| 摘要 |
<p>In the radio data system are transmitted, inside a radio signal, digital data (AF-code and/or PI-code), on the basis of which it is possible to know directly or deduce on which alternative broadcasting frequencies it is also possible to receive the programme signal of the current reception frequency. The alternative broadcasting frequencies to the current receiving frequency are determined by evaluation of the AF-code and/or PI-code. For this purpose a reception part of the receiver is tuned briefly and successively to the alternative frequencies, and the reception quality is noted for each alternative frequency as well as for the current receiving frequency. The optimum reception frequency chosen is the frequency which offers the best reception quality possible for the moment. The reception quality is evaluated by means of programme signal distortions alone or in addition to the field intensity received, by adopting as criterium for these distortions the bit errors noted in the RDS data signal. To improve reception quality, the alternative frequencies transmitted as necessary with an associated transmission service frequency in the form of frequency pairs are addressed and possibly stored depending on the transmission service frequency which immediately precedes or follows them. On the receiver side means are provided for selecting another alternative frequency in the event that the alternative frequency offering the best possible reception for the moment allows only an acoustically distorted reproduction.</p> |
