| 摘要 |
PURPOSE:To prevent presetting by a spurious wave, by making it possible to preset only the broadcast radio wave of a local station by bringing presetting operation to effect only when a broadcast radio wave whose electric field intensity surpasses a fixed value is received. CONSTITUTION:The electric field intensity of a received broadcast radio wave is inferred from variation in AGC voltage, developed by video IF circuit 3 and applied to electronic tuner 2, by detecting the AGC voltage. When the electric field intensity exceeds normal value 60dBmu, presetting operation is carried out and when not, the presetting operation is inhibited, so that only broadcast radio waves of intermediate and high electric fields can be preset. |
