| 摘要 |
<p>It is possible to generate an S meter signal indicating an accurate reception sensitivity. An IF signal SIF is filtered by a lower narrow band filter (2) having a predetermined low frequency range as a passing band F2 around a carrier frequency (center frequency) fo of the IF signal SIF and a higher narrow band filter (3) having a predetermined high frequency range as a passing band F3. Each of the filtered signal components (SL, SU) are envelope-detected by envelope detection units (4, 5) to generate the respective envelope signals (EL, EU). Peak hold units (6, 7) peak-hold the respective envelope signals (EL, EU) so as to generate smoothed signals (Sma, Smb). A selector unit (8) selects the signal (Sma) or (Smb) which is smaller for output and generates the reception sensitivity signal SMT.</p> |
