RDS RADIO SYSTEM

摘要

PCT No. PCT/GB89/01544 Sec. 371 Date Aug. 8, 1991 Sec. 102(e) Date Aug. 8, 1991 PCT Filed Dec. 15, 1989 PCT Pub. No. WO90/07237 PCT Pub. Date Jun. 28, 1990.A radio data system transmits message groups comprising four blocks of which the first block always carries the program identification code for the transmitting network (P1(TN)). One type of message group, identified by a corresponding group type code (GT) in a second block always carries a program identification code for another network (PI(ON) in a fourth block and carries various corresponding items of information in a third block. Which of these various items is in the third block is identified by a user code (UC) in the second block. The items of information in the third block may in particular include alternative frequency codes for the other network identified in the fourth block.