給定調(diào)頻波的中心頻率fc=50MHz,最大頻偏Δfm=75kHz,求: A.當(dāng)調(diào)制信號(hào)頻率F=300Hz時(shí),調(diào)頻指數(shù)mf及調(diào)頻波有效帶寬BW B.當(dāng)調(diào)制信號(hào)頻率F=15kHz時(shí),調(diào)頻指數(shù)mf及調(diào)頻波有效帶寬BW