CARRIER ACTIVATION FOR DATA COMMUNICATION

摘要

PROBLEM TO BE SOLVED: To prevent a carrier from being activated by means of the calling of duplex data by receiving input data in a format which can contain an idle signal showing that user data do not exist, comparing input data with a bit pattern matched with the idle signal with more than one related bit array and stopping transmission when matching is detected. SOLUTION: A modem interface unit MIU connected to a fixed ground station LES 10 and a moving ground station MES 6 detects whether information to be transmitted is absent or only redundant information exists. When it is detected, a signal is transmitted to the LES 10 or the MES 6. Then, a transmitter is stopped until the MIU detects that the preparation of information to be transmitted is ready. When the LES 10 receives the carrier which is not activated, the LES 10 informs the fixed ground station modem interface unit LESMIU 12 of it. The LESMIU 12 maintains connection with a public switch telephone network modem 16.