| 摘要 |
PURPOSE:To perform optimum NB operation without paying any special attention to the operation of a receiver by selecting an optimum combination of AGC time constants and performing switching to it at a time according to an in-use mode or in-use band width. CONSTITUTION:A noise elimination gate 2 is provided to the intermediate frequency stage of the receiver, and an NB circuit leads a gate control output out of the output side of, for example, the mixer 1 of the leading-stage part. In this case, constants of the resistances 4 and capacitors 46 (46A-46C) of a time constant circuit for AGC over a preamplification stage 41 from detection and rectification parts 42 and 43 are switched with a switch 47 associatively with either or both of reception band width changeover switches 31 and 32 and a mode changeover switch. Therefore, the optimum NB operation is carried out by single-time selective switching without paying any special attention to the mode or reception band of the receiver. |
