| 摘要 |
Transmission of GPS correction data by means of RDS on the FM commercial network. Consisting of a commercial chain of radio stations installed in known geographical positions, each of them equipped with a differential GPS receiver capable of calculating the distance and velocity corrections of the visible satellites and of transmitting them to the users by means of the Radio Data System (RDS) of the commercial Frequency Modulated (FM) transmitters, in RTCM format with or without encryption. The users have an FM RDS commercial receiver or a dedicated receiver, in which once the baseband 11 is obtained, the RDS is demodulated 15 and decoded 17 to obtain the DGPS correction messages 18, which are decrypted and formatted 20 to be used by any commercial DGPS receiver 23. The encryption and decryption is based on logical operations and receiving corrections can be barred to a user or user group from the transmitter. <IMAGE>
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