| 摘要 |
PURPOSE:To make it possible to demodulate a desired wave even if a disturbing wave is stronger than the desired wave, by extracting the desired wave form beat signals of the disturbing wave and the desired wave. CONSTITUTION:When desired wave D/disturbing wave U is smaller than 1, FM modulation components of the desired wave appear as amplitude modulation in beat signals. Then, local signals obtained in local signal generator 16 are inputted to adder 15 to generate beat signals positively. Signals obtained in this manner are inputted to band-pass filter 20 through amplitude limiter 17 and frequency discriminator 18. The pass band of the band-pass filter is selected within the range of difference of frequencies of IF band input signals and local signals, and only required beat signal components can pass through this band-pass filter. This filter output is inputted to envelope detector 21, so that FM modulation components of the desired wave can be taken out. |
