the received line inspection answer signal, and consequently the ship transmits message data having been modulated at high speed by the selected proper modulation system to the control station. COPYRIGHT: (C)2006,JPO&NCIPI
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