| 摘要 |
A method for automatic replacement of wireless link 15 between target FM receiver 50 and FM transmitter-receiver apparatus 20, transmitting to the receiver 50 over a current frequency, comprises: scanning an FM spectrum for available frequencies; selecting an available frequency as an alternative to the current frequency; sending a signal incorporating the alternative frequency to the target FM receiver, including a command to cause the target FM receiver to change to the alternative frequency; measuring the current frequency signal quality, and determining its suitability for transmission; and using the alternative frequency for transmission to the target receiver when the current frequency is unsuitable. Also claimed is a similar system in which the FM transmitter transmits, over a current frequency, an FM signal plus radio data system (RDS / RBDS) messages, and wherein respective transmitter and receiver antennas operate in the 87.5 to 108 MHz spectrum. RDS / RBDS messages may include programme identification (PI) and alternative frequency (AF) commands. Alternative frequencies may be excluded if their signal strengths are changing gradually, i.e. stable frequency signals are selected. As shown, the system is applicable to vehicle relayed entertainment systems.
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