| 摘要 |
PROBLEM TO BE SOLVED: To enable the radio broadcast receiver, which has a one-system diversity function, to receive a broadcast wave by using an antenna in the best reception state even when reception environment is in a weak electric field area. SOLUTION: An electric filed intensity detector 28 detects the intensity of a circumferential electric field by checking the output level of an amplifier as to an intermediate frequency measured by an S meter 27. When the electric field intensity is weak, a noise switch 29 lowers the gain of a noise amplifier 29. Further, a time constant switch 30 shortens the time constant of an AGC signal generator 22. Consequently, the dynamic range of the AGC signal generator 22 is apparently expanded to quicken its response.
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