| 摘要 |
PURPOSE:To receive an emergency broadcasting always in optimum receiving status by connecting a means to detect the existence or absence of the emergency broadcasting automatically. CONSTITUTION:When an automatic search starting switch 13 is turned on to send an command to a microcomputer 10 at the time of poor receiving status, the microcomputer 10 starts to search automatically. Namely, the microcomputer 10 compares the carrier wave level detected by a field intensity detecting circuit 14 and an A/D converter 15 with the optimum receiving field intensity and, when the carrier level is more than a prescribed carrier level, a demodulated signal DC level detecting circuit 16 detects the DC level of a demodulated output and a level comparator 17 compares the DC level with a previously set noise level. The received wave carrier level is written in a memory as the new optimum receiving field intensity and the receiving frequency under the newly set up electric field is written in the memory as the optimum receiving frequency. |
